Improve the frame callbacks handling

Improve the way wl_surface's frame callbacks are handled. The sooner
they are sent the better is for the clients, as they have more time to
render the next frame, but reducing the time for the compositor to
render its frame. The best compromise is probably to send them out
after the compositor has issued its GL calls but before calling
eglSwapBuffers(), and before the GPU actually draws anything.
Rename the function to send the callbacks to only reflect its purpose,
leaving the compositors free to choose when they want to send them.

Change-Id: Ifcdfcad9e54b4d07d5c087898123ac724395a194
Reviewed-by: Jørgen Lind <jorgen.lind@digia.com>

1 files changed, 49 insertions, 13 deletions

diff --git a/src/compositor/wayland_wrapper/qwlsurface.cpp b/src/compositor/wayland_wrapper/qwlsurface.cpp
index 00a69d289..b7f45c675 100644
--- a/src/compositor/wayland_wrapper/qwlsurface.cpp
+++ b/src/compositor/wayland_wrapper/qwlsurface.cpp
@@ -73,6 +73,39 @@ namespace QtWayland {
 
 static bool QT_WAYLAND_PRINT_BUFFERING_WARNINGS = qEnvironmentVariableIsSet("QT_WAYLAND_PRINT_BUFFERING_WARNINGS");
 
+class FrameCallback {
+public:
+    FrameCallback(Surface *surf, wl_resource *res)
+        : surface(surf)
+        , resource(res)
+    {
+        wl_resource_set_implementation(res, 0, this, destroyCallback);
+    }
+    ~FrameCallback()
+    {
+    }
+    void destroy()
+    {
+        if (resource)
+            wl_resource_destroy(resource);
+        else
+            delete this;
+    }
+    void send(uint time)
+    {
+        wl_callback_send_done(resource, time);
+        wl_resource_destroy(resource);
+    }
+    static void destroyCallback(wl_resource *res)
+    {
+        FrameCallback *_this = static_cast<FrameCallback *>(wl_resource_get_user_data(res));
+        _this->surface->removeFrameCallback(_this);
+        delete _this;
+    }
+    Surface *surface;
+    wl_resource *resource;
+};
+
 Surface::Surface(struct wl_client *client, uint32_t id, Compositor *compositor)
     : QtWaylandServer::wl_surface(client, id)
     , m_compositor(compositor)
@@ -87,7 +120,6 @@ Surface::Surface(struct wl_client *client, uint32_t id, Compositor *compositor)
     , m_transientInactive(false)
     , m_isCursorSurface(false)
 {
-    wl_list_init(&m_frame_callback_list);
 }
 
 Surface::~Surface()
@@ -97,6 +129,11 @@ Surface::~Surface()
 
     for (int i = 0; i < m_bufferPool.size(); i++)
         delete m_bufferPool[i];
+
+    foreach (FrameCallback *c, m_pendingFrameCallbacks)
+        c->destroy();
+    foreach (FrameCallback *c, m_frameCallbacks)
+        c->destroy();
 }
 
 void Surface::releaseSurfaces()
@@ -146,9 +183,8 @@ bool Surface::isYInverted() const
 
 bool Surface::visible() const
 {
-
     SurfaceBuffer *surfacebuffer = currentSurfaceBuffer();
-    return surfacebuffer->waylandBufferHandle();
+    return surfacebuffer ? surfacebuffer->waylandBufferHandle() : 0;
 }
 
 QPointF Surface::pos() const
@@ -222,17 +258,15 @@ GLuint Surface::textureId() const
 void Surface::sendFrameCallback()
 {
     uint time = m_compositor->currentTimeMsecs();
-    struct wl_resource *frame_callback, *next;
-    wl_list_for_each_safe(frame_callback, next, &m_frame_callback_list, link) {
-        wl_callback_send_done(frame_callback, time);
-        wl_resource_destroy(frame_callback);
-    }
-    wl_list_init(&m_frame_callback_list);
+    foreach (FrameCallback *callback, m_frameCallbacks)
+        callback->send(time);
+    m_frameCallbacks.clear();
 }
 
-void Surface::frameFinished()
+void Surface::removeFrameCallback(FrameCallback *callback)
 {
-    m_compositor->frameFinished(this);
+    m_pendingFrameCallbacks.removeOne(callback);
+    m_frameCallbacks.removeOne(callback);
 }
 
 QWaylandSurface * Surface::waylandSurface() const
@@ -344,7 +378,6 @@ void Surface::setBackBuffer(SurfaceBuffer *buffer)
              emit m_waylandSurface->unmapped();
         }
 
-        m_compositor->markSurfaceAsDirty(this);
         emit m_waylandSurface->damaged(m_backBuffer->damageRect());
     } else {
         InputDevice *inputDevice = m_compositor->defaultInputDevice();
@@ -438,7 +471,7 @@ void Surface::surface_damage(Resource *, int32_t x, int32_t y, int32_t width, in
 void Surface::surface_frame(Resource *resource, uint32_t callback)
 {
     struct wl_resource *frame_callback = wl_client_add_object(resource->client(), &wl_callback_interface, 0, callback, this);
-    wl_list_insert(&m_frame_callback_list, &frame_callback->link);
+    m_pendingFrameCallbacks << new FrameCallback(this, frame_callback);
 }
 
 void Surface::surface_set_opaque_region(Resource *, struct wl_resource *region)
@@ -474,6 +507,9 @@ void Surface::surface_commit(Resource *)
         setBackBuffer(surfaceBuffer);
         m_bufferQueue.takeFirst();
     }
+
+    m_frameCallbacks << m_pendingFrameCallbacks;
+    m_pendingFrameCallbacks.clear();
 }
 
 void Surface::setClassName(const QString &className)