Consider transparency in raster renderer

Author: mhugent

src/core/raster/qgspalettedrasterrenderer.cpp

@@ -19,6 +19,7 @@
 #include "qgscoordinatetransform.h"
 #include "qgsmaptopixel.h"
 #include "qgsrasterresampler.h"
+#include "qgsrastertransparency.h"
 #include "qgsrasterviewport.h"
 #include <QColor>
 #include <QImage>
@@ -43,18 +44,42 @@ void QgsPalettedRasterRenderer::draw( QPainter* p, QgsRasterViewPort* viewPort,
   }
 
   double oversampling;
+  QgsRasterDataProvider::DataType transparencyType;
+  if ( mAlphaBand > 0 )
+  {
+    transparencyType = ( QgsRasterDataProvider::DataType )mProvider->dataType( mAlphaBand );
+  }
   startRasterRead( mBandNumber, viewPort, theQgsMapToPixel, oversampling );
 
+  //Read alpha band if necessary
+  if ( mAlphaBand > 0 && mAlphaBand != mBandNumber )
+  {
+    startRasterRead( mAlphaBand, viewPort, theQgsMapToPixel, oversampling );
+  }
+
   int nCols = 0;
   int nRows = 0;
   int topLeftCol = 0;
   int topLeftRow = 0;
   int currentRasterPos = 0;
   QgsRasterDataProvider::DataType rasterType = ( QgsRasterDataProvider::DataType )mProvider->dataType( mBandNumber );
   void* rasterData;
+  double currentOpacity = mOpacity;
+
+  bool hasTransparency = usesTransparency();
+  void* transparencyData;
 
   while ( readNextRasterPart( mBandNumber, viewPort, nCols, nRows, &rasterData, topLeftCol, topLeftRow ) )
   {
+    if ( mAlphaBand > 0 && mAlphaBand != mBandNumber )
+    {
+      readNextRasterPart( mAlphaBand, viewPort, nCols, nRows, &transparencyData, topLeftCol, topLeftRow );
+    }
+    else if ( mAlphaBand == mBandNumber )
+    {
+      transparencyData = rasterData;
+    }
+
     //create image
     QImage img( nCols, nRows, QImage::Format_ARGB32_Premultiplied );
     QRgb* imageScanLine = 0;
@@ -67,9 +92,24 @@ void QgsPalettedRasterRenderer::draw( QPainter* p, QgsRasterViewPort* viewPort,
       for ( int j = 0; j < nCols; ++j )
       {
         val = readValue( rasterData, rasterType, currentRasterPos );
-        //imageScanLine[j] = mColors[ val ].rgba();
-        QColor& currentColor = mColors[val];
-        imageScanLine[j] = qRgba( mOpacity * currentColor.red(), mOpacity * currentColor.green(), mOpacity * currentColor.blue(), mOpacity * 255 );
+        if ( !hasTransparency )
+        {
+          imageScanLine[j] = mColors[ val ].rgba();
+        }
+        else
+        {
+          currentOpacity = mOpacity;
+          if ( mRasterTransparency )
+          {
+            currentOpacity = mRasterTransparency->alphaValue( val, mOpacity * 255 ) / 255.0;
+          }
+          if ( mAlphaBand >= 0 )
+          {
+            currentOpacity *= ( readValue( transparencyData, transparencyType, currentRasterPos ) / 255.0 );
+          }
+          QColor& currentColor = mColors[val];
+          imageScanLine[j] = qRgba( currentOpacity * currentColor.red(), currentOpacity * currentColor.green(), currentOpacity * currentColor.blue(), currentOpacity * 255 );
+        }
         ++currentRasterPos;
       }
     }
@@ -90,5 +130,11 @@ void QgsPalettedRasterRenderer::draw( QPainter* p, QgsRasterViewPort* viewPort,
       p->drawImage( tlPoint, img );
     }
   }
+
+  //stop raster reading
   stopRasterRead( mBandNumber );
+  if ( mAlphaBand > 0 && mAlphaBand != mBandNumber )
+  {
+    stopRasterRead( mAlphaBand );
+  }
 }

src/core/raster/qgsrasterlayer.cpp

@@ -843,7 +843,7 @@ void QgsRasterLayer::draw( QPainter * theQPainter,
       {
         QgsDebugMsg( "PalettedColor drawing type detected..." );
 
-        //test
+        //create color array for renderer
         int bNumber = bandNumber( mGrayBandName );
         QList<QgsColorRampShader::ColorRampItem> itemList = mRasterStatsList[ bNumber - 1].colorTable;
         QColor* colorArray = new QColor[itemList.size()];
@@ -854,7 +854,17 @@ void QgsRasterLayer::draw( QPainter * theQPainter,
         }
 
         QgsPalettedRasterRenderer renderer( mDataProvider, bNumber, colorArray, itemList.size(), mResampler );
+        //opacity settings for renderer
         renderer.setOpacity( mTransparencyLevel / 255.0 );
+        renderer.setRasterTransparency( &mRasterTransparency );
+        if ( mTransparencyBandName != TRSTRING_NOT_SET )
+        {
+          int tBandNr = bandNumber( mTransparencyBandName );
+          if ( tBandNr > 0 )
+          {
+            renderer.setAlphaBand( tBandNr );
+          }
+        }
         renderer.draw( theQPainter, theRasterViewPort, theQgsMapToPixel );
 #if 0
         drawPalettedSingleBandColor( theQPainter, theRasterViewPort,
@@ -946,6 +956,19 @@ void QgsRasterLayer::draw( QPainter * theQPainter,
         int green = bandNumber( mGreenBandName );
         int blue = bandNumber( mBlueBandName );
         QgsMultiBandColorRenderer r( mDataProvider, red, green, blue, mResampler );
+
+        //opacity settings for renderer
+        r.setOpacity( mTransparencyLevel / 255.0 );
+        r.setRasterTransparency( &mRasterTransparency );
+        if ( mTransparencyBandName != TRSTRING_NOT_SET )
+        {
+          int tBandNr = bandNumber( mTransparencyBandName );
+          if ( tBandNr > 0 )
+          {
+            r.setAlphaBand( tBandNr );
+          }
+        }
+
         r.draw( theQPainter, theRasterViewPort, theQgsMapToPixel );
 #if 0
         drawMultiBandColor( theQPainter, theRasterViewPort,

src/core/raster/qgsrasterrenderer.cpp

@@ -16,11 +16,12 @@
  ***************************************************************************/
 
 #include "qgsrasterrenderer.h"
+#include "qgsrastertransparency.h"
 #include "qgsrasterviewport.h"
 #include "qgsmaptopixel.h"
 
 QgsRasterRenderer::QgsRasterRenderer( QgsRasterDataProvider* provider, QgsRasterResampler* resampler ): mProvider( provider ), mResampler( resampler ),
-    mOpacity( 255 )
+    mOpacity( 1.0 ), mRasterTransparency( 0 ), mAlphaBand( -1 )
 {
 }
 
@@ -147,3 +148,8 @@ void QgsRasterRenderer::removePartInfo( int bandNumber )
     mRasterPartInfos.remove( bandNumber );
   }
 }
+
+bool QgsRasterRenderer::usesTransparency() const
+{
+  return ( mAlphaBand > 0 || ( mRasterTransparency && !mRasterTransparency->isEmpty() ) || !doubleNear( mOpacity, 1.0 ) );
+}

src/core/raster/qgsrasterrenderer.h

@@ -23,6 +23,7 @@
 class QPainter;
 class QgsMapToPixel;
 class QgsRasterResampler;
+class QgsRasterTransparency;
 class QgsRasterViewPort;
 
 class QgsRasterRenderer
@@ -45,9 +46,17 @@ class QgsRasterRenderer
     virtual ~QgsRasterRenderer();
     virtual void draw( QPainter* p, QgsRasterViewPort* viewPort, const QgsMapToPixel* theQgsMapToPixel ) = 0;
 
+    bool usesTransparency() const;
+
     void setOpacity( double opacity ) { mOpacity = opacity; }
     double opacity() const { return mOpacity; }
 
+    void setRasterTransparency( QgsRasterTransparency* t ) { mRasterTransparency = t; }
+    const QgsRasterTransparency* rasterTransparency() const { return mRasterTransparency; }
+
+    void setAlphaBand( int band ) { mAlphaBand = band; }
+    int alphaBand() const { return mAlphaBand; }
+
   protected:
     inline double readValue( void *data, QgsRasterDataProvider::DataType type, int index );
 
@@ -59,7 +68,14 @@ class QgsRasterRenderer
     QgsRasterDataProvider* mProvider;
     QgsRasterResampler* mResampler;
     QMap<int, RasterPartInfo> mRasterPartInfos;
-    double mOpacity; //global alpha value
+
+    /**Global alpha value (0-1)*/
+    double mOpacity;
+    /**Raster transparency per color or value. Overwrites global alpha value*/
+    QgsRasterTransparency* mRasterTransparency;
+    /**Read alpha value from band. Is combined with value from raster transparency / global alpha value.
+        Default: -1 (not set)*/
+    int mAlphaBand;
 
   private:
     /**Remove part into and release memory*/

src/core/raster/qgsrastertransparency.cpp

@@ -168,3 +168,8 @@ int QgsRasterTransparency::alphaValue( double theRedValue, double theGreenValue,
 
   return theGlobalTransparency;
 }
+
+bool QgsRasterTransparency::isEmpty() const
+{
+  return ( mTransparentThreeValuePixelList.isEmpty() && mTransparentSingleValuePixelList.isEmpty() );
+}

src/core/raster/qgsrastertransparency.h

@@ -72,6 +72,9 @@ class CORE_EXPORT QgsRasterTransparency
     /** \brief Return the transparency value for a RGB Pixel */
     int alphaValue( double, double, double, int theGlobalTransparency = 255 ) const;
 
+    /**True if there are no entries in the pixel lists*/
+    bool isEmpty() const;
+
   private:
     /** \brief The list to hold transparency values for RGB layers */
     QList<QgsRasterTransparency::TransparentThreeValuePixel> mTransparentThreeValuePixelList;