First working version of color quantization. Not optimized yet

qgis · Oct 2, 2012 · e0ab410 · e0ab410
1 parent 52d053d
commit e0ab410
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Showing 2 changed files with 37 additions and 3 deletions.
diff --git a/src/mapserver/qgshttprequesthandler.cpp b/src/mapserver/qgshttprequesthandler.cpp
@@ -522,9 +522,15 @@ void QgsHttpRequestHandler::medianCut( QVector<QRgb>& colorTable, int nColors, c
     }
   }
 
-  bool debug = true; //only for breakpoint
-
-  //todo: evaluate the colors of the final boxes
+  //get representative colors for the boxes
+  int index = 0;
+  colorTable.resize( colorBoxMap.size() );
+  QgsColorBoxMap::const_iterator colorBoxIt = colorBoxMap.constBegin();
+  for ( ; colorBoxIt != colorBoxMap.constEnd(); ++colorBoxIt )
+  {
+    colorTable[index] = boxColor( colorBoxIt.value(), colorBoxIt.key() );
+    ++index;
+  }
 }
 
 void QgsHttpRequestHandler::imageColors( QHash<QRgb, int>& colors, const QImage& image )
@@ -715,3 +721,29 @@ bool QgsHttpRequestHandler::alphaCompare( const QPair<QRgb, int>& c1, const QPai
 {
   return qAlpha( c1.first ) < qAlpha( c2.first );
 }
+
+QRgb QgsHttpRequestHandler::boxColor( const QgsColorBox& box, int boxPixels )
+{
+  double avRed = 0;
+  double avGreen = 0;
+  double avBlue = 0;
+  double avAlpha = 0;
+  QRgb currentColor;
+  int currentPixel;
+
+  double weight;
+
+  QgsColorBox::const_iterator colorBoxIt = box.constBegin();
+  for ( ; colorBoxIt != box.constEnd(); ++colorBoxIt )
+  {
+    currentColor = colorBoxIt->first;
+    currentPixel = colorBoxIt->second;
+    weight = currentPixel / boxPixels;
+    avRed += ( qRed( currentColor ) * weight );
+    avGreen += ( qGreen( currentColor ) * weight );
+    avBlue += ( qBlue( currentColor ) * weight );
+    avAlpha += ( qAlpha( currentColor ) * weight );
+  }
+
+  return qRgba( avRed, avGreen, avBlue, avAlpha );
+}
diff --git a/src/mapserver/qgshttprequesthandler.h b/src/mapserver/qgshttprequesthandler.h
@@ -63,6 +63,8 @@ class QgsHttpRequestHandler: public QgsRequestHandler
     static bool greenCompare( const QPair<QRgb, int>& c1, const QPair<QRgb, int>& c2 );
     static bool blueCompare( const QPair<QRgb, int>& c1, const QPair<QRgb, int>& c2 );
     static bool alphaCompare( const QPair<QRgb, int>& c1, const QPair<QRgb, int>& c2 );
+    /**Calculates a representative color for a box (pixel weighted average)*/
+    static QRgb boxColor( const QgsColorBox& box, int boxPixels );
 };
 
 #endif