Added a layer compositor for the Cairo backend.

common/CMakeLists.txt

@@ -50,6 +50,7 @@ set(GAL_SRCS
 
     # Cairo GAL
     gal/cairo/cairo_gal.cpp
+    gal/cairo/cairo_compositor.cpp
     )
 
 add_library(gal STATIC ${GAL_SRCS})

common/gal/cairo/cairo_compositor.cpp

@@ -0,0 +1,161 @@
+/*i
+ * This program source code file is part of KiCad, a free EDA CAD application.
+ *
+ * Copyright (C) 2013 CERN
+ * @author Maciej Suminski <maciej.suminski@cern.ch>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you may find one here:
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * or you may search the http:O//www.gnu.org website for the version 2 license,
+ * or you may write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
+/**
+ * @file cairo_compositor.cpp
+ * @brief Class that handles multitarget rendering (ie. to different textures/surfaces) and
+ * later compositing into a single image (Cairo flavour).
+ */
+
+#include <gal/cairo/cairo_compositor.h>
+#include <wx/log.h>
+
+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 );
+}
+
+
+CAIRO_COMPOSITOR::~CAIRO_COMPOSITOR()
+{
+    clean();
+}
+
+
+void CAIRO_COMPOSITOR::Initialize()
+{
+    // Nothing has to be done
+}
+
+
+void CAIRO_COMPOSITOR::Resize( unsigned int aWidth, unsigned int aHeight )
+{
+    clean();
+
+    m_width  = aWidth;
+    m_height = aHeight;
+
+    m_stride     = cairo_format_stride_for_width( CAIRO_FORMAT_ARGB32, m_width );
+    m_bufferSize = m_stride * m_height;
+}
+
+
+unsigned int CAIRO_COMPOSITOR::GetBuffer()
+{
+    // Pixel storage
+    BitmapPtr bitmap( new unsigned int[m_bufferSize] );
+
+    // Create the Cairo surface
+    cairo_surface_t* surface = cairo_image_surface_create_for_data(
+                                                        (unsigned char*) bitmap.get(),
+                                                        CAIRO_FORMAT_ARGB32, m_width,
+                                                        m_height, m_stride );
+    cairo_t* context = cairo_create( surface );
+    #ifdef __WXDEBUG__
+        cairo_status_t status = cairo_status( context );
+        wxASSERT_MSG( status == CAIRO_STATUS_SUCCESS, "Cairo context creation error" );
+    #endif /* __WXDEBUG__ */
+
+    // Set default settings for the buffer
+    cairo_set_antialias( context, CAIRO_ANTIALIAS_SUBPIXEL );
+    cairo_set_line_join( context, CAIRO_LINE_JOIN_ROUND );
+    cairo_set_line_cap( context, CAIRO_LINE_CAP_ROUND );
+
+    // Use the same transformation matrix as the main context
+    cairo_set_matrix( context, &m_matrix );
+
+    // Store the new buffer
+    CAIRO_BUFFER buffer = { context, surface, bitmap };
+    m_buffers.push_back( buffer );
+
+    return usedBuffers();
+}
+
+
+void CAIRO_COMPOSITOR::SetBuffer( unsigned int aBufferHandle )
+{
+    if( aBufferHandle <= usedBuffers() )
+    {
+        m_current = aBufferHandle - 1;
+        *m_currentContext = m_buffers[m_current].context;
+    }
+#ifdef __WXDEBUG__
+    else
+        wxLogDebug( wxT( "Tried to use a not existing buffer" ) );
+#endif
+}
+
+
+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 );
+}
+
+
+void CAIRO_COMPOSITOR::DrawBuffer( unsigned int aBufferHandle )
+{
+    if( aBufferHandle <= usedBuffers() )
+    {
+        // Reset the transformation matrix, so it is possible to composite images using
+        // screen coordinates instead of world coordinates
+        cairo_identity_matrix( m_mainContext );
+
+        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
+}
+
+
+void CAIRO_COMPOSITOR::clean()
+{
+    CAIRO_BUFFERS::const_iterator it;
+
+    for( it = m_buffers.begin(); it != m_buffers.end(); ++it )
+    {
+        cairo_destroy( it->context );
+        cairo_surface_destroy( it->surface );
+    }
+
+    m_buffers.clear();
+}

common/gal/cairo/cairo_gal.cpp

@@ -29,6 +29,7 @@
 #include <wx/log.h>
 
 #include <gal/cairo/cairo_gal.h>
+#include <gal/cairo/cairo_compositor.h>
 #include <gal/definitions.h>
 
 #include <limits>
@@ -89,13 +90,12 @@ CAIRO_GAL::CAIRO_GAL( wxWindow* aParent, wxEvtHandler* aMouseListener,
 CAIRO_GAL::~CAIRO_GAL()
 {
     deinitSurface();
+    deleteBitmaps();
 
     delete cursorPixels;
     delete cursorPixelsSaved;
 
     ClearCache();
-
-    deleteBitmaps();
 }
 
 
@@ -107,11 +107,10 @@ void CAIRO_GAL::onPaint( wxPaintEvent& aEvent )
 
 void CAIRO_GAL::ResizeScreen( int aWidth, int aHeight )
 {
-    deleteBitmaps();
-
     screenSize  = VECTOR2D( aWidth, aHeight );
 
     // Recreate the bitmaps
+    deleteBitmaps();
     allocateBitmaps();
 
     SetSize( wxSize( aWidth, aHeight ) );
@@ -128,28 +127,19 @@ void CAIRO_GAL::skipMouseEvent( wxMouseEvent& aEvent )
 
 void CAIRO_GAL::initSurface()
 {
-    if( isInitialized )
+    wxASSERT( !isInitialized );
-        return;
-
-    // The size of the client area needs to be greater than zero
-    clientRectangle = parentWindow->GetClientRect();
-
-    if( clientRectangle.width == 0 || clientRectangle.height == 0 )
-        throw EXCEPTION_ZERO_CLIENT_RECTANGLE;
 
     // Create the Cairo surface
-    cairoSurface = cairo_image_surface_create_for_data( (unsigned char*) bitmapBuffer,
+    surface = cairo_image_surface_create_for_data( (unsigned char*) bitmapBuffer, GAL_FORMAT,
-                                                        CAIRO_FORMAT_RGB24, clientRectangle.width,
+                                                   screenSize.x, screenSize.y, stride );
-                                                        clientRectangle.height, stride );
+    context = cairo_create( surface );
-    cairoImage = cairo_create( cairoSurface );
 #ifdef __WXDEBUG__
-    cairo_status_t status = cairo_status( cairoImage );
+    cairo_status_t status = cairo_status( context );
     wxASSERT_MSG( status == CAIRO_STATUS_SUCCESS, "Cairo context creation error" );
 #endif /* __WXDEBUG__ */
+    currentContext = context;
 
-    // -----------------------------------------------------------------
+    cairo_set_antialias( context, CAIRO_ANTIALIAS_SUBPIXEL );
-
-    cairo_set_antialias( cairoImage, CAIRO_ANTIALIAS_SUBPIXEL );
 
     // Clear the screen
     ClearScreen();
@@ -162,21 +152,20 @@ void CAIRO_GAL::initSurface()
                        worldScreenMatrix.m_data[1][1], worldScreenMatrix.m_data[0][2],
                        worldScreenMatrix.m_data[1][2] );
 
-    cairo_set_matrix( cairoImage, &cairoWorldScreenMatrix );
+    cairo_set_matrix( context, &cairoWorldScreenMatrix );
 
     isSetAttributes = false;
 
     // Start drawing with a new path
-    cairo_new_path( cairoImage );
+    cairo_new_path( context );
     isElementAdded = true;
 
-    cairo_set_line_join( cairoImage, CAIRO_LINE_JOIN_ROUND );
+    cairo_set_line_join( context, CAIRO_LINE_JOIN_ROUND );
-    cairo_set_line_cap( cairoImage, CAIRO_LINE_CAP_ROUND );
+    cairo_set_line_cap( context, CAIRO_LINE_CAP_ROUND );
 
     lineWidth = 0;
 
     isDeleteSavedPixels = true;
-
     isInitialized = true;
 }
 
@@ -187,13 +176,25 @@ void CAIRO_GAL::deinitSurface()
         return;
 
     // Destroy Cairo objects
-    cairo_destroy( cairoImage );
+    cairo_destroy( context );
-    cairo_surface_destroy( cairoSurface );
+    cairo_surface_destroy( surface );
 
     isInitialized = false;
 }
 
 
+void CAIRO_GAL::setCompositor()
+{
+    // Recreate the compositor with the new Cairo context
+    compositor.reset( new CAIRO_COMPOSITOR( &currentContext ) );
+    compositor->Resize( screenSize.x, screenSize.y );
+
+    // Prepare buffers
+    mainBuffer = compositor->GetBuffer();
+    overlayBuffer = compositor->GetBuffer();
+}
+
+
 unsigned int CAIRO_GAL::getNewGroupNumber()
 {
     wxASSERT_MSG( groups.size() < std::numeric_limits<unsigned int>::max(),
@@ -211,8 +212,10 @@ unsigned int CAIRO_GAL::getNewGroupNumber()
 void CAIRO_GAL::BeginDrawing() throw( int )
 {
     initSurface();
+    setCompositor();
 
-    cairo_push_group( cairoImage );
+    // Cairo grouping prevents display of overlapping items on the same layer in the lighter color
+    cairo_push_group( currentContext );
 }
 
 
@@ -221,13 +224,18 @@ void CAIRO_GAL::EndDrawing()
     // Force remaining objects to be drawn
     Flush();
 
-    cairo_pop_group_to_source( cairoImage );
+    // Cairo grouping prevents display of overlapping items on the same layer in the lighter color
-    cairo_paint_with_alpha( cairoImage, fillColor.a );
+    cairo_pop_group_to_source( currentContext );
+    cairo_paint_with_alpha( currentContext, fillColor.a );
+
+    // Merge buffers on the screen
+    compositor->DrawBuffer( mainBuffer );
+    compositor->DrawBuffer( overlayBuffer );
 
     // This code was taken from the wxCairo example - it's not the most efficient one
     // Here is a good place for optimizations
 
-    // Now translate the raw image data from the format stored
+    // Now translate the raw context data from the format stored
     // by cairo into a format understood by wxImage.
     unsigned char* wxOutputPtr = wxOutput;
 
@@ -282,14 +290,36 @@ void CAIRO_GAL::RestoreScreen()
 
 void CAIRO_GAL::SetTarget( RenderTarget aTarget )
 {
-    wxASSERT_MSG( false, wxT( "Not implemented yet" ) );
+    // 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 )
+        return;
+
+    // Cairo grouping prevents display of overlapping items on the same layer in the lighter color
+    cairo_pop_group_to_source( currentContext );
+    cairo_paint_with_alpha( currentContext, fillColor.a );
+
+    switch( aTarget )
+    {
+    default:
+    case TARGET_CACHED:
+    case TARGET_NONCACHED:
+        compositor->SetBuffer( mainBuffer );
+        break;
+
+    case TARGET_OVERLAY:
+        compositor->SetBuffer( overlayBuffer );
+        break;
+    }
+
+    cairo_push_group( currentContext );
 }
 
 
 void CAIRO_GAL::DrawLine( const VECTOR2D& aStartPoint, const VECTOR2D& aEndPoint )
 {
-    cairo_move_to( cairoImage, aStartPoint.x, aStartPoint.y );
+    cairo_move_to( currentContext, aStartPoint.x, aStartPoint.y );
-    cairo_line_to( cairoImage, aEndPoint.x, aEndPoint.y );
+    cairo_line_to( currentContext, aEndPoint.x, aEndPoint.y );
     isElementAdded = true;
 }
 
@@ -299,32 +329,34 @@ void CAIRO_GAL::DrawSegment( const VECTOR2D& aStartPoint, const VECTOR2D& aEndPo
 {
     if( isFillEnabled )
     {
+        // Filled tracks mode
         SetLineWidth( aWidth );
 
-        cairo_move_to( cairoImage, (double) aStartPoint.x, (double) aStartPoint.y );
+        cairo_move_to( currentContext, (double) aStartPoint.x, (double) aStartPoint.y );
-        cairo_line_to( cairoImage, (double) aEndPoint.x, (double) aEndPoint.y );
+        cairo_line_to( currentContext, (double) aEndPoint.x, (double) aEndPoint.y );
     }
     else
     {
+        // Outline mode for tracks
         VECTOR2D startEndVector = aEndPoint - aStartPoint;
         double   lineAngle      = atan2( startEndVector.y, startEndVector.x );
         double   lineLength     = startEndVector.EuclideanNorm();
 
-        cairo_save( cairoImage );
+        cairo_save( currentContext );
 
-        cairo_translate( cairoImage, aStartPoint.x, aStartPoint.y );
+        cairo_translate( currentContext, aStartPoint.x, aStartPoint.y );
-        cairo_rotate( cairoImage, lineAngle );
+        cairo_rotate( currentContext, lineAngle );
 
-        cairo_arc( cairoImage, 0.0, 0.0,        aWidth / 2.0,  M_PI / 2.0, 3.0 * M_PI / 2.0 );
+        cairo_arc( currentContext, 0.0, 0.0,        aWidth / 2.0,  M_PI / 2.0, 3.0 * M_PI / 2.0 );
-        cairo_arc( cairoImage, lineLength, 0.0, aWidth / 2.0, -M_PI / 2.0, M_PI / 2.0 );
+        cairo_arc( currentContext, lineLength, 0.0, aWidth / 2.0, -M_PI / 2.0, M_PI / 2.0 );
 
-        cairo_move_to( cairoImage, 0.0,        aWidth / 2.0 );
+        cairo_move_to( currentContext, 0.0,        aWidth / 2.0 );
-        cairo_line_to( cairoImage, lineLength, aWidth / 2.0 );
+        cairo_line_to( currentContext, lineLength, aWidth / 2.0 );
 
-        cairo_move_to( cairoImage, 0.0,        -aWidth / 2.0 );
+        cairo_move_to( currentContext, 0.0,        -aWidth / 2.0 );
-        cairo_line_to( cairoImage, lineLength, -aWidth / 2.0 );
+        cairo_line_to( currentContext, lineLength, -aWidth / 2.0 );
 
-        cairo_restore( cairoImage );
+        cairo_restore( currentContext );
     }
 
     isElementAdded = true;
@@ -334,8 +366,8 @@ void CAIRO_GAL::DrawSegment( const VECTOR2D& aStartPoint, const VECTOR2D& aEndPo
 void CAIRO_GAL::DrawCircle( const VECTOR2D& aCenterPoint, double aRadius )
 {
     // A circle is drawn using an arc
-    cairo_new_sub_path( cairoImage );
+    cairo_new_sub_path( currentContext );
-    cairo_arc( cairoImage, aCenterPoint.x, aCenterPoint.y, aRadius, 0.0, 2 * M_PI );
+    cairo_arc( currentContext, aCenterPoint.x, aCenterPoint.y, aRadius, 0.0, 2 * M_PI );
 
     isElementAdded = true;
 }
@@ -346,8 +378,8 @@ void CAIRO_GAL::DrawArc( const VECTOR2D& aCenterPoint, double aRadius, double aS
 {
     SWAP( aStartAngle, >, aEndAngle );
 
-    cairo_new_sub_path( cairoImage );
+    cairo_new_sub_path( currentContext );
-    cairo_arc( cairoImage, aCenterPoint.x, aCenterPoint.y, aRadius, aStartAngle, aEndAngle );
+    cairo_arc( currentContext, aCenterPoint.x, aCenterPoint.y, aRadius, aStartAngle, aEndAngle );
 
     isElementAdded = true;
 }
@@ -355,21 +387,13 @@ void CAIRO_GAL::DrawArc( const VECTOR2D& aCenterPoint, double aRadius, double aS
 
 void CAIRO_GAL::DrawPolyline( std::deque<VECTOR2D>& aPointList )
 {
-    bool isFirstPoint = true;
-
     // Iterate over the point list and draw the segments
-    std::deque<VECTOR2D>::const_iterator it;
+    std::deque<VECTOR2D>::const_iterator it = aPointList.begin();
-    for( it = aPointList.begin(); it != aPointList.end(); ++it )
+
+    cairo_move_to( currentContext, it->x, it->y );
+    for( ++it; it != aPointList.end(); ++it )
     {
-        if( isFirstPoint )
+        cairo_line_to( currentContext, it->x, it->y );
-        {
-            cairo_move_to( cairoImage, it->x, it->y );
-            isFirstPoint = false;
-        }
-        else
-        {
-            cairo_line_to( cairoImage, it->x, it->y );
-        }
     }
 
     isElementAdded = true;
@@ -378,21 +402,13 @@ void CAIRO_GAL::DrawPolyline( std::deque<VECTOR2D>& aPointList )
 
 void CAIRO_GAL::DrawPolygon( const std::deque<VECTOR2D>& aPointList )
 {
-    bool isFirstPoint = true;
-
     // Iterate over the point list and draw the polygon
-    std::deque<VECTOR2D>::const_iterator it;
+    std::deque<VECTOR2D>::const_iterator it = aPointList.begin();
-    for( it = aPointList.begin(); it != aPointList.end(); ++it )
+
+    cairo_move_to( currentContext, it->x, it->y );
+    for( ++it; it != aPointList.end(); ++it )
     {
-        if( isFirstPoint )
+        cairo_line_to( currentContext, it->x, it->y );
-        {
-            cairo_move_to( cairoImage, it->x, it->y );
-            isFirstPoint = false;
-        }
-        else
-        {
-            cairo_line_to( cairoImage, it->x, it->y );
-        }
     }
 
     isElementAdded = true;
@@ -406,11 +422,11 @@ void CAIRO_GAL::DrawRectangle( const VECTOR2D& aStartPoint, const VECTOR2D& aEnd
     VECTOR2D diagonalPointB( aStartPoint.x, aEndPoint.y );
 
     // The path is composed from 4 segments
-    cairo_move_to( cairoImage, aStartPoint.x, aStartPoint.y );
+    cairo_move_to( currentContext, aStartPoint.x, aStartPoint.y );
-    cairo_line_to( cairoImage, diagonalPointA.x, diagonalPointA.y );
+    cairo_line_to( currentContext, diagonalPointA.x, diagonalPointA.y );
-    cairo_line_to( cairoImage, aEndPoint.x, aEndPoint.y );
+    cairo_line_to( currentContext, aEndPoint.x, aEndPoint.y );
-    cairo_line_to( cairoImage, diagonalPointB.x, diagonalPointB.y );
+    cairo_line_to( currentContext, diagonalPointB.x, diagonalPointB.y );
-    cairo_close_path( cairoImage );
+    cairo_close_path( currentContext );
 
     isElementAdded = true;
 }
@@ -419,10 +435,11 @@ void CAIRO_GAL::DrawRectangle( const VECTOR2D& aStartPoint, const VECTOR2D& aEnd
 void CAIRO_GAL::DrawCurve( const VECTOR2D& aStartPoint, const VECTOR2D& aControlPointA,
                            const VECTOR2D& aControlPointB, const VECTOR2D& aEndPoint )
 {
-    cairo_move_to( cairoImage, aStartPoint.x, aStartPoint.y );
+    cairo_move_to( currentContext, aStartPoint.x, aStartPoint.y );
-    cairo_curve_to( cairoImage, aControlPointA.x, aControlPointA.y, aControlPointB.x,
+    cairo_curve_to( currentContext, aControlPointA.x, aControlPointA.y, aControlPointB.x,
                     aControlPointB.y, aEndPoint.x, aEndPoint.y );
-    cairo_line_to( cairoImage, aEndPoint.x, aEndPoint.y );
+    cairo_line_to( currentContext, aEndPoint.x, aEndPoint.y );
+
     isElementAdded = true;
 }
 
@@ -466,7 +483,6 @@ void CAIRO_GAL::SetIsStroke( bool aIsStrokeEnabled )
 void CAIRO_GAL::SetStrokeColor( const COLOR4D& aColor )
 {
     storePath();
-
     strokeColor = aColor;
 
     if( isGrouping )
@@ -506,12 +522,6 @@ void CAIRO_GAL::SetLineWidth( double aLineWidth )
 
     lineWidth = aLineWidth;
 
-    // Make lines appear at least 1 pixel wide, no matter of zoom
-    double x = 1.0, y = 1.0;
-    cairo_device_to_user_distance( cairoImage, &x, &y );
-    double minWidth = std::min( fabs( x ), fabs( y ) );
-    cairo_set_line_width( cairoImage, std::max( aLineWidth, minWidth ) );
-
     if( isGrouping )
     {
         GroupElement groupElement;
@@ -519,16 +529,23 @@ void CAIRO_GAL::SetLineWidth( double aLineWidth )
         groupElement.arguments[0] = aLineWidth;
         currentGroup->push_back( groupElement );
     }
+    else
+    {
+        // Make lines appear at least 1 pixel wide, no matter of zoom
+        double x = 1.0, y = 1.0;
+        cairo_device_to_user_distance( currentContext, &x, &y );
+        double minWidth = std::min( fabs( x ), fabs( y ) );
+        cairo_set_line_width( currentContext, std::max( aLineWidth, minWidth ) );
+    }
 }
 
 
 void CAIRO_GAL::ClearScreen()
 {
-    // Clear screen
+    cairo_set_source_rgb( currentContext,
-    cairo_set_source_rgba( cairoImage,
+                           backgroundColor.r, backgroundColor.g, backgroundColor.b );
-                           backgroundColor.r, backgroundColor.g, backgroundColor.b, 1.0 );
+    cairo_rectangle( currentContext, 0.0, 0.0, screenSize.x, screenSize.y );
-    cairo_rectangle( cairoImage, 0.0, 0.0, screenSize.x, screenSize.y );
+    cairo_fill( currentContext );
-    cairo_fill( cairoImage );
 }
 
 
@@ -540,10 +557,10 @@ void CAIRO_GAL::SetLayerDepth( double aLayerDepth )
     {
         storePath();
 
-        cairo_pop_group_to_source( cairoImage );
+//        cairo_pop_group_to_source( currentContext );
-        cairo_paint_with_alpha( cairoImage, fillColor.a );
+//        cairo_paint_with_alpha( currentContext, fillColor.a );
-
+//
-        cairo_push_group( cairoImage );
+//        cairo_push_group( currentContext );
     }
 }
 
@@ -560,7 +577,7 @@ void CAIRO_GAL::Transform( MATRIX3x3D aTransformation )
                        aTransformation.m_data[0][2],
                        aTransformation.m_data[1][2] );
 
-    cairo_transform( cairoImage, &cairoTransformation );
+    cairo_transform( currentContext, &cairoTransformation );
 }
 
 
@@ -568,8 +585,6 @@ void CAIRO_GAL::Rotate( double aAngle )
 {
     storePath();
 
-    cairo_rotate( cairoImage, aAngle );
-
     if( isGrouping )
     {
         GroupElement groupElement;
@@ -577,6 +592,10 @@ void CAIRO_GAL::Rotate( double aAngle )
         groupElement.arguments[0] = aAngle;
         currentGroup->push_back( groupElement );
     }
+    else
+    {
+        cairo_rotate( currentContext, aAngle );
+    }
 }
 
 
@@ -584,8 +603,6 @@ void CAIRO_GAL::Translate( const VECTOR2D& aTranslation )
 {
     storePath();
 
-    cairo_translate( cairoImage, aTranslation.x, aTranslation.y );
-
     if( isGrouping )
     {
         GroupElement groupElement;
@@ -594,6 +611,10 @@ void CAIRO_GAL::Translate( const VECTOR2D& aTranslation )
         groupElement.arguments[1] = aTranslation.y;
         currentGroup->push_back( groupElement );
     }
+    else
+    {
+        cairo_translate( currentContext, aTranslation.x, aTranslation.y );
+    }
 }
 
 
@@ -601,8 +622,6 @@ void CAIRO_GAL::Scale( const VECTOR2D& aScale )
 {
     storePath();
 
-    cairo_scale( cairoImage, aScale.x, aScale.y );
-
     if( isGrouping )
     {
         GroupElement groupElement;
@@ -611,6 +630,10 @@ void CAIRO_GAL::Scale( const VECTOR2D& aScale )
         groupElement.arguments[1] = aScale.y;
         currentGroup->push_back( groupElement );
     }
+    else
+    {
+        cairo_scale( currentContext, aScale.x, aScale.y );
+    }
 }
 
 
@@ -618,14 +641,16 @@ void CAIRO_GAL::Save()
 {
     storePath();
 
-    cairo_save( cairoImage );
-
     if( isGrouping )
     {
         GroupElement groupElement;
         groupElement.command = CMD_SAVE;
         currentGroup->push_back( groupElement );
     }
+    else
+    {
+        cairo_save( currentContext );
+    }
 }
 
 
@@ -633,14 +658,16 @@ void CAIRO_GAL::Restore()
 {
     storePath();
 
-    cairo_restore( cairoImage );
-
     if( isGrouping )
     {
         GroupElement groupElement;
         groupElement.command = CMD_RESTORE;
         currentGroup->push_back( groupElement );
     }
+    else
+    {
+        cairo_restore( currentContext );
+    }
 }
 
 
@@ -734,50 +761,50 @@ void CAIRO_GAL::DrawGroup( int aGroupNumber )
             {
                 // Make lines appear at least 1 pixel wide, no matter of zoom
                 double x = 1.0, y = 1.0;
-                cairo_device_to_user_distance( cairoImage, &x, &y );
+                cairo_device_to_user_distance( currentContext, &x, &y );
                 double minWidth = std::min( fabs( x ), fabs( y ) );
-                cairo_set_line_width( cairoImage, std::max( it->arguments[0], minWidth ) );
+                cairo_set_line_width( currentContext, std::max( it->arguments[0], minWidth ) );
             }
             break;
 
 
         case CMD_STROKE_PATH:
-            cairo_set_source_rgb( cairoImage, strokeColor.r, strokeColor.g, strokeColor.b );
+            cairo_set_source_rgb( currentContext, strokeColor.r, strokeColor.g, strokeColor.b );
-            cairo_append_path( cairoImage, it->cairoPath );
+            cairo_append_path( currentContext, it->cairoPath );
-            cairo_stroke( cairoImage );
+            cairo_stroke( currentContext );
             break;
 
         case CMD_FILL_PATH:
-            cairo_set_source_rgb( cairoImage, fillColor.r, fillColor.g, fillColor.b );
+            cairo_set_source_rgb( currentContext, fillColor.r, fillColor.g, fillColor.b );
-            cairo_append_path( cairoImage, it->cairoPath );
+            cairo_append_path( currentContext, it->cairoPath );
-            cairo_fill( cairoImage );
+            cairo_fill( currentContext );
             break;
 
         case CMD_TRANSFORM:
             cairo_matrix_t matrix;
             cairo_matrix_init( &matrix, it->arguments[0], it->arguments[1], it->arguments[2],
                                it->arguments[3], it->arguments[4], it->arguments[5] );
-            cairo_transform( cairoImage, &matrix );
+            cairo_transform( currentContext, &matrix );
             break;
 
         case CMD_ROTATE:
-            cairo_rotate( cairoImage, it->arguments[0] );
+            cairo_rotate( currentContext, it->arguments[0] );
             break;
 
         case CMD_TRANSLATE:
-            cairo_translate( cairoImage, it->arguments[0], it->arguments[1] );
+            cairo_translate( currentContext, it->arguments[0], it->arguments[1] );
             break;
 
         case CMD_SCALE:
-            cairo_scale( cairoImage, it->arguments[0], it->arguments[1] );
+            cairo_scale( currentContext, it->arguments[0], it->arguments[1] );
             break;
 
         case CMD_SAVE:
-            cairo_save( cairoImage );
+            cairo_save( currentContext );
             break;
 
         case CMD_RESTORE:
-            cairo_restore( cairoImage );
+            cairo_restore( currentContext );
             break;
 
         case CMD_CALL_GROUP:
@@ -851,14 +878,14 @@ void CAIRO_GAL::storePath()
         {
             if( isFillEnabled )
             {
-                cairo_set_source_rgb( cairoImage, fillColor.r, fillColor.g, fillColor.b );
+                cairo_set_source_rgb( currentContext, fillColor.r, fillColor.g, fillColor.b );
-                cairo_fill_preserve( cairoImage );
+                cairo_fill_preserve( currentContext );
             }
 
             if( isStrokeEnabled )
             {
-                cairo_set_source_rgb( cairoImage, strokeColor.r, strokeColor.g, strokeColor.b );
+                cairo_set_source_rgb( currentContext, strokeColor.r, strokeColor.g, strokeColor.b );
-                cairo_stroke_preserve( cairoImage );
+                cairo_stroke_preserve( currentContext );
             }
         }
         else
@@ -869,7 +896,7 @@ void CAIRO_GAL::storePath()
             if( isStrokeEnabled )
             {
                 GroupElement groupElement;
-                groupElement.cairoPath = cairo_copy_path( cairoImage );
+                groupElement.cairoPath = cairo_copy_path( currentContext );
                 groupElement.command   = CMD_STROKE_PATH;
                 currentGroup->push_back( groupElement );
             }
@@ -877,13 +904,13 @@ void CAIRO_GAL::storePath()
             if( isFillEnabled )
             {
                 GroupElement groupElement;
-                groupElement.cairoPath = cairo_copy_path( cairoImage );
+                groupElement.cairoPath = cairo_copy_path( currentContext );
                 groupElement.command   = CMD_FILL_PATH;
                 currentGroup->push_back( groupElement );
             }
         }
 
-        cairo_new_path( cairoImage );
+        cairo_new_path( currentContext );
     }
 }
 
@@ -962,17 +989,17 @@ void CAIRO_GAL::DrawCursor( VECTOR2D aCursorPosition )
 
 void CAIRO_GAL::DrawGridLine( const VECTOR2D& aStartPoint, const VECTOR2D& aEndPoint )
 {
-    cairo_move_to( cairoImage, aStartPoint.x, aStartPoint.y );
+    cairo_move_to( currentContext, aStartPoint.x, aStartPoint.y );
-    cairo_line_to( cairoImage, aEndPoint.x, aEndPoint.y );
+    cairo_line_to( currentContext, aEndPoint.x, aEndPoint.y );
-    cairo_set_source_rgba( cairoImage, gridColor.r, gridColor.g, gridColor.b, gridColor.a );
+    cairo_set_source_rgb( currentContext, gridColor.r, gridColor.g, gridColor.b );
-    cairo_stroke( cairoImage );
+    cairo_stroke( currentContext );
 }
 
 
 void CAIRO_GAL::allocateBitmaps()
 {
-    // Create buffer, use the system independent Cairo image backend
+    // Create buffer, use the system independent Cairo context backend
-    stride     = cairo_format_stride_for_width( CAIRO_FORMAT_RGB24, screenSize.x );
+    stride     = cairo_format_stride_for_width( GAL_FORMAT, screenSize.x );
     bufferSize = stride * screenSize.y;
 
     bitmapBuffer       	= new unsigned int[bufferSize];

include/gal/cairo/cairo_compositor.h

@@ -0,0 +1,108 @@
+/*
+ * This program source code file is part of KiCad, a free EDA CAD application.
+ *
+ * Copyright (C) 2013 CERN
+ * @author Maciej Suminski <maciej.suminski@cern.ch>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you may find one here:
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * or you may search the http://www.gnu.org website for the version 2 license,
+ * or you may write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
+/**
+ * @file cairo_compositor.h
+ * @brief Class that handles multitarget rendering (ie. to different textures/surfaces) and
+ * later compositing into a single image (Cairo flavour).
+ */
+
+#ifndef CAIRO_COMPOSITOR_H_
+#define CAIRO_COMPOSITOR_H_
+
+#include <gal/compositor.h>
+#include <cairo.h>
+#include <boost/smart_ptr/shared_array.hpp>
+#include <deque>
+
+namespace KiGfx
+{
+
+class CAIRO_COMPOSITOR : public COMPOSITOR
+{
+public:
+    CAIRO_COMPOSITOR( cairo_t** aMainContext );
+    virtual ~CAIRO_COMPOSITOR();
+
+    /// @copydoc COMPOSITOR::Initialize()
+    virtual void Initialize();
+
+    /// @copydoc COMPOSITOR::Resize()
+    virtual void Resize( unsigned int aWidth, unsigned int aHeight );
+
+    /// @copydoc COMPOSITOR::GetBuffer()
+    virtual unsigned int GetBuffer();
+
+    /// @copydoc COMPOSITOR::SetBuffer()
+    virtual void SetBuffer( unsigned int aBufferHandle );
+
+    /// @copydoc COMPOSITOR::ClearBuffer()
+    virtual void ClearBuffer();
+
+    /// @copydoc COMPOSITOR::DrawBuffer()
+    virtual void DrawBuffer( unsigned int aBufferHandle );
+
+protected:
+    typedef boost::shared_array<unsigned int> BitmapPtr;
+    typedef struct
+    {
+        cairo_t* context;                   ///< Main texture handle
+        cairo_surface_t* surface;           ///< Point to which an image from texture is attached
+        BitmapPtr bitmap;                   ///< Pixel storage
+    } CAIRO_BUFFER;
+
+    unsigned int                m_current;                ///< Currently used buffer handle
+    typedef std::deque<CAIRO_BUFFER> CAIRO_BUFFERS;
+
+    /// Pointer to the current context, so it can be changed
+    cairo_t**                   m_currentContext;
+
+    /// Rendering target used for compositing (the main display)
+    cairo_t*                    m_mainContext;
+
+    /// Transformation matrix
+    cairo_matrix_t              m_matrix;
+
+    /// Stores information about initialized buffers
+    CAIRO_BUFFERS               m_buffers;
+
+    unsigned int m_stride;              ///< Stride to use given the desired format and width
+    unsigned int m_bufferSize;          ///< Amount of memory needed to store a buffer
+
+    /**
+     * Function clean()
+     * performs freeing of resources.
+     */
+    void clean();
+
+    /// Returns number of currently used buffers
+    unsigned int usedBuffers()
+    {
+        return m_buffers.size();
+    }
+};
+
+} // namespace KiGfx
+
+#endif /* COMPOSITOR_H_ */

include/gal/cairo/cairo_gal.h

@@ -33,7 +33,7 @@
 #include <cairo.h>
 
 #include <gal/graphics_abstraction_layer.h>
-
+#include <boost/smart_ptr/shared_ptr.hpp>
 
 #if defined(__WXMSW__)
 #define SCREEN_DEPTH 24
@@ -62,6 +62,8 @@
  */
 namespace KiGfx
 {
+class CAIRO_COMPOSITOR;
+
 class CAIRO_GAL : public GAL, public wxWindow
 {
 public:
@@ -81,7 +83,7 @@ public:
      * @param aName is the name of this window for use by wxWindow::FindWindowByName()
      */
     CAIRO_GAL( wxWindow* aParent, wxEvtHandler* aMouseListener = NULL,
-               wxEvtHandler* aPaintListener = NULL, const wxString& aName = wxT("CairoCanvas") );
+               wxEvtHandler* aPaintListener = NULL, const wxString& aName = wxT( "CairoCanvas" ) );
 
     virtual ~CAIRO_GAL();
 
@@ -299,11 +301,15 @@ private:
     /// Super class definition
     typedef GAL super;
 
+    // Compositing variables
+    boost::shared_ptr<CAIRO_COMPOSITOR> compositor; ///< Object for layers compositing
+    unsigned int mainBuffer;                        ///< Handle to the main buffer
+    unsigned int overlayBuffer;                     ///< Handle to the overlay buffer
+
     // Variables related to wxWidgets
     wxWindow*                   parentWindow;       ///< Parent window
     wxEvtHandler*               mouseListener;      ///< Mouse listener
     wxEvtHandler*               paintListener;      ///< Paint listener
-    wxRect                      clientRectangle;    ///< Area definition of the surface
     unsigned int                bufferSize;         ///< Size of buffers cairoOutput, bitmapBuffers
     unsigned char*              wxOutput;           ///< wxImage comaptible buffer
 
@@ -315,11 +321,6 @@ private:
     wxBitmap*                   cursorPixelsSaved;      ///< Saved cursor pixels
     int                         cursorSize;             ///< Cursor size
 
-    // Variables for the grouping function
-    int                         actualGroupIndex;   ///< The index of the actual group
-    bool                        isGrouping;         ///< Is grouping enabled ?
-    bool                        isElementAdded;     ///< Was an graphic element added ?
-
     /// Maximum number of arguments for one command
     static const int MAX_CAIRO_ARGUMENTS = 6;
 
@@ -352,15 +353,19 @@ private:
         cairo_path_t* cairoPath;                    ///< Pointer to a Cairo path
     } GroupElement;
 
+    // Variables for the grouping function
+    bool                        isGrouping;         ///< Is grouping enabled ?
+    bool                        isElementAdded;     ///< Was an graphic element added ?
     typedef std::deque<GroupElement> Group;         ///< A graphic group type definition
-    std::map<int, Group> groups;                    ///< List of graphic groups
+    std::map<int, Group>        groups;             ///< List of graphic groups
-    unsigned int groupCounter;                      ///< Counter used for generating keys for groups
+    unsigned int                groupCounter;       ///< Counter used for generating keys for groups
-    Group* currentGroup;                            ///< Currently used group
+    Group*                      currentGroup;       ///< Currently used group
 
     // Variables related to Cairo <-> wxWidgets
     cairo_matrix_t      cairoWorldScreenMatrix; ///< Cairo world to screen transformation matrix
-    cairo_t*            cairoImage;             ///< Cairo image
+    cairo_t*            currentContext;         ///< Currently used Cairo context for drawing
-    cairo_surface_t*    cairoSurface;           ///< Cairo surface
+    cairo_t*            context;                ///< Cairo image
+    cairo_surface_t*    surface;                ///< Cairo surface
     unsigned int*       bitmapBuffer;           ///< Storage of the cairo image
     unsigned int*       bitmapBufferBackup;     ///< Backup storage of the cairo image
     int                 stride;                 ///< Stride value for Cairo
@@ -400,15 +405,21 @@ private:
     /// Prepare Cairo surfaces for drawing
     void initSurface();
 
-    // Destroy Cairo surfaces when are not needed anymore
+    /// Destroy Cairo surfaces when are not needed anymore
     void deinitSurface();
 
+    /// Prepare the compositor
+    void setCompositor();
+
     /**
      * @brief Returns a valid key that can be used as a new group number.
      *
      * @return An unique group number that is not used by any other group.
      */
     unsigned int getNewGroupNumber();
+
+    /// Format used to store pixels
+    static const cairo_format_t GAL_FORMAT = CAIRO_FORMAT_RGB24;
 };
 } // namespace KiGfx