[FEATURE][raster] transparency support for paletted renderer

doc/api_break.dox

@@ -1246,6 +1246,11 @@ has improved sort capabilities including the ability to set custom sort values f
 and for forcing certain items to always sort on top.
 
 
+QgsPalettedRasterRenderer        {#qgis_api_break_3_0_QgsPalettedRasterRenderer}
+-------------------------
+
+- The rgbArray() method was made private
+
 QgsPalLabeling        {#qgis_api_break_3_0_QgsPalLabeling}
 --------------
 

python/core/raster/qgspalettedrasterrenderer.sip

@@ -17,11 +17,6 @@ class QgsPalettedRasterRenderer : QgsRasterRenderer
     /** Returns copy of color array (caller takes ownership)*/
     QColor* colors() const /Factory/;
 
-    /** Returns copy of rgb array (caller takes ownership)
-     @note not available in python bindings
-     */
-    // QRgb* rgbArray() const;
-
     /** Return optional category label
      *  @note added in 2.1 */
     QString label( int idx ) const;

src/core/raster/qgspalettedrasterrenderer.cpp

@@ -18,6 +18,7 @@
 #include "qgspalettedrasterrenderer.h"
 #include "qgsrastertransparency.h"
 #include "qgsrasterviewport.h"
+
 #include <QColor>
 #include <QDomDocument>
 #include <QDomElement>
@@ -31,7 +32,7 @@ QgsPalettedRasterRenderer::QgsPalettedRasterRenderer( QgsRasterInterface* input,
   mColors = new QRgb[nColors];
   for ( int i = 0; i < nColors; ++i )
   {
-    mColors[i] = colorArray[i].rgba();
+    mColors[i] = qPremultiply( colorArray[i].rgba() );
   }
   delete[] colorArray;
 }
@@ -95,7 +96,9 @@ QgsRasterRenderer* QgsPalettedRasterRenderer::create( const QDomElement& elem, Q
       QgsDebugMsgLevel( entryElem.attribute( "color", "#000000" ), 4 );
       if ( value >= 0 && value < nColors )
       {
-        colors[value] = QColor( entryElem.attribute( QStringLiteral( "color" ), QStringLiteral( "#000000" ) ) ).rgba();
+        QColor color = QColor( entryElem.attribute( QStringLiteral( "color" ), QStringLiteral( "#000000" ) ) );
+        color.setAlpha( entryElem.attribute( QStringLiteral( "alpha" ), QStringLiteral( "255" ) ).toInt() );
+        colors[value] = qPremultiply( color.rgba() );
         QString label = entryElem.attribute( QStringLiteral( "label" ) );
         if ( !label.isEmpty() )
         {
@@ -123,7 +126,7 @@ QColor* QgsPalettedRasterRenderer::colors() const
   QColor* colorArray = new QColor[ mNColors ];
   for ( int i = 0; i < mNColors; ++i )
   {
-    colorArray[i] = QColor( mColors[i] );
+    colorArray[i] = QColor::fromRgba( qUnpremultiply( mColors[i] ) );
   }
   return colorArray;
 }
@@ -172,6 +175,7 @@ QgsRasterBlock * QgsPalettedRasterRenderer::block( int bandNo, QgsRectangle  con
 
   //rendering is faster without considering user-defined transparency
   bool hasTransparency = usesTransparency();
+
   QgsRasterBlock *alphaBlock = nullptr;
 
   if ( mAlphaBand > 0 && mAlphaBand != mBand )
@@ -211,6 +215,7 @@ QgsRasterBlock * QgsPalettedRasterRenderer::block( int bandNo, QgsRectangle  con
       continue;
     }
     int val = ( int ) inputBlock->value( i );
+
     if ( !hasTransparency )
     {
       outputData[i] = mColors[val];
@@ -226,8 +231,9 @@ QgsRasterBlock * QgsPalettedRasterRenderer::block( int bandNo, QgsRectangle  con
       {
         currentOpacity *=  alphaBlock->value( i ) / 255.0;
       }
-      QColor currentColor = QColor( mColors[val] );
-      outputData[i] = qRgba( currentOpacity * currentColor.red(), currentOpacity * currentColor.green(), currentOpacity * currentColor.blue(), currentOpacity * 255 );
+
+      QRgb c = mColors[val];
+      outputData[i] = qRgba( currentOpacity * qRed( c ), currentOpacity * qGreen( c ), currentOpacity * qBlue( c ), currentOpacity * qAlpha( c ) );
     }
   }
 
@@ -254,9 +260,11 @@ void QgsPalettedRasterRenderer::writeXml( QDomDocument& doc, QDomElement& parent
   QDomElement colorPaletteElem = doc.createElement( QStringLiteral( "colorPalette" ) );
   for ( int i = 0; i < mNColors; ++i )
   {
+    QColor color = QColor::fromRgba( qUnpremultiply( mColors[i] ) );
     QDomElement colorElem = doc.createElement( QStringLiteral( "paletteEntry" ) );
     colorElem.setAttribute( QStringLiteral( "value" ), i );
-    colorElem.setAttribute( QStringLiteral( "color" ), QColor( mColors[i] ).name() );
+    colorElem.setAttribute( QStringLiteral( "color" ), color.name() );
+    colorElem.setAttribute( QStringLiteral( "alpha" ), color.alpha() );
     if ( !label( i ).isEmpty() )
     {
       colorElem.setAttribute( QStringLiteral( "label" ), label( i ) );
@@ -273,7 +281,7 @@ void QgsPalettedRasterRenderer::legendSymbologyItems( QList< QPair< QString, QCo
   for ( int i = 0; i < mNColors; ++i )
   {
     QString lab = label( i ).isEmpty() ? QString::number( i ) : label( i );
-    symbolItems.push_back( qMakePair( lab, QColor( mColors[i] ) ) );
+    symbolItems.push_back( qMakePair( lab, QColor::fromRgba( qUnpremultiply( mColors[i] ) ) ) );
   }
 }
 

src/core/raster/qgspalettedrasterrenderer.h

@@ -31,6 +31,7 @@ class QDomElement;
 class CORE_EXPORT QgsPalettedRasterRenderer: public QgsRasterRenderer
 {
   public:
+
     //! Renderer owns color array
     QgsPalettedRasterRenderer( QgsRasterInterface* input, int bandNumber, QColor* colorArray, int nColors, const QVector<QString>& labels = QVector<QString>() );
     QgsPalettedRasterRenderer( QgsRasterInterface* input, int bandNumber, QRgb* colorArray, int nColors, const QVector<QString>& labels = QVector<QString>() );
@@ -45,11 +46,6 @@ class CORE_EXPORT QgsPalettedRasterRenderer: public QgsRasterRenderer
     //! Returns copy of color array (caller takes ownership)
     QColor* colors() const;
 
-    /** Returns copy of rgb array (caller takes ownership)
-     @note not available in python bindings
-     */
-    QRgb* rgbArray() const;
-
     /** Return optional category label
      *  @note added in 2.1 */
     QString label( int idx ) const { return mLabels.value( idx ); }
@@ -65,8 +61,13 @@ class CORE_EXPORT QgsPalettedRasterRenderer: public QgsRasterRenderer
     QList<int> usesBands() const override;
 
   private:
+
+    /** Returns copy of premultiplied rgb array (caller takes ownership)
+     */
+    QRgb* rgbArray() const;
+
     int mBand;
-    //! Color array
+    //! Premultiplied color array
     QRgb* mColors;
     //! Number of colors
     int mNColors;

src/gui/raster/qgspalettedrendererwidget.cpp

@@ -31,6 +31,7 @@ QgsPalettedRendererWidget::QgsPalettedRendererWidget( QgsRasterLayer* layer, con
 
   contextMenu = new QMenu( tr( "Options" ), this );
   contextMenu->addAction( tr( "Change color" ), this, SLOT( changeColor() ) );
+  contextMenu->addAction( tr( "Change transparency" ), this, SLOT( changeTransparency() ) );
 
   mTreeWidget->setColumnWidth( ColorColumn, 50 );
   mTreeWidget->setContextMenuPolicy( Qt::CustomContextMenu );
@@ -87,7 +88,7 @@ void QgsPalettedRendererWidget::on_mTreeWidget_itemDoubleClicked( QTreeWidgetIte
   if ( column == ColorColumn && item ) //change item color
   {
     item->setFlags( Qt::ItemIsEnabled | Qt::ItemIsSelectable );
-    QColor c = QgsColorDialog::getColor( item->background( column ).color(), nullptr );
+    QColor c = QgsColorDialog::getColor( item->background( column ).color(), this, QStringLiteral( "Change color" ), true );
     if ( c.isValid() )
     {
       item->setBackground( column, QBrush( c ) );
@@ -167,3 +168,29 @@ void QgsPalettedRendererWidget::changeColor()
     emit widgetChanged();
   }
 }
+
+void QgsPalettedRendererWidget::changeTransparency()
+{
+  QList<QTreeWidgetItem *> itemList;
+  itemList = mTreeWidget->selectedItems();
+  if ( itemList.isEmpty() )
+  {
+    return;
+  }
+  QTreeWidgetItem* firstItem = itemList.first();
+
+  bool ok;
+  double oldTransparency = ( firstItem->background( ColorColumn ).color().alpha() / 255.0 ) * 100.0;
+  double transparency = QInputDialog::getDouble( this, tr( "Transparency" ), tr( "Change color transparency [%]" ), oldTransparency, 0.0, 100.0, 0, &ok );
+  if ( ok )
+  {
+    int newTransparency = transparency / 100 * 255;
+    Q_FOREACH ( QTreeWidgetItem *item, itemList )
+    {
+      QColor newColor = item->background( ColorColumn ).color();
+      newColor.setAlpha( newTransparency );
+      item->setBackground( ColorColumn, QBrush( newColor ) );
+    }
+    emit widgetChanged();
+  }
+}

src/gui/raster/qgspalettedrendererwidget.h

@@ -56,6 +56,7 @@ class GUI_EXPORT QgsPalettedRendererWidget: public QgsRasterRendererWidget, priv
     void on_mTreeWidget_itemDoubleClicked( QTreeWidgetItem * item, int column );
     void on_mTreeWidget_itemChanged( QTreeWidgetItem * item, int column );
     void changeColor();
+    void changeTransparency();
 };
 
 #endif // QGSPALETTEDRENDERERWIDGET_H

src/gui/raster/qgssinglebandpseudocolorrendererwidget.cpp

@@ -982,7 +982,7 @@ void QgsSingleBandPseudoColorRendererWidget::changeTransparency()
 
   bool ok;
   double oldTransparency = firstItem->background( ColorColumn ).color().alpha() / 255 * 100;
-  double transparency = QInputDialog::getDouble( this, tr( "Transparency" ), tr( "Change symbol transparency [%]" ), oldTransparency, 0.0, 100.0, 0, &ok );
+  double transparency = QInputDialog::getDouble( this, tr( "Transparency" ), tr( "Change color transparency [%]" ), oldTransparency, 0.0, 100.0, 0, &ok );
   if ( ok )
   {
     int newTransparency = transparency / 100 * 255;