Smarter way of the overlay rendering (overlay is always refreshed, while...

Smarter way of the overlay rendering (overlay is always refreshed, while cached&noncached targets only if the viewport or items have changed).

common/drawpanel_gal.cpp

@@ -127,6 +127,8 @@ void EDA_DRAW_PANEL_GAL::onPaint( wxPaintEvent& WXUNUSED( aEvent ) )
 void EDA_DRAW_PANEL_GAL::onSize( wxSizeEvent& aEvent )
 {
     m_gal->ResizeScreen( aEvent.GetSize().x, aEvent.GetSize().y );
+    m_view->SetTargetDirty( KiGfx::TARGET_CACHED );
+    m_view->SetTargetDirty( KiGfx::TARGET_NONCACHED );
 }
 
 
@@ -134,24 +136,19 @@ void EDA_DRAW_PANEL_GAL::Refresh( bool eraseBackground, const wxRect* rect )
 {
 #ifdef __WXDEBUG__
     prof_counter time;
-
     prof_start( &time, false );
 #endif /* __WXDEBUG__ */
 
-    printf("Refresh!\n");
-
     m_gal->BeginDrawing();
     m_gal->SetBackgroundColor( KiGfx::COLOR4D( 0.0, 0.0, 0.0, 1.0 ) );
     m_gal->ClearScreen();
 
-    m_gal->DrawGrid();
     m_view->Redraw();
 
     m_gal->EndDrawing();
 
 #ifdef __WXDEBUG__
     prof_end( &time );
-
     wxLogDebug( wxT( "EDA_DRAW_PANEL_GAL::Refresh: %.0f ms (%.0f fps)" ),
         static_cast<double>( time.value ) / 1000.0, 1000000.0 / static_cast<double>( time.value ) );
 #endif /* __WXDEBUG__ */
@@ -184,6 +181,9 @@ void EDA_DRAW_PANEL_GAL::SwitchBackend( GalType aGalType )
     m_gal->SetScreenDPI( 106 );                                     // Display resolution setting
     m_gal->ComputeWorldScreenMatrix();
 
+    wxSize size = GetClientSize();
+    m_gal->ResizeScreen( size.GetX(), size.GetY() );
+
     if( m_painter )
         m_painter->SetGAL( m_gal );
 
@@ -193,9 +193,6 @@ void EDA_DRAW_PANEL_GAL::SwitchBackend( GalType aGalType )
         m_view->RecacheAllItems( true );
     }
 
-    wxSize size = GetClientSize();
-    m_gal->ResizeScreen( size.GetX(), size.GetY() );
-
     m_currentGal = aGalType;
 }
 

common/gal/cairo/cairo_compositor.cpp

@@ -36,8 +36,6 @@ using namespace KiGfx;
 CAIRO_COMPOSITOR::CAIRO_COMPOSITOR( cairo_t** aMainContext ) :
     m_current( 0 ), m_currentContext( aMainContext ), m_mainContext( *aMainContext )
 {
-    // Obtain the transformation matrix used in the main context
-    cairo_get_matrix( m_mainContext, &m_matrix );
 }
 
 
@@ -65,11 +63,10 @@ void CAIRO_COMPOSITOR::Resize( unsigned int aWidth, unsigned int aHeight )
 }
 
 
-unsigned int CAIRO_COMPOSITOR::GetBuffer()
+unsigned int CAIRO_COMPOSITOR::CreateBuffer()
 {
     // Pixel storage
     BitmapPtr bitmap( new unsigned int[m_bufferSize] );
-
     memset( bitmap.get(), 0x00, m_bufferSize * sizeof(int) );
 
     // Create the Cairo surface
@@ -78,10 +75,10 @@ unsigned int CAIRO_COMPOSITOR::GetBuffer()
                                                         CAIRO_FORMAT_ARGB32, m_width,
                                                         m_height, m_stride );
     cairo_t* context = cairo_create( surface );
-    #ifdef __WXDEBUG__
+#ifdef __WXDEBUG__
     cairo_status_t status = cairo_status( context );
     wxASSERT_MSG( status == CAIRO_STATUS_SUCCESS, "Cairo context creation error" );
-    #endif /* __WXDEBUG__ */
+#endif /* __WXDEBUG__ */
 
     // Set default settings for the buffer
     cairo_set_antialias( context, CAIRO_ANTIALIAS_SUBPIXEL );
@@ -89,6 +86,7 @@ unsigned int CAIRO_COMPOSITOR::GetBuffer()
     cairo_set_line_cap( context, CAIRO_LINE_CAP_ROUND );
 
     // Use the same transformation matrix as the main context
+    cairo_get_matrix( m_mainContext, &m_matrix );
     cairo_set_matrix( context, &m_matrix );
 
     // Store the new buffer
@@ -101,53 +99,41 @@ unsigned int CAIRO_COMPOSITOR::GetBuffer()
 
 void CAIRO_COMPOSITOR::SetBuffer( unsigned int aBufferHandle )
 {
-    if( aBufferHandle <= usedBuffers() )
-    {
+    wxASSERT_MSG( aBufferHandle <= usedBuffers(), wxT( "Tried to use a not existing buffer" ) );
+
+    // Get currently used transformation matrix, so it can be applied to the new buffer
+    cairo_get_matrix( *m_currentContext, &m_matrix );
+
     m_current = aBufferHandle - 1;
     *m_currentContext = m_buffers[m_current].context;
-    }
 
-#ifdef __WXDEBUG__
-    else
-        wxLogDebug( wxT( "Tried to use a not existing buffer" ) );
-#endif
+    // Apply the current transformation matrix
+    cairo_set_matrix( *m_currentContext, &m_matrix );
 }
 
 
 void CAIRO_COMPOSITOR::ClearBuffer()
 {
-    // Reset the transformation matrix, so it is possible to composite images using
-    // screen coordinates instead of world coordinates
-    cairo_identity_matrix( m_buffers[m_current].context );
-
-    cairo_set_source_rgba( m_buffers[m_current].context, 0.0, 0.0, 0.0, 0.0 );
-    cairo_rectangle( m_buffers[m_current].context, 0.0, 0.0, m_width, m_height );
-    cairo_fill( m_buffers[m_current].context );
-
-    // Restore the transformation matrix
-    cairo_set_matrix( m_buffers[m_current].context, &m_matrix );
+    // Clear the pixel storage
+    memset( m_buffers[m_current].bitmap.get(), 0x00, m_bufferSize * sizeof(int) );
 }
 
 
 void CAIRO_COMPOSITOR::DrawBuffer( unsigned int aBufferHandle )
 {
-    if( aBufferHandle <= usedBuffers() )
-    {
+    wxASSERT_MSG( aBufferHandle <= usedBuffers(), wxT( "Tried to use a not existing buffer" ) );
+
     // Reset the transformation matrix, so it is possible to composite images using
     // screen coordinates instead of world coordinates
+    cairo_get_matrix( m_mainContext, &m_matrix );
     cairo_identity_matrix( m_mainContext );
 
+    // Draw the selected buffer contents
     cairo_set_source_surface( m_mainContext, m_buffers[aBufferHandle - 1].surface, 0.0, 0.0 );
     cairo_paint( m_mainContext );
 
     // Restore the transformation matrix
     cairo_set_matrix( m_mainContext, &m_matrix );
-    }
-
-#ifdef __WXDEBUG__
-    else
-        wxLogDebug( wxT( "Tried to use a not existing buffer" ) );
-#endif
 }
 
 

common/gal/cairo/cairo_gal.cpp

@@ -48,6 +48,7 @@ CAIRO_GAL::CAIRO_GAL( wxWindow* aParent, wxEvtHandler* aMouseListener,
     isGrouping          = false;
     isInitialized       = false;
     isDeleteSavedPixels = false;
+    validCompositor     = false;
     groupCounter        = 0;
 
     // Connecting the event handlers
@@ -90,8 +91,12 @@ CAIRO_GAL::~CAIRO_GAL()
 void CAIRO_GAL::BeginDrawing()
 {
     initSurface();
+    if( !validCompositor )
         setCompositor();
 
+    compositor->SetMainContext( context );
+    compositor->SetBuffer( mainBuffer );
+
     // Cairo grouping prevents display of overlapping items on the same layer in the lighter color
     cairo_push_group( currentContext );
 }
@@ -120,8 +125,8 @@ void CAIRO_GAL::EndDrawing()
     for( size_t count = 0; count < bufferSize; count++ )
     {
         unsigned int value = bitmapBuffer[count];
-        *wxOutputPtr++ = (value >> 16) & 0xff;  // Red pixel
-        *wxOutputPtr++ = (value >> 8) & 0xff;   // Green pixel
+        *wxOutputPtr++ = ( value >> 16 ) & 0xff;  // Red pixel
+        *wxOutputPtr++ = ( value >> 8 ) & 0xff;   // Green pixel
         *wxOutputPtr++ = value & 0xff;            // Blue pixel
     }
 
@@ -273,6 +278,10 @@ void CAIRO_GAL::ResizeScreen( int aWidth, int aHeight )
     deleteBitmaps();
     allocateBitmaps();
 
+    if( validCompositor )
+        compositor->Resize( aWidth, aHeight );
+    validCompositor = false;
+
     SetSize( wxSize( aWidth, aHeight ) );
 }
 
@@ -719,7 +728,7 @@ void CAIRO_GAL::SetTarget( RenderTarget aTarget )
 {
     // If the compositor is not set, that means that there is a recaching process going on
     // and we do not need the compositor now
-    if( !compositor )
+    if( !validCompositor )
         return;
 
     // Cairo grouping prevents display of overlapping items on the same layer in the lighter color
@@ -751,6 +760,31 @@ RenderTarget CAIRO_GAL::GetTarget() const
 }
 
 
+void CAIRO_GAL::ClearTarget( RenderTarget aTarget )
+{
+    // Save the current state
+    unsigned int currentBuffer = compositor->GetBuffer();
+
+    switch( aTarget )
+    {
+    // Cached and noncached items are rendered to the same buffer
+    default:
+    case TARGET_CACHED:
+    case TARGET_NONCACHED:
+        compositor->SetBuffer( mainBuffer );
+        break;
+
+    case TARGET_OVERLAY:
+        compositor->SetBuffer( overlayBuffer );
+        break;
+    }
+    compositor->ClearBuffer();
+
+    // Restore the previous state
+    compositor->SetBuffer( currentBuffer );
+}
+
+
 VECTOR2D CAIRO_GAL::ComputeCursorToWorld( const VECTOR2D& aCursorPosition )
 {
     MATRIX3x3D inverseMatrix = worldScreenMatrix.Inverse();
@@ -972,8 +1006,10 @@ void CAIRO_GAL::setCompositor()
     compositor->Resize( screenSize.x, screenSize.y );
 
     // Prepare buffers
-    mainBuffer = compositor->GetBuffer();
-    overlayBuffer = compositor->GetBuffer();
+    mainBuffer = compositor->CreateBuffer();
+    overlayBuffer = compositor->CreateBuffer();
+
+    validCompositor = true;
 }
 
 

common/gal/opengl/opengl_compositor.cpp

@@ -74,7 +74,7 @@ void OPENGL_COMPOSITOR::Initialize()
                                GL_RENDERBUFFER, m_depthBuffer );
 
     // Unbind the framebuffer, so by default all the rendering goes directly to the display
-    glBindFramebuffer( GL_FRAMEBUFFER, 0 );
+    glBindFramebuffer( GL_FRAMEBUFFER, DIRECT_RENDERING );
     m_currentFbo = 0;
 
     m_initialized = true;
@@ -91,7 +91,7 @@ void OPENGL_COMPOSITOR::Resize( unsigned int aWidth, unsigned int aHeight )
 }
 
 
-unsigned int OPENGL_COMPOSITOR::GetBuffer()
+unsigned int OPENGL_COMPOSITOR::CreateBuffer()
 {
     wxASSERT( m_initialized );
 
@@ -169,8 +169,8 @@ unsigned int OPENGL_COMPOSITOR::GetBuffer()
 
 
     ClearBuffer();
-    glBindFramebuffer( GL_FRAMEBUFFER, 0 );
-    m_currentFbo = 0;
+    glBindFramebuffer( GL_FRAMEBUFFER, DIRECT_RENDERING );
+    m_currentFbo = DIRECT_RENDERING;
 
     // Store the new buffer
     OPENGL_BUFFER buffer = { textureTarget, attachmentPoint };
@@ -186,10 +186,10 @@ void OPENGL_COMPOSITOR::SetBuffer( unsigned int aBufferHandle )
         return;
 
     // Change the rendering destination to the selected attachment point
-    if( aBufferHandle == 0 )
+    if( aBufferHandle == DIRECT_RENDERING )
     {
-        glBindFramebuffer( GL_FRAMEBUFFER, 0 );
-        m_currentFbo = 0;
+        glBindFramebuffer( GL_FRAMEBUFFER, DIRECT_RENDERING );
+        m_currentFbo = DIRECT_RENDERING;
     }
     else if( m_currentFbo != m_framebuffer )
     {
@@ -197,7 +197,7 @@ void OPENGL_COMPOSITOR::SetBuffer( unsigned int aBufferHandle )
         m_currentFbo = m_framebuffer;
     }
 
-    if( m_currentFbo != 0 && m_current != aBufferHandle - 1 )
+    if( m_currentFbo != DIRECT_RENDERING )
     {
         m_current = aBufferHandle - 1;
         glDrawBuffer( m_buffers[m_current].attachmentPoint );
@@ -219,8 +219,8 @@ void OPENGL_COMPOSITOR::DrawBuffer( unsigned int aBufferHandle )
     wxASSERT( m_initialized );
 
     // Switch to the main framebuffer and blit the scene
-    glBindFramebuffer( GL_FRAMEBUFFER, 0 );
-    m_currentFbo = 0;
+    glBindFramebuffer( GL_FRAMEBUFFER, DIRECT_RENDERING );
+    m_currentFbo = DIRECT_RENDERING;
 
     // Depth test has to be disabled to make transparency working
     glDisable( GL_DEPTH_TEST );
@@ -279,4 +279,4 @@ void OPENGL_COMPOSITOR::clean()
 }
 
 
-GLuint OPENGL_COMPOSITOR::m_currentFbo = 0;
+GLuint OPENGL_COMPOSITOR::m_currentFbo = DIRECT_RENDERING;

common/gal/opengl/opengl_gal.cpp

@@ -130,8 +130,8 @@ void OPENGL_GAL::BeginDrawing()
 
         // Prepare rendering target buffers
         compositor.Initialize();
-        mainBuffer = compositor.GetBuffer();
-        overlayBuffer = compositor.GetBuffer();
+        mainBuffer = compositor.CreateBuffer();
+        overlayBuffer = compositor.CreateBuffer();
 
         isFramebufferInitialized = true;
     }
@@ -187,13 +187,10 @@ void OPENGL_GAL::BeginDrawing()
     SetFillColor( fillColor );
     SetStrokeColor( strokeColor );
 
-    // Prepare buffers for drawing
-    compositor.SetBuffer( mainBuffer );
-    compositor.ClearBuffer();
-    compositor.SetBuffer( overlayBuffer );
-    compositor.ClearBuffer();
-    compositor.SetBuffer( 0 );    // Unbind buffers
+    // Unbind buffers - set compositor for direct drawing
+    compositor.SetBuffer( OPENGL_COMPOSITOR::DIRECT_RENDERING );
 
+    // Remove all previously stored items
     nonCachedManager.Clear();
     overlayManager.Clear();
 
@@ -711,6 +708,31 @@ RenderTarget OPENGL_GAL::GetTarget() const
 }
 
 
+void OPENGL_GAL::ClearTarget( RenderTarget aTarget )
+{
+    // Save the current state
+    unsigned int oldTarget = compositor.GetBuffer();
+
+    switch( aTarget )
+    {
+    // Cached and noncached items are rendered to the same buffer
+    default:
+    case TARGET_CACHED:
+    case TARGET_NONCACHED:
+        compositor.SetBuffer( mainBuffer );
+        break;
+
+    case TARGET_OVERLAY:
+        compositor.SetBuffer( overlayBuffer );
+        break;
+    }
+    compositor.ClearBuffer();
+
+    // Restore the previous state
+    compositor.SetBuffer( oldTarget );
+}
+
+
 VECTOR2D OPENGL_GAL::ComputeCursorToWorld( const VECTOR2D& aCursorPosition )
 {
     VECTOR2D cursorPosition = aCursorPosition;

common/view/view.cpp

@@ -39,6 +39,28 @@
 
 using namespace KiGfx;
 
+VIEW::VIEW( bool aIsDynamic ) :
+    m_enableOrderModifier( false ),
+    m_scale( 1.0 ),
+    m_painter( NULL ),
+    m_gal( NULL ),
+    m_dynamic( aIsDynamic )
+{
+    // Redraw everything at the beginning
+    for( int i = 0; i < TARGETS_NUMBER; ++i )
+        SetTargetDirty( i );
+}
+
+
+VIEW::~VIEW()
+{
+    BOOST_FOREACH( LayerMap::value_type& l, m_layers )
+    {
+        delete l.second.items;
+    }
+}
+
+
 void VIEW::AddLayer( int aLayer, bool aDisplayOnly )
 {
     if( m_layers.find( aLayer ) == m_layers.end() )
@@ -197,25 +219,6 @@ int VIEW::Query( const BOX2I& aRect, std::vector<LayerItemPair>& aResult )
 }
 
 
-VIEW::VIEW( bool aIsDynamic ) :
-    m_enableOrderModifier( false ),
-    m_scale( 1.0 ),
-    m_painter( NULL ),
-    m_gal( NULL ),
-    m_dynamic( aIsDynamic )
-{
-}
-
-
-VIEW::~VIEW()
-{
-    BOOST_FOREACH( LayerMap::value_type& l, m_layers )
-    {
-        delete l.second.items;
-    }
-}
-
-
 VECTOR2D VIEW::ToWorld( const VECTOR2D& aCoord, bool aAbsolute ) const
 {
     MATRIX3x3D matrix = m_gal->GetWorldScreenMatrix().Inverse();
@@ -267,6 +270,11 @@ void VIEW::SetGAL( GAL* aGal )
     // clear group numbers, so everything is going to be recached
     clearGroupCache();
 
+    // every target has to be refreshed
+    SetTargetDirty( TARGET_CACHED );
+    SetTargetDirty( TARGET_NONCACHED );
+    SetTargetDirty( TARGET_OVERLAY );
+
     // force the new GAL to display the current viewport.
     SetCenter( m_center );
     SetScale( m_scale );
@@ -326,6 +334,10 @@ void VIEW::SetScale( double aScale, const VECTOR2D& aAnchor )
 
     SetCenter( m_center - delta );
     m_scale = aScale;
+
+    // Redraw everything after the viewport has changed
+    SetTargetDirty( TARGET_CACHED );
+    SetTargetDirty( TARGET_NONCACHED );
 }
 
 
@@ -334,6 +346,10 @@ void VIEW::SetCenter( const VECTOR2D& aCenter )
     m_center = aCenter;
     m_gal->SetLookAtPoint( m_center );
     m_gal->ComputeWorldScreenMatrix();
+
+    // Redraw everything after the viewport has changed
+    SetTargetDirty( TARGET_CACHED );
+    SetTargetDirty( TARGET_NONCACHED );
 }
 
 
@@ -347,6 +363,8 @@ void VIEW::sortLayers()
         m_orderedLayers[n++] = &i->second;
 
     sort( m_orderedLayers.begin(), m_orderedLayers.end(), compareRenderingOrder );
+
+    SetTargetDirty( TARGET_CACHED );
 }
 
 
@@ -554,15 +572,15 @@ void VIEW::redrawRect( const BOX2I& aRect )
 {
     BOOST_FOREACH( VIEW_LAYER* l, m_orderedLayers )
     {
-        if( l->enabled && areRequiredLayersEnabled( l->id ) )
+        if( l->enabled && isTargetDirty( l->target ) && areRequiredLayersEnabled( l->id ) )
         {
             drawItem drawFunc( this, l );
 
             m_gal->SetTarget( l->target );
             m_gal->SetLayerDepth( l->renderingOrder );
             l->items->Query( aRect, drawFunc );
-            l->isDirty = false;
         }
+        l->isDirty = false;
     }
 }
 
@@ -648,9 +666,27 @@ void VIEW::Redraw()
     VECTOR2D screenSize = m_gal->GetScreenPixelSize();
     BOX2I    rect( ToWorld( VECTOR2D( 0, 0 ) ),
                    ToWorld( screenSize ) - ToWorld( VECTOR2D( 0, 0 ) ) );
-
     rect.Normalize();
+
+    if( isTargetDirty( TARGET_CACHED ) || isTargetDirty( TARGET_NONCACHED ) )
+    {
+        // TARGET_CACHED and TARGET_NONCACHED have to be redrawn together, as they contain
+        // layers that rely on each other (eg. netnames are noncached, but tracks - are cached)
+        m_gal->ClearTarget( TARGET_NONCACHED );
+        m_gal->ClearTarget( TARGET_CACHED );
+
+        SetTargetDirty( TARGET_NONCACHED );
+        SetTargetDirty( TARGET_CACHED );
+
+        m_gal->DrawGrid();
+    }
+    m_gal->ClearTarget( TARGET_OVERLAY );
+
     redrawRect( rect );
+
+    // All targets were redrawn, so nothing is dirty
+    SetTargetDirty( TARGET_CACHED, false );
+    SetTargetDirty( TARGET_NONCACHED, false );
 }
 
 
@@ -801,3 +837,19 @@ void VIEW::RecacheAllItems( bool aImmediately )
     wxLogDebug( wxT( "RecacheAllItems::%.1f ms" ), (double) totalRealTime.value / 1000.0 );
 #endif /* __WXDEBUG__ */
 }
+
+
+bool VIEW::isTargetDirty( int aTarget ) const
+{
+    wxASSERT( aTarget < TARGETS_NUMBER );
+
+    // Check if any of layers belonging to the target is dirty
+    BOOST_FOREACH( VIEW_LAYER* l, m_orderedLayers )
+    {
+        if( l->target == aTarget && l->isDirty )
+            return true;
+    }
+
+    // If no layer is dirty, just check the target status itself
+    return m_dirtyTargets[aTarget];
+}

include/gal/cairo/cairo_compositor.h

@@ -50,8 +50,14 @@ public:
     /// @copydoc COMPOSITOR::Resize()
     virtual void Resize( unsigned int aWidth, unsigned int aHeight );
 
+    /// @copydoc COMPOSITOR::CreateBuffer()
+    virtual unsigned int CreateBuffer();
+
     /// @copydoc COMPOSITOR::GetBuffer()
-    virtual unsigned int GetBuffer();
+    inline virtual unsigned int GetBuffer() const
+    {
+        return m_current + 1;
+    }
 
     /// @copydoc COMPOSITOR::SetBuffer()
     virtual void SetBuffer( unsigned int aBufferHandle );
@@ -62,6 +68,21 @@ public:
     /// @copydoc COMPOSITOR::DrawBuffer()
     virtual void DrawBuffer( unsigned int aBufferHandle );
 
+    /**
+     * Function SetMainContext()
+     * Sets a context to be treated as the main context (ie. as a target of buffers rendering and
+     * as a source of settings for newly created buffers).
+     *
+     * @param aMainContext is the context that should be treated as the main one.
+     */
+    inline virtual void SetMainContext( cairo_t* aMainContext )
+    {
+        m_mainContext = aMainContext;
+
+        // Use the context's transformation matrix
+        cairo_get_matrix( m_mainContext, &m_matrix );
+    }
+
 protected:
     typedef boost::shared_array<unsigned int> BitmapPtr;
     typedef struct

include/gal/cairo/cairo_gal.h

@@ -221,6 +221,9 @@ public:
     /// @copydoc GAL::GetTarget()
     virtual RenderTarget GetTarget() const;
 
+    /// @copydoc GAL::ClearTarget()
+    virtual void ClearTarget( RenderTarget aTarget );
+
     // -------
     // Cursor
     // -------
@@ -267,6 +270,7 @@ private:
     unsigned int            mainBuffer;             ///< Handle to the main buffer
     unsigned int            overlayBuffer;          ///< Handle to the overlay buffer
     RenderTarget            currentTarget;          ///< Current rendering target
+    bool                    validCompositor;        ///< Compositor initialization flag
 
     // Variables related to wxWidgets
     wxWindow*               parentWindow;           ///< Parent window

include/gal/compositor.h

@@ -57,12 +57,20 @@ public:
     virtual void Resize( unsigned int aWidth, unsigned int aHeight ) = 0;
 
     /**
-     * Function GetBuffer()
+     * Function CreateBuffer()
      * prepares a new buffer that may be used as a rendering target.
      *
      * @return is the handle of the buffer. In case of failure 0 (zero) is returned as the handle.
      */
-    virtual unsigned int GetBuffer() = 0;
+    virtual unsigned int CreateBuffer() = 0;
+
+    /**
+     * Function GetBuffer()
+     * returns currently used buffer handle.
+     *
+     * @return Currently used buffer handle.
+     */
+    virtual unsigned int GetBuffer() const = 0;
 
     /**
      * Function SetBuffer()

include/gal/definitions.h

@@ -42,6 +42,9 @@ namespace KiGfx
         TARGET_NONCACHED,   ///< Auxiliary rendering target (noncached)
         TARGET_OVERLAY      ///< Items that may change while the view stays the same (noncached)
     };
+
+    /// Number of available rendering targets
+    static const int TARGETS_NUMBER = 3;
 }
 
 #endif /* DEFINITIONS_H_ */

include/gal/graphics_abstraction_layer.h

@@ -579,6 +579,13 @@ public:
      */
     virtual RenderTarget GetTarget() const = 0;
 
+    /**
+     * @brief Clears the target for rendering.
+     *
+     * @param aTarget is the target to be cleared.
+     */
+    virtual void ClearTarget( RenderTarget aTarget ) = 0;
+
     // -------------
     // Grid methods
     // -------------

include/gal/opengl/opengl_compositor.h

@@ -49,18 +49,30 @@ public:
     /// @copydoc COMPOSITOR::Resize()
     virtual void Resize( unsigned int aWidth, unsigned int aHeight );
 
-    /// @copydoc COMPOSITOR::GetBuffer()
-    virtual unsigned int GetBuffer();
+    /// @copydoc COMPOSITOR::CreateBuffer()
+    virtual unsigned int CreateBuffer();
 
     /// @copydoc COMPOSITOR::SetBuffer()
     virtual void SetBuffer( unsigned int aBufferHandle );
 
+    /// @copydoc COMPOSITOR::GetBuffer()
+    inline virtual unsigned int GetBuffer() const
+    {
+        if( m_currentFbo == DIRECT_RENDERING )
+            return DIRECT_RENDERING;
+
+        return m_current + 1;
+    }
+
     /// @copydoc COMPOSITOR::ClearBuffer()
     virtual void ClearBuffer();
 
     /// @copydoc COMPOSITOR::DrawBuffer()
     virtual void DrawBuffer( unsigned int aBufferHandle );
 
+    // Constant used by glBindFramebuffer to turn off rendering to framebuffers
+    static const unsigned int DIRECT_RENDERING = 0;
+
 protected:
     typedef struct
     {

include/gal/opengl/opengl_gal.h

@@ -214,6 +214,9 @@ public:
     /// @copydoc GAL::GetTarget()
     virtual RenderTarget GetTarget() const;
 
+    /// @copydoc GAL::ClearTarget()
+    virtual void ClearTarget( RenderTarget aTarget );
+
     // -------
     // Cursor
     // -------

include/view/view.h

@@ -392,6 +392,20 @@ public:
      */
     bool IsDirty() const;
 
+    /**
+     * Function SetTargetDirty()
+     * Sets or clears target 'dirty' flag.
+     * @param aTarget is the target to set.
+     * @param aState says if the flag should be set or cleared.
+     */
+    inline void SetTargetDirty( int aTarget, bool aState = true )
+    {
+        wxASSERT( aTarget < TARGETS_NUMBER );
+
+        m_dirtyTargets[aTarget] = aState;
+    }
+
+
     static const int VIEW_MAX_LAYERS = 128;      ///* maximum number of layers that may be shown
 
 private:
@@ -462,6 +476,14 @@ private:
         return ( m_layers.at( aLayer ).target == TARGET_CACHED );
     }
 
+    /**
+     * Function isTargetDirty()
+     * Returns true if any of layers belonging to the target or the target itself should be
+     * redrawn.
+     * @return True if the above condition is fulfilled.
+     */
+    bool isTargetDirty( int aTarget ) const;
+
     /// Contains set of possible displayed layers and its properties
     LayerMap    m_layers;
 
@@ -487,6 +509,9 @@ private:
     /// static (eg. image/PDF) - does not.
     bool        m_dynamic;
 
+    /// Flags to mark targets as dirty, so they have to be redrawn on the next refresh event
+    bool        m_dirtyTargets[TARGETS_NUMBER];
+
     /// Rendering order modifier for layers that are marked as top layers
     static const int TOP_LAYER_MODIFIER = -VIEW_MAX_LAYERS;
 };