Reading of rasters in several parts

qgis · Dec 24, 2011 · c81f4fb · c81f4fb
1 parent 583d61f
commit c81f4fb
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Showing 4 changed files with 167 additions and 1 deletion.
diff --git a/src/core/raster/qgspalettedrasterrenderer.cpp b/src/core/raster/qgspalettedrasterrenderer.cpp
@@ -42,6 +42,53 @@ void QgsPalettedRasterRenderer::draw( QPainter* p, QgsRasterViewPort* viewPort,
     return;
   }
 
+  double oversampling;
+  startRasterRead( mBandNumber, 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;
+
+  while ( readNextRasterPart( mBandNumber, viewPort, nCols, nRows, &rasterData, topLeftCol, topLeftRow ) )
+  {
+    //create image
+    QImage img( nCols, nRows, QImage::Format_ARGB32_Premultiplied );
+    QRgb* imageScanLine = 0;
+    int val = 0;
+
+    for ( int i = 0; i < nRows; ++i )
+    {
+      imageScanLine = ( QRgb* )( img.scanLine( i ) );
+      for ( int j = 0; j < nCols; ++j )
+      {
+        val = readValue( rasterData, rasterType, currentRasterPos );
+        imageScanLine[j] = mColors[ val ].rgba();
+        ++currentRasterPos;
+      }
+    }
+
+    //top left position in device coords
+    QPointF tlPoint = QPointF( viewPort->topLeftPoint.x(), viewPort->topLeftPoint.y() );
+    tlPoint += QPointF( topLeftCol / oversampling, topLeftRow / oversampling );
+
+    //draw image
+    if ( mResampler ) //resample to output resolution
+    {
+      QImage dstImg( viewPort->drawableAreaXDim, viewPort->drawableAreaYDim, QImage::Format_ARGB32_Premultiplied );
+      mResampler->resample( img, dstImg );
+      p->drawImage( tlPoint, dstImg );
+    }
+    else //use original image
+    {
+      p->drawImage( tlPoint, img );
+    }
+  }
+
+#if 0
   int nCols, nRows;
   if ( mResampler )
   {
@@ -97,4 +144,5 @@ void QgsPalettedRasterRenderer::draw( QPainter* p, QgsRasterViewPort* viewPort,
   {
     p->drawImage( QPointF( viewPort->topLeftPoint.x(), viewPort->topLeftPoint.y() ), img );
   }
+#endif //0
 }
diff --git a/src/core/raster/qgsrasterlayer.cpp b/src/core/raster/qgsrasterlayer.cpp
@@ -851,7 +851,7 @@ void QgsRasterLayer::draw( QPainter * theQPainter,
 
         //QgsBilinearRasterResampler resampler;
         QgsCubicRasterResampler resampler;
-        QgsPalettedRasterRenderer renderer( mDataProvider, bNumber, colorArray, itemList.size(), &resampler );
+        QgsPalettedRasterRenderer renderer( mDataProvider, bNumber, colorArray, itemList.size(), 0 /*&resampler*/ );
         renderer.draw( theQPainter, theRasterViewPort, theQgsMapToPixel );
 #if 0
         drawPalettedSingleBandColor( theQPainter, theRasterViewPort,

diff --git a/src/core/raster/qgsrasterrenderer.cpp b/src/core/raster/qgsrasterrenderer.cpp
@@ -16,6 +16,8 @@
  ***************************************************************************/
 
 #include "qgsrasterrenderer.h"
+#include "qgsrasterviewport.h"
+#include "qgsmaptopixel.h"
 
 QgsRasterRenderer::QgsRasterRenderer( QgsRasterDataProvider* provider, QgsRasterResampler* resampler ): mProvider( provider ), mResampler( resampler )
 {
@@ -24,3 +26,100 @@ QgsRasterRenderer::QgsRasterRenderer( QgsRasterDataProvider* provider, QgsRaster
 QgsRasterRenderer::~QgsRasterRenderer()
 {
 }
+
+void QgsRasterRenderer::startRasterRead( int bandNumber, QgsRasterViewPort* viewPort, const QgsMapToPixel* mapToPixel, double& oversampling )
+{
+  oversampling = 1.0; //default (e.g. for nearest neighbour)
+  if ( !viewPort || !mapToPixel || !mProvider )
+  {
+    return;
+  }
+
+  //calculate oversampling factor
+  if ( mResampler )
+  {
+    QgsRectangle providerExtent = mProvider->extent();
+    if ( viewPort->mSrcCRS.isValid() && viewPort->mDestCRS.isValid() && viewPort->mSrcCRS != viewPort->mDestCRS )
+    {
+      QgsCoordinateTransform t( viewPort->mSrcCRS, viewPort->mDestCRS );
+      providerExtent = t.transformBoundingBox( providerExtent );
+    }
+    double pixelRatio = mapToPixel->mapUnitsPerPixel() / ( providerExtent.width() / mProvider->xSize() );
+    oversampling = pixelRatio > 1.0 ? 2.5 : pixelRatio;
+  }
+
+  //split raster into small portions if necessary
+  RasterPartInfo pInfo;
+  pInfo.nCols = viewPort->drawableAreaXDim * oversampling;
+  pInfo.nRows = viewPort->drawableAreaYDim * oversampling;
+  int totalMemoryUsage = pInfo.nCols * pInfo.nRows * mProvider->dataTypeSize( bandNumber );
+  int parts = totalMemoryUsage / 100000000 + 1;
+  pInfo.nPartsPerDimension = sqrt( parts );
+  pInfo.nColsPerPart = pInfo.nCols / pInfo.nPartsPerDimension;
+  pInfo.nRowsPerPart = pInfo.nRows / pInfo.nPartsPerDimension;
+  pInfo.currentCol = 0;
+  pInfo.currentRow = 0;
+  pInfo.data = 0;
+  mRasterPartInfos.insert( bandNumber, pInfo );
+}
+
+bool QgsRasterRenderer::readNextRasterPart( int bandNumber, QgsRasterViewPort* viewPort, int& nCols, int& nRows, void** rasterData, int& topLeftCol, int& topLeftRow )
+{
+  if ( !viewPort )
+  {
+    return false;
+  }
+
+  //get partinfo
+  QMap<int, RasterPartInfo>::iterator partIt = mRasterPartInfos.find( bandNumber );
+  if ( partIt == mRasterPartInfos.end() )
+  {
+    return false;
+  }
+
+  RasterPartInfo& pInfo = partIt.value();
+
+  //remove last data block
+  CPLFree( pInfo.data );
+  pInfo.data = 0;
+
+  //already at end
+  if ( pInfo.currentCol == pInfo.nCols && pInfo.currentRow == pInfo.nRows )
+  {
+    return false;
+  }
+
+  //read data block
+  nCols = qMin( pInfo.nColsPerPart, pInfo.nCols - pInfo.currentCol );
+  nRows = qMin( pInfo.nRowsPerPart, pInfo.nRows - pInfo.currentRow );
+  int typeSize = mProvider->dataTypeSize( bandNumber ) / 8;
+  pInfo.data = VSIMalloc( typeSize * nCols *  nRows );
+
+  //get subrectangle
+  QgsRectangle viewPortExtent = viewPort->mDrawnExtent;
+  double xmin = viewPortExtent.xMinimum() + pInfo.currentCol / pInfo.nCols * viewPortExtent.width();
+  double xmax = viewPortExtent.xMinimum() + ( pInfo.currentCol + nCols ) / pInfo.nCols * viewPortExtent.width();
+  double ymin = viewPortExtent.yMinimum() + ( pInfo.currentRow + nRows ) / pInfo.nRows * viewPortExtent.height();
+  double ymax = viewPortExtent.yMinimum() + pInfo.currentRow / pInfo.nRows * viewPortExtent.height();
+  QgsRectangle blockRect( xmin, ymin, xmax, ymax );
+
+  mProvider->readBlock( bandNumber, blockRect, nCols, nRows, viewPort->mSrcCRS, viewPort->mDestCRS, pInfo.data );
+  *rasterData = pInfo.data;
+  topLeftCol = pInfo.currentCol;
+  topLeftRow = pInfo.currentRow;
+
+  pInfo.currentCol += nCols;
+  pInfo.currentRow += nRows;
+
+  if ( pInfo.currentCol == pInfo.nCols && pInfo.currentRow != pInfo.nRows ) //start new row
+  {
+    pInfo.currentCol = 0;
+    pInfo.currentRow += pInfo.nRowsPerPart;
+  }
+
+  return true;
+}
+
+void QgsRasterRenderer::stopRasterRead( int bandNumber )
+{
+}
diff --git a/src/core/raster/qgsrasterrenderer.h b/src/core/raster/qgsrasterrenderer.h
@@ -28,15 +28,34 @@ class QgsRasterViewPort;
 class QgsRasterRenderer
 {
   public:
+
+    struct RasterPartInfo
+    {
+      int currentCol;
+      int currentRow;
+      int nCols;
+      int nRows;
+      int nColsPerPart;
+      int nRowsPerPart;
+      int nPartsPerDimension;
+      void* data;
+    };
+
     QgsRasterRenderer( QgsRasterDataProvider* provider, QgsRasterResampler* resampler = 0 );
     virtual ~QgsRasterRenderer();
     virtual void draw( QPainter* p, QgsRasterViewPort* viewPort, const QgsMapToPixel* theQgsMapToPixel ) = 0;
 
   protected:
     inline double readValue( void *data, QgsRasterDataProvider::DataType type, int index );
 
+    void startRasterRead( int bandNumber, QgsRasterViewPort* viewPort, const QgsMapToPixel* mapToPixel, double& oversampling );
+    bool readNextRasterPart( int bandNumber, QgsRasterViewPort* viewPort, int& nCols, int& nRows, void** rasterData, int& topLeftCol, int& topLeftRow );
+    void stopRasterRead( int bandNumber );
+
+
     QgsRasterDataProvider* mProvider;
     QgsRasterResampler* mResampler;
+    QMap<int, RasterPartInfo> mRasterPartInfos;
 };
 
 inline double QgsRasterRenderer::readValue( void *data, QgsRasterDataProvider::DataType type, int index )