Copyright © 2017 Drew DeVault Permission to use, copy, modify, distribute, and sell this software and its documentation for any purpose is hereby granted without fee, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation, and that the name of the copyright holders not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission. The copyright holders make no representations about the suitability of this software for any purpose. It is provided "as is" without express or implied warranty. THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. Clients can use this interface to assign the surface_layer role to wl_surfaces. Such surfaces are assigned to a "layer" of the output and rendered with a defined z-depth respective to each other. They may also be anchored to the edges and corners of a screen and specify input handling semantics. This interface should be suitable for the implementation of many desktop shell components, and a broad number of other applications that interact with the desktop. Create a layer surface for an existing surface. This assigns the role of layer_surface, or raises a protocol error if another role is already assigned. Creating a layer surface from a wl_surface which has a buffer attached or committed is a client error, and any attempts by a client to attach or manipulate a buffer prior to the first layer_surface.configure call must also be treated as errors. You may pass NULL for output to allow the compositor to decide which output to use. Generally this will be the one that the user most recently interacted with. Clients can specify a namespace that defines the purpose of the layer surface. These values indicate which layers a surface can be rendered in. They are ordered by z depth, bottom-most first. Traditional shell surfaces will typically be rendered between the bottom and top layers. Fullscreen shell surfaces are typically rendered at the top layer. Multiple surfaces can share a single layer, and ordering within a single layer is undefined. An interface that may be implemented by a wl_surface, for surfaces that are designed to be rendered as a layer of a stacked desktop-like environment. Layer surface state (size, anchor, exclusive zone, margin, interactivity) is double-buffered, and will be applied at the time wl_surface.commit of the corresponding wl_surface is called. Sets the size of the surface in surface-local coordinates. The compositor will display the surface centered with respect to its anchors. If you pass 0 for either value, the compositor will assign it and inform you of the assignment in the configure event. You must set your anchor to opposite edges in the dimensions you omit; not doing so is a protocol error. Both values are 0 by default. Size is double-buffered, see wl_surface.commit. Requests that the compositor anchor the surface to the specified edges and corners. If two orthoginal edges are specified (e.g. 'top' and 'left'), then the anchor point will be the intersection of the edges (e.g. the top left corner of the output); otherwise the anchor point will be centered on that edge, or in the center if none is specified. Anchor is double-buffered, see wl_surface.commit. Requests that the compositor avoids occluding an area of the surface with other surfaces. The compositor's use of this information is implementation-dependent - do not assume that this region will not actually be occluded. A positive value is only meaningful if the surface is anchored to an edge, rather than a corner. The zone is the number of surface-local coordinates from the edge that are considered exclusive. Surfaces that do not wish to have an exclusive zone may instead specify how they should interact with surfaces that do. If set to zero, the surface indicates that it would like to be moved to avoid occluding surfaces with a positive excluzive zone. If set to -1, the surface indicates that it would not like to be moved to accommodate for other surfaces, and the compositor should extend it all the way to the edges it is anchored to. For example, a panel might set its exclusive zone to 10, so that maximized shell surfaces are not shown on top of it. A notification might set its exclusive zone to 0, so that it is moved to avoid occluding the panel, but shell surfaces are shown underneath it. A wallpaper or lock screen might set their exclusive zone to -1, so that they stretch below or over the panel. The default value is 0. Exclusive zone is double-buffered, see wl_surface.commit. Requests that the surface be placed some distance away from the anchor point on the output, in surface-local coordinates. Setting this value for edges you are not anchored to has no effect. The exclusive zone includes the margin. Margin is double-buffered, see wl_surface.commit. Set to 1 to request that the seat send keyboard events to this layer surface. For layers below the shell surface layer, the seat will use normal focus semantics. For layers above the shell surface layers, the seat will always give exclusive keyboard focus to the top-most layer which has keyboard interactivity set to true. Layer surfaces receive pointer, touch, and tablet events normally. If you do not want to receive them, set the input region on your surface to an empty region. Events is double-buffered, see wl_surface.commit. This assigns an xdg_popup's parent to this layer_surface. This popup should have been created via xdg_surface::get_popup with the parent set to NULL, and this request must be invoked before committing the popup's initial state. See the documentation of xdg_popup for more details about what an xdg_popup is and how it is used. When a configure event is received, if a client commits the surface in response to the configure event, then the client must make an ack_configure request sometime before the commit request, passing along the serial of the configure event. If the client receives multiple configure events before it can respond to one, it only has to ack the last configure event. A client is not required to commit immediately after sending an ack_configure request - it may even ack_configure several times before its next surface commit. A client may send multiple ack_configure requests before committing, but only the last request sent before a commit indicates which configure event the client really is responding to. This request destroys the layer surface. The configure event asks the client to resize its surface. Clients should arrange their surface for the new states, and then send an ack_configure request with the serial sent in this configure event at some point before committing the new surface. The client is free to dismiss all but the last configure event it received. The width and height arguments specify the size of the window in surface-local coordinates. The size is a hint, in the sense that the client is free to ignore it if it doesn't resize, pick a smaller size (to satisfy aspect ratio or resize in steps of NxM pixels). If the client picks a smaller size and is anchored to two opposite anchors (e.g. 'top' and 'bottom'), the surface will be centered on this axis. If the width or height arguments are zero, it means the client should decide its own window dimension. The closed event is sent by the compositor when the surface will no longer be shown. The output may have been destroyed or the user may have asked for it to be removed. Further changes to the surface will be ignored. The client should destroy the resource after receiving this event, and create a new surface if they so choose.