finish up viewport widget with screen previews

2019-07-26 20:26:37 -04:00 · 2019-07-26 20:26:37 -04:00 · 43a2d18075
commit 43a2d18075
parent dcf130616f
11 changed files with 1927 additions and 157 deletions
--- a/protocol/meson.build
+++ b/protocol/meson.build
@ -1,5 +1,8 @@
 wayland_scanner = find_program('wayland-scanner')
 wayland_client = dependency('wayland-client')
 wayland_protos = dependency('wayland-protocols', version: '>=1.17')
 wl_protocol_dir = wayland_protos.get_pkgconfig_variable('pkgdatadir')
 wayland_scanner_code = generator(
 	wayland_scanner,
@ -14,7 +17,9 @@ wayland_scanner_client = generator(
 )
 client_protocols = [
 	[wl_protocol_dir, 'unstable/xdg-output/xdg-output-unstable-v1.xml'],
 	['wlr-output-management-unstable-v1.xml'],
 	['wlr-screencopy-unstable-v1.xml']
 ]
 client_protos_src = []
--- a/protocol/wlr-screencopy-unstable-v1.xml
+++ b/protocol/wlr-screencopy-unstable-v1.xml
@ -0,0 +1,179 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <protocol name="wlr_screencopy_unstable_v1">
  <copyright>
    Copyright © 2018 Simon Ser
    Permission is hereby granted, free of charge, to any person obtaining a
    copy of this software and associated documentation files (the "Software"),
    to deal in the Software without restriction, including without limitation
    the rights to use, copy, modify, merge, publish, distribute, sublicense,
    and/or sell copies of the Software, and to permit persons to whom the
    Software is furnished to do so, subject to the following conditions:
    The above copyright notice and this permission notice (including the next
    paragraph) shall be included in all copies or substantial portions of the
    Software.
    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
    DEALINGS IN THE SOFTWARE.
  </copyright>
  <description summary="screen content capturing on client buffers">
    This protocol allows clients to ask the compositor to copy part of the
    screen content to a client buffer.
    Warning! The protocol described in this file is experimental and
    backward incompatible changes may be made. Backward compatible changes
    may be added together with the corresponding interface version bump.
    Backward incompatible changes are done by bumping the version number in
    the protocol and interface names and resetting the interface version.
    Once the protocol is to be declared stable, the 'z' prefix and the
    version number in the protocol and interface names are removed and the
    interface version number is reset.
  </description>
  <interface name="zwlr_screencopy_manager_v1" version="1">
    <description summary="manager to inform clients and begin capturing">
      This object is a manager which offers requests to start capturing from a
      source.
    </description>
    <request name="capture_output">
      <description summary="capture an output">
        Capture the next frame of an entire output.
      </description>
      <arg name="frame" type="new_id" interface="zwlr_screencopy_frame_v1"/>
      <arg name="overlay_cursor" type="int"
        summary="composite cursor onto the frame"/>
      <arg name="output" type="object" interface="wl_output"/>
    </request>
    <request name="capture_output_region">
      <description summary="capture an output's region">
        Capture the next frame of an output's region.
        The region is given in output logical coordinates, see
        xdg_output.logical_size. The region will be clipped to the output's
        extents.
      </description>
      <arg name="frame" type="new_id" interface="zwlr_screencopy_frame_v1"/>
      <arg name="overlay_cursor" type="int"
        summary="composite cursor onto the frame"/>
      <arg name="output" type="object" interface="wl_output"/>
      <arg name="x" type="int"/>
      <arg name="y" type="int"/>
      <arg name="width" type="int"/>
      <arg name="height" type="int"/>
    </request>
    <request name="destroy" type="destructor">
      <description summary="destroy the manager">
        All objects created by the manager will still remain valid, until their
        appropriate destroy request has been called.
      </description>
    </request>
  </interface>
  <interface name="zwlr_screencopy_frame_v1" version="1">
    <description summary="a frame ready for copy">
      This object represents a single frame.
      When created, a "buffer" event will be sent. The client will then be able
      to send a "copy" request. If the capture is successful, the compositor
      will send a "flags" followed by a "ready" event.
      If the capture failed, the "failed" event is sent. This can happen anytime
      before the "ready" event.
      Once either a "ready" or a "failed" event is received, the client should
      destroy the frame.
    </description>
    <event name="buffer">
      <description summary="buffer information">
        Provides information about the frame's buffer. This event is sent once
        as soon as the frame is created.
        The client should then create a buffer with the provided attributes, and
        send a "copy" request.
      </description>
      <arg name="format" type="uint" summary="buffer format"/>
      <arg name="width" type="uint" summary="buffer width"/>
      <arg name="height" type="uint" summary="buffer height"/>
      <arg name="stride" type="uint" summary="buffer stride"/>
    </event>
    <request name="copy">
      <description summary="copy the frame">
        Copy the frame to the supplied buffer. The buffer must have a the
        correct size, see zwlr_screencopy_frame_v1.buffer. The buffer needs to
        have a supported format.
        If the frame is successfully copied, a "flags" and a "ready" events are
        sent. Otherwise, a "failed" event is sent.
      </description>
      <arg name="buffer" type="object" interface="wl_buffer"/>
    </request>
    <enum name="error">
      <entry name="already_used" value="0"
        summary="the object has already been used to copy a wl_buffer"/>
      <entry name="invalid_buffer" value="1"
        summary="buffer attributes are invalid"/>
    </enum>
    <enum name="flags" bitfield="true">
      <entry name="y_invert" value="1" summary="contents are y-inverted"/>
    </enum>
    <event name="flags">
      <description summary="frame flags">
        Provides flags about the frame. This event is sent once before the
        "ready" event.
      </description>
      <arg name="flags" type="uint" enum="flags" summary="frame flags"/>
    </event>
    <event name="ready">
      <description summary="indicates frame is available for reading">
        Called as soon as the frame is copied, indicating it is available
        for reading. This event includes the time at which presentation happened
        at.
        The timestamp is expressed as tv_sec_hi, tv_sec_lo, tv_nsec triples,
        each component being an unsigned 32-bit value. Whole seconds are in
        tv_sec which is a 64-bit value combined from tv_sec_hi and tv_sec_lo,
        and the additional fractional part in tv_nsec as nanoseconds. Hence,
        for valid timestamps tv_nsec must be in [0, 999999999]. The seconds part
        may have an arbitrary offset at start.
        After receiving this event, the client should destroy the object.
      </description>
      <arg name="tv_sec_hi" type="uint"
           summary="high 32 bits of the seconds part of the timestamp"/>
      <arg name="tv_sec_lo" type="uint"
           summary="low 32 bits of the seconds part of the timestamp"/>
      <arg name="tv_nsec" type="uint"
           summary="nanoseconds part of the timestamp"/>
    </event>
    <event name="failed">
      <description summary="frame copy failed">
        This event indicates that the attempted frame copy has failed.
        After receiving this event, the client should destroy the object.
      </description>
    </event>
    <request name="destroy" type="destructor">
      <description summary="delete this object, used or not">
        Destroys the frame. This request can be sent at any time by the client.
      </description>
    </request>
  </interface>
 </protocol>
--- a/resources/head.ui
+++ b/resources/head.ui
@ -25,13 +25,11 @@
    </child>
  </object>
  <object class="GtkAdjustment" id="pos_x_adjustment">
    <property name="lower">-16384</property>
    <property name="upper">16383</property>
    <property name="step_increment">1</property>
    <property name="page_increment">10</property>
  </object>
  <object class="GtkAdjustment" id="pos_y_adjustment">
    <property name="lower">-16384</property>
    <property name="upper">16383</property>
    <property name="step_increment">1</property>
    <property name="page_increment">10</property>
--- a/resources/wdisplay.ui
+++ b/resources/wdisplay.ui
@ -3,6 +3,14 @@
 <interface>
  <requires lib="gtk+" version="3.22"/>
  <!-- interface-css-provider-path style.css -->
  <object class="GtkAdjustment" id="canvas_horiz">
    <property name="step_increment">1</property>
    <property name="page_increment">10</property>
  </object>
  <object class="GtkAdjustment" id="canvas_vert">
    <property name="step_increment">1</property>
    <property name="page_increment">10</property>
  </object>
  <object class="GtkPopover" id="main_menu">
    <property name="can_focus">False</property>
    <child>
@ -28,6 +36,20 @@
            <property name="position">0</property>
          </packing>
        </child>
        <child>
          <object class="GtkModelButton">
            <property name="visible">True</property>
            <property name="can_focus">True</property>
            <property name="receives_default">True</property>
            <property name="action_name">app.capture-screens</property>
            <property name="text" translatable="yes">Show Screen Contents</property>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">1</property>
          </packing>
        </child>
      </object>
    </child>
  </object>
@ -112,13 +134,12 @@
                  <object class="GtkScrolledWindow" id="heads_scroll">
                    <property name="visible">True</property>
                    <property name="can_focus">True</property>
                    <property name="hadjustment">canvas_horiz</property>
                    <property name="vadjustment">canvas_vert</property>
                    <property name="min_content_width">300</property>
                    <property name="min_content_height">300</property>
                    <child>
-                      <object class="GtkLayout" id="heads_layout">
+                      <placeholder/>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="width">400</property>
                        <signal name="draw" handler="heads_draw" swapped="no"/>
                      </object>
                    </child>
                  </object>
                  <packing>
@ -221,7 +242,7 @@
                    <property name="can_focus">True</property>
                    <property name="receives_default">True</property>
                    <property name="tooltip_text" translatable="yes">Zoom Out</property>
-                    <signal name="clicked" handler="zoom_out" swapped="no"/>
+                    <signal name="clicked" handler="zoom_out" swapped="yes"/>
                    <child>
                      <object class="GtkImage">
                        <property name="visible">True</property>
@ -244,7 +265,7 @@
                    <property name="can_focus">True</property>
                    <property name="receives_default">True</property>
                    <property name="tooltip_text" translatable="yes">Zoom Reset</property>
-                    <signal name="clicked" handler="zoom_reset" swapped="no"/>
+                    <signal name="clicked" handler="zoom_reset" swapped="yes"/>
                    <accelerator key="0" signal="clicked" modifiers="GDK_CONTROL_MASK"/>
                  </object>
                  <packing>
@ -260,7 +281,7 @@
                    <property name="can_focus">True</property>
                    <property name="receives_default">True</property>
                    <property name="tooltip_text" translatable="yes">Zoom In</property>
-                    <signal name="clicked" handler="zoom_in" swapped="no"/>
+                    <signal name="clicked" handler="zoom_in" swapped="yes"/>
                    <child>
                      <object class="GtkImage">
                        <property name="visible">True</property>
--- a/src/glviewport.c
+++ b/src/glviewport.c
@ -0,0 +1,135 @@
 /*
 * Copyright (C) 2019 cyclopsian
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE X CONSORTIUM BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
 #include "glviewport.h"
 typedef struct _WdGLViewportPrivate {
  GtkAdjustment  *hadjustment;
  GtkAdjustment  *vadjustment;
  guint hscroll_policy : 1;
  guint vscroll_policy : 1;
 } WdGLViewportPrivate;
 enum {
  PROP_0,
  PROP_HADJUSTMENT,
  PROP_VADJUSTMENT,
  PROP_HSCROLL_POLICY,
  PROP_VSCROLL_POLICY
 };
 static void wd_gl_viewport_set_property(
    GObject *object, guint prop_id, const GValue *value, GParamSpec *pspec);
 static void wd_gl_viewport_get_property(
    GObject *object, guint prop_id, GValue *value, GParamSpec *pspec);
 G_DEFINE_TYPE_WITH_CODE(WdGLViewport, wd_gl_viewport, GTK_TYPE_GL_AREA,
    G_ADD_PRIVATE(WdGLViewport)
    G_IMPLEMENT_INTERFACE(GTK_TYPE_SCROLLABLE, NULL))
 static void wd_gl_viewport_class_init(WdGLViewportClass *class) {
  GObjectClass *gobject_class = G_OBJECT_CLASS(class);
  gobject_class->set_property = wd_gl_viewport_set_property;
  gobject_class->get_property = wd_gl_viewport_get_property;
  g_object_class_override_property(gobject_class, PROP_HADJUSTMENT, "hadjustment");
  g_object_class_override_property(gobject_class, PROP_VADJUSTMENT, "vadjustment");
  g_object_class_override_property(gobject_class, PROP_HSCROLL_POLICY, "hscroll-policy");
  g_object_class_override_property(gobject_class, PROP_VSCROLL_POLICY, "vscroll-policy");
 }
 static void viewport_set_adjustment(GtkAdjustment *adjustment,
    GtkAdjustment **store) {
  if (!adjustment) {
    adjustment = gtk_adjustment_new(0., 0., 0., 0., 0., 0.);
  }
  if (adjustment != *store) {
    if (*store != NULL) {
      g_object_unref(*store);
    }
    *store = adjustment;
    g_object_ref_sink(adjustment);
  }
 }
 static void wd_gl_viewport_set_property(
    GObject *object, guint prop_id, const GValue *value, GParamSpec *pspec) {
  WdGLViewport *viewport = WD_GL_VIEWPORT(object);
  WdGLViewportPrivate *priv = wd_gl_viewport_get_instance_private(viewport);
  switch (prop_id) {
  case PROP_HADJUSTMENT:
    viewport_set_adjustment(g_value_get_object(value), &priv->hadjustment);
    break;
  case PROP_VADJUSTMENT:
    viewport_set_adjustment(g_value_get_object(value), &priv->vadjustment);
    break;
  case PROP_HSCROLL_POLICY:
    if (priv->hscroll_policy != g_value_get_enum(value)) {
      priv->hscroll_policy = g_value_get_enum(value);
      g_object_notify_by_pspec(object, pspec);
    }
    break;
  case PROP_VSCROLL_POLICY:
    if (priv->vscroll_policy != g_value_get_enum(value)) {
      priv->vscroll_policy = g_value_get_enum(value);
      g_object_notify_by_pspec (object, pspec);
    }
    break;
  default:
    G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
    break;
  }
 }
 static void wd_gl_viewport_get_property(
    GObject *object, guint prop_id, GValue *value, GParamSpec *pspec) {
  WdGLViewport *viewport = WD_GL_VIEWPORT(object);
  WdGLViewportPrivate *priv = wd_gl_viewport_get_instance_private(viewport);
  switch (prop_id) {
  case PROP_HADJUSTMENT:
    g_value_set_object(value, priv->hadjustment);
    break;
  case PROP_VADJUSTMENT:
    g_value_set_object(value, priv->vadjustment);
    break;
  case PROP_HSCROLL_POLICY:
    g_value_set_enum(value, priv->hscroll_policy);
    break;
  case PROP_VSCROLL_POLICY:
    g_value_set_enum(value, priv->vscroll_policy);
    break;
  default:
    G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
    break;
  }
 }
 static void wd_gl_viewport_init(WdGLViewport *viewport) {
 }
 GtkWidget *wd_gl_viewport_new(void) {
  return gtk_widget_new(WD_TYPE_GL_VIEWPORT, NULL);
 }
--- a/src/glviewport.h
+++ b/src/glviewport.h
@ -0,0 +1,43 @@
 /*
 * Copyright (C) 2019 cyclopsian
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE X CONSORTIUM BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
 #ifndef WDISPLAY_GLVIEWPORT_H
 #define WDISPLAY_GLVIEWPORT_H
 #include <gtk/gtk.h>
 G_BEGIN_DECLS
 #define WD_TYPE_GL_VIEWPORT (wd_gl_viewport_get_type())
 G_DECLARE_DERIVABLE_TYPE(
    WdGLViewport, wd_gl_viewport, WD, GL_VIEWPORT,GtkGLArea)
 struct _WdGLViewportClass {
  GtkGLAreaClass parent_class;
 };
 GtkWidget *wd_gl_viewport_new(void);
 G_END_DECLS
 #endif
--- a/src/main.c
+++ b/src/main.c
@ -25,6 +25,7 @@
 #include <gdk/gdkwayland.h>
 #include "wdisplay.h"
 #include "glviewport.h"
 __attribute__((noreturn)) void wd_fatal_error(int status, const char *message) {
  GtkWindow *parent = gtk_application_get_active_window(GTK_APPLICATION(g_application_get_default()));
@ -180,6 +181,208 @@ static gboolean apply_done_reset(gpointer data) {
  return FALSE;
 }
 static void update_scroll_size(struct wd_state *state) {
  state->render.viewport_width = gtk_widget_get_allocated_width(state->canvas);
  state->render.viewport_height = gtk_widget_get_allocated_height(state->canvas);
  GtkAdjustment *scroll_x_adj = gtk_scrolled_window_get_hadjustment(GTK_SCROLLED_WINDOW(state->scroller));
  GtkAdjustment *scroll_y_adj = gtk_scrolled_window_get_vadjustment(GTK_SCROLLED_WINDOW(state->scroller));
  int scroll_x_upper = state->render.width;
  int scroll_y_upper = state->render.height;
  gtk_adjustment_set_upper(scroll_x_adj, MAX(0, scroll_x_upper));
  gtk_adjustment_set_upper(scroll_y_adj, MAX(0, scroll_y_upper));
  gtk_adjustment_set_page_size(scroll_x_adj, state->render.viewport_width);
  gtk_adjustment_set_page_size(scroll_y_adj, state->render.viewport_height);
  gtk_adjustment_set_page_increment(scroll_x_adj, state->render.viewport_width);
  gtk_adjustment_set_page_increment(scroll_y_adj, state->render.viewport_height);
  gtk_adjustment_set_step_increment(scroll_x_adj, state->render.viewport_width / 10);
  gtk_adjustment_set_step_increment(scroll_y_adj, state->render.viewport_height / 10);
 }
 /*
 * Recalculates the desired canvas size, accounting for zoom + margins.
 */
 static void update_canvas_size(struct wd_state *state) {
  int xmin = 0;
  int xmax = 0;
  int ymin = 0;
  int ymax = 0;
  struct wd_head *head;
  wl_list_for_each(head, &state->heads, link) {
    int w = head->custom_mode.width;
    int h = head->custom_mode.height;
    if (head->enabled && head->mode != NULL) {
      w = head->mode->width;
      h = head->mode->height;
    }
    if (head->scale > 0.) {
      w /= head->scale;
      h /= head->scale;
    }
    int x2 = head->x + w;
    int y2 = head->y + h;
    xmin = MIN(xmin, head->x);
    xmax = MAX(xmax, x2);
    ymin = MIN(ymin, head->y);
    ymax = MAX(ymax, y2);
  }
  // update canvas sizings
  state->render.x_origin = floor(xmin * state->zoom) - CANVAS_MARGIN;
  state->render.y_origin = floor(ymin * state->zoom) - CANVAS_MARGIN;
  state->render.width = ceil((xmax - xmin) * state->zoom) + CANVAS_MARGIN * 2;
  state->render.height = ceil((ymax - ymin) * state->zoom) + CANVAS_MARGIN * 2;
  update_scroll_size(state);
 }
 static void cache_scroll(struct wd_state *state) {
  GtkAdjustment *scroll_x_adj = gtk_scrolled_window_get_hadjustment(GTK_SCROLLED_WINDOW(state->scroller));
  GtkAdjustment *scroll_y_adj = gtk_scrolled_window_get_vadjustment(GTK_SCROLLED_WINDOW(state->scroller));
  state->render.scroll_x = gtk_adjustment_get_value(scroll_x_adj);
  state->render.scroll_y = gtk_adjustment_get_value(scroll_y_adj);
 }
 static gboolean redraw_canvas(GtkWidget *widget, GdkFrameClock *frame_clock, gpointer data);
 static void update_tick_callback(struct wd_state *state) {
  bool any_animate = false;
  for (int i = 0; i < state->render.head_count; i++) {
    struct wd_render_head_data *head = &state->render.heads[i];
    if (state->render.updated_at < head->transition_begin + HOVER_USECS) {
      any_animate = true;
      break;
    }
  }
  if (!any_animate && !state->capture) {
    if (state->canvas_tick != -1) {
      gtk_widget_remove_tick_callback(state->canvas, state->canvas_tick);
      state->canvas_tick = -1;
    }
  } else if (state->canvas_tick == -1) {
    state->canvas_tick =
      gtk_widget_add_tick_callback(state->canvas, redraw_canvas, state, NULL);
  }
  gtk_gl_area_queue_render(GTK_GL_AREA(state->canvas));
  gtk_gl_area_set_auto_render(GTK_GL_AREA(state->canvas), state->capture);
 }
 static void update_cursor(struct wd_state *state) {
  bool any_hovered = false;
  struct wd_head *head;
  wl_list_for_each(head, &state->heads, link) {
    struct wd_render_head_data *render = head->render;
    if (render != NULL && render->hovered) {
      any_hovered = true;
      break;
    }
  }
  GdkWindow *window = gtk_widget_get_window(state->canvas);
  if (any_hovered) {
    gdk_window_set_cursor(window, state->grab_cursor);
  } else if (state->clicked != NULL) {
    gdk_window_set_cursor(window, state->grabbing_cursor);
  } else if (state->panning) {
    gdk_window_set_cursor(window, state->move_cursor);
  } else {
    gdk_window_set_cursor(window, NULL);
  }
 }
 static void update_hovered(struct wd_state *state) {
  GdkDisplay *display = gdk_display_get_default();
  GdkWindow *window = gtk_widget_get_window(state->canvas);
  if (!gtk_widget_get_realized(state->canvas)) {
    return;
  }
  GdkFrameClock *clock = gtk_widget_get_frame_clock(state->canvas);
  uint64_t tick = gdk_frame_clock_get_frame_time(clock);
  g_autoptr(GList) seats = gdk_display_list_seats(display);
  struct wd_head *head;
  wl_list_for_each(head, &state->heads, link) {
    struct wd_render_head_data *render = head->render;
    if (render != NULL) {
      bool init_hovered = render->hovered;
      render->hovered = false;
      if (state->clicked == head) {
        render->hovered = true;
      } else if (state->clicked == NULL) {
        for (GList *iter = seats; iter != NULL; iter = iter->next) {
          double mouse_x;
          double mouse_y;
          GdkDevice *pointer = gdk_seat_get_pointer(GDK_SEAT(iter->data));
          gdk_window_get_device_position_double(window, pointer, &mouse_x, &mouse_y, NULL);
          if (mouse_x >= render->x1 && mouse_x < render->x2 &&
              mouse_y >= render->y1 && mouse_y < render->y2) {
            render->hovered = true;
            break;
          }
        }
      }
      if (init_hovered != render->hovered) {
        render->transition_begin = tick;
      }
    }
  }
  update_cursor(state);
  update_tick_callback(state);
 }
 static inline void color_to_float_array(GtkStyleContext *ctx,
    const char *color_name, float out[4]) {
  GdkRGBA color;
  gtk_style_context_lookup_color(ctx, color_name, &color);
  out[0] = color.red;
  out[1] = color.green;
  out[2] = color.blue;
  out[3] = color.alpha;
 }
 static void queue_canvas_draw(struct wd_state *state) {
  GtkStyleContext *style_ctx = gtk_widget_get_style_context(state->canvas);
  color_to_float_array(style_ctx,
      "theme_fg_color", state->render.fg_color);
  color_to_float_array(style_ctx,
      "theme_bg_color", state->render.bg_color);
  color_to_float_array(style_ctx,
      "borders", state->render.border_color);
  color_to_float_array(style_ctx,
      "theme_selected_bg_color", state->render.selection_color);
  cache_scroll(state);
  state->render.head_count = 0;
  g_autoptr(GList) forms = gtk_container_get_children(GTK_CONTAINER(state->stack));
  for (GList *form_iter = forms; form_iter != NULL; form_iter = form_iter->next) {
    GtkBuilder *builder = GTK_BUILDER(g_object_get_data(G_OBJECT(form_iter->data), "builder"));
    gboolean enabled = gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(gtk_builder_get_object(builder, "enabled")));
    if (enabled) {
      int x = gtk_spin_button_get_value(GTK_SPIN_BUTTON(gtk_builder_get_object(builder, "pos_x")));
      int y = gtk_spin_button_get_value(GTK_SPIN_BUTTON(gtk_builder_get_object(builder, "pos_y")));
      int w = gtk_spin_button_get_value(GTK_SPIN_BUTTON(gtk_builder_get_object(builder, "width")));
      int h = gtk_spin_button_get_value(GTK_SPIN_BUTTON(gtk_builder_get_object(builder, "height")));
      double scale = gtk_spin_button_get_value(GTK_SPIN_BUTTON(gtk_builder_get_object(builder, "scale")));
      if (scale <= 0.)
        scale = 1.;
      struct wd_head *head = g_object_get_data(G_OBJECT(form_iter->data), "head");
      struct wd_render_head_data *render = &state->render.heads[state->render.head_count];
      render->x1 = floor(x * state->zoom - state->render.scroll_x - state->render.x_origin);
      render->y1 = floor(y * state->zoom - state->render.scroll_y - state->render.y_origin);
      render->x2 = floor(render->x1 + w * state->zoom / scale);
      render->y2 = floor(render->y1 + h * state->zoom / scale);
      head->render = render;
      state->render.head_count++;
      if (state->render.head_count >= HEADS_MAX)
        break;
    }
  }
  gtk_gl_area_queue_render(GTK_GL_AREA(state->canvas));
 }
 // BEGIN FORM CALLBACKS
 static void show_apply(struct wd_state *state) {
  const gchar *page = "title";
@ -191,7 +394,12 @@ static void show_apply(struct wd_state *state) {
    }
  }
  gtk_stack_set_visible_child_name(GTK_STACK(state->header_stack), page);
-  gtk_widget_queue_draw(state->canvas);
+}
 static void update_ui(struct wd_state *state) {
  show_apply(state);
  update_canvas_size(state);
  queue_canvas_draw(state);
 }
 static void update_sensitivity(GtkWidget *form) {
@ -226,7 +434,7 @@ static void select_rotate_option(GtkWidget *form, GtkWidget *model_button) {
 static void rotate_selected(GSimpleAction *action, GVariant *param, gpointer data) {
  select_rotate_option(GTK_WIDGET(data), g_object_get_data(G_OBJECT(action), "widget"));
  const struct wd_head *head = g_object_get_data(G_OBJECT(data), "head");
-  show_apply(head->state);
+  update_ui(head->state);
 }
 static void select_mode_option(GtkWidget *form, int32_t w, int32_t h, int32_t r) {
@ -257,47 +465,10 @@ static void mode_selected(GSimpleAction *action, GVariant *param, gpointer data)
  update_mode_entries(form, mode->width, mode->height, mode->refresh);
  select_mode_option(form, mode->width, mode->height, mode->refresh);
-  show_apply(head->state);
+  update_ui(head->state);
 }
 // END FORM CALLBACKS
 /*
 * Recalculates the desired canvas size, accounting for zoom + margins.
 */
 static void update_canvas_size(struct wd_state *state) {
  int xmin = 0;
  int xmax = 0;
  int ymin = 0;
  int ymax = 0;
  struct wd_head *head;
  wl_list_for_each(head, &state->heads, link) {
    int w = head->custom_mode.width;
    int h = head->custom_mode.height;
    if (head->enabled && head->mode != NULL) {
      w = head->mode->width;
      h = head->mode->height;
    }
    if (head->scale > 0.) {
      w /= head->scale;
      h /= head->scale;
    }
    int x2 = head->x + w;
    int y2 = head->y + h;
    xmin = MIN(xmin, head->x);
    xmax = MAX(xmax, x2);
    ymin = MIN(ymin, head->y);
    ymax = MAX(ymax, y2);
  }
  // update canvas sizings
  state->xorigin = floor(xmin * state->zoom) - CANVAS_MARGIN;
  state->yorigin = floor(ymin * state->zoom) - CANVAS_MARGIN;
  int heads_width = ceil((xmax - xmin) * state->zoom) + CANVAS_MARGIN * 2;
  int heads_height = ceil((ymax - ymin) * state->zoom) + CANVAS_MARGIN * 2;
  gtk_layout_set_size(GTK_LAYOUT(state->canvas), heads_width, heads_height);
 }
 static void clear_menu(GtkWidget *box, GActionMap *action_map) {
  g_autoptr(GList) children = gtk_container_get_children(GTK_CONTAINER(box));
  for (GList *child = children; child != NULL; child = child->next) {
@ -305,6 +476,7 @@ static void clear_menu(GtkWidget *box, GActionMap *action_map) {
    gtk_container_remove(GTK_CONTAINER(box), GTK_WIDGET(child->data));
  }
 }
 static void update_head_form(GtkWidget *form, unsigned int fields) {
  GtkBuilder *builder = GTK_BUILDER(g_object_get_data(G_OBJECT(form), "builder"));
  GtkWidget *description = GTK_WIDGET(gtk_builder_get_object(builder, "description"));
@ -368,7 +540,18 @@ static void update_head_form(GtkWidget *form, unsigned int fields) {
      w = head->mode->width;
      h = head->mode->height;
      r = head->mode->refresh;
    } else if (!head->enabled && w == 0 && h == 0) {
      struct wd_mode *mode;
      wl_list_for_each(mode, &head->modes, link) {
        if (mode->preferred) {
          w = mode->width;
          h = mode->height;
          r = mode->refresh;
          break;
        }
      }
    }
    update_mode_entries(form, w, h, r);
    select_mode_option(form, w, h, r);
    gtk_widget_show_all(mode_box);
@ -389,8 +572,7 @@ static void update_head_form(GtkWidget *form, unsigned int fields) {
  if (fields & WD_FIELD_ENABLED) {
    update_sensitivity(form);
  }
-  show_apply(head->state);
+  update_ui(head->state);
  gtk_widget_queue_draw(head->state->canvas);
 }
 void wd_ui_reset_heads(struct wd_state *state) {
@ -437,14 +619,14 @@ void wd_ui_reset_heads(struct wd_state *state) {
      gtk_widget_show_all(form);
      g_signal_connect_swapped(gtk_builder_get_object(builder, "enabled"), "toggled", G_CALLBACK(update_sensitivity), form);
-      g_signal_connect_swapped(gtk_builder_get_object(builder, "enabled"), "toggled", G_CALLBACK(show_apply), state);
+      g_signal_connect_swapped(gtk_builder_get_object(builder, "enabled"), "toggled", G_CALLBACK(update_ui), state);
-      g_signal_connect_swapped(gtk_builder_get_object(builder, "scale"), "value-changed", G_CALLBACK(show_apply), state);
+      g_signal_connect_swapped(gtk_builder_get_object(builder, "scale"), "value-changed", G_CALLBACK(update_ui), state);
-      g_signal_connect_swapped(gtk_builder_get_object(builder, "pos_x"), "value-changed", G_CALLBACK(show_apply), state);
+      g_signal_connect_swapped(gtk_builder_get_object(builder, "pos_x"), "value-changed", G_CALLBACK(update_ui), state);
-      g_signal_connect_swapped(gtk_builder_get_object(builder, "pos_y"), "value-changed", G_CALLBACK(show_apply), state);
+      g_signal_connect_swapped(gtk_builder_get_object(builder, "pos_y"), "value-changed", G_CALLBACK(update_ui), state);
-      g_signal_connect_swapped(gtk_builder_get_object(builder, "width"), "value-changed", G_CALLBACK(show_apply), state);
+      g_signal_connect_swapped(gtk_builder_get_object(builder, "width"), "value-changed", G_CALLBACK(update_ui), state);
-      g_signal_connect_swapped(gtk_builder_get_object(builder, "height"), "value-changed", G_CALLBACK(show_apply), state);
+      g_signal_connect_swapped(gtk_builder_get_object(builder, "height"), "value-changed", G_CALLBACK(update_ui), state);
-      g_signal_connect_swapped(gtk_builder_get_object(builder, "refresh"), "value-changed", G_CALLBACK(show_apply), state);
+      g_signal_connect_swapped(gtk_builder_get_object(builder, "refresh"), "value-changed", G_CALLBACK(update_ui), state);
-      g_signal_connect_swapped(gtk_builder_get_object(builder, "flipped"), "toggled", G_CALLBACK(show_apply), state);
+      g_signal_connect_swapped(gtk_builder_get_object(builder, "flipped"), "toggled", G_CALLBACK(update_ui), state);
    } else {
      form = form_iter->data;
@ -458,13 +640,10 @@ void wd_ui_reset_heads(struct wd_state *state) {
    g_object_unref(builder);
    gtk_container_remove(GTK_CONTAINER(state->stack), GTK_WIDGET(form_iter->data));
  }
-  gtk_widget_queue_draw(state->canvas);
+  update_canvas_size(state);
  queue_canvas_draw(state);
 }
 /*
 * Updates the UI form for a single head. Useful for when the compositor notifies us of
 * updated configuration caused by another program.
 */
 void wd_ui_reset_head(const struct wd_head *head, unsigned int fields) {
  if (head->state->stack == NULL) {
    return;
@ -474,8 +653,11 @@ void wd_ui_reset_head(const struct wd_head *head, unsigned int fields) {
    const struct wd_head *other = g_object_get_data(G_OBJECT(form_iter->data), "head");
    if (head == other) {
      update_head_form(GTK_WIDGET(form_iter->data), fields);
      break;
    }
  }
  update_canvas_size(head->state);
  queue_canvas_draw(head->state);
 }
 void wd_ui_reset_all(struct wd_state *state) {
@ -484,6 +666,8 @@ void wd_ui_reset_all(struct wd_state *state) {
  for (GList *form_iter = forms; form_iter != NULL; form_iter = form_iter->next) {
    update_head_form(GTK_WIDGET(form_iter->data), WD_FIELDS_ALL);
  }
  update_canvas_size(state);
  queue_canvas_draw(state);
 }
 void wd_ui_apply_done(struct wd_state *state, struct wl_list *outputs) {
@ -509,51 +693,398 @@ void wd_ui_show_error(struct wd_state *state, const char *message) {
 }
 // BEGIN GLOBAL CALLBACKS
-static void cleanup(GtkWidget *window, gpointer state) {
+static void cleanup(GtkWidget *window, gpointer data) {
-  g_free(state);
+  struct wd_state *state = data;
  g_object_unref(state->grab_cursor);
  g_object_unref(state->grabbing_cursor);
  g_object_unref(state->move_cursor);
  wd_state_destroy(state);
 }
-gboolean draw(GtkWidget *widget, cairo_t *cr, gpointer data) {
+static void monitor_added(GdkDisplay *display, GdkMonitor *monitor, gpointer data) {
  wd_add_output(data, gdk_wayland_monitor_get_wl_output(monitor));
 }
 static void monitor_removed(GdkDisplay *display, GdkMonitor *monitor, gpointer data) {
  struct wl_display *wl_display = gdk_wayland_display_get_wl_display(display);
  wd_remove_output(data, gdk_wayland_monitor_get_wl_output(monitor), wl_display);
 }
 static void canvas_realize(GtkWidget *widget, gpointer data) {
  gtk_gl_area_make_current(GTK_GL_AREA(widget));
  if (gtk_gl_area_get_error(GTK_GL_AREA(widget)) != NULL) {
    return;
  }
  struct wd_state *state = data;
  state->gl_data = wd_gl_setup();
 }
 static inline bool size_changed(const struct wd_render_head_data *render) {
  return render->x2 - render->x1 != render->tex_width ||
    render->y2 - render->y1 != render->tex_height;
 }
 static inline void cairo_set_source_color(cairo_t *cr, float color[4]) {
  cairo_set_source_rgba(cr, color[0], color[1], color[2], color[3]);
 }
 static void update_zoom(struct wd_state *state) {
  g_autofree gchar *zoom_percent = g_strdup_printf("%.f%%", state->zoom * 100.);
  gtk_button_set_label(GTK_BUTTON(state->zoom_reset), zoom_percent);
  gtk_widget_set_sensitive(state->zoom_in, state->zoom < MAX_ZOOM);
  gtk_widget_set_sensitive(state->zoom_out, state->zoom > MIN_ZOOM);
  update_canvas_size(state);
-  GtkStyleContext *style_ctx = gtk_widget_get_style_context(widget);
+  queue_canvas_draw(state);
-  GtkAdjustment *scroll_x_adj = gtk_scrolled_window_get_hadjustment(GTK_SCROLLED_WINDOW(state->scroller));
+}
  GtkAdjustment *scroll_y_adj = gtk_scrolled_window_get_vadjustment(GTK_SCROLLED_WINDOW(state->scroller));
  double scroll_x = gtk_adjustment_get_value(scroll_x_adj);
  double scroll_y = gtk_adjustment_get_value(scroll_y_adj);
  int width = gtk_widget_get_allocated_width(widget);
  int height = gtk_widget_get_allocated_height(widget);
-  GdkRGBA border;
+static void zoom_to(struct wd_state *state, double zoom) {
-  gtk_style_context_lookup_color(style_ctx, "borders", &border);
+  state->zoom = zoom;
  state->zoom = MAX(state->zoom, MIN_ZOOM);
  state->zoom = MIN(state->zoom, MAX_ZOOM);
  update_zoom(state);
 }
-  gdk_cairo_set_source_rgba(cr, &border);
+static void zoom_out(struct wd_state *state) {
-  cairo_set_line_width(cr, .5);
+  zoom_to(state, state->zoom * 0.75);
 }
-  gtk_render_background(style_ctx, cr, 0, 0, width, height);
+static void zoom_reset(struct wd_state *state) {
-  g_autoptr(GList) forms = gtk_container_get_children(GTK_CONTAINER(state->stack));
+  zoom_to(state, DEFAULT_ZOOM);
-  for (GList *form_iter = forms; form_iter != NULL; form_iter = form_iter->next) {
+}
-    GtkBuilder *builder = GTK_BUILDER(g_object_get_data(G_OBJECT(form_iter->data), "builder"));
+
-    gboolean enabled = gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(gtk_builder_get_object(builder, "enabled")));
+static void zoom_in(struct wd_state *state) {
-    if (enabled) {
+  zoom_to(state, state->zoom / 0.75);
-      int x = gtk_spin_button_get_value(GTK_SPIN_BUTTON(gtk_builder_get_object(builder, "pos_x")));
+}
-      int y = gtk_spin_button_get_value(GTK_SPIN_BUTTON(gtk_builder_get_object(builder, "pos_y")));
+
-      int w = gtk_spin_button_get_value(GTK_SPIN_BUTTON(gtk_builder_get_object(builder, "width")));
+#define TEXT_MARGIN 5
-      int h = gtk_spin_button_get_value(GTK_SPIN_BUTTON(gtk_builder_get_object(builder, "height")));
+
-      double scale = gtk_spin_button_get_value(GTK_SPIN_BUTTON(gtk_builder_get_object(builder, "scale")));
+static cairo_surface_t *draw_head(PangoContext *pango,
-      if (scale <= 0.) scale = 1.;
+    struct wd_render_data *info, const char *name,
-      cairo_rectangle(cr,
+    unsigned width, unsigned height) {
-          x * state->zoom + .5 - scroll_x - state->xorigin,
+  cairo_surface_t *surface = cairo_image_surface_create(CAIRO_FORMAT_ARGB32,
-          y * state->zoom + .5 - scroll_y - state->yorigin,
+      width, height);
-          w * state->zoom / scale,
+  cairo_t *cr = cairo_create(surface);
-          h * state->zoom / scale);
+
-      cairo_stroke(cr);
+  cairo_rectangle(cr, 0., 0., width, height);
  cairo_set_source_color(cr, info->border_color);
  cairo_fill(cr);
  cairo_set_line_width(cr, 1.);
  cairo_rectangle(cr, 0, 0, width, height);
  cairo_set_source_color(cr, info->fg_color);
  cairo_stroke(cr);
  PangoLayout *layout = pango_layout_new(pango);
  pango_layout_set_text(layout, name, -1);
  int text_width = pango_units_from_double(width - TEXT_MARGIN * 2);
  int text_height = pango_units_from_double(height - TEXT_MARGIN * 2);
  pango_layout_set_width(layout, MAX(text_width, 0));
  pango_layout_set_height(layout, MAX(text_height, 0));
  pango_layout_set_wrap(layout, PANGO_WRAP_WORD_CHAR);
  pango_layout_set_ellipsize(layout, PANGO_ELLIPSIZE_END);
  pango_layout_set_alignment(layout, PANGO_ALIGN_CENTER);
  cairo_set_source_color(cr, info->fg_color);
  pango_layout_get_size(layout, &text_width, &text_height);
  cairo_move_to(cr, TEXT_MARGIN, (height - PANGO_PIXELS(text_height)) / 2);
  pango_cairo_show_layout(cr, layout);
  g_object_unref(layout);
  cairo_destroy(cr);
  cairo_surface_flush(surface);
  return surface;
 }
 static void canvas_render(GtkGLArea *area, GdkGLContext *context, gpointer data) {
  struct wd_state *state = data;
  PangoContext *pango = gtk_widget_get_pango_context(state->canvas);
  GdkFrameClock *clock = gtk_widget_get_frame_clock(state->canvas);
  uint64_t tick = gdk_frame_clock_get_frame_time(clock);
  wd_capture_frame(state);
  struct wd_head *head;
  wl_list_for_each(head, &state->heads, link) {
    struct wd_render_head_data *render = head->render;
    struct wd_output *output = wd_find_output(state, head);
    struct wd_frame *frame = NULL;
    if (output != NULL && !wl_list_empty(&output->frames)) {
      frame = wl_container_of(output->frames.prev, frame, link);
    }
    if (render != NULL) {
      if (state->capture && frame != NULL && frame->pixels != NULL) {
        if (frame->tick > render->updated_at) {
          render->tex_stride = frame->stride;
          render->tex_width = frame->width;
          render->tex_height = frame->height;
          render->pixels = frame->pixels;
          render->preview = true;
          render->updated_at = tick;
          render->y_invert = frame->y_invert;
        }
      } else if (render->preview
          || render->pixels == NULL || size_changed(render)) {
        render->tex_width = render->x2 - render->x1;
        render->tex_height = render->y2 - render->y1;
        render->preview = false;
        if (head->surface != NULL) {
          cairo_surface_destroy(head->surface);
        }
        head->surface = draw_head(pango, &state->render, head->name,
            render->tex_width, render->tex_height);
        render->pixels = cairo_image_surface_get_data(head->surface);
        render->tex_stride = cairo_image_surface_get_stride(head->surface);
        render->updated_at = tick;
        render->y_invert = false;
      }
    }
  }
  wd_gl_render(state->gl_data, &state->render, tick);
  state->render.updated_at = tick;
 }
 static void canvas_unrealize(GtkWidget *widget, gpointer data) {
  gtk_gl_area_make_current(GTK_GL_AREA(widget));
  if (gtk_gl_area_get_error(GTK_GL_AREA(widget)) != NULL) {
    return;
  }
  struct wd_state *state = data;
  GdkDisplay *gdk_display = gdk_display_get_default();
  struct wl_display *display = gdk_wayland_display_get_wl_display(gdk_display);
  wd_capture_wait(state, display);
  wd_gl_cleanup(state->gl_data);
  state->gl_data = NULL;
 }
 static gboolean canvas_click(GtkWidget *widget, GdkEvent *event,
    gpointer data) {
  struct wd_state *state = data;
  if (event->button.type == GDK_BUTTON_PRESS) {
    if (event->button.button == 1) {
      int i = 0;
      struct wd_head *head;
      wl_list_for_each(head, &state->heads, link) {
        struct wd_render_head_data *render = head->render;
        if (render != NULL) {
          double mouse_x = event->button.x;
          double mouse_y = event->button.y;
          if (mouse_x >= render->x1 && mouse_x < render->x2 &&
              mouse_y >= render->y1 && mouse_y < render->y2) {
            state->clicked = head;
            state->click_offset.x = event->button.x - render->x1;
            state->click_offset.y = event->button.y - render->y1;
            break;
          }
        }
        i++;
      }
      if (state->clicked != NULL) {
        g_autoptr(GList) forms = gtk_container_get_children(GTK_CONTAINER(state->stack));
        for (GList *form_iter = forms; form_iter != NULL; form_iter = form_iter->next) {
          const struct wd_head *other = g_object_get_data(G_OBJECT(form_iter->data), "head");
          if (state->clicked == other) {
            gtk_stack_set_visible_child(GTK_STACK(state->stack), form_iter->data);
            break;
          }
        }
      }
    } else if (event->button.button == 2) {
      state->panning = true;
      state->pan_last.x = event->button.x;
      state->pan_last.y = event->button.y;
    }
  }
  return TRUE;
 }
 static gboolean canvas_release(GtkWidget *widget, GdkEvent *event,
    gpointer data) {
  struct wd_state *state = data;
  if (event->button.button == 1) {
    state->clicked = NULL;
  }
  if (event->button.button == 2) {
    state->panning = false;
  }
  update_cursor(state);
  return TRUE;
 }
 #define SNAP_DIST 6.
 static gboolean canvas_motion(GtkWidget *widget, GdkEvent *event,
    gpointer data) {
  struct wd_state *state = data;
  if (event->motion.state & GDK_BUTTON2_MASK) {
    GtkAdjustment *xadj = gtk_scrolled_window_get_hadjustment(GTK_SCROLLED_WINDOW(state->scroller));
    GtkAdjustment *yadj = gtk_scrolled_window_get_vadjustment(GTK_SCROLLED_WINDOW(state->scroller));
    double delta_x = event->motion.x - state->pan_last.x;
    double delta_y = event->motion.y - state->pan_last.y;
    gtk_adjustment_set_value(xadj, gtk_adjustment_get_value(xadj) + delta_x);
    gtk_adjustment_set_value(yadj, gtk_adjustment_get_value(yadj) + delta_y);
    state->pan_last.x = event->motion.x;
    state->pan_last.y = event->motion.y;
    queue_canvas_draw(state);
  }
  if ((event->motion.state & GDK_BUTTON1_MASK) && state->clicked != NULL) {
    GtkWidget *form = NULL;
    g_autoptr(GList) forms = gtk_container_get_children(GTK_CONTAINER(state->stack));
    for (GList *form_iter = forms; form_iter != NULL; form_iter = form_iter->next) {
      const struct wd_head *other = g_object_get_data(G_OBJECT(form_iter->data), "head");
      if (state->clicked == other) {
        form = form_iter->data;
        break;
      }
    }
    if (form != NULL) {
      GtkBuilder *builder = GTK_BUILDER(g_object_get_data(G_OBJECT(form), "builder"));
      struct wd_point size = {
        .x = gtk_spin_button_get_value(GTK_SPIN_BUTTON(gtk_builder_get_object(builder, "width"))),
        .y = gtk_spin_button_get_value(GTK_SPIN_BUTTON(gtk_builder_get_object(builder, "height"))),
      };
      struct wd_point tl = {
        .x = (event->motion.x - state->click_offset.x
            + state->render.x_origin + state->render.scroll_x) / state->zoom,
        .y = (event->motion.y - state->click_offset.y
            + state->render.y_origin + state->render.scroll_y) / state->zoom
      };
      const struct wd_point br = {
        .x = tl.x + size.x,
        .y = tl.y + size.y
      };
      struct wd_point new_pos = tl;
      float snap = SNAP_DIST / state->zoom;
      for (GList *form_iter = forms; form_iter != NULL; form_iter = form_iter->next) {
        const struct wd_head *other = g_object_get_data(G_OBJECT(form_iter->data), "head");
        if (other != state->clicked && !(event->motion.state & GDK_SHIFT_MASK)) {
          GtkBuilder *other_builder = GTK_BUILDER(g_object_get_data(G_OBJECT(form_iter->data), "builder"));
          double x1 = gtk_spin_button_get_value(GTK_SPIN_BUTTON(gtk_builder_get_object(other_builder, "pos_x")));
          double y1 = gtk_spin_button_get_value(GTK_SPIN_BUTTON(gtk_builder_get_object(other_builder, "pos_y")));
          double x2 = x1 + gtk_spin_button_get_value(GTK_SPIN_BUTTON(gtk_builder_get_object(other_builder, "width")));
          double y2 = y1 + gtk_spin_button_get_value(GTK_SPIN_BUTTON(gtk_builder_get_object(other_builder, "height")));
          if (fabs(br.x) <= snap)
            new_pos.x = -size.x;
          if (fabs(br.y) <= snap)
            new_pos.y = -size.y;
          if (fabs(br.x - x1) <= snap)
            new_pos.x = x1 - size.x;
          if (fabs(br.x - x2) <= snap)
            new_pos.x = x2 - size.x;
          if (fabs(br.y - y1) <= snap)
            new_pos.y = y1 - size.y;
          if (fabs(br.y - y2) <= snap)
            new_pos.y = y2 - size.y;
          if (fabs(tl.x) <= snap)
            new_pos.x = 0.;
          if (fabs(tl.y) <= snap)
            new_pos.y = 0.;
          if (fabs(tl.x - x1) <= snap)
            new_pos.x = x1;
          if (fabs(tl.x - x2) <= snap)
            new_pos.x = x2;
          if (fabs(tl.y - y1) <= snap)
            new_pos.y = y1;
          if (fabs(tl.y - y2) <= snap)
            new_pos.y = y2;
        }
      }
      GtkWidget *pos_x = GTK_WIDGET(gtk_builder_get_object(builder, "pos_x"));
      GtkWidget *pos_y = GTK_WIDGET(gtk_builder_get_object(builder, "pos_y"));
      gtk_spin_button_set_value(GTK_SPIN_BUTTON(pos_x), new_pos.x);
      gtk_spin_button_set_value(GTK_SPIN_BUTTON(pos_y), new_pos.y);
    }
  }
  update_hovered(state);
  return TRUE;
 }
 static gboolean canvas_enter(GtkWidget *widget, GdkEvent *event,
    gpointer data) {
  struct wd_state *state = data;
  if (!(event->crossing.state & GDK_BUTTON1_MASK)) {
    state->clicked = NULL;
  }
  if (!(event->crossing.state & GDK_BUTTON2_MASK)) {
    state->panning = false;
  }
  update_cursor(state);
  return TRUE;
 }
 static gboolean canvas_leave(GtkWidget *widget, GdkEvent *event,
    gpointer data) {
  struct wd_state *state = data;
  for (int i = 0; i < state->render.head_count; i++) {
    struct wd_render_head_data *head = &state->render.heads[i];
    head->hovered = false;
  }
  update_tick_callback(state);
  return TRUE;
 }
 static gboolean canvas_scroll(GtkWidget *widget, GdkEvent *event,
    gpointer data) {
  struct wd_state *state = data;
  if (event->scroll.state & GDK_CONTROL_MASK) {
    switch (event->scroll.direction) {
    case GDK_SCROLL_UP:
      zoom_in(state);
      break;
    case GDK_SCROLL_DOWN:
      zoom_out(state);
      break;
    case GDK_SCROLL_SMOOTH:
      if (event->scroll.delta_y)
        zoom_to(state, state->zoom * pow(0.75, event->scroll.delta_y));
      break;
    default:
      break;
    }
  } else {
    GtkAdjustment *xadj = gtk_scrolled_window_get_hadjustment(GTK_SCROLLED_WINDOW(state->scroller));
    GtkAdjustment *yadj = gtk_scrolled_window_get_vadjustment(GTK_SCROLLED_WINDOW(state->scroller));
    double xstep = gtk_adjustment_get_step_increment(xadj);
    double ystep = gtk_adjustment_get_step_increment(yadj);
    switch (event->scroll.direction) {
    case GDK_SCROLL_UP:
      gtk_adjustment_set_value(yadj, gtk_adjustment_get_value(yadj) - ystep);
      break;
    case GDK_SCROLL_DOWN:
      gtk_adjustment_set_value(yadj, gtk_adjustment_get_value(yadj) + ystep);
      break;
    case GDK_SCROLL_LEFT:
      gtk_adjustment_set_value(xadj, gtk_adjustment_get_value(xadj) - xstep);
      break;
    case GDK_SCROLL_RIGHT:
      gtk_adjustment_set_value(xadj, gtk_adjustment_get_value(xadj) + xstep);
      break;
    case GDK_SCROLL_SMOOTH:
      if (event->scroll.delta_x)
        gtk_adjustment_set_value(xadj, gtk_adjustment_get_value(xadj) + xstep * event->scroll.delta_x);
      if (event->scroll.delta_y)
        gtk_adjustment_set_value(yadj, gtk_adjustment_get_value(yadj) + ystep * event->scroll.delta_y);
      break;
    default:
      break;
    }
  }
  return FALSE;
 }
 static void canvas_resize(GtkWidget *widget, GdkRectangle *allocation,
    gpointer data) {
  struct wd_state *state = data;
  update_scroll_size(state);
 }
 static void cancel_changes(GtkButton *button, gpointer data) {
  struct wd_state *state = data;
  gtk_stack_set_visible_child_name(GTK_STACK(state->header_stack), "title");
@ -564,34 +1095,6 @@ static void apply_changes(GtkButton *button, gpointer data) {
  apply_state(data);
 }
 static void update_zoom(struct wd_state *state) {
  g_autofree gchar *zoom_percent = g_strdup_printf("%.f%%", state->zoom * 100.);
  gtk_button_set_label(GTK_BUTTON(state->zoom_reset), zoom_percent);
  gtk_widget_set_sensitive(state->zoom_in, state->zoom < MAX_ZOOM);
  gtk_widget_set_sensitive(state->zoom_out, state->zoom > MIN_ZOOM);
  gtk_widget_queue_draw(state->canvas);
 }
 static void zoom_out(GtkButton *button, gpointer data) {
  struct wd_state *state = data;
  state->zoom *= 0.75;
  state->zoom = MAX(state->zoom, MIN_ZOOM);
  update_zoom(state);
 }
 static void zoom_reset(GtkButton *button, gpointer data) {
  struct wd_state *state = data;
  state->zoom = DEFAULT_ZOOM;
  update_zoom(state);
 }
 static void zoom_in(GtkButton *button, gpointer data) {
  struct wd_state *state = data;
  state->zoom /= 0.75;
  state->zoom = MIN(state->zoom, MAX_ZOOM);
  update_zoom(state);
 }
 static void info_response(GtkInfoBar *info_bar, gint response_id, gpointer data) {
  gtk_info_bar_set_revealed(info_bar, FALSE);
 }
@ -610,28 +1113,47 @@ static void auto_apply_selected(GSimpleAction *action, GVariant *param, gpointer
  g_simple_action_set_state(action, g_variant_new_boolean(state->autoapply));
 }
 static gboolean redraw_canvas(GtkWidget *widget, GdkFrameClock *frame_clock, gpointer data) {
  struct wd_state *state = data;
  if (state->capture) {
    wd_capture_frame(state);
  }
  queue_canvas_draw(state);
  return G_SOURCE_CONTINUE;
 }
 static void capture_selected(GSimpleAction *action, GVariant *param, gpointer data) {
  struct wd_state *state = data;
  state->capture = !state->capture;
  g_simple_action_set_state(action, g_variant_new_boolean(state->capture));
  update_tick_callback(state);
 }
 static void activate(GtkApplication* app, gpointer user_data) {
  GdkDisplay *gdk_display = gdk_display_get_default();
  if (!GDK_IS_WAYLAND_DISPLAY(gdk_display)) {
    wd_fatal_error(1, "This program is only usable on Wayland sessions.");
  }
-  struct wd_state *state = g_new0(struct wd_state, 1);
+  struct wd_state *state = wd_state_create();
  state->zoom = DEFAULT_ZOOM;
-  wl_list_init(&state->heads);
+  state->canvas_tick = -1;
  GtkCssProvider *css_provider = gtk_css_provider_new();
  gtk_css_provider_load_from_resource(css_provider, "/style.css");
  gtk_style_context_add_provider_for_screen(gdk_screen_get_default(), GTK_STYLE_PROVIDER(css_provider),
      GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
  state->grab_cursor = gdk_cursor_new_from_name(gdk_display, "grab");
  state->grabbing_cursor = gdk_cursor_new_from_name(gdk_display, "grabbing");
  state->move_cursor = gdk_cursor_new_from_name(gdk_display, "move");
  GtkBuilder *builder = gtk_builder_new_from_resource("/wdisplay.ui");
  GtkWidget *window = GTK_WIDGET(gtk_builder_get_object(builder, "heads_window"));
  state->header_stack = GTK_WIDGET(gtk_builder_get_object(builder, "header_stack"));
  state->stack_switcher = GTK_WIDGET(gtk_builder_get_object(builder, "heads_stack_switcher"));
  state->stack = GTK_WIDGET(gtk_builder_get_object(builder, "heads_stack"));
  state->scroller = GTK_WIDGET(gtk_builder_get_object(builder, "heads_scroll"));
  state->canvas = GTK_WIDGET(gtk_builder_get_object(builder, "heads_layout"));
  state->spinner = GTK_WIDGET(gtk_builder_get_object(builder, "spinner"));
  state->zoom_out = GTK_WIDGET(gtk_builder_get_object(builder, "zoom_out"));
  state->zoom_reset = GTK_WIDGET(gtk_builder_get_object(builder, "zoom_reset"));
@ -640,7 +1162,7 @@ static void activate(GtkApplication* app, gpointer user_data) {
  state->info_bar = GTK_WIDGET(gtk_builder_get_object(builder, "heads_info"));
  state->info_label = GTK_WIDGET(gtk_builder_get_object(builder, "heads_info_label"));
  state->menu_button = GTK_WIDGET(gtk_builder_get_object(builder, "menu_button"));
-  gtk_builder_add_callback_symbol(builder, "heads_draw", G_CALLBACK(draw));
+
  gtk_builder_add_callback_symbol(builder, "apply_changes", G_CALLBACK(apply_changes));
  gtk_builder_add_callback_symbol(builder, "cancel_changes", G_CALLBACK(cancel_changes));
  gtk_builder_add_callback_symbol(builder, "zoom_out", G_CALLBACK(zoom_out));
@ -650,6 +1172,31 @@ static void activate(GtkApplication* app, gpointer user_data) {
  gtk_builder_add_callback_symbol(builder, "destroy", G_CALLBACK(cleanup));
  gtk_builder_connect_signals(builder, state);
  gtk_box_set_homogeneous(GTK_BOX(gtk_builder_get_object(builder, "zoom_box")), FALSE);
  state->canvas = wd_gl_viewport_new();
  gtk_container_add(GTK_CONTAINER(state->scroller), state->canvas);
  gtk_widget_add_events(state->canvas, GDK_POINTER_MOTION_MASK
      | GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK | GDK_SCROLL_MASK
      | GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK);
  g_signal_connect(state->canvas, "realize", G_CALLBACK(canvas_realize), state);
  g_signal_connect(state->canvas, "render", G_CALLBACK(canvas_render), state);
  g_signal_connect(state->canvas, "unrealize", G_CALLBACK(canvas_unrealize), state);
  g_signal_connect(state->canvas, "button-press-event", G_CALLBACK(canvas_click), state);
  g_signal_connect(state->canvas, "button-release-event", G_CALLBACK(canvas_release), state);
  g_signal_connect(state->canvas, "enter-notify-event", G_CALLBACK(canvas_enter), state);
  g_signal_connect(state->canvas, "leave-notify-event", G_CALLBACK(canvas_leave), state);
  g_signal_connect(state->canvas, "motion-notify-event", G_CALLBACK(canvas_motion), state);
  g_signal_connect(state->canvas, "scroll-event", G_CALLBACK(canvas_scroll), state);
  g_signal_connect(state->canvas, "size-allocate", G_CALLBACK(canvas_resize), state);
  gtk_gl_area_set_use_es(GTK_GL_AREA(state->canvas), TRUE);
  gtk_gl_area_set_has_alpha(GTK_GL_AREA(state->canvas), TRUE);
  gtk_gl_area_set_auto_render(GTK_GL_AREA(state->canvas), state->capture);
  GtkAdjustment *scroll_x_adj = gtk_scrolled_window_get_hadjustment(GTK_SCROLLED_WINDOW(state->scroller));
  GtkAdjustment *scroll_y_adj = gtk_scrolled_window_get_vadjustment(GTK_SCROLLED_WINDOW(state->scroller));
  g_signal_connect_swapped(scroll_x_adj, "value-changed", G_CALLBACK(queue_canvas_draw), state);
  g_signal_connect_swapped(scroll_y_adj, "value-changed", G_CALLBACK(queue_canvas_draw), state);
  update_zoom(state);
  GSimpleActionGroup *main_actions = g_simple_action_group_new();
@ -661,6 +1208,11 @@ static void activate(GtkApplication* app, gpointer user_data) {
  g_signal_connect(autoapply_action, "activate", G_CALLBACK(auto_apply_selected), state);
  g_action_map_add_action(G_ACTION_MAP(main_actions), G_ACTION(autoapply_action));
  GSimpleAction *capture_action = g_simple_action_new_stateful("capture-screens", NULL,
      g_variant_new_boolean(state->capture));
  g_signal_connect(capture_action, "activate", G_CALLBACK(capture_selected), state);
  g_action_map_add_action(G_ACTION_MAP(main_actions), G_ACTION(capture_action));
  /* first child of GtkInfoBar is always GtkRevealer */
  g_autoptr(GList) info_children = gtk_container_get_children(GTK_CONTAINER(state->info_bar));
  g_signal_connect(info_children->data, "notify::child-revealed", G_CALLBACK(info_bar_animation_done), state);
@ -671,6 +1223,23 @@ static void activate(GtkApplication* app, gpointer user_data) {
  if (state->output_manager == NULL) {
    wd_fatal_error(1, "Compositor doesn't support wlr-output-management-unstable-v1");
  }
  if (state->xdg_output_manager == NULL) {
    wd_fatal_error(1, "Compositor doesn't support xdg-output-unstable-v1");
  }
  if (state->copy_manager == NULL) {
    state->capture = false;
    g_simple_action_set_state(capture_action, g_variant_new_boolean(state->capture));
    g_simple_action_set_enabled(capture_action, FALSE);
  }
  int n_monitors = gdk_display_get_n_monitors(gdk_display);
  for (int i = 0; i < n_monitors; i++) {
    GdkMonitor *monitor = gdk_display_get_monitor(gdk_display, i);
    wd_add_output(state, gdk_wayland_monitor_get_wl_output(monitor));
  }
  g_signal_connect(gdk_display, "monitor-added", G_CALLBACK(monitor_added), state);
  g_signal_connect(gdk_display, "monitor-removed", G_CALLBACK(monitor_removed), state);
  gtk_application_add_window(app, GTK_WINDOW(window));
  gtk_widget_show_all(window);
--- a/src/meson.build
+++ b/src/meson.build
@ -1,21 +1,27 @@
 cc = meson.get_compiler('c')
 m_dep = cc.find_library('m', required : false)
 rt_dep = cc.find_library('rt', required : false)
 gdk = dependency('gdk-3.0')
 gtk = dependency('gtk+-3.0')
 assert(gdk.get_pkgconfig_variable('targets').split().contains('wayland'), 'Wayland GDK backend not present')
 epoxy = dependency('epoxy')
 executable(
  'wdisplay',
  [
    'main.c',
    'outputs.c',
    'render.c',
    'glviewport.c',
    resources,
  ],
  dependencies : [
    m_dep,
    rt_dep,
    wayland_client,
    client_protos,
    epoxy,
    gtk
  ],
  install: true
--- a/src/outputs.c
+++ b/src/outputs.c
@ -28,15 +28,26 @@
 * https://github.com/emersion/kanshi/blob/38d27474b686fcc8324cc5e454741a49577c0988/main.c
 */
 #define _GNU_SOURCE
 #include <assert.h>
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 #include <errno.h>
 #include <sys/mman.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include "wdisplay.h"
 #include "wlr-output-management-unstable-v1-client-protocol.h"
-#define HEADS_MAX 64
+#include "wlr-output-management-unstable-v1-client-protocol.h"
 #include "xdg-output-unstable-v1-client-protocol.h"
 #include "wlr-screencopy-unstable-v1-client-protocol.h"
 static void noop() {
  // This space is intentionally left blank
 }
 struct wd_pending_config {
  struct wd_state *state;
@ -143,6 +154,171 @@ void wd_apply_state(struct wd_state *state, struct wl_list *new_outputs) {
  zwlr_output_configuration_v1_apply(config);
 }
 static void wd_frame_destroy(struct wd_frame *frame) {
  if (frame->pixels != NULL)
    munmap(frame->pixels, frame->height * frame->stride);
  if (frame->buffer != NULL)
    wl_buffer_destroy(frame->buffer);
  if (frame->pool != NULL)
    wl_shm_pool_destroy(frame->pool);
  if (frame->capture_fd != -1)
    close(frame->capture_fd);
  if (frame->wlr_frame != NULL)
    zwlr_screencopy_frame_v1_destroy(frame->wlr_frame);
  wl_list_remove(&frame->link);
  free(frame);
 }
 static void capture_buffer(void *data,
    struct zwlr_screencopy_frame_v1 *copy_frame,
    uint32_t format, uint32_t width, uint32_t height, uint32_t stride) {
  struct wd_frame *frame = data;
  char *shm_name = NULL;
  if (asprintf(&shm_name, "/wd-%s", frame->output->name) == -1) {
    fprintf(stderr, "asprintf: %s\n", strerror(errno));
    shm_name = NULL;
    goto err;
  }
  frame->capture_fd = shm_open(shm_name, O_CREAT | O_RDWR, 0);
  if (frame->capture_fd == -1) {
    fprintf(stderr, "shm_open: %s\n", strerror(errno));
    goto err;
  }
  shm_unlink(shm_name);
  free(shm_name);
  size_t size = stride * height;
  ftruncate(frame->capture_fd, size);
  frame->pool = wl_shm_create_pool(frame->output->state->shm,
      frame->capture_fd, size);
  frame->buffer = wl_shm_pool_create_buffer(frame->pool, 0,
      width, height, stride, format);
  zwlr_screencopy_frame_v1_copy(copy_frame, frame->buffer);
  frame->stride = stride;
  frame->width = width;
  frame->height = height;
  return;
 err:
  if (shm_name != NULL) {
    free(shm_name);
  }
  wd_frame_destroy(frame);
 }
 static void capture_flags(void *data,
    struct zwlr_screencopy_frame_v1 *wlr_frame,
    uint32_t flags) {
  struct wd_frame *frame = data;
  frame->y_invert = !!(flags & ZWLR_SCREENCOPY_FRAME_V1_FLAGS_Y_INVERT);
 }
 static void capture_ready(void *data,
    struct zwlr_screencopy_frame_v1 *wlr_frame,
    uint32_t tv_sec_hi, uint32_t tv_sec_lo, uint32_t tv_nsec) {
  struct wd_frame *frame = data;
  frame->pixels = mmap(NULL, frame->stride * frame->height,
      PROT_READ, MAP_SHARED, frame->capture_fd, 0);
  if (frame->pixels == MAP_FAILED) {
    frame->pixels = NULL;
    fprintf(stderr, "mmap: %d: %s\n", frame->capture_fd, strerror(errno));
    wd_frame_destroy(frame);
    return;
  } else {
    uint64_t tv_sec = (uint64_t) tv_sec_hi << 32 | tv_sec_lo;
    frame->tick = (tv_sec * 1000000) + (tv_nsec / 1000);
  }
  zwlr_screencopy_frame_v1_destroy(frame->wlr_frame);
  frame->wlr_frame = NULL;
  struct wd_frame *frame_iter, *frame_tmp;
  wl_list_for_each_safe(frame_iter, frame_tmp, &frame->output->frames, link) {
    if (frame != frame_iter) {
      wd_frame_destroy(frame_iter);
    }
  }
 }
 static void capture_failed(void *data,
    struct zwlr_screencopy_frame_v1 *wlr_frame) {
  struct wd_frame *frame = data;
  wd_frame_destroy(frame);
 }
 struct zwlr_screencopy_frame_v1_listener capture_listener = {
  .buffer = capture_buffer,
  .flags = capture_flags,
  .ready = capture_ready,
  .failed = capture_failed
 };
 static bool has_pending_captures(struct wd_state *state) {
  struct wd_output *output;
  wl_list_for_each(output, &state->outputs, link) {
    struct wd_frame *frame;
    wl_list_for_each(frame, &output->frames, link) {
      if (frame->pixels == NULL) {
        return true;
      }
    }
  }
  return false;
 }
 void wd_capture_frame(struct wd_state *state) {
  if (state->copy_manager == NULL || has_pending_captures(state)
      || !state->capture) {
    return;
  }
  struct wd_output *output;
  wl_list_for_each(output, &state->outputs, link) {
    struct wd_frame *frame = calloc(1, sizeof(*frame));
    frame->output = output;
    frame->capture_fd = -1;
    frame->wlr_frame =
      zwlr_screencopy_manager_v1_capture_output(state->copy_manager, 1,
        output->wl_output);
    zwlr_screencopy_frame_v1_add_listener(frame->wlr_frame, &capture_listener,
        frame);
    wl_list_insert(&output->frames, &frame->link);
  }
 }
 static void wd_output_destroy(struct wd_output *output) {
  struct wd_frame *frame, *frame_tmp;
  wl_list_for_each_safe(frame, frame_tmp, &output->frames, link) {
    wd_frame_destroy(frame);
  }
  zxdg_output_v1_destroy(output->xdg_output);
  free(output->name);
  free(output);
 }
 static void wd_mode_destroy(struct wd_mode* mode) {
  zwlr_output_mode_v1_destroy(mode->wlr_mode);
  free(mode);
 }
 static void wd_head_destroy(struct wd_head *head) {
  struct wd_mode *mode, *mode_tmp;
  if (head->state->clicked == head) {
    head->state->clicked = NULL;
  }
  wl_list_for_each_safe(mode, mode_tmp, &head->modes, link) {
    zwlr_output_mode_v1_destroy(mode->wlr_mode);
    free(mode);
  }
  zwlr_output_head_v1_destroy(head->wlr_head);
  free(head->name);
  free(head->description);
  free(head);
 }
 static void mode_handle_size(void *data, struct zwlr_output_mode_v1 *wlr_mode,
    int32_t width, int32_t height) {
  struct wd_mode *mode = data;
@ -166,8 +342,7 @@ static void mode_handle_finished(void *data,
    struct zwlr_output_mode_v1 *wlr_mode) {
  struct wd_mode *mode = data;
  wl_list_remove(&mode->link);
-  zwlr_output_mode_v1_destroy(mode->wlr_mode);
+  wd_mode_destroy(mode);
  free(mode);
 }
 static const struct zwlr_output_mode_v1_listener mode_listener = {
@ -217,6 +392,7 @@ static void head_handle_enabled(void *data,
  struct wd_head *head = data;
  head->enabled = !!enabled;
  if (!enabled) {
    head->output = NULL;
    head->mode = NULL;
  }
  wd_ui_reset_head(head, WD_FIELD_ENABLED);
@ -264,10 +440,7 @@ static void head_handle_finished(void *data,
    struct zwlr_output_head_v1 *wlr_head) {
  struct wd_head *head = data;
  wl_list_remove(&head->link);
-  zwlr_output_head_v1_destroy(head->wlr_head);
+  wd_head_destroy(head);
  free(head->name);
  free(head->description);
  free(head);
 }
 static const struct zwlr_output_head_v1_listener head_listener = {
@ -307,41 +480,169 @@ static void output_manager_handle_done(void *data,
  wd_ui_reset_heads(state);
 }
 static void output_manager_handle_finished(void *data,
    struct zwlr_output_manager_v1 *manager) {
  // This space is intentionally left blank
 }
 static const struct zwlr_output_manager_v1_listener output_manager_listener = {
  .head = output_manager_handle_head,
  .done = output_manager_handle_done,
-  .finished = output_manager_handle_finished,
+  .finished = noop,
 };
 static void registry_handle_global(void *data, struct wl_registry *registry,
    uint32_t name, const char *interface, uint32_t version) {
  struct wd_state *state = data;
  if (strcmp(interface, zwlr_output_manager_v1_interface.name) == 0) {
-    state->output_manager = wl_registry_bind(registry, name, &zwlr_output_manager_v1_interface, 1);
+    state->output_manager = wl_registry_bind(registry, name,
-    zwlr_output_manager_v1_add_listener(state->output_manager, &output_manager_listener, state);
+        &zwlr_output_manager_v1_interface, version);
    zwlr_output_manager_v1_add_listener(state->output_manager,
        &output_manager_listener, state);
  } else if (strcmp(interface, zxdg_output_manager_v1_interface.name) == 0) {
    state->xdg_output_manager = wl_registry_bind(registry, name,
        &zxdg_output_manager_v1_interface, version);
  } else if(strcmp(interface, zwlr_screencopy_manager_v1_interface.name) == 0) {
    state->copy_manager = wl_registry_bind(registry, name,
        &zwlr_screencopy_manager_v1_interface, version);
  } else if(strcmp(interface, wl_shm_interface.name) == 0) {
    state->shm = wl_registry_bind(registry, name, &wl_shm_interface, version);
  }
 }
 static void registry_handle_global_remove(void *data,
    struct wl_registry *registry, uint32_t name) {
  // This space is intentionally left blank
 }
 static const struct wl_registry_listener registry_listener = {
  .global = registry_handle_global,
-  .global_remove = registry_handle_global_remove,
+  .global_remove = noop,
 };
-void wd_add_output_management_listener(struct wd_state *state, struct wl_display *display) {
+void wd_add_output_management_listener(struct wd_state *state, struct
    wl_display *display) {
  struct wl_registry *registry = wl_display_get_registry(display);
  wl_registry_add_listener(registry, &registry_listener, state);
  wl_display_dispatch(display);
  wl_display_roundtrip(display);
 }
 static struct wd_head *wd_find_head(struct wd_state *state,
    struct wd_output *output) {
  struct wd_head *head;
  wl_list_for_each(head, &state->heads, link) {
    if (output->name != NULL && strcmp(output->name, head->name) == 0) {
      return head;
    }
  }
  return NULL;
 }
 static void output_logical_position(void *data, struct zxdg_output_v1 *zxdg_output_v1,
    int32_t x, int32_t y) {
  struct wd_output *output = data;
  struct wd_head *head = wd_find_head(output->state, output);
  if (head != NULL) {
    head->x = x;
    head->y = y;
    wd_ui_reset_head(head, WD_FIELD_POSITION);
  }
 }
 static void output_logical_size(void *data, struct zxdg_output_v1 *zxdg_output_v1,
    int32_t width, int32_t height) {
  struct wd_output *output = data;
  struct wd_head *head = wd_find_head(output->state, output);
  if (head != NULL) {
    struct wd_mode *mode;
    head->custom_mode.width = width;
    head->custom_mode.height = height;
    head->mode = NULL;
    wl_list_for_each(mode, &head->modes, link) {
      if (mode->width == width && mode->height == height) {
        head->mode = mode;
        return;
      }
    }
    wd_ui_reset_head(head, WD_FIELD_MODE);
  }
 }
 static void output_name(void *data, struct zxdg_output_v1 *zxdg_output_v1,
    const char *name) {
  struct wd_output *output = data;
  output->name = strdup(name);
 }
 static const struct zxdg_output_v1_listener output_listener = {
  .logical_position = output_logical_position,
  .logical_size = output_logical_size,
  .done = noop,
  .name = output_name,
  .description = noop
 };
 void wd_add_output(struct wd_state *state, struct wl_output *wl_output) {
  struct wd_output *output = calloc(1, sizeof(*output));
  output->state = state;
  output->wl_output = wl_output;
  output->xdg_output = zxdg_output_manager_v1_get_xdg_output(
      state->xdg_output_manager, wl_output);
  wl_list_init(&output->frames);
  zxdg_output_v1_add_listener(output->xdg_output, &output_listener, output);
  wl_list_insert(&output->state->outputs, &output->link);
 }
 void wd_remove_output(struct wd_state *state, struct wl_output *wl_output,
    struct wl_display *display) {
  struct wd_output *output, *output_tmp;
  wl_list_for_each_safe(output, output_tmp, &state->outputs, link) {
    if (output->wl_output == wl_output) {
      wl_list_remove(&output->link);
      wd_output_destroy(output);
      break;
    }
  }
  wd_capture_wait(state, display);
 }
 struct wd_output *wd_find_output(struct wd_state *state, struct wd_head
    *head) {
  if (!head->enabled) {
    return NULL;
  }
  if (head->output != NULL) {
    return head->output;
  }
  struct wd_output *output;
  wl_list_for_each(output, &state->outputs, link) {
    if (output->name != NULL && strcmp(output->name, head->name) == 0) {
      head->output = output;
      return output;
    }
  }
  head->output = NULL;
  return NULL;
 }
 struct wd_state *wd_state_create(void) {
  struct wd_state *state = calloc(1, sizeof(*state));
  state->zoom = 1.;
  state->capture = true;
  wl_list_init(&state->heads);
  wl_list_init(&state->outputs);
  return state;
 }
 void wd_capture_wait(struct wd_state *state, struct wl_display *display) {
  wl_display_flush(display);
  while (has_pending_captures(state)) {
    if (wl_display_dispatch(display) == -1) {
      break;
    }
  }
 }
 void wd_state_destroy(struct wd_state *state) {
  struct wd_head *head, *head_tmp;
  wl_list_for_each_safe(head, head_tmp, &state->heads, link) {
    wd_head_destroy(head);
  }
  struct wd_output *output, *output_tmp;
  wl_list_for_each_safe(output, output_tmp, &state->outputs, link) {
    wd_output_destroy(output);
  }
  free(state);
 }
--- a/src/render.c
+++ b/src/render.c
@ -0,0 +1,360 @@
 /*
 * Copyright (C) 2019 cyclopsian
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE X CONSORTIUM BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
 #include "wdisplay.h"
 #include <stdlib.h>
 #include <stdio.h>
 #include <math.h>
 #include <epoxy/gl.h>
 #define CANVAS_MARGIN 100
 #define BT_UV_VERT_SIZE (2 + 2)
 #define BT_UV_QUAD_SIZE (6 * BT_UV_VERT_SIZE)
 #define BT_UV_MAX (BT_COLOR_QUAD_SIZE * HEADS_MAX)
 #define BT_COLOR_VERT_SIZE (2 + 4)
 #define BT_COLOR_QUAD_SIZE (6 * BT_COLOR_VERT_SIZE)
 #define BT_COLOR_MAX (BT_COLOR_QUAD_SIZE * HEADS_MAX)
 struct wd_gl_data {
  GLuint color_program;
  GLuint color_vertex_shader;
  GLuint color_fragment_shader;
  GLuint color_position_attribute;
  GLuint color_color_attribute;
  GLuint color_screen_size_uniform;
  GLuint texture_program;
  GLuint texture_vertex_shader;
  GLuint texture_fragment_shader;
  GLuint texture_position_attribute;
  GLuint texture_uv_attribute;
  GLuint texture_screen_size_uniform;
  GLuint texture_texture_uniform;
  GLuint buffers[2];
  unsigned texture_count;
  GLuint textures[HEADS_MAX];
  float tris[BT_COLOR_MAX];
 };
 static const char *color_vertex_shader_src = "\
 attribute vec2 position;\n\
 attribute vec4 color;\n\
 varying vec4 color_out;\n\
 uniform vec2 screen_size;\n\
 void main(void) {\n\
  vec2 screen_pos = (position / screen_size * 2. - 1.) * vec2(1., -1.);\n\
  gl_Position = vec4(screen_pos, 0., 1.);\n\
  color_out = color;\n\
 }";
 static const char *color_fragment_shader_src = "\
 varying vec4 color_out;\n\
 void main(void) {\n\
  gl_FragColor = color_out;\n\
 }";
 static const char *texture_vertex_shader_src = "\
 attribute vec2 position;\n\
 attribute vec2 uv;\n\
 varying vec2 uv_out;\n\
 uniform vec2 screen_size;\n\
 void main(void) {\n\
  vec2 screen_pos = (position / screen_size * 2. - 1.) * vec2(1., -1.);\n\
  gl_Position = vec4(screen_pos, 0., 1.);\n\
  uv_out = uv;\n\
 }";
 static const char *texture_fragment_shader_src = "\
 varying vec2 uv_out;\n\
 uniform sampler2D texture;\n\
 void main(void) {\n\
  gl_FragColor = texture2D(texture, uv_out);\n\
 }";
 static GLuint gl_make_shader(GLenum type, const char *src) {
  GLuint shader = glCreateShader(type);
  glShaderSource(shader, 1, &src, NULL);
  glCompileShader(shader);
  GLint status;
  glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
  if (status == GL_FALSE) {
    GLsizei length;
    glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &length);
    GLchar *log = "Failed";
    if (length > 0) {
      log = malloc(length);
      glGetShaderInfoLog(shader, length, NULL, log);
    }
    fprintf(stderr, "glCompileShader: %s\n", log);
    if (length > 0) {
      free(log);
    }
  }
  return shader;
 }
 static void gl_link_and_validate(GLint program) {
  GLint status;
  glLinkProgram(program);
  glGetProgramiv(program, GL_LINK_STATUS, &status);
  if (status == GL_FALSE) {
    GLsizei length;
    glGetProgramiv(program, GL_INFO_LOG_LENGTH, &length);
    GLchar *log = malloc(length);
    glGetProgramInfoLog(program, length, NULL, log);
    fprintf(stderr, "glLinkProgram: %s\n", log);
    free(log);
    return;
  }
  glValidateProgram(program);
  glGetProgramiv(program, GL_VALIDATE_STATUS, &status);
  if (status == GL_FALSE) {
    GLsizei length;
    glGetProgramiv(program, GL_INFO_LOG_LENGTH, &length);
    GLchar *log = malloc(length);
    glGetProgramInfoLog(program, length, NULL, log);
    fprintf(stderr, "glValidateProgram: %s\n", log);
    free(log);
  }
 }
 struct wd_gl_data *wd_gl_setup(void) {
  struct wd_gl_data *res = calloc(1, sizeof(struct wd_gl_data));
  res->color_program = glCreateProgram();
  res->color_vertex_shader = gl_make_shader(GL_VERTEX_SHADER,
      color_vertex_shader_src);
  glAttachShader(res->color_program, res->color_vertex_shader);
  res->color_fragment_shader = gl_make_shader(GL_FRAGMENT_SHADER,
      color_fragment_shader_src);
  glAttachShader(res->color_program, res->color_fragment_shader);
  gl_link_and_validate(res->color_program);
  res->color_position_attribute = glGetAttribLocation(res->color_program,
      "position");
  res->color_color_attribute = glGetAttribLocation(res->color_program,
      "color");
  res->color_screen_size_uniform = glGetUniformLocation(res->color_program,
      "screen_size");
  res->texture_program = glCreateProgram();
  res->texture_vertex_shader = gl_make_shader(GL_VERTEX_SHADER,
      texture_vertex_shader_src);
  glAttachShader(res->texture_program, res->texture_vertex_shader);
  res->texture_fragment_shader = gl_make_shader(GL_FRAGMENT_SHADER,
      texture_fragment_shader_src);
  glAttachShader(res->texture_program, res->texture_fragment_shader);
  gl_link_and_validate(res->texture_program);
  res->texture_position_attribute = glGetAttribLocation(res->texture_program,
      "position");
  res->texture_uv_attribute = glGetAttribLocation(res->texture_program,
      "uv");
  res->texture_screen_size_uniform = glGetUniformLocation(res->texture_program,
      "screen_size");
  res->texture_texture_uniform = glGetUniformLocation(res->texture_program,
      "texture");
  glGenBuffers(2, res->buffers);
  glBindBuffer(GL_ARRAY_BUFFER, res->buffers[0]);
  glBufferData(GL_ARRAY_BUFFER, BT_UV_MAX * sizeof(float),
      NULL, GL_DYNAMIC_DRAW);
  glBindBuffer(GL_ARRAY_BUFFER, res->buffers[1]);
  glBufferData(GL_ARRAY_BUFFER, BT_COLOR_MAX * sizeof(float),
      NULL, GL_DYNAMIC_DRAW);
  return res;
 }
 #define PUSH_POINT(_start, _a, _b) \
    *((_start)++) = (_a);\
    *((_start)++) = (_b);
 #define PUSH_COLOR(_start, _a, _b, _c, _d) \
    *((_start)++) = (_a);\
    *((_start)++) = (_b);\
    *((_start)++) = (_c);\
    *((_start)++) = (_d);
 #define PUSH_POINT_UV(_start, _a, _b, _c, _d) \
    PUSH_COLOR(_start, _a, _b, _c, _d)
 void wd_gl_render(struct wd_gl_data *res, struct wd_render_data *info,
    uint64_t tick) {
  unsigned int tris = 0;
  if (info->head_count > res->texture_count) {
    glGenTextures(info->head_count - res->texture_count,
        res->textures + res->texture_count);
    for (int i = res->texture_count; i < info->head_count; i++) {
      glBindTexture(GL_TEXTURE_2D, res->textures[i]);
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
      glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    }
    glBindTexture(GL_TEXTURE_2D, 0);
    res->texture_count = info->head_count;
  }
  for (int i = 0; i < info->head_count; i++) {
    struct wd_render_head_data *head = &info->heads[i];
    float *tri_ptr = res->tris + i * BT_UV_QUAD_SIZE;
    float x1 = head->x1;
    float y1 = head->y1;
    float x2 = head->x2;
    float y2 = head->y2;
    float t1 = head->y_invert ? 1.f : 0.f;
    float t2 = head->y_invert ? 0.f : 1.f;
    PUSH_POINT_UV(tri_ptr, x1, y1, 0.f, t1)
    PUSH_POINT_UV(tri_ptr, x2, y1, 1.f, t1)
    PUSH_POINT_UV(tri_ptr, x1, y2, 0.f, t2)
    PUSH_POINT_UV(tri_ptr, x1, y2, 0.f, t2)
    PUSH_POINT_UV(tri_ptr, x2, y1, 1.f, t1)
    PUSH_POINT_UV(tri_ptr, x2, y2, 1.f, t2)
    tris += 6;
  }
  glClearColor(info->bg_color[0], info->bg_color[1], info->bg_color[2], 1.f);
  glClear(GL_COLOR_BUFFER_BIT);
  float screen_size[2] = { info->viewport_width, info->viewport_height };
  if (tris > 0) {
    glUseProgram(res->texture_program);
    glBindBuffer(GL_ARRAY_BUFFER, res->buffers[0]);
    glBufferSubData(GL_ARRAY_BUFFER, 0,
        tris * BT_UV_VERT_SIZE * sizeof(float), res->tris);
    glEnableVertexAttribArray(res->texture_position_attribute);
    glEnableVertexAttribArray(res->texture_uv_attribute);
    glVertexAttribPointer(res->texture_position_attribute,
        2, GL_FLOAT, GL_FALSE,
        BT_UV_VERT_SIZE * sizeof(float), (void *) (0 * sizeof(float)));
    glVertexAttribPointer(res->texture_uv_attribute, 2, GL_FLOAT, GL_FALSE,
        BT_UV_VERT_SIZE * sizeof(float), (void *) (2 * sizeof(float)));
    glUniform2fv(res->texture_screen_size_uniform, 1, screen_size);
    glUniform1i(res->texture_texture_uniform, 0);
    glActiveTexture(GL_TEXTURE0);
    for (int i = 0; i < info->head_count; i++) {
      struct wd_render_head_data *head = &info->heads[i];
      glBindTexture(GL_TEXTURE_2D, res->textures[i]);
      if (head->updated_at == tick) {
        glPixelStorei(GL_UNPACK_ROW_LENGTH_EXT, head->tex_stride / 4);
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA,
            head->tex_width, head->tex_height,
            0, GL_RGBA, GL_UNSIGNED_BYTE, head->pixels);
        glPixelStorei(GL_UNPACK_ROW_LENGTH_EXT, 0);
      }
      glDrawArrays(GL_TRIANGLES, i * 6, 6);
    }
  }
  tris = 0;
  int j = 0;
  for (int i = 0; i < info->head_count; i++) {
    struct wd_render_head_data *head = &info->heads[i];
    if (head->hovered || tick < head->transition_begin + HOVER_USECS) {
      float *tri_ptr = res->tris + j++ * BT_COLOR_QUAD_SIZE;
      float x1 = head->x1;
      float y1 = head->y1;
      float x2 = head->x2;
      float y2 = head->y2;
      float *color = info->selection_color;
      float d = fminf(
          (tick - head->transition_begin) / (double) HOVER_USECS, 1.f);
      if (!head->hovered) {
        d = 1.f - d;
      }
      d *= 2.f;
      if (d <= 1.f) {
        d = d * d;
      } else {
        d -= 1.f;
        d = d * (2.f - d) + 1.f;
      }
      d /= 2.f;
      float alpha = color[3] * d * .5f;
      PUSH_POINT(tri_ptr, x1, y1)
      PUSH_COLOR(tri_ptr, color[0], color[1], color[2], alpha)
      PUSH_POINT(tri_ptr, x2, y1)
      PUSH_COLOR(tri_ptr, color[0], color[1], color[2], alpha)
      PUSH_POINT(tri_ptr, x1, y2)
      PUSH_COLOR(tri_ptr, color[0], color[1], color[2], alpha)
      PUSH_POINT(tri_ptr, x1, y2)
      PUSH_COLOR(tri_ptr, color[0], color[1], color[2], alpha)
      PUSH_POINT(tri_ptr, x2, y1)
      PUSH_COLOR(tri_ptr, color[0], color[1], color[2], alpha)
      PUSH_POINT(tri_ptr, x2, y2)
      PUSH_COLOR(tri_ptr, color[0], color[1], color[2], alpha)
      tris += 6;
    }
  }
  if (tris > 0) {
    glEnable(GL_BLEND);
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
    glUseProgram(res->color_program);
    glBindBuffer(GL_ARRAY_BUFFER, res->buffers[1]);
    glBufferSubData(GL_ARRAY_BUFFER, 0,
        tris * BT_COLOR_VERT_SIZE * sizeof(float), res->tris);
    glEnableVertexAttribArray(res->color_position_attribute);
    glEnableVertexAttribArray(res->color_color_attribute);
    glVertexAttribPointer(res->color_position_attribute, 2, GL_FLOAT, GL_FALSE,
        BT_COLOR_VERT_SIZE * sizeof(float), (void *) (0 * sizeof(float)));
    glVertexAttribPointer(res->color_color_attribute, 4, GL_FLOAT, GL_FALSE,
        BT_COLOR_VERT_SIZE * sizeof(float), (void *) (2 * sizeof(float)));
    glUniform2fv(res->color_screen_size_uniform, 1, screen_size);
    glDrawArrays(GL_TRIANGLES, 0, tris);
    glDisable(GL_BLEND);
  }
 }
 void wd_gl_cleanup(struct wd_gl_data *res) {
  glDeleteBuffers(2, res->buffers);
  glDeleteShader(res->texture_fragment_shader);
  glDeleteShader(res->texture_vertex_shader);
  glDeleteProgram(res->texture_program);
  glDeleteShader(res->color_fragment_shader);
  glDeleteShader(res->color_vertex_shader);
  glDeleteProgram(res->color_program);
  free(res);
 }
--- a/src/wdisplay.h
+++ b/src/wdisplay.h
@ -31,16 +31,28 @@
 #ifndef WDISPLAY_WDISPLAY_H
 #define WDISPLAY_WDISPLAY_H
 #define HEADS_MAX 64
 #define HOVER_USECS (100 * 1000)
 #include <stdbool.h>
 #include <wayland-client.h>
 struct zxdg_output_v1;
 struct zxdg_output_manager_v1;
 struct zwlr_output_mode_v1;
 struct zwlr_output_head_v1;
 struct zwlr_output_manager_v1;
 struct zwlr_screencopy_manager_v1;
 struct zwlr_screencopy_frame_v1;
 struct _GtkWidget;
 typedef struct _GtkWidget GtkWidget;
 struct _GtkBuilder;
 typedef struct _GtkBuilder GtkBuilder;
 struct _GdkCursor;
 typedef struct _GdkCursor GdkCursor;
 struct _cairo_surface;
 typedef struct _cairo_surface cairo_surface_t;
 enum wd_head_fields {
  WD_FIELD_NAME           = 1 << 0,
@ -54,6 +66,32 @@ enum wd_head_fields {
  WD_FIELDS_ALL           = (1 << 8) - 1
 };
 struct wd_output {
  struct wd_state *state;
  struct zxdg_output_v1 *xdg_output;
  struct wl_output *wl_output;
  struct wl_list link;
  char *name;
  struct wl_list frames;
 };
 struct wd_frame {
  struct wd_output *output;
  struct zwlr_screencopy_frame_v1 *wlr_frame;
  struct wl_list link;
  int capture_fd;
  unsigned stride;
  unsigned width;
  unsigned height;
  struct wl_shm_pool *pool;
  struct wl_buffer *buffer;
  uint8_t *pixels;
  uint64_t tick;
  bool y_invert;
 };
 struct wd_head_config {
  struct wl_list link;
@ -83,6 +121,10 @@ struct wd_head {
  struct zwlr_output_head_v1 *wlr_head;
  struct wl_list link;
  struct wd_output *output;
  struct wd_render_head_data *render;
  cairo_surface_t *surface;
  char *name, *description;
  int32_t phys_width, phys_height; // mm
  struct wl_list modes;
@ -98,16 +140,69 @@ struct wd_head {
  double scale;
 };
 struct wd_gl_data;
 struct wd_render_head_data {
  float x1;
  float y1;
  float x2;
  float y2;
  uint8_t *pixels;
  unsigned tex_stride;
  unsigned tex_width;
  unsigned tex_height;
  bool preview;
  bool y_invert;
  uint64_t updated_at;
  bool hovered;
  uint64_t transition_begin;
 };
 struct wd_render_data {
  float fg_color[4];
  float bg_color[4];
  float border_color[4];
  float selection_color[4];
  unsigned int viewport_width;
  unsigned int viewport_height;
  unsigned int width;
  unsigned int height;
  int scroll_x;
  int scroll_y;
  int x_origin;
  int y_origin;
  uint64_t updated_at;
  unsigned int head_count;
  struct wd_render_head_data heads[HEADS_MAX];
 };
 struct wd_point {
  double x;
  double y;
 };
 struct wd_state {
  struct zxdg_output_manager_v1 *xdg_output_manager;
  struct zwlr_output_manager_v1 *output_manager;
  struct zwlr_screencopy_manager_v1 *copy_manager;
  struct wl_shm *shm;
  struct wl_list heads;
  struct wl_list outputs;
  uint32_t serial;
  bool apply_pending;
  bool autoapply;
  bool capture;
  double zoom;
-  int xorigin;
+
-  int yorigin;
+  struct wd_head *clicked;
  /* top left, bottom right */
  struct wd_point click_offset;
  bool panning;
  struct wd_point pan_last;
  GtkWidget *header_stack;
  GtkWidget *stack_switcher;
@ -122,13 +217,47 @@ struct wd_state {
  GtkWidget *info_bar;
  GtkWidget *info_label;
  GtkWidget *menu_button;
  GdkCursor *grab_cursor;
  GdkCursor *grabbing_cursor;
  GdkCursor *move_cursor;
  unsigned int canvas_tick;
  struct wd_gl_data *gl_data;
  struct wd_render_data render;
 };
 /*
 * Creates the application state structure.
 */
 struct wd_state *wd_state_create(void);
 /*
 * Frees the application state structure.
 */
 void wd_state_destroy(struct wd_state *state);
 /*
 * Displays an error message and then exits the program.
 */
 void wd_fatal_error(int status, const char *message);
 /*
 * Add an output to the list of screen captured outputs.
 */
 void wd_add_output(struct wd_state *state, struct wl_output *wl_output);
 /*
 * Remove an output from the list of screen captured outputs.
 */
 void wd_remove_output(struct wd_state *state, struct wl_output *wl_output, struct wl_display *display);
 /*
 * Finds the output associated with a given head. Can return NULL if the head's
 * output is disabled.
 */
 struct wd_output *wd_find_output(struct wd_state *state, struct wd_head *head);
 /*
 * Starts listening for output management events from the compositor.
 */
@ -139,6 +268,16 @@ void wd_add_output_management_listener(struct wd_state *state, struct wl_display
 */
 void wd_apply_state(struct wd_state *state, struct wl_list *new_outputs);
 /*
 * Queues capture of the next frame of all screens.
 */
 void wd_capture_frame(struct wd_state *state);
 /*
 * Blocks until all captures are finished.
 */
 void wd_capture_wait(struct wd_state *state, struct wl_display *display);
 /*
 * Updates the UI stack of all heads. Does not update individual head forms.
 * Useful for when a display is plugged/unplugged and we want to add/remove
@ -147,7 +286,8 @@ void wd_apply_state(struct wd_state *state, struct wl_list *new_outputs);
 void wd_ui_reset_heads(struct wd_state *state);
 /*
- * Updates a form with head configuration from the server. Only updates specified fields.
+ * Updates the UI form for a single head. Useful for when the compositor
 * notifies us of updated configuration caused by another program.
 */
 void wd_ui_reset_head(const struct wd_head *head, unsigned int fields);
@ -166,4 +306,17 @@ void wd_ui_apply_done(struct wd_state *state, struct wl_list *outputs);
 */
 void wd_ui_show_error(struct wd_state *state, const char *message);
 /*
 * Compiles the GL shaders.
 */
 struct wd_gl_data *wd_gl_setup(void);
 /*
 * Renders the GL scene.
 */
 void wd_gl_render(struct wd_gl_data *res, struct wd_render_data *info, uint64_t tick);
 /*
 * Destroys the GL shaders.
 */
 void wd_gl_cleanup(struct wd_gl_data *res);
 #endif