Faster draw for multiband color in case there is no transparency, str…

…ech, inversion
qgis · Jan 28, 2012 · 3b36620 · 3b36620
1 parent 91c37fb
commit 3b36620
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Showing 3 changed files with 35 additions and 7 deletions.
diff --git a/src/core/raster/qgsmultibandcolorrenderer.cpp b/src/core/raster/qgsmultibandcolorrenderer.cpp
@@ -18,6 +18,7 @@
 #include "qgsmultibandcolorrenderer.h"
 #include "qgscontrastenhancement.h"
 #include "qgsrastertransparency.h"
+#include "qgsrasterviewport.h"
 #include <QImage>
 #include <QSet>
 
@@ -41,6 +42,13 @@ void QgsMultiBandColorRenderer::draw( QPainter* p, QgsRasterViewPort* viewPort,
     return;
   }
 
+  //In some (common) cases, we can simplify the drawing loop considerably and save render time
+  bool fastDraw = (
+                    !usesTransparency( viewPort->mSrcCRS, viewPort->mDestCRS )
+                    && mRedBand > 0 && mGreenBand > 0 && mBlueBand > 0
+                    && mAlphaBand < 1 && !mRedContrastEnhancement && !mGreenContrastEnhancement && !mBlueContrastEnhancement
+                    && !mInvertColor );
+
   QgsRasterDataProvider::DataType redType;
   if ( mRedBand > 0 )
   {
@@ -155,15 +163,26 @@ void QgsMultiBandColorRenderer::draw( QPainter* p, QgsRasterViewPort* viewPort,
       imageScanLine = ( QRgb* )( img.scanLine( i ) );
       for ( int j = 0; j < nRasterCols; ++j )
       {
-        if ( mRedBand )
+
+        if ( fastDraw ) //fast rendering if no transparency, stretching, color inversion, etc.
+        {
+          redVal = readValue( redData, redType, currentRasterPos );
+          greenVal = readValue( greenData, greenType, currentRasterPos );
+          blueVal = readValue( blueData, blueType, currentRasterPos );
+          imageScanLine[j] = qRgba( redVal, greenVal, blueVal, 255 );
+          ++currentRasterPos;
+          continue;
+        }
+
+        if ( mRedBand > 0 )
         {
           redVal = readValue( redData, redType, currentRasterPos );
         }
-        if ( mGreenBand )
+        if ( mGreenBand > 0 )
         {
           greenVal = readValue( greenData, greenType, currentRasterPos );
         }
-        if ( mBlueBand )
+        if ( mBlueBand > 0 )
         {
           blueVal = readValue( blueData, blueType, currentRasterPos );
         }

diff --git a/src/core/raster/qgsrasterlayer.cpp b/src/core/raster/qgsrasterlayer.cpp
@@ -693,21 +693,30 @@ void QgsRasterLayer::setRendererForDrawingStyle( const DrawingStyle &  theDrawin
       if ( mRedBandName != TRSTRING_NOT_SET )
       {
         red = bandNumber( mRedBandName );
-        redEnhancement = contrastEnhancement( red );
+        if ( contrastEnhancementAlgorithm() != QgsContrastEnhancement::NoEnhancement )
+        {
+          redEnhancement = contrastEnhancement( red );
+        }
       }
       int green = -1;
       QgsContrastEnhancement* greenEnhancement = 0;
       if ( mGreenBandName != TRSTRING_NOT_SET )
       {
         green = bandNumber( mGreenBandName );
-        greenEnhancement = contrastEnhancement( green );
+        if ( contrastEnhancementAlgorithm() != QgsContrastEnhancement::NoEnhancement )
+        {
+          greenEnhancement = contrastEnhancement( green );
+        }
       }
       int blue = -1;
       QgsContrastEnhancement* blueEnhancement = 0;
       if ( mBlueBandName != TRSTRING_NOT_SET )
       {
         blue = bandNumber( mBlueBandName );
-        blueEnhancement = contrastEnhancement( blue );
+        if ( contrastEnhancementAlgorithm() != QgsContrastEnhancement::NoEnhancement )
+        {
+          blueEnhancement = contrastEnhancement( blue );
+        }
       }
       renderer = new QgsMultiBandColorRenderer( mDataProvider, red, green, blue,
           redEnhancement, greenEnhancement, blueEnhancement );

diff --git a/src/core/raster/qgsrastertransparency.cpp b/src/core/raster/qgsrastertransparency.cpp
@@ -177,6 +177,6 @@ bool QgsRasterTransparency::isEmpty( double nodataValue ) const
              ( mTransparentSingleValuePixelList.size() == 1 && doubleNear( mTransparentSingleValuePixelList.at( 0 ).pixelValue, nodataValue ) ) )
            &&
            ( mTransparentThreeValuePixelList.isEmpty() ||
-             ( mTransparentThreeValuePixelList.size() == 1 && doubleNear( mTransparentThreeValuePixelList.at( 0 ).red, nodataValue ) &&
+             ( mTransparentThreeValuePixelList.size() < 4 && doubleNear( mTransparentThreeValuePixelList.at( 0 ).red, nodataValue ) &&
                doubleNear( mTransparentThreeValuePixelList.at( 0 ).green, nodataValue ) && doubleNear( mTransparentThreeValuePixelList.at( 0 ).blue, nodataValue ) ) ) );
 }