Fix bug causing raster blocks to be cleared when reprojecting

If a QgsRasterBlock had no nodata value set, then reprojecting the raster using QgsRasterProjector would result in the entire block being set to nodata. Cherry-picked from 920f2eb
qgis · Jun 24, 2015 · 8702138 · 8702138
1 parent 4fbda18
commit 8702138
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diff --git a/python/core/raster/qgsrasterblock.sip b/python/core/raster/qgsrasterblock.sip
@@ -180,6 +180,23 @@ class QgsRasterBlock
      *  @return true on success */
     bool setIsNoDataExcept( const QRect & theExceptRect );
 
+    /** \brief Remove no data flag on pixel. If the raster block does not have an explicit
+     * no data value set then an internal map of no data pixels is maintained for the block.
+     * In this case it is possible to reset a pixel to flag it as having valid data using this
+     * method. This method has no effect for raster blocks with an explicit no data value set.
+     *  @param row row index
+     *  @param column column index
+     *  @note added in QGIS 2.10 */
+    void setIsData( int row, int column );
+
+    /** \brief Remove no data flag on pixel. If the raster block does not have an explicit
+     * no data value set then an internal map of no data pixels is maintained for the block.
+     * In this case it is possible to reset a pixel to flag it as having valid data using this
+     * method. This method has no effect for raster blocks with an explicit no data value set.
+     *  @param index data matrix index (long type in Python)
+     *  @note added in QGIS 2.10 */
+    void setIsData( qgssize index );
+
     /** \brief Get pointer to data
      *  @param row row index
      *  @param column column index

diff --git a/src/core/raster/qgsrasterblock.cpp b/src/core/raster/qgsrasterblock.cpp
@@ -633,6 +633,33 @@ bool QgsRasterBlock::setIsNoDataExcept( const QRect & theExceptRect )
   }
 }
 
+void QgsRasterBlock::setIsData( int row, int column )
+{
+  setIsData(( qgssize )row*mWidth + column );
+}
+
+void QgsRasterBlock::setIsData( qgssize index )
+{
+  if ( mHasNoDataValue )
+  {
+    //no data value set, so mNoDataBitmap is not being used
+    return;
+  }
+
+  if ( mNoDataBitmap == 0 )
+  {
+    return;
+  }
+
+  // TODO: optimize
+  int row = ( int ) index / mWidth;
+  int column = index % mWidth;
+  qgssize byte = ( qgssize )row * mNoDataBitmapWidth + column / 8;
+  int bit = column % 8;
+  int nodata = 0x80 >> bit;
+  mNoDataBitmap[byte] = mNoDataBitmap[byte] & ~nodata;
+}
+
 char * QgsRasterBlock::bits( qgssize index )
 {
   // Not testing type to avoid too much overhead because this method is called per pixel

diff --git a/src/core/raster/qgsrasterblock.h b/src/core/raster/qgsrasterblock.h
@@ -242,6 +242,23 @@ class CORE_EXPORT QgsRasterBlock
      *  @return true on success */
     bool setIsNoDataExcept( const QRect & theExceptRect );
 
+    /** \brief Remove no data flag on pixel. If the raster block does not have an explicit
+     * no data value set then an internal map of no data pixels is maintained for the block.
+     * In this case it is possible to reset a pixel to flag it as having valid data using this
+     * method. This method has no effect for raster blocks with an explicit no data value set.
+     *  @param row row index
+     *  @param column column index
+     *  @note added in QGIS 2.10 */
+    void setIsData( int row, int column );
+
+    /** \brief Remove no data flag on pixel. If the raster block does not have an explicit
+     * no data value set then an internal map of no data pixels is maintained for the block.
+     * In this case it is possible to reset a pixel to flag it as having valid data using this
+     * method. This method has no effect for raster blocks with an explicit no data value set.
+     *  @param index data matrix index (long type in Python)
+     *  @note added in QGIS 2.10 */
+    void setIsData( qgssize index );
+
     /** \brief Get pointer to data
      *  @param row row index
      *  @param column column index

diff --git a/src/core/raster/qgsrasterprojector.cpp b/src/core/raster/qgsrasterprojector.cpp
@@ -934,6 +934,7 @@ QgsRasterBlock * QgsRasterProjector::block( int bandNo, QgsRectangle  const & ex
         continue;
       }
       memcpy( destBits, srcBits, pixelSize );
+      outputBlock->setIsData( i, j );
     }
   }