-Added a new option to the legend menu that will stretch the current layer using the min and max pixel values of the current extent

-Added a convenience function QgsRasterLayer::setMinimumMaximumUsingLastExtent that will set the min max of the current band or bands being displayed using the pixel values from the last extent

git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@14031 c8812cc2-4d05-0410-92ff-de0c093fc19c

Author: ersts

python/core/qgsrasterlayer.sip

@@ -417,6 +417,9 @@ public:
     /** \brief Mutator for setting the maximum value for contrast enhancement */
     void setMaximumValue( QString theBand, double theValue, bool theGenerateLookupTableFlag = true );
 
+    /** \brief Sets the minimum and maximum values for the band(s) currently being displayed using the only pixel values from the last/current extent */
+    void setMinimumMaximumUsingLastExtent();
+
     /** \brief Mutator for setting the minimum value for contrast enhancement */
     void setMinimumValue( unsigned int theBand, double theValue, bool theGenerateLookupTableFlag = true );
 

src/app/legend/qgslegend.cpp

@@ -1624,6 +1624,35 @@ void QgsLegend::legendLayerZoomNative()
   }
 }
 
+void QgsLegend::legendLayerStretchUsingCurrentExtent()
+{
+  //find current Layer
+  QgsLegendLayer* currentLayer = dynamic_cast<QgsLegendLayer *>( currentItem() );
+  if ( !currentLayer )
+    return;
+
+  QgsRasterLayer *layer =  qobject_cast<QgsRasterLayer *>( currentLayer->layer() );
+  if ( layer )
+  {
+    if ( layer->drawingStyle() == QgsRasterLayer::SingleBandPseudoColor )
+    {
+      layer->setDrawingStyle( QgsRasterLayer::SingleBandGray );
+    }
+    else if ( layer->drawingStyle() == QgsRasterLayer::MultiBandSingleBandPseudoColor )
+    {
+      layer->setDrawingStyle( QgsRasterLayer::MultiBandSingleGandGray );
+    }
+
+    if ( layer->contrastEnhancementAlgorithmAsString() == "NoEnhancement" )
+    {
+      layer->setContrastEnhancementAlgorithm( "StretchToMinimumMaximum" );
+    }
+
+    layer->setMinimumMaximumUsingLastExtent();
+    mMapCanvas->refresh();
+  }
+}
+
 void QgsLegend::readProject( const QDomDocument & doc )
 {
   QDomNodeList nodes = doc.elementsByTagName( "legend" );

src/app/legend/qgslegend.h

@@ -253,10 +253,14 @@ class QgsLegend : public QTreeWidget
     legend layer files*/
     void legendLayerZoom();
 
-    /***Zooms so that the pixels of the raster layer occupies exactly one screen pixel.
+    /**Zooms so that the pixels of the raster layer occupies exactly one screen pixel.
         Only works on raster layers*/
     void legendLayerZoomNative();
 
+    /**Stretches the raster layer, if stretching is active, based on the min and max of the current extent.
+        Only workds on raster layers*/
+    void legendLayerStretchUsingCurrentExtent();
+
     /**Updates check states when the map canvas layer set is changed */
     void refreshCheckStates();
   protected:

src/app/legend/qgslegendlayer.cpp

@@ -395,6 +395,12 @@ void QgsLegendLayer::addToPopupMenu( QMenu& theMenu )
   if ( lyr->type() == QgsMapLayer::RasterLayer )
   {
     theMenu.addAction( tr( "&Zoom to best scale (100%)" ), legend(), SLOT( legendLayerZoomNative() ) );
+
+    QgsRasterLayer *rasterLayer =  qobject_cast<QgsRasterLayer *>( lyr );
+    if( rasterLayer && rasterLayer->rasterType() != QgsRasterLayer::Palette )
+    {
+      theMenu.addAction( tr( "&Stretch using current extent" ), legend(), SLOT( legendLayerStretchUsingCurrentExtent() ) );
+    }
   }
 
   // show in overview

src/core/raster/qgsrasterlayer.cpp

@@ -3490,6 +3490,35 @@ void QgsRasterLayer::setMaximumValue( QString theBand, double theValue, bool the
   }
 }
 
+void QgsRasterLayer::setMinimumMaximumUsingLastExtent()
+{
+  double myMinMax[2];
+  if ( rasterType() == QgsRasterLayer::GrayOrUndefined || drawingStyle() == QgsRasterLayer::SingleBandGray || drawingStyle() == QgsRasterLayer::MultiBandSingleGandGray )
+  {
+    computeMinimumMaximumFromLastExtent( grayBandName(), myMinMax );
+    setMinimumValue( grayBandName(), myMinMax[0] );
+    setMaximumValue( grayBandName(), myMinMax[1] );
+
+    setUserDefinedGrayMinimumMaximum( true );
+  }
+  else if ( rasterType() == QgsRasterLayer::Multiband )
+  {
+    computeMinimumMaximumFromLastExtent( redBandName(), myMinMax );
+    setMinimumValue( redBandName(), myMinMax[0], false );
+    setMaximumValue( redBandName(), myMinMax[1], false );
+
+    computeMinimumMaximumFromLastExtent( greenBandName(), myMinMax );
+    setMinimumValue( greenBandName(), myMinMax[0], false );
+    setMaximumValue( greenBandName(), myMinMax[1], false );
+
+    computeMinimumMaximumFromLastExtent( blueBandName(), myMinMax );
+    setMinimumValue( blueBandName(), myMinMax[0], false );
+    setMaximumValue( blueBandName(), myMinMax[1], false );
+
+    setUserDefinedRGBMinimumMaximum( true );
+  }
+}
+
 void QgsRasterLayer::setMinimumValue( unsigned int theBand, double theValue, bool theGenerateLookupTableFlag )
 {
   if ( 0 < theBand && theBand <= bandCount() )

src/core/raster/qgsrasterlayer.h

@@ -583,6 +583,9 @@ class CORE_EXPORT QgsRasterLayer : public QgsMapLayer
     /** \brief Mutator for setting the maximum value for contrast enhancement */
     void setMaximumValue( QString theBand, double theValue, bool theGenerateLookupTableFlag = true );
 
+    /** \brief Sets the minimum and maximum values for the band(s) currently being displayed using the only pixel values from the last/current extent */
+    void setMinimumMaximumUsingLastExtent();
+
     /** \brief Mutator for setting the minimum value for contrast enhancement */
     void setMinimumValue( unsigned int theBand, double theValue, bool theGenerateLookupTableFlag = true );