Base class implementation of sample uses identify

This allows derived classes with optimised identify methods to utilise the same optimisations for sample. Better would be for them to implement optimised sample methods, but this is better than using the unoptimised block approach for all providers.
qgis · Jul 19, 2018 · 04708b7 · 04708b7
1 parent 74c2ed1
commit 04708b7
Showing 1 changed file with 7 additions and 34 deletions.
diff --git a/src/core/raster/qgsrasterdataprovider.cpp b/src/core/raster/qgsrasterdataprovider.cpp
@@ -301,48 +301,21 @@ QgsRasterIdentifyResult QgsRasterDataProvider::identify( const QgsPointXY &point
 }
 
 double QgsRasterDataProvider::sample( const QgsPointXY &point, int band,
-                                      bool *ok, const QgsRectangle &boundingBox, int width, int height, int )
+                                      bool *ok, const QgsRectangle &boundingBox, int width, int height, int dpi )
 {
   if ( ok )
     *ok = false;
 
-  if ( !extent().contains( point ) )
-  {
-    // Outside the raster
-    return std::numeric_limits<double>::quiet_NaN();
-  }
-
-  QgsRectangle finalExtent = boundingBox;
-  if ( finalExtent.isEmpty() )
-    finalExtent = extent();
-
-  if ( width == 0 )
-  {
-    width = capabilities() & Size ? xSize() : 1000;
-  }
-  if ( height == 0 )
-  {
-    height = capabilities() & Size ? ySize() : 1000;
-  }
-
-  // Calculate the row / column where the point falls
-  double xres = ( finalExtent.width() ) / width;
-  double yres = ( finalExtent.height() ) / height;
-
-  int col = static_cast< int >( std::floor( ( point.x() - finalExtent.xMinimum() ) / xres ) );
-  int row = static_cast< int >( std::floor( ( finalExtent.yMaximum() - point.y() ) / yres ) );
+  const auto res = identify( point, QgsRaster::IdentifyFormatValue, boundingBox, width, height, dpi );
+  const QVariant value = res.results().value( band );
 
-  double xMin = finalExtent.xMinimum() + col * xres;
-  double xMax = xMin + xres;
-  double yMax = finalExtent.yMaximum() - row * yres;
-  double yMin = yMax - yres;
-  QgsRectangle pixelExtent( xMin, yMin, xMax, yMax );
+  if ( !value.isValid() )
+    return std::numeric_limits<double>::quiet_NaN();
 
-  std::unique_ptr< QgsRasterBlock > bandBlock( block( band, pixelExtent, 1, 1 ) );
-  if ( bandBlock && ok )
+  if ( ok )
     *ok = true;
 
-  return bandBlock ? bandBlock->value( 0 ) : std::numeric_limits<double>::quiet_NaN();
+  return value.toDouble( ok );
 }
 
 QString QgsRasterDataProvider::lastErrorFormat()