Support for global transparency in raster renderer

Author: mhugent

src/core/raster/qgspalettedrasterrenderer.cpp

@@ -67,7 +67,9 @@ void QgsPalettedRasterRenderer::draw( QPainter* p, QgsRasterViewPort* viewPort,
       for ( int j = 0; j < nCols; ++j )
       {
         val = readValue( rasterData, rasterType, currentRasterPos );
-        imageScanLine[j] = mColors[ val ].rgba();
+        //imageScanLine[j] = mColors[ val ].rgba();
+        QColor& currentColor = mColors[val];
+        imageScanLine[j] = qRgba( mOpacity * currentColor.red(), mOpacity * currentColor.green(), mOpacity * currentColor.blue(), mOpacity * 255 );
         ++currentRasterPos;
       }
     }

src/core/raster/qgsrasterlayer.cpp

@@ -852,6 +852,7 @@ void QgsRasterLayer::draw( QPainter * theQPainter,
         //QgsBilinearRasterResampler resampler;
         QgsCubicRasterResampler resampler;
         QgsPalettedRasterRenderer renderer( mDataProvider, bNumber, colorArray, itemList.size(), 0 /*&resampler*/ );
+        renderer.setOpacity( mTransparencyLevel / 255.0 );
         renderer.draw( theQPainter, theRasterViewPort, theQgsMapToPixel );
 #if 0
         drawPalettedSingleBandColor( theQPainter, theRasterViewPort,

src/core/raster/qgsrasterrenderer.cpp

@@ -19,7 +19,8 @@
 #include "qgsrasterviewport.h"
 #include "qgsmaptopixel.h"
 
-QgsRasterRenderer::QgsRasterRenderer( QgsRasterDataProvider* provider, QgsRasterResampler* resampler ): mProvider( provider ), mResampler( resampler )
+QgsRasterRenderer::QgsRasterRenderer( QgsRasterDataProvider* provider, QgsRasterResampler* resampler ): mProvider( provider ), mResampler( resampler ),
+    mOpacity( 255 )
 {
 }
 

src/core/raster/qgsrasterrenderer.h

@@ -45,6 +45,9 @@ class QgsRasterRenderer
     virtual ~QgsRasterRenderer();
     virtual void draw( QPainter* p, QgsRasterViewPort* viewPort, const QgsMapToPixel* theQgsMapToPixel ) = 0;
 
+    void setOpacity( double opacity ) { mOpacity = opacity; }
+    double opacity() const { return mOpacity; }
+
   protected:
     inline double readValue( void *data, QgsRasterDataProvider::DataType type, int index );
 
@@ -56,6 +59,7 @@ class QgsRasterRenderer
     QgsRasterDataProvider* mProvider;
     QgsRasterResampler* mResampler;
     QMap<int, RasterPartInfo> mRasterPartInfos;
+    double mOpacity; //global alpha value
 
   private:
     /**Remove part into and release memory*/