Allow non-square pixels for raster formats with exact resolution

qgis · Jul 19, 2012 · 47b8d60 · 47b8d60
1 parent 2eade8d
commit 47b8d60
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Showing 3 changed files with 30 additions and 20 deletions.
diff --git a/src/app/qgisapp.cpp b/src/app/qgisapp.cpp
@@ -3785,8 +3785,18 @@ void QgisApp::saveAsRasterFile()
 
     QProgressDialog pd( 0, tr( "Abort..." ), 0, 0 );
     pd.setWindowModality( Qt::WindowModal );
-    QgsRasterIterator iterator( rasterLayer->dataProvider() );
-    fileWriter.writeRaster( &iterator, d.nColumns(), d.outputRectangle(), rasterLayer->crs(), &pd );
+    QgsRasterDataProvider* provider = rasterLayer->dataProvider();
+    if ( !provider )
+    {
+      return;
+    }
+    QgsRasterIterator iterator( provider );
+    int nRows = -1; //calculate number of rows such that pixels are squares
+    if ( provider->capabilities() & QgsRasterDataProvider::ExactResolution )
+    {
+      nRows = d.nRows();
+    }
+    fileWriter.writeRaster( &iterator, d.nColumns(), nRows, d.outputRectangle(), rasterLayer->crs(), &pd );
   }
 }
 

diff --git a/src/core/raster/qgsrasterfilewriter.cpp b/src/core/raster/qgsrasterfilewriter.cpp
@@ -24,7 +24,7 @@ QgsRasterFileWriter::~QgsRasterFileWriter()
 
 }
 
-QgsRasterFileWriter::WriterError QgsRasterFileWriter::writeRaster( QgsRasterIterator* iter, int nCols, QgsRectangle outputExtent,
+QgsRasterFileWriter::WriterError QgsRasterFileWriter::writeRaster( QgsRasterIterator* iter, int nCols, int nRows, QgsRectangle outputExtent,
     const QgsCoordinateReferenceSystem& crs, QProgressDialog* p )
 {
   if ( !iter )
@@ -42,19 +42,19 @@ QgsRasterFileWriter::WriterError QgsRasterFileWriter::writeRaster( QgsRasterIter
 
   if ( iface->dataType( 1 ) == QgsRasterInterface::ARGB32 )
   {
-    WriterError e = writeImageRaster( iter, nCols, outputExtent, crs );
+    WriterError e = writeImageRaster( iter, nCols, nRows, outputExtent, crs );
     mProgressDialog = 0;
     return e;
   }
   else
   {
     mProgressDialog = 0;
-    WriterError e = writeDataRaster( iter, nCols, outputExtent, crs );
+    WriterError e = writeDataRaster( iter, nCols, nRows, outputExtent, crs );
     return e;
   }
 }
 
-QgsRasterFileWriter::WriterError QgsRasterFileWriter::writeDataRaster( QgsRasterIterator* iter, int nCols, const QgsRectangle& outputExtent,
+QgsRasterFileWriter::WriterError QgsRasterFileWriter::writeDataRaster( QgsRasterIterator* iter, int nCols, int nRows, const QgsRectangle& outputExtent,
     const QgsCoordinateReferenceSystem& crs )
 {
   if ( !iter )
@@ -76,7 +76,6 @@ QgsRasterFileWriter::WriterError QgsRasterFileWriter::writeDataRaster( QgsRaster
   }
 
   //Get output map units per pixel
-  double outputMapUnitsPerPixel = outputExtent.width() / nCols;
   int iterLeft, iterTop, iterCols, iterRows;
 
   iter->setMaximumTileWidth( mMaxTileWidth );
@@ -90,7 +89,6 @@ QgsRasterFileWriter::WriterError QgsRasterFileWriter::writeDataRaster( QgsRaster
 
   //create destProvider for whole dataset here
   QgsRasterDataProvider* destProvider = 0;
-  int nRows;
   double pixelSize;
   double geoTransform[6];
   globalOutputParameters( outputExtent, nCols, nRows, geoTransform, pixelSize );
@@ -160,7 +158,7 @@ QgsRasterFileWriter::WriterError QgsRasterFileWriter::writeDataRaster( QgsRaster
   }
 }
 
-QgsRasterFileWriter::WriterError QgsRasterFileWriter::writeImageRaster( QgsRasterIterator* iter, int nCols, const QgsRectangle& outputExtent,
+QgsRasterFileWriter::WriterError QgsRasterFileWriter::writeImageRaster( QgsRasterIterator* iter, int nCols, int nRows, const QgsRectangle& outputExtent,
     const QgsCoordinateReferenceSystem& crs )
 {
   if ( !iter )
@@ -181,10 +179,6 @@ QgsRasterFileWriter::WriterError QgsRasterFileWriter::writeImageRaster( QgsRaste
     destDir.mkdir( mOutputUrl );
   }
 
-  //Get output map units per pixel
-  double outputMapUnitsPerPixel = outputExtent.width() / nCols;
-
-
   iter->setMaximumTileWidth( mMaxTileWidth );
   iter->setMaximumTileHeight( mMaxTileHeight );
 
@@ -195,12 +189,10 @@ QgsRasterFileWriter::WriterError QgsRasterFileWriter::writeImageRaster( QgsRaste
   void* alphaData = VSIMalloc( mMaxTileWidth * mMaxTileHeight );
   QgsRectangle mapRect;
   int iterLeft, iterTop, iterCols, iterRows;
-  double progress = 0;
   int fileIndex = 0;
 
   //create destProvider for whole dataset here
   QgsRasterDataProvider* destProvider = 0;
-  int nRows;
   double pixelSize;
   double geoTransform[6];
   globalOutputParameters( outputExtent, nCols, nRows, geoTransform, pixelSize );
@@ -531,13 +523,18 @@ void QgsRasterFileWriter::globalOutputParameters( const QgsRectangle& extent, in
     double* geoTransform, double& pixelSize )
 {
   pixelSize = extent.width() / nCols;
-  nRows = ( double )nCols / extent.width() * extent.height() + 0.5;
+
+  //calculate nRows automatically for providers without exact resolution
+  if ( nRows < 0 )
+  {
+    nRows = ( double )nCols / extent.width() * extent.height() + 0.5;
+  }
   geoTransform[0] = extent.xMinimum();
   geoTransform[1] = pixelSize;
   geoTransform[2] = 0.0;
   geoTransform[3] = extent.yMaximum();
   geoTransform[4] = 0.0;
-  geoTransform[5] = -pixelSize;
+  geoTransform[5] = -( extent.height() / nRows );
 }
 
 

diff --git a/src/core/raster/qgsrasterfilewriter.h b/src/core/raster/qgsrasterfilewriter.h
@@ -26,7 +26,10 @@ class CORE_EXPORT QgsRasterFileWriter
     QgsRasterFileWriter( const QString& outputUrl );
     ~QgsRasterFileWriter();
 
-    WriterError writeRaster( QgsRasterIterator* iter, int nCols, QgsRectangle outputExtent,
+    /**Write raster file
+        @param nCols number of output columns
+        @param nRows number of output rows (or -1 to automatically calculate row number to have square pixels)*/
+    WriterError writeRaster( QgsRasterIterator* iter, int nCols, int nRows, QgsRectangle outputExtent,
                              const QgsCoordinateReferenceSystem& crs, QProgressDialog* p = 0 );
 
     void setOutputFormat( const QString& format ) { mOutputFormat = format; }
@@ -46,9 +49,9 @@ class CORE_EXPORT QgsRasterFileWriter
 
   private:
     QgsRasterFileWriter(); //forbidden
-    WriterError writeDataRaster( QgsRasterIterator* iter, int nCols, const QgsRectangle& outputExtent,
+    WriterError writeDataRaster( QgsRasterIterator* iter, int nCols, int nRows, const QgsRectangle& outputExtent,
                                  const QgsCoordinateReferenceSystem& crs );
-    WriterError writeImageRaster( QgsRasterIterator* iter, int nCols, const QgsRectangle& outputExtent,
+    WriterError writeImageRaster( QgsRasterIterator* iter, int nCols, int nRows, const QgsRectangle& outputExtent,
                                   const QgsCoordinateReferenceSystem& crs );
 
     //initialize vrt member variables