Remove the buffer queue.

A client calling attach(A);commit();attach(B);commit() should result
in its back buffer be set to B, and A be discarded.
If the client wants to have a queue it should keep it client side or
a protocol extension tailored for that purpose should be developed.

Change-Id: Ia0048f311504d85821df9f5b9225887801efec71
Reviewed-by: Jørgen Lind <jorgen.lind@digia.com>

11 files changed, 59 insertions, 112 deletions

diff --git a/examples/qwidget-compositor/main.cpp b/examples/qwidget-compositor/main.cpp
index c0e688cf..cf7fdda7 100644
--- a/examples/qwidget-compositor/main.cpp
+++ b/examples/qwidget-compositor/main.cpp
@@ -110,13 +110,13 @@ private slots:
         update();
     }
 
-    void surfaceDamaged(const QRect &rect) {
+    void surfaceDamaged(const QRegion &rect) {
         QWaylandSurface *surface = qobject_cast<QWaylandSurface *>(sender());
         surfaceDamaged(surface, rect);
     }
 
 protected:
-    void surfaceDamaged(QWaylandSurface *surface, const QRect &rect)
+    void surfaceDamaged(QWaylandSurface *surface, const QRegion &rect)
     {
 #ifdef QT_COMPOSITOR_WAYLAND_GL
         Q_UNUSED(surface);
@@ -130,7 +130,7 @@ protected:
     void surfaceCreated(QWaylandSurface *surface) {
         connect(surface, SIGNAL(destroyed(QObject *)), this, SLOT(surfaceDestroyed(QObject *)));
         connect(surface, SIGNAL(mapped()), this, SLOT(surfaceMapped()));
-        connect(surface, SIGNAL(damaged(const QRect &)), this, SLOT(surfaceDamaged(const QRect &)));
+        connect(surface, SIGNAL(damaged(const QRegion &)), this, SLOT(surfaceDamaged(const QRegion &)));
         update();
     }
 
@@ -140,7 +140,7 @@ protected:
         QOpenGLFunctions *functions = QOpenGLContext::currentContext()->functions();
 
         QSize windowSize = surface->size();
-        surface->advanceBufferQueue();
+        surface->swapBuffers();
 
         if (!m_surfaceCompositorFbo)
             functions->glGenFramebuffers(1,&m_surfaceCompositorFbo);
@@ -173,7 +173,7 @@ protected:
             QWaylandSurface *subSurface = i.next();
             QPointF p = subSurface->mapTo(window,QPoint(0,0));
             QSize size = subSurface->size();
-            subSurface->advanceBufferQueue();
+            subSurface->swapBuffers();
             if (size.isValid()) {
                 GLuint texture = 0;
                 if (subSurface->type() == QWaylandSurface::Texture) {
diff --git a/examples/qwindow-compositor/qwindowcompositor.cpp b/examples/qwindow-compositor/qwindowcompositor.cpp
index 1d9c3d5e..9eef717e 100644
--- a/examples/qwindow-compositor/qwindowcompositor.cpp
+++ b/examples/qwindow-compositor/qwindowcompositor.cpp
@@ -159,7 +159,7 @@ void QWindowCompositor::surfaceUnmapped()
     ensureKeyboardFocusSurface(surface);
 }
 
-void QWindowCompositor::surfaceDamaged(const QRect &rect)
+void QWindowCompositor::surfaceDamaged(const QRegion &rect)
 {
     QWaylandSurface *surface = qobject_cast<QWaylandSurface *>(sender());
     surfaceDamaged(surface, rect);
@@ -170,7 +170,7 @@ void QWindowCompositor::surfacePosChanged()
     m_renderScheduler.start(0);
 }
 
-void QWindowCompositor::surfaceDamaged(QWaylandSurface *surface, const QRect &rect)
+void QWindowCompositor::surfaceDamaged(QWaylandSurface *surface, const QRegion &rect)
 {
     Q_UNUSED(surface)
     Q_UNUSED(rect)
@@ -182,7 +182,7 @@ void QWindowCompositor::surfaceCreated(QWaylandSurface *surface)
     connect(surface, SIGNAL(destroyed(QObject *)), this, SLOT(surfaceDestroyed(QObject *)));
     connect(surface, SIGNAL(mapped()), this, SLOT(surfaceMapped()));
     connect(surface, SIGNAL(unmapped()), this, SLOT(surfaceUnmapped()));
-    connect(surface, SIGNAL(damaged(const QRect &)), this, SLOT(surfaceDamaged(const QRect &)));
+    connect(surface, SIGNAL(damaged(const QRegion &)), this, SLOT(surfaceDamaged(const QRegion &)));
     connect(surface, SIGNAL(extendedSurfaceReady()), this, SLOT(sendExpose()));
     connect(surface, SIGNAL(posChanged()), this, SLOT(surfacePosChanged()));
     m_renderScheduler.start(0);
@@ -253,7 +253,7 @@ GLuint QWindowCompositor::composeSurface(QWaylandSurface *surface, bool *texture
     GLuint texture = 0;
 
     QSize windowSize = surface->size();
-    surface->advanceBufferQueue();
+    surface->swapBuffers();
 
     QOpenGLFunctions *functions = QOpenGLContext::currentContext()->functions();
     functions->glBindFramebuffer(GL_FRAMEBUFFER, m_surface_fbo);
@@ -288,7 +288,7 @@ void QWindowCompositor::paintChildren(QWaylandSurface *surface, QWaylandSurface
         QWaylandSurface *subSurface = i.next();
         QPointF p = subSurface->mapTo(window,QPointF(0,0));
         QSize subSize = subSurface->size();
-        subSurface->advanceBufferQueue();
+        subSurface->swapBuffers();
         if (subSize.isValid()) {
             GLuint texture = 0;
             if (subSurface->type() == QWaylandSurface::Texture) {
diff --git a/examples/qwindow-compositor/qwindowcompositor.h b/examples/qwindow-compositor/qwindowcompositor.h
index c58c0d57..f8d354c3 100644
--- a/examples/qwindow-compositor/qwindowcompositor.h
+++ b/examples/qwindow-compositor/qwindowcompositor.h
@@ -61,12 +61,12 @@ private slots:
     void surfaceDestroyed(QObject *object);
     void surfaceMapped();
     void surfaceUnmapped();
-    void surfaceDamaged(const QRect &rect);
+    void surfaceDamaged(const QRegion &rect);
     void surfacePosChanged();
 
     void render();
 protected:
-    void surfaceDamaged(QWaylandSurface *surface, const QRect &rect);
+    void surfaceDamaged(QWaylandSurface *surface, const QRegion &rect);
     void surfaceCreated(QWaylandSurface *surface);
 
     QWaylandSurface* surfaceAt(const QPointF &point, QPointF *local = 0);
diff --git a/src/compositor/compositor_api/qwaylandsurface.cpp b/src/compositor/compositor_api/qwaylandsurface.cpp
index a865f32d..f9eda135 100644
--- a/src/compositor/compositor_api/qwaylandsurface.cpp
+++ b/src/compositor/compositor_api/qwaylandsurface.cpp
@@ -104,10 +104,10 @@ QWaylandSurface::QWaylandSurface(QtWayland::Surface *surface)
 #endif
 }
 
-void QWaylandSurface::advanceBufferQueue()
+void QWaylandSurface::swapBuffers()
 {
     Q_D(const QWaylandSurface);
-    d->surface->advanceBufferQueue();
+    d->surface->swapBuffers();
 }
 
 WaylandClient *QWaylandSurface::client() const
diff --git a/src/compositor/compositor_api/qwaylandsurface.h b/src/compositor/compositor_api/qwaylandsurface.h
index 7dc219d9..774464a8 100644
--- a/src/compositor/compositor_api/qwaylandsurface.h
+++ b/src/compositor/compositor_api/qwaylandsurface.h
@@ -178,7 +178,7 @@ public:
     Q_INVOKABLE void destroySurfaceByForce();
     Q_INVOKABLE void ping();
 
-    void advanceBufferQueue();
+    void swapBuffers();
 
 public slots:
     void updateSelection();
@@ -186,7 +186,7 @@ public slots:
 signals:
     void mapped();
     void unmapped();
-    void damaged(const QRect &rect);
+    void damaged(const QRegion &rect);
     void parentChanged(QWaylandSurface *newParent, QWaylandSurface *oldParent);
     void sizeChanged();
     void posChanged();
diff --git a/src/compositor/compositor_api/qwaylandsurfaceitem.cpp b/src/compositor/compositor_api/qwaylandsurfaceitem.cpp
index 04649fa7..b87bbb61 100644
--- a/src/compositor/compositor_api/qwaylandsurfaceitem.cpp
+++ b/src/compositor/compositor_api/qwaylandsurfaceitem.cpp
@@ -298,7 +298,7 @@ void QWaylandSurfaceItem::setDamagedFlag(bool on)
 }
 
 
-void QWaylandSurfaceItem::surfaceDamaged(const QRect &)
+void QWaylandSurfaceItem::surfaceDamaged(const QRegion &)
 {
     m_damaged = true;
     if (m_surface) {
@@ -390,7 +390,7 @@ QSGNode *QWaylandSurfaceItem::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeD
     // Order here is important, as the state of visible is that of the pending
     // buffer but will be replaced after we advance the buffer queue.
     bool visible = m_surface->visible();
-    surface()->advanceBufferQueue();
+    surface()->swapBuffers();
     if (visible)
         updateTexture();
 
diff --git a/src/compositor/compositor_api/qwaylandsurfaceitem.h b/src/compositor/compositor_api/qwaylandsurfaceitem.h
index 26288a7d..b17b892f 100644
--- a/src/compositor/compositor_api/qwaylandsurfaceitem.h
+++ b/src/compositor/compositor_api/qwaylandsurfaceitem.h
@@ -112,7 +112,7 @@ private slots:
     void surfaceMapped();
     void surfaceUnmapped();
     void surfaceDestroyed(QObject *object);
-    void surfaceDamaged(const QRect &);
+    void surfaceDamaged(const QRegion &);
     void parentChanged(QWaylandSurface *newParent, QWaylandSurface *oldParent);
     void updateSize();
     void updateSurfaceSize();
diff --git a/src/compositor/wayland_wrapper/qwlsurface.cpp b/src/compositor/wayland_wrapper/qwlsurface.cpp
index 79b83ab7..a0e61bc2 100644
--- a/src/compositor/wayland_wrapper/qwlsurface.cpp
+++ b/src/compositor/wayland_wrapper/qwlsurface.cpp
@@ -129,6 +129,8 @@ Surface::Surface(struct wl_client *client, uint32_t id, Compositor *compositor)
     , m_transientInactive(false)
     , m_isCursorSurface(false)
 {
+    m_pending.buffer = 0;
+    m_pending.newlyAttached = false;
 }
 
 Surface::~Surface()
@@ -335,7 +337,7 @@ Compositor *Surface::compositor() const
     return m_compositor;
 }
 
-void Surface::advanceBufferQueue()
+void Surface::swapBuffers()
  {
     SurfaceBuffer *front = m_frontBuffer;
 
@@ -349,16 +351,6 @@ void Surface::advanceBufferQueue()
         m_backBuffer = 0;
     }
 
-    // Set a new back buffer if there is something in the queue.
-    if (m_bufferQueue.size() && m_bufferQueue.first()->isComitted()) {
-        SurfaceBuffer *next = m_bufferQueue.takeFirst();
-        while (next && next->isDestroyed()) {
-            next->disown();
-            next = m_bufferQueue.size() ? m_bufferQueue.takeFirst() : 0;
-        }
-        setBackBuffer(next);
-    }
-
     // Release the old front buffer if we changed it.
     if (front && front != m_frontBuffer)
         front->disown();
@@ -366,7 +358,7 @@ void Surface::advanceBufferQueue()
 
 /*!
  * Sets the backbuffer for this surface. The back buffer is not yet on
- * screen and will become live during the next advanceBufferQueue().
+ * screen and will become live during the next swapBuffers().
  *
  * The backbuffer represents the current state of the surface for the
  * purpose of GUI-thread accessible properties such as size and visibility.
@@ -387,7 +379,8 @@ void Surface::setBackBuffer(SurfaceBuffer *buffer)
              emit m_waylandSurface->unmapped();
         }
 
-        emit m_waylandSurface->damaged(m_backBuffer->damageRect());
+        m_damage = m_damage.intersected(QRect(QPoint(), m_size));
+        emit m_waylandSurface->damaged(m_damage);
     } else {
         InputDevice *inputDevice = m_compositor->defaultInputDevice();
         if (inputDevice->keyboardFocus() == this)
@@ -395,6 +388,7 @@ void Surface::setBackBuffer(SurfaceBuffer *buffer)
         if (inputDevice->mouseFocus() == this)
             inputDevice->setMouseFocus(0, QPointF(), QPointF());
     }
+    m_damage = QRegion();
 }
 
 SurfaceBuffer *Surface::createSurfaceBuffer(struct ::wl_resource *buffer)
@@ -419,41 +413,6 @@ SurfaceBuffer *Surface::createSurfaceBuffer(struct ::wl_resource *buffer)
     return newBuffer;
 }
 
-void Surface::attach(struct ::wl_resource *buffer)
-{
-    SurfaceBuffer *last = m_bufferQueue.size()?m_bufferQueue.last():0;
-    if (last) {
-        if (last->waylandBufferHandle() == buffer) {
-            if (QT_WAYLAND_PRINT_BUFFERING_WARNINGS)
-                qWarning() << "attaching already attached buffer";
-            return;
-        }
-        if (!last->damageRect().isValid() || !last->isComitted() || isCursorSurface() ){
-            last->disown();
-            m_bufferQueue.takeLast();
-        }
-    }
-
-    SurfaceBuffer *surfBuf = createSurfaceBuffer(buffer);
-    m_bufferQueue << surfBuf;
-}
-
-void Surface::damage(const QRect &rect)
-{
-    if (m_bufferQueue.empty()) {
-        if (QT_WAYLAND_PRINT_BUFFERING_WARNINGS)
-            qWarning() << "Surface::damage() null buffer";
-        return;
-    }
-    SurfaceBuffer *surfaceBuffer =  m_bufferQueue.last();
-    if (surfaceBuffer->isComitted()) {
-        if (QT_WAYLAND_PRINT_BUFFERING_WARNINGS)
-            qWarning("Surface::damage() on a committed surface");
-    } else{
-        surfaceBuffer->setDamage(rect);
-    }
-}
-
 void Surface::surface_destroy_resource(Resource *)
 {
     compositor()->destroySurface(this);
@@ -466,15 +425,16 @@ void Surface::surface_destroy(Resource *resource)
 
 void Surface::surface_attach(Resource *, struct wl_resource *buffer, int x, int y)
 {
-    Q_UNUSED(x);
-    Q_UNUSED(y);
-
-    attach(buffer);
+    if (m_pending.buffer)
+        m_pending.buffer->disown();
+    m_pending.buffer = createSurfaceBuffer(buffer);
+    m_pending.offset = QPoint(x, y);
+    m_pending.newlyAttached = true;
 }
 
 void Surface::surface_damage(Resource *, int32_t x, int32_t y, int32_t width, int32_t height)
 {
-    damage(QRect(x, y, width, height));
+    m_pending.damage = m_pending.damage.united(QRect(x, y, width, height));
 }
 
 void Surface::surface_frame(Resource *resource, uint32_t callback)
@@ -495,28 +455,27 @@ void Surface::surface_set_input_region(Resource *, struct wl_resource *region)
 
 void Surface::surface_commit(Resource *)
 {
-    if (m_bufferQueue.empty()) {
-        if (QT_WAYLAND_PRINT_BUFFERING_WARNINGS)
-            qWarning("Commit on invalid surface");
-        return;
-    }
+    m_damage = m_pending.damage;
 
-    SurfaceBuffer *surfaceBuffer = m_bufferQueue.last();
-    if (surfaceBuffer->isComitted()) {
-        if (QT_WAYLAND_PRINT_BUFFERING_WARNINGS)
-            qWarning("Committing buffer that has already been committed");
-    } else {
-        surfaceBuffer->setCommitted();
-    }
+    if (m_pending.buffer || m_pending.newlyAttached) {
+        if (m_backBuffer && m_backBuffer != m_pending.buffer)
+            m_backBuffer->disown();
 
-    // A new buffer was added to the queue, so we set it as the current
-    // back buffer. Second and third buffers, if the come, will be handled
-    // in advanceBufferQueue().
-    if (!m_backBuffer && m_bufferQueue.size() == 1) {
-        setBackBuffer(surfaceBuffer);
-        m_bufferQueue.takeFirst();
+        setBackBuffer(m_pending.buffer);
+        if (!m_backBuffer && m_surfaceMapped) {
+            m_surfaceMapped = false;
+            emit m_waylandSurface->unmapped();
+        }
     }
 
+    m_pending.buffer = 0;
+    m_pending.offset = QPoint();
+    m_pending.newlyAttached = false;
+    m_pending.damage = QRegion();
+
+    if (m_backBuffer)
+        m_backBuffer->setCommitted();
+
     m_frameCallbacks << m_pendingFrameCallbacks;
     m_pendingFrameCallbacks.clear();
 }
diff --git a/src/compositor/wayland_wrapper/qwlsurface_p.h b/src/compositor/wayland_wrapper/qwlsurface_p.h
index bad65e93..af7d1e0c 100644
--- a/src/compositor/wayland_wrapper/qwlsurface_p.h
+++ b/src/compositor/wayland_wrapper/qwlsurface_p.h
@@ -48,6 +48,7 @@
 
 #include <QtCore/QVector>
 #include <QtCore/QRect>
+#include <QtGui/QRegion>
 #include <QtGui/QImage>
 
 #include <QtCore/QTextStream>
@@ -139,7 +140,7 @@ public:
     bool isCursorSurface() const { return m_isCursorSurface; }
     void setCursorSurface(bool isCursor) { m_isCursorSurface = isCursor; }
 
-    void advanceBufferQueue();
+    void swapBuffers();
     void releaseSurfaces();
 
 private:
@@ -149,10 +150,17 @@ private:
     QWaylandSurface *m_waylandSurface;
 
     SurfaceBuffer *m_backBuffer;
+    QRegion m_damage;
     SurfaceBuffer *m_frontBuffer;
-    QList<SurfaceBuffer *> m_bufferQueue;
     bool m_surfaceMapped;
 
+    struct {
+        SurfaceBuffer *buffer;
+        QRegion damage;
+        QPoint offset;
+        bool newlyAttached;
+    } m_pending;
+
     QPoint m_lastLocalMousePos;
     QPoint m_lastGlobalMousePos;
 
@@ -177,12 +185,9 @@ private:
     bool m_isCursorSurface;
 
     inline SurfaceBuffer *currentSurfaceBuffer() const;
-    void damage(const QRect &rect);
     void setBackBuffer(SurfaceBuffer *buffer);
     SurfaceBuffer *createSurfaceBuffer(struct ::wl_resource *buffer);
 
-    void attach(struct ::wl_resource *buffer);
-
     void surface_destroy_resource(Resource *resource) Q_DECL_OVERRIDE;
 
     void surface_destroy(Resource *resource) Q_DECL_OVERRIDE;
diff --git a/src/compositor/wayland_wrapper/qwlsurfacebuffer.cpp b/src/compositor/wayland_wrapper/qwlsurfacebuffer.cpp
index 1d919cdf..b0e67e1f 100644
--- a/src/compositor/wayland_wrapper/qwlsurfacebuffer.cpp
+++ b/src/compositor/wayland_wrapper/qwlsurfacebuffer.cpp
@@ -96,7 +96,6 @@ void SurfaceBuffer::initialize(struct ::wl_resource *buffer)
     m_destroy_listener.listener.notify = destroy_listener_callback;
     if (buffer)
         wl_signal_add(&buffer->destroy_signal, &m_destroy_listener.listener);
-    m_damageRect = QRect();
 }
 
 void SurfaceBuffer::destructBufferState()
@@ -171,18 +170,6 @@ void SurfaceBuffer::disown()
 void SurfaceBuffer::setDisplayed()
 {
     m_is_displayed = true;
-    m_damageRect = QRect();
-}
-
-void SurfaceBuffer::setDamage(const QRect &rect)
-{
-    if (m_damageRect.isValid()) {
-        m_damageRect = m_damageRect.united(rect);
-    } else {
-        m_damageRect = rect;
-    }
-    m_image = QImage();
-
 }
 
 void SurfaceBuffer::destroyTexture()
diff --git a/src/compositor/wayland_wrapper/qwlsurfacebuffer_p.h b/src/compositor/wayland_wrapper/qwlsurfacebuffer_p.h
index 257c8246..c2c39253 100644
--- a/src/compositor/wayland_wrapper/qwlsurfacebuffer_p.h
+++ b/src/compositor/wayland_wrapper/qwlsurfacebuffer_p.h
@@ -87,9 +87,6 @@ public:
     inline void setCommitted() { m_committed = true; }
     inline bool isDisplayed() const { return m_is_displayed; }
 
-    inline QRect damageRect() const { return m_damageRect; }
-    void setDamage(const QRect &rect);
-
     inline bool textureCreated() const { return m_texture; }
 
     bool isDestroyed() { return m_destroyed; }
@@ -112,7 +109,6 @@ private:
     Compositor *m_compositor;
     struct ::wl_resource *m_buffer;
     struct surface_buffer_destroy_listener m_destroy_listener;
-    QRect m_damageRect;
     bool m_committed;
     bool m_is_registered_for_buffer;
     bool m_surface_has_buffer;