wayland: Initially paint the window white so that they always exist

src/platform/linux/wayland/window.rs

@@ -1,8 +1,9 @@
+use std::fs::File;
 use std::sync::{Arc, Mutex};
 use std::sync::atomic::AtomicBool;
 
 use wayland_client::{EventQueue, EventQueueHandle, Proxy};
-use wayland_client::protocol::{wl_display,wl_surface,wl_shell_surface};
+use wayland_client::protocol::{wl_display,wl_surface,wl_shell_surface,wl_buffer};
 
 use {CreationError, MouseCursor, CursorState, WindowAttributes};
 use platform::MonitorId as PlatformMonitorId;
@@ -39,16 +40,27 @@ impl Window {
     {
         let (width, height) = attributes.dimensions.unwrap_or((800,600));
 
-        let (surface, decorated) = ctxt.create_window::<DecoratedHandler>();
+        let (surface, decorated, buffer, tmpfile) = ctxt.create_window::<DecoratedHandler>(width, height);
 
         // init DecoratedSurface
         let (evq, cleanup_signal) = evlp.get_window_init();
         let decorated_id = {
             let mut evq_guard = evq.lock().unwrap();
+            // create a handler to clean up initial buffer
+            let initial_buffer_handler_id = evq_guard.add_handler(InitialBufferHandler::new());
+            // register the buffer to it
+            evq_guard.register::<_, InitialBufferHandler>(&buffer, initial_buffer_handler_id);
+            // store the DecoratedSurface handler
             let decorated_id = evq_guard.add_handler_with_init(decorated);
             {
-                // initialize the DecoratedHandler
                 let mut state = evq_guard.state();
+                {
+                    // store the buffer and tempfile in the handler, to be cleanded up at the right
+                    // time
+                    let initial_buffer_h = state.get_mut_handler::<InitialBufferHandler>(initial_buffer_handler_id);
+                    initial_buffer_h.initial_buffer = Some((buffer, tmpfile));
+                }
+                // initialize the DecoratedHandler
                 let decorated = state.get_mut_handler::<DecoratedSurface<DecoratedHandler>>(decorated_id);
                 *(decorated.handler()) = Some(DecoratedHandler::new());
 
@@ -203,3 +215,29 @@ impl wayland_window::Handler for DecoratedHandler {
         self.newsize = Some((max(width,1) as u32, max(height,1) as u32));
     }
 }
+
+// a handler to release the ressources acquired to draw the initial white screen as soon as
+// the compositor does not use them any more
+
+pub struct InitialBufferHandler {
+    initial_buffer: Option<(wl_buffer::WlBuffer, File)>
+}
+
+impl InitialBufferHandler {
+    fn new() -> InitialBufferHandler {
+        InitialBufferHandler {
+            initial_buffer: None,
+        }
+    }
+}
+
+
+impl wl_buffer::Handler for InitialBufferHandler {
+    fn release(&mut self, _: &mut EventQueueHandle, buffer: &wl_buffer::WlBuffer) {
+        // release the ressources we've acquired for initial white window
+        buffer.destroy();
+        self.initial_buffer = None;
+    }
+}
+
+declare_handler!(InitialBufferHandler, wl_buffer::Handler, wl_buffer::WlBuffer);