New class to encapsulate a Window's Pixmap

The behavior for creating a pixmap for a window is moved from Toplevel
into a dedicated class WindowPixmap. Scene::Window holds a reference to
this class and creates a new WindowPixmap whenever the pixmap needs to be
discarded. In addition it also keeps the old WindowPixmap around for the
case that creating the new pixmap fails. The compositor can in that case
use the previous pixmap which reduces possible flickering. Also this
referencing can be used to improve transition effects like the maximize
windows effect which would benefit from starting with the old pixmap.

For XRender and OpenGL a dedicated sub-class of the WindowPixmap is
created which provides the additional mapping to an XRender picture and
OpenGL texture respectively.

BUG: 319563
FIXED-IN: 4.11
REVIEW: 110577

composite.cpp

@@ -881,45 +881,10 @@ void Toplevel::finishCompositing()
 void Toplevel::discardWindowPixmap()
 {
     addDamageFull();
-    if (window_pix == XCB_PIXMAP_NONE)
-        return;
-    xcb_free_pixmap(connection(), window_pix);
-    window_pix = XCB_PIXMAP_NONE;
     if (effectWindow() != NULL && effectWindow()->sceneWindow() != NULL)
         effectWindow()->sceneWindow()->pixmapDiscarded();
 }
 
-xcb_pixmap_t Toplevel::createWindowPixmap()
-{
-    assert(compositing());
-    if (unredirected())
-        return XCB_PIXMAP_NONE;
-    XServerGrabber grabber();
-    xcb_pixmap_t pix = xcb_generate_id(connection());
-    xcb_void_cookie_t namePixmapCookie = xcb_composite_name_window_pixmap_checked(connection(), frameId(), pix);
-    Xcb::WindowAttributes windowAttributes(frameId());
-    Xcb::WindowGeometry windowGeometry(frameId());
-    if (xcb_generic_error_t *error = xcb_request_check(connection(), namePixmapCookie)) {
-        kDebug(1212) << "Creating window pixmap failed: " << error->error_code;
-        free(error);
-        return XCB_PIXMAP_NONE;
-    }
-    // check that the received pixmap is valid and actually matches what we
-    // know about the window (i.e. size)
-    if (!windowAttributes || windowAttributes->map_state != XCB_MAP_STATE_VIEWABLE) {
-        kDebug(1212) << "Creating window pixmap failed: " << this;
-        xcb_free_pixmap(connection(), pix);
-        return XCB_PIXMAP_NONE;
-    }
-    if (!windowGeometry ||
-        windowGeometry->width != width() || windowGeometry->height != height()) {
-        kDebug(1212) << "Creating window pixmap failed: " << this;
-        xcb_free_pixmap(connection(), pix);
-        return XCB_PIXMAP_NONE;
-    }
-    return pix;
-}
-
 void Toplevel::damageNotifyEvent()
 {
     m_isDamaged = true;

scene.cpp

@@ -581,6 +581,9 @@ Scene::Window::Window(Toplevel * c)
     : toplevel(c)
     , filter(ImageFilterFast)
     , m_shadow(NULL)
+    , m_currentPixmap()
+    , m_previousPixmap()
+    , m_referencePixmapCounter(0)
     , disable_painting(0)
     , shape_valid(false)
     , cached_quad_list(NULL)
@@ -593,6 +596,32 @@ Scene::Window::~Window()
     delete m_shadow;
 }
 
+void Scene::Window::referencePreviousPixmap()
+{
+    if (!m_previousPixmap.isNull() && m_previousPixmap->isDiscarded()) {
+        m_referencePixmapCounter++;
+    }
+}
+
+void Scene::Window::unreferencePreviousPixmap()
+{
+    if (m_previousPixmap.isNull() || !m_previousPixmap->isDiscarded()) {
+        return;
+    }
+    m_referencePixmapCounter--;
+    if (m_referencePixmapCounter == 0) {
+        m_previousPixmap.reset();
+    }
+}
+
+void Scene::Window::pixmapDiscarded()
+{
+    if (!m_currentPixmap.isNull() && m_currentPixmap->isValid()) {
+        m_previousPixmap.reset(m_currentPixmap.take());
+        m_previousPixmap->markAsDiscarded();
+    }
+}
+
 void Scene::Window::discardShape()
 {
     // it is created on-demand and cached, simply
@@ -797,6 +826,56 @@ WindowQuadList Scene::Window::makeQuads(WindowQuadType type, const QRegion& reg)
     return ret;
 }
 
+//****************************************
+// WindowPixmap
+//****************************************
+WindowPixmap::WindowPixmap(Scene::Window *window)
+    : m_window(window)
+    , m_pixmap(XCB_PIXMAP_NONE)
+    , m_discarded(false)
+{
+}
+
+WindowPixmap::~WindowPixmap()
+{
+    if (isValid()) {
+        xcb_free_pixmap(connection(), m_pixmap);
+    }
+}
+
+void WindowPixmap::create()
+{
+    if (isValid()) {
+        return;
+    }
+    XServerGrabber grabber();
+    xcb_pixmap_t pix = xcb_generate_id(connection());
+    xcb_void_cookie_t namePixmapCookie = xcb_composite_name_window_pixmap_checked(connection(), toplevel()->frameId(), pix);
+    Xcb::WindowAttributes windowAttributes(toplevel()->frameId());
+    Xcb::WindowGeometry windowGeometry(toplevel()->frameId());
+    if (xcb_generic_error_t *error = xcb_request_check(connection(), namePixmapCookie)) {
+        kDebug(1212) << "Creating window pixmap failed: " << error->error_code;
+        free(error);
+        return;
+    }
+    // check that the received pixmap is valid and actually matches what we
+    // know about the window (i.e. size)
+    if (!windowAttributes || windowAttributes->map_state != XCB_MAP_STATE_VIEWABLE) {
+        kDebug(1212) << "Creating window pixmap failed: " << this;
+        xcb_free_pixmap(connection(), pix);
+        return;
+    }
+    if (!windowGeometry ||
+        windowGeometry->width != toplevel()->width() || windowGeometry->height != toplevel()->height()) {
+        kDebug(1212) << "Creating window pixmap failed: " << this;
+        xcb_free_pixmap(connection(), pix);
+        return;
+    }
+    m_pixmap = pix;
+    m_pixmapSize = QSize(toplevel()->width(), toplevel()->height());
+    m_window->unreferencePreviousPixmap();
+}
+
 //****************************************
 // Scene::EffectFrame
 //****************************************

scene.h

@@ -39,6 +39,7 @@ class EffectFrameImpl;
 class EffectWindowImpl;
 class OverlayWindow;
 class Shadow;
+class WindowPixmap;
 
 // The base class for compositing backends.
 class Scene : public QObject
@@ -184,7 +185,7 @@ public:
     // perform the actual painting of the window
     virtual void performPaint(int mask, QRegion region, WindowPaintData data) = 0;
     // do any cleanup needed when the window's composite pixmap is discarded
-    virtual void pixmapDiscarded()  {}
+    void pixmapDiscarded();
     int x() const;
     int y() const;
     int width() const;
@@ -231,13 +232,41 @@ public:
     void updateShadow(Shadow* shadow);
     const Shadow* shadow() const;
     Shadow* shadow();
+    void referencePreviousPixmap();
+    void unreferencePreviousPixmap();
 protected:
     WindowQuadList makeQuads(WindowQuadType type, const QRegion& reg) const;
     WindowQuadList makeDecorationQuads(const QRect *rects, const QRegion &region) const;
+    /**
+     * @brief Returns the WindowPixmap for this Window.
+     *
+     * If the WindowPixmap does not yet exist, this method will invoke @link createWindowPixmap.
+     * If the WindowPixmap is not valid it tries to create it, in case this succeeds the WindowPixmap is
+     * returned. In case it fails, the previous (and still valid) WindowPixmap is returned.
+     *
+     * Note: this method can return @c NULL as there might neither be a valid previous nor current WindowPixmap
+     * around.
+     *
+     * The WindowPixmap gets casted to the type passed in as a template parameter. That way this class does not
+     * need to know the actual WindowPixmap subclass used by the concrete Scene implementations.
+     *
+     * @return The WindowPixmap casted to T* or @c NULL if there is no valid window pixmap.
+     */
+    template<typename T> T *windowPixmap();
+    /**
+     * @brief Factory method to create a WindowPixmap.
+     *
+     * The inheriting classes need to implement this method to create a new instance of their WindowPixmap subclass.
+     * Note: do not use @link WindowPixmap::create on the created instance. The Scene will take care of that.
+     */
+    virtual WindowPixmap *createWindowPixmap() = 0;
     Toplevel* toplevel;
     ImageFilterType filter;
     Shadow *m_shadow;
 private:
+    QScopedPointer<WindowPixmap> m_currentPixmap;
+    QScopedPointer<WindowPixmap> m_previousPixmap;
+    int m_referencePixmapCounter;
     int disable_painting;
     mutable QRegion shape_region;
     mutable bool shape_valid;
@@ -245,6 +274,78 @@ private:
     Q_DISABLE_COPY(Window)
 };
 
+/**
+ * @brief Wrapper for a pixmap of the @link Scene::Window.
+ *
+ * This class encapsulates the functionality to get the pixmap for a window. When initialized the pixmap is not yet
+ * mapped to the window and @link isValid will return @c false. The pixmap mapping to the window can be established
+ * through @link create. If it succeeds @link isValid will return @c true, otherwise it will keep in the non valid
+ * state and it can be tried to create the pixmap mapping again (e.g. in the next frame).
+ *
+ * This class is not intended to be updated when the pixmap is no longer valid due to e.g. resizing the window.
+ * Instead a new instance of this class should be instantiated. The idea behind this is that a valid pixmap does not
+ * get destroyed, but can continue to be used. To indicate that a newer pixmap should in generally be around, one can
+ * use @link markAsDiscarded.
+ *
+ * This class is intended to be inherited for the needs of the compositor backends which need further mapping from
+ * the native pixmap to the respective rendering format.
+ */
+class WindowPixmap
+{
+public:
+    virtual ~WindowPixmap();
+    /**
+     * @brief Tries to create the mapping between the Window and the pixmap.
+     *
+     * In case this method succeeds in creating the pixmap for the window, @link isValid will return @c true otherwise
+     * @c false.
+     *
+     * Inheriting classes should re-implement this method in case they need to add further functionality for mapping the
+     * native pixmap to the rendering format.
+     */
+    virtual void create();
+    /**
+     * @return @c true if the pixmap has been created and is valid, @c false otherwise
+     */
+    bool isValid() const;
+    /**
+     * @return The native X11 pixmap handle
+     */
+    xcb_pixmap_t pixmap() const;
+    /**
+     * @brief Whether this WindowPixmap is considered as discarded. This means the window has changed in a way that a new
+     * WindowPixmap should have been created already.
+     *
+     * @return @c true if this WindowPixmap is considered as discarded, @c false otherwise.
+     * @see markAsDiscarded
+     */
+    bool isDiscarded() const;
+    /**
+     * @brief Marks this WindowPixmap as discarded. From now on @link isDiscarded will return @c true. This method should
+     * only be used by the Window when it changes in a way that a new pixmap is required.
+     *
+     * @see isDiscarded
+     */
+    void markAsDiscarded();
+
+protected:
+    explicit WindowPixmap(Scene::Window *window);
+    /**
+     * @brief Returns the Toplevel this WindowPixmap belongs to.
+     * Note: the Toplevel can change over the lifetime of the WindowPixmap in case the Toplevel is copied to Deleted.
+     */
+    Toplevel *toplevel();
+    /**
+     * @return The Window this WindowPixmap belongs to
+     */
+    Scene::Window *window();
+private:
+    Scene::Window *m_window;
+    xcb_pixmap_t m_pixmap;
+    QSize m_pixmapSize;
+    bool m_discarded;
+};
+
 class Scene::EffectFrame
 {
 public:
@@ -346,6 +447,55 @@ Shadow* Scene::Window::shadow()
     return m_shadow;
 }
 
+inline
+bool WindowPixmap::isValid() const
+{
+    return m_pixmap != XCB_PIXMAP_NONE;
+}
+
+template <typename T>
+inline
+T* Scene::Window::windowPixmap()
+{
+    if (m_currentPixmap.isNull()) {
+        m_currentPixmap.reset(createWindowPixmap());
+    }
+    if (m_currentPixmap->isValid()) {
+        return static_cast<T*>(m_currentPixmap.data());
+    }
+    m_currentPixmap->create();
+    if (m_currentPixmap->isValid()) {
+        return static_cast<T*>(m_currentPixmap.data());
+    } else {
+        return static_cast<T*>(m_previousPixmap.data());
+    }
+}
+
+inline
+Toplevel* WindowPixmap::toplevel()
+{
+    return m_window->window();
+}
+
+inline
+xcb_pixmap_t WindowPixmap::pixmap() const
+{
+    return m_pixmap;
+}
+
+inline
+bool WindowPixmap::isDiscarded() const
+{
+    return m_discarded;
+}
+
+inline
+void WindowPixmap::markAsDiscarded()
+{
+    m_discarded = true;
+    m_window->referencePreviousPixmap();
+}
+
 } // namespace
 
 #endif

scene_opengl.cpp

@@ -479,7 +479,6 @@ void SceneOpenGL::windowGeometryShapeChanged(KWin::Toplevel* c)
         return;                 // by default
     Window* w = windows[ c ];
     w->discardShape();
-    w->checkTextureSize();
 }
 
 void SceneOpenGL::windowOpacityChanged(KWin::Toplevel* t)
@@ -960,73 +959,27 @@ SceneOpenGL::TexturePrivate::~TexturePrivate()
 SceneOpenGL::Window::Window(Toplevel* c)
     : Scene::Window(c)
     , m_scene(NULL)
-    , m_texture(NULL)
 {
 }
 
 SceneOpenGL::Window::~Window()
 {
-    delete m_texture;
 }
 
+static SceneOpenGL::Texture *s_frameTexture = NULL;
 // Bind the window pixmap to an OpenGL texture.
 bool SceneOpenGL::Window::bindTexture()
 {
-    if (!m_texture) {
+    s_frameTexture = NULL;
-        m_texture = m_scene->createTexture();
+    OpenGLWindowPixmap *pixmap = windowPixmap<OpenGLWindowPixmap>();
-    }
+    if (!pixmap) {
-    if (!m_texture->isNull()) {
-        if (!toplevel->damage().isEmpty()) {
-            // mipmaps need to be updated
-            m_texture->setDirty();
-            toplevel->resetDamage();
-        }
-        return true;
-    }
-    // Get the pixmap with the window contents
-    Pixmap pix = toplevel->windowPixmap();
-    if (pix == None)
         return false;
-
+    }
-    bool success = m_texture->load(pix, toplevel->size(), toplevel->depth(),
+    s_frameTexture = pixmap->texture();
-                                   toplevel->damage());
+    if (pixmap->isDiscarded()) {
-
+        return !pixmap->texture()->isNull();
-    if (success)
+    }
-        toplevel->resetDamage();
+    return pixmap->bind();
-    else
-        kDebug(1212) << "Failed to bind window";
-
-    return success;
-}
-
-void SceneOpenGL::Window::discardTexture()
-{
-    if (m_texture)
-        m_texture->discard();
-}
-
-// This call is used in SceneOpenGL::windowGeometryShapeChanged(),
-// which originally called discardTexture(), however this was causing performance
-// problems with the launch feedback icon - large number of texture rebinds.
-// Since the launch feedback icon does not resize, only changes shape, it
-// is not necessary to rebind the texture (with no strict binding), therefore
-// discard the texture only if size changes.
-void SceneOpenGL::Window::checkTextureSize()
-{
-    if (!m_texture)
-        return;
-
-    if (m_texture->size() != size())
-        discardTexture();
-}
-
-// when the window's composite pixmap is discarded, undo binding it to the texture
-void SceneOpenGL::Window::pixmapDiscarded()
-{
-    if (!m_texture)
-        return;
-
-    m_texture->discard();
 }
 
 QMatrix4x4 SceneOpenGL::Window::transformation(int mask, const WindowPaintData &data) const
@@ -1082,7 +1035,7 @@ bool SceneOpenGL::Window::beginRenderWindow(int mask, const QRegion &region, Win
         data.quads = quads;
     }
 
-    if (!bindTexture()) {
+    if (!bindTexture() || !s_frameTexture) {
         return false;
     }
 
@@ -1097,7 +1050,7 @@ bool SceneOpenGL::Window::beginRenderWindow(int mask, const QRegion &region, Win
     else
         filter = ImageFilterFast;
 
-    m_texture->setFilter(filter == ImageFilterGood ? GL_LINEAR : GL_NEAREST);
+    s_frameTexture->setFilter(filter == ImageFilterGood ? GL_LINEAR : GL_NEAREST);
 
     const GLVertexAttrib attribs[] = {
         { VA_Position, 2, GL_FLOAT, offsetof(GLVertex2D, position) },
@@ -1309,7 +1262,7 @@ GLTexture *SceneOpenGL::Window::textureForType(SceneOpenGL::Window::TextureType
 
     switch(type) {
     case Content:
-        tex = m_texture;
+        tex = s_frameTexture;
         break;
 
     case DecorationLeftRight:
@@ -1326,6 +1279,10 @@ GLTexture *SceneOpenGL::Window::textureForType(SceneOpenGL::Window::TextureType
     return tex;
 }
 
+WindowPixmap* SceneOpenGL::Window::createWindowPixmap()
+{
+    return new OpenGLWindowPixmap(this, m_scene);
+}
 
 //***************************************
 // SceneOpenGL2Window
@@ -1382,7 +1339,7 @@ void SceneOpenGL2Window::setupLeafNodes(LeafNode *nodes, const WindowQuadList *q
         nodes[TopBottomLeaf].coordinateType = UnnormalizedCoordinates;
     }
 
-    nodes[ContentLeaf].texture = m_texture;
+    nodes[ContentLeaf].texture = s_frameTexture;
     nodes[ContentLeaf].hasAlpha = !isOpaque();
     nodes[ContentLeaf].opacity = data.opacity();
     nodes[ContentLeaf].coordinateType = UnnormalizedCoordinates;
@@ -1589,16 +1546,16 @@ void SceneOpenGL1Window::performPaint(int mask, QRegion region, WindowPaintData
     // paint the content
     WindowQuadList contentQuads = data.quads.select(WindowQuadContents);
     if (!contentQuads.empty()) {
-        m_texture->bind();
+        s_frameTexture->bind();
         prepareStates(Content, data.opacity(), data.brightness(), data.saturation(), data.screen());
-        renderQuads(mask, region, contentQuads, m_texture, false);
+        renderQuads(mask, region, contentQuads, s_frameTexture, false);
         restoreStates(Content, data.opacity(), data.brightness(), data.saturation());
-        m_texture->unbind();
+        s_frameTexture->unbind();
 
 #ifndef KWIN_HAVE_OPENGLES
         if (m_scene && m_scene->debug()) {
             glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
-            renderQuads(mask, region, contentQuads, m_texture, false);
+            renderQuads(mask, region, contentQuads, s_frameTexture, false);
             glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
         }
 #endif
@@ -1763,6 +1720,44 @@ void SceneOpenGL1Window::restoreStates(TextureType type, qreal opacity, qreal br
 }
 #endif
 
+//****************************************
+// OpenGLWindowPixmap
+//****************************************
+
+OpenGLWindowPixmap::OpenGLWindowPixmap(Scene::Window *window, SceneOpenGL* scene)
+    : WindowPixmap(window)
+    , m_scene(scene)
+    , m_texture(scene->createTexture())
+{
+}
+
+OpenGLWindowPixmap::~OpenGLWindowPixmap()
+{
+}
+
+bool OpenGLWindowPixmap::bind()
+{
+    if (!m_texture->isNull()) {
+        if (!toplevel()->damage().isEmpty()) {
+            // mipmaps need to be updated
+            m_texture->setDirty();
+            toplevel()->resetDamage();
+        }
+        return true;
+    }
+    if (!isValid()) {
+        return false;
+    }
+
+    bool success = m_texture->load(pixmap(), toplevel()->size(), toplevel()->depth(), toplevel()->damage());
+
+    if (success)
+        toplevel()->resetDamage();
+    else
+        kDebug(1212) << "Failed to bind window";
+    return success;
+}
+
 //****************************************
 // SceneOpenGL::EffectFrame
 //****************************************

scene_opengl.h

@@ -207,7 +207,7 @@ protected:
 private:
     Q_DECLARE_PRIVATE(Texture)
 
-    friend class SceneOpenGL::Window;
+    friend class OpenGLWindowPixmap;
 };
 
 class SceneOpenGL::Window
@@ -218,15 +218,13 @@ public:
     bool beginRenderWindow(int mask, const QRegion &region, WindowPaintData &data);
     virtual void performPaint(int mask, QRegion region, WindowPaintData data) = 0;
     void endRenderWindow();
-    virtual void pixmapDiscarded();
     bool bindTexture();
-    void discardTexture();
-    void checkTextureSize();
     void setScene(SceneOpenGL *scene) {
         m_scene = scene;
     }
 
 protected:
+    virtual WindowPixmap* createWindowPixmap();
     Window(Toplevel* c);
     enum TextureType {
         Content,
@@ -274,7 +272,6 @@ protected:
 protected:
     SceneOpenGL *m_scene;
     bool m_hardwareClipping;
-    Texture *m_texture;
 
 private:
     OpenGLPaintRedirector *paintRedirector() const;
@@ -337,6 +334,18 @@ protected:
 };
 #endif
 
+class OpenGLWindowPixmap : public WindowPixmap
+{
+public:
+    explicit OpenGLWindowPixmap(Scene::Window *window, SceneOpenGL *scene);
+    virtual ~OpenGLWindowPixmap();
+    SceneOpenGL::Texture *texture() const;
+    bool bind();
+private:
+    SceneOpenGL *m_scene;
+    QScopedPointer<SceneOpenGL::Texture> m_texture;
+};
+
 class SceneOpenGL::EffectFrame
     : public Scene::EffectFrame
 {
@@ -624,6 +633,11 @@ inline bool SceneOpenGL::hasPendingFlush() const
     return m_backend->hasPendingFlush();
 }
 
+inline SceneOpenGL::Texture* OpenGLWindowPixmap::texture() const
+{
+    return m_texture.data();
+}
+
 } // namespace
 
 #endif

scene_xrender.cpp

@@ -244,7 +244,6 @@ void SceneXrender::windowGeometryShapeChanged(KWin::Toplevel* c)
     if (!windows.contains(c))    // this is ok, shape is not valid by default
         return;
     Window* w = windows[ c ];
-    w->discardPicture();
     w->discardShape();
 }
 
@@ -297,7 +296,6 @@ QRect SceneXrender::Window::temp_visibleRect;
 
 SceneXrender::Window::Window(Toplevel* c)
     : Scene::Window(c)
-    , _picture(XCB_RENDER_PICTURE_NONE)
     , format(findFormatForVisual(c->visual()->visualid))
     , alpha_cached_opacity(0.0)
 {
@@ -305,7 +303,6 @@ SceneXrender::Window::Window(Toplevel* c)
 
 SceneXrender::Window::~Window()
 {
-    discardPicture();
     discardShape();
 }
 
@@ -315,33 +312,6 @@ void SceneXrender::Window::cleanup()
     s_tempPicture = NULL;
 }
 
-// Create XRender picture for the pixmap with the window contents.
-xcb_render_picture_t SceneXrender::Window::picture()
-{
-    if (!toplevel->damage().isEmpty() && _picture != XCB_RENDER_PICTURE_NONE) {
-        xcb_render_free_picture(connection(), _picture);
-        _picture = XCB_RENDER_PICTURE_NONE;
-    }
-    if (_picture == XCB_RENDER_PICTURE_NONE && format != 0) {
-        // Get the pixmap with the window contents.
-        xcb_pixmap_t pix = toplevel->windowPixmap();
-        if (pix == XCB_PIXMAP_NONE)
-            return XCB_RENDER_PICTURE_NONE;
-        _picture = xcb_generate_id(connection());
-        xcb_render_create_picture(connection(), _picture, pix, format, 0, NULL);
-        toplevel->resetDamage();
-    }
-    return _picture;
-}
-
-
-void SceneXrender::Window::discardPicture()
-{
-    if (_picture != XCB_RENDER_PICTURE_NONE)
-        xcb_render_free_picture(connection(), _picture);
-    _picture = XCB_RENDER_PICTURE_NONE;
-}
-
 // Maps window coordinates to screen coordinates
 QRect SceneXrender::Window::mapToScreen(int mask, const WindowPaintData &data, const QRect &rect) const
 {
@@ -432,9 +402,14 @@ void SceneXrender::Window::performPaint(int mask, QRegion region, WindowPaintDat
 
     if (region.isEmpty())
         return;
-    xcb_render_picture_t pic = picture(); // get XRender picture
+    XRenderWindowPixmap *pixmap = windowPixmap<XRenderWindowPixmap>();
+    if (!pixmap || !pixmap->isValid()) {
+        return;
+    }
+    xcb_render_picture_t pic = pixmap->picture();
     if (pic == XCB_RENDER_PICTURE_NONE)   // The render format can be null for GL and/or Xv visuals
         return;
+    toplevel->resetDamage();
     // set picture filter
     if (options->isXrenderSmoothScale()) { // only when forced, it's slow
         if (mask & PAINT_WINDOW_TRANSFORMED)
@@ -734,12 +709,48 @@ void SceneXrender::Window::setPictureFilter(xcb_render_picture_t pic, Scene::Ima
     xcb_render_set_picture_filter(connection(), pic, filterName.length(), filterName.constData(), 0, NULL);
 }
 
+WindowPixmap* SceneXrender::Window::createWindowPixmap()
+{
+    return new XRenderWindowPixmap(this, format);
+}
+
 void SceneXrender::screenGeometryChanged(const QSize &size)
 {
     Scene::screenGeometryChanged(size);
     initXRender(false);
 }
 
+//****************************************
+// XRenderWindowPixmap
+//****************************************
+
+XRenderWindowPixmap::XRenderWindowPixmap(Scene::Window *window, xcb_render_pictformat_t format)
+    : WindowPixmap(window)
+    , m_picture(XCB_RENDER_PICTURE_NONE)
+    , m_format(format)
+{
+}
+
+XRenderWindowPixmap::~XRenderWindowPixmap()
+{
+    if (m_picture != XCB_RENDER_PICTURE_NONE) {
+        xcb_render_free_picture(connection(), m_picture);
+    }
+}
+
+void XRenderWindowPixmap::create()
+{
+    if (isValid()) {
+        return;
+    }
+    KWin::WindowPixmap::create();
+    if (!isValid()) {
+        return;
+    }
+    m_picture = xcb_generate_id(connection());
+    xcb_render_create_picture(connection(), m_picture, pixmap(), m_format, 0, NULL);
+}
+
 //****************************************
 // SceneXrender::EffectFrame
 //****************************************

scene_xrender.h

@@ -79,17 +79,16 @@ public:
     Window(Toplevel* c);
     virtual ~Window();
     virtual void performPaint(int mask, QRegion region, WindowPaintData data);
-    void discardPicture();
     QRegion transformedShape() const;
     void setTransformedShape(const QRegion& shape);
     static void cleanup();
+protected:
+    virtual WindowPixmap* createWindowPixmap();
 private:
-    xcb_render_picture_t picture();
     QRect mapToScreen(int mask, const WindowPaintData &data, const QRect &rect) const;
     QPoint mapToScreen(int mask, const WindowPaintData &data, const QPoint &point) const;
     void prepareTempPixmap();
     void setPictureFilter(xcb_render_picture_t pic, ImageFilterType filter);
-    xcb_render_picture_t _picture;
     xcb_render_pictformat_t format;
     double alpha_cached_opacity;
     QRegion transformed_shape;
@@ -97,6 +96,18 @@ private:
     static XRenderPicture *s_tempPicture;
 };
 
+class XRenderWindowPixmap : public WindowPixmap
+{
+public:
+    explicit XRenderWindowPixmap(Scene::Window *window, xcb_render_pictformat_t format);
+    virtual ~XRenderWindowPixmap();
+    xcb_render_picture_t picture() const;
+    virtual void create();
+private:
+    xcb_render_picture_t m_picture;
+    xcb_render_pictformat_t m_format;
+};
+
 class SceneXrender::EffectFrame
     : public Scene::EffectFrame
 {
@@ -143,6 +154,12 @@ void SceneXrender::Window::setTransformedShape(const QRegion& shape)
     transformed_shape = shape;
 }
 
+inline
+xcb_render_picture_t XRenderWindowPixmap::picture() const
+{
+    return m_picture;
+}
+
 /**
  * @short XRender implementation of Shadow.
  *

toplevel.cpp

@@ -43,7 +43,6 @@ Toplevel::Toplevel()
     , m_isDamaged(false)
     , client(None)
     , frame(None)
-    , window_pix(None)
     , damage_handle(None)
     , is_shape(false)
     , effect_window(NULL)
@@ -63,7 +62,6 @@ Toplevel::Toplevel()
 Toplevel::~Toplevel()
 {
     assert(damage_handle == None);
-    discardWindowPixmap();
     delete info;
 }
 
@@ -114,7 +112,6 @@ void Toplevel::copyToDeleted(Toplevel* c)
     info = c->info;
     client = c->client;
     frame = c->frame;
-    window_pix = c->window_pix;
     ready_for_painting = c->ready_for_painting;
     damage_handle = None;
     damage_region = c->damage_region;
@@ -131,9 +128,6 @@ void Toplevel::copyToDeleted(Toplevel* c)
     window_role = c->windowRole();
     opaque_region = c->opaqueRegion();
     m_screen = c->m_screen;
-    // this needs to be done already here, otherwise 'c' could very likely
-    // call discardWindowPixmap() in something called during cleanup
-    c->window_pix = None;
 }
 
 // before being deleted, remove references to everything that's now

toplevel.h

@@ -226,7 +226,6 @@ public:
     pid_t pid() const;
     static bool resourceMatch(const Toplevel* c1, const Toplevel* c2);
 
-    Pixmap windowPixmap(bool allow_create = true);   // may return None (e.g. at a bad moment while resizing)
     bool readyForPainting() const; // true if the window has been already painted its contents
     Visual* visual() const;
     bool shape() const;
@@ -350,7 +349,6 @@ protected:
     void detectShape(Window id);
     virtual void propertyNotifyEvent(XPropertyEvent* e);
     virtual void damageNotifyEvent();
-    xcb_pixmap_t createWindowPixmap();
     void discardWindowPixmap();
     void addDamageFull();
     void getWmClientLeader();
@@ -395,7 +393,6 @@ private:
     // when adding new data members, check also copyToDeleted()
     Window client;
     Window frame;
-    Pixmap window_pix;
     xcb_damage_damage_t damage_handle;
     QRegion damage_region; // damage is really damaged window (XDamage) and texture needs
     bool is_shape;
@@ -557,13 +554,6 @@ inline bool Toplevel::isDNDIcon() const
     return windowType() == NET::DNDIcon;
 }
 
-inline Pixmap Toplevel::windowPixmap(bool allow_create)
-{
-    if (window_pix == None && allow_create)
-        window_pix = createWindowPixmap();
-    return window_pix;
-}
-
 inline QRegion Toplevel::damage() const
 {
     return damage_region;