seat: allow toggling whole output selection

Closes: https://codeberg.org/vyivel/dulcepan/issues/20

src/dulcepan.h

@@ -126,6 +126,14 @@ struct dp_selection {
 	int resize_edges;
 	// Resize anchor
 	double resize_x, resize_y;
+
+	// Used for toggling
+	struct {
+		// If not NULL, the current output has been selected via the dedicated
+		// action rather than by persistent state loading or manual resizing
+		struct dp_output *output;
+		double x, y, width, height;
+	} last_partial;
 };
 
 enum dp_file_format {
@@ -232,7 +240,7 @@ void dp_select_stop_interactive(struct dp_selection *selection);
 void dp_select_notify_pointer_position(
 		struct dp_selection *selection, struct dp_output *output, double x, double y);
 
-void dp_select_whole(struct dp_selection *selection, struct dp_output *output);
+void dp_select_toggle_whole(struct dp_selection *selection, struct dp_output *output);
 
 void dp_save(struct dp_state *state);
 

src/main.c

@@ -176,7 +176,7 @@ static void help(const char *prog) {
 			"\n"
 			"Use the left or right mouse button to select a part of the output. A selection\n"
 			"can also be moved and resized with the left mouse button. Clicking the middle\n"
-			"mouse button selects the entire output.\n",
+			"mouse button toggles the selection of the entire output.\n",
 			prog);
 }
 

src/seat.c

@@ -201,9 +201,9 @@ static void pointer_handle_button(void *data, struct wl_pointer *wl_pointer, uin
 		update_cursor(seat);
 		break;
 	case BTN_MIDDLE:
-		dp_select_whole(selection, seat->ptr_output);
+		dp_select_toggle_whole(selection, seat->ptr_output);
 
-		// dp_select_whole() doesn't invalidate the interactive state, so do it manually
+		// Update the interaction state manually
 		dp_select_notify_pointer_position(selection, seat->ptr_output, seat->ptr_x, seat->ptr_y);
 		update_cursor(seat);
 

src/select.c

@@ -20,6 +20,24 @@ static void set_selected_output(struct dp_selection *selection, struct dp_output
 	}
 }
 
+static inline bool has_last_partial(struct dp_selection *selection) {
+	return selection->last_partial.output != NULL;
+}
+
+static inline void reset_last_partial(struct dp_selection *selection) {
+	selection->last_partial.output = NULL;
+}
+
+static bool has_partial(struct dp_selection *selection) {
+	struct dp_output *output = selection->output;
+	if (output == NULL) {
+		return false;
+	}
+
+	return selection->x != 0 || selection->y != 0 || selection->width != output->effective_width ||
+			selection->height != output->effective_height;
+}
+
 static void update_action(
 		struct dp_selection *selection, struct dp_output *output, double x, double y) {
 	if (output == selection->output) {
@@ -161,6 +179,8 @@ void dp_select_start_interactive(struct dp_selection *selection, struct dp_outpu
 	update_action(selection, output, x, y);
 	selection->action_active = true;
 
+	reset_last_partial(selection);
+
 	if (modify_existing) {
 		switch (selection->action) {
 		case DP_SELECTION_ACTION_NONE:
@@ -213,13 +233,35 @@ void dp_select_notify_pointer_position(
 	}
 }
 
-void dp_select_whole(struct dp_selection *selection, struct dp_output *output) {
+void dp_select_toggle_whole(struct dp_selection *selection, struct dp_output *output) {
+	if (selection->output == output && has_last_partial(selection)) {
+		// Toggle the selection back to the last partial one
+		set_selected_output(selection, selection->last_partial.output);
+
+		selection->x = selection->last_partial.x;
+		selection->y = selection->last_partial.y;
+		selection->width = selection->last_partial.width;
+		selection->height = selection->last_partial.height;
+
+		reset_last_partial(selection);
+	} else {
+		// Don't save another whole output selection as partial
+		if (has_partial(selection) && !has_last_partial(selection)) {
+			selection->last_partial.output = selection->output;
+
+			selection->last_partial.x = selection->x;
+			selection->last_partial.y = selection->y;
+			selection->last_partial.width = selection->width;
+			selection->last_partial.height = selection->height;
+		}
+
 		set_selected_output(selection, output);
 
 		selection->x = 0;
 		selection->y = 0;
 		selection->width = output->effective_width;
 		selection->height = output->effective_height;
-
+	}
-	dp_output_redraw(output);
+
+	dp_output_redraw(selection->output);
 }