Fix loss of transparency information in style dock (fixes #15229)

python/core/raster/qgsrasterrenderer.sip

@@ -57,6 +57,11 @@ class QgsRasterRenderer : QgsRasterInterface
     /** Sets base class members from xml. Usually called from create() methods of subclasses*/
     void readXML( const QDomElement& rendererElem );
 
+    /** Copies common properties like opacity / transparency data from other renderer.
+     *  Useful when cloning renderers.
+     *  @note added in 2.16  */
+    void copyCommonProperties( const QgsRasterRenderer* other );
+
     /** Returns a list of band numbers used by the renderer*/
     virtual QList<int> usesBands() const;
 

src/core/raster/qgshillshaderenderer.cpp

@@ -38,12 +38,10 @@ QgsHillshadeRenderer::QgsHillshadeRenderer( QgsRasterInterface *input, int band,
 QgsHillshadeRenderer *QgsHillshadeRenderer::clone() const
 {
   QgsHillshadeRenderer* r = new QgsHillshadeRenderer( nullptr, mBand, mLightAzimuth, mLightAngle );
+  r->copyCommonProperties( this );
+
   r->setZFactor( mZFactor );
   r->setMultiDirectional( mMultiDirectional );
-  // "Effects"
-  r->setOpacity( mOpacity );
-  r->setAlphaBand( mAlphaBand );
-  r->setRasterTransparency( mRasterTransparency ? new QgsRasterTransparency( *mRasterTransparency ) : nullptr );
   return r;
 }
 

src/core/raster/qgsmultibandcolorrenderer.cpp

@@ -48,6 +48,8 @@ QgsMultiBandColorRenderer::~QgsMultiBandColorRenderer()
 QgsMultiBandColorRenderer* QgsMultiBandColorRenderer::clone() const
 {
   QgsMultiBandColorRenderer * renderer = new QgsMultiBandColorRenderer( nullptr, mRedBand, mGreenBand, mBlueBand );
+  renderer->copyCommonProperties( this );
+
   if ( mRedContrastEnhancement )
   {
     renderer->setRedContrastEnhancement( new QgsContrastEnhancement( *mRedContrastEnhancement ) );
@@ -60,9 +62,6 @@ QgsMultiBandColorRenderer* QgsMultiBandColorRenderer::clone() const
   {
     renderer->setBlueContrastEnhancement( new QgsContrastEnhancement( *mBlueContrastEnhancement ) );
   }
-  renderer->setOpacity( mOpacity );
-  renderer->setAlphaBand( mAlphaBand );
-  renderer->setRasterTransparency( mRasterTransparency ? new QgsRasterTransparency( *mRasterTransparency ) : nullptr );
 
   return renderer;
 }

src/core/raster/qgspalettedrasterrenderer.cpp

@@ -49,9 +49,8 @@ QgsPalettedRasterRenderer::~QgsPalettedRasterRenderer()
 QgsPalettedRasterRenderer* QgsPalettedRasterRenderer::clone() const
 {
   QgsPalettedRasterRenderer * renderer = new QgsPalettedRasterRenderer( nullptr, mBand, rgbArray(), mNColors );
-  renderer->setOpacity( mOpacity );
-  renderer->setAlphaBand( mAlphaBand );
-  renderer->setRasterTransparency( mRasterTransparency ? new QgsRasterTransparency( *mRasterTransparency ) : nullptr );
+  renderer->copyCommonProperties( this );
+
   renderer->mLabels = mLabels;
   return renderer;
 }

src/core/raster/qgsrasterrenderer.cpp

@@ -134,6 +134,16 @@ void QgsRasterRenderer::readXML( const QDomElement& rendererElem )
   }
 }
 
+void QgsRasterRenderer::copyCommonProperties( const QgsRasterRenderer* other )
+{
+  if ( !other )
+    return;
+
+  setOpacity( other->opacity() );
+  setAlphaBand( other->alphaBand() );
+  setRasterTransparency( other->rasterTransparency() ? new QgsRasterTransparency( *other->rasterTransparency() ) : nullptr );
+}
+
 QString QgsRasterRenderer::minMaxOriginName( int theOrigin )
 {
   if ( theOrigin == MinMaxUnknown )

src/core/raster/qgsrasterrenderer.h

@@ -88,6 +88,11 @@ class CORE_EXPORT QgsRasterRenderer : public QgsRasterInterface
     /** Sets base class members from xml. Usually called from create() methods of subclasses*/
     void readXML( const QDomElement& rendererElem ) override;
 
+    /** Copies common properties like opacity / transparency data from other renderer.
+     *  Useful when cloning renderers.
+     *  @note added in 2.16  */
+    void copyCommonProperties( const QgsRasterRenderer* other );
+
     /** Returns a list of band numbers used by the renderer*/
     virtual QList<int> usesBands() const { return QList<int>(); }
 

src/core/raster/qgssinglebandcolordatarenderer.cpp

@@ -35,9 +35,7 @@ QgsSingleBandColorDataRenderer::~QgsSingleBandColorDataRenderer()
 QgsSingleBandColorDataRenderer* QgsSingleBandColorDataRenderer::clone() const
 {
   QgsSingleBandColorDataRenderer * renderer = new QgsSingleBandColorDataRenderer( nullptr, mBand );
-  renderer->setOpacity( mOpacity );
-  renderer->setAlphaBand( mAlphaBand );
-  renderer->setRasterTransparency( mRasterTransparency ? new QgsRasterTransparency( *mRasterTransparency ) : nullptr );
+  renderer->copyCommonProperties( this );
   return renderer;
 }
 

src/core/raster/qgssinglebandgrayrenderer.cpp

@@ -35,9 +35,8 @@ QgsSingleBandGrayRenderer::~QgsSingleBandGrayRenderer()
 QgsSingleBandGrayRenderer* QgsSingleBandGrayRenderer::clone() const
 {
   QgsSingleBandGrayRenderer * renderer = new QgsSingleBandGrayRenderer( nullptr, mGrayBand );
-  renderer->setOpacity( mOpacity );
-  renderer->setAlphaBand( mAlphaBand );
-  renderer->setRasterTransparency( mRasterTransparency ? new QgsRasterTransparency( *mRasterTransparency ) : nullptr );
+  renderer->copyCommonProperties( this );
+
   renderer->setGradient( mGradient );
   if ( mContrastEnhancement )
   {

src/core/raster/qgssinglebandpseudocolorrenderer.cpp

@@ -69,10 +69,7 @@ QgsSingleBandPseudoColorRenderer* QgsSingleBandPseudoColorRenderer::clone() cons
     }
   }
   QgsSingleBandPseudoColorRenderer * renderer = new QgsSingleBandPseudoColorRenderer( nullptr, mBand, shader );
-
-  renderer->setOpacity( mOpacity );
-  renderer->setAlphaBand( mAlphaBand );
-  renderer->setRasterTransparency( mRasterTransparency ? new QgsRasterTransparency( *mRasterTransparency ) : nullptr );
+  renderer->copyCommonProperties( this );
 
   return renderer;
 }

src/gui/raster/qgsrendererrasterpropertieswidget.cpp

@@ -133,7 +133,15 @@ void QgsRendererRasterPropertiesWidget::apply()
   QgsRasterRendererWidget* rendererWidget = dynamic_cast<QgsRasterRendererWidget*>( stackedWidget->currentWidget() );
   if ( rendererWidget )
   {
-    mRasterLayer->setRenderer( rendererWidget->renderer() );
+    QgsRasterRenderer* newRenderer = rendererWidget->renderer();
+
+    // there are transparency related data stored in renderer instances, but they
+    // are not configured in the widget, so we need to copy them over from existing renderer
+    QgsRasterRenderer* oldRenderer = mRasterLayer->renderer();
+    if ( oldRenderer )
+      newRenderer->copyCommonProperties( oldRenderer );
+
+    mRasterLayer->setRenderer( newRenderer );
   }
 
   // Hue and saturation controls