Add drop shadow option to labels

- Add option to show debug rectangles for shadows to PAL engine properties
- Add small container class, QgsLabelComponent, for temporal values during generation of label components
- Add static image blurring function to QgsSymbolLayerV2Utils
- Fix rotational offset issue with label backgrounds

python/core/qgspallabeling.sip

@@ -80,6 +80,14 @@ class QgsPalLayerSettings
       Percent
     };
 
+    enum ShadowType
+    {
+      ShadowLowest = 0,
+      ShadowText,
+      ShadowBuffer,
+      ShadowShape
+    };
+
     // update mDataDefinedNames QList in constructor when adding/deleting enum value
     enum DataDefinedProperties
     {
@@ -172,6 +180,21 @@ class QgsPalLayerSettings
     int shapeTransparency;
     QPainter::CompositionMode shapeBlendMode;
 
+    // drop shadow
+    bool shadowDraw;
+    ShadowType shadowUnder;
+    int shadowOffsetAngle;
+    double shadowOffsetDist;
+    SizeUnit shadowOffsetUnits;
+    bool shadowOffsetGlobal;
+    double shadowRadius;
+    SizeUnit shadowRadiusUnits;
+    bool shadowRadiusAlphaOnly;
+    int shadowTransparency;
+    int shadowScale;
+    QColor shadowColor;
+    QPainter::CompositionMode shadowBlendMode;
+
     bool formatNumbers;
     int decimals;
     bool plusSign;
@@ -228,7 +251,7 @@ class QgsPalLayerSettings
      * @param rasterfactor whether to consider oversampling
      * @return font pixel size
      */
-    int sizeToPixel( double size, const QgsRenderContext& c , SizeUnit unit, bool rasterfactor ) const;
+    int sizeToPixel( double size, const QgsRenderContext& c , SizeUnit unit, bool rasterfactor = false ) const;
 
     /** List of data defined enum names
      * @note adding in 1.9
@@ -249,6 +272,53 @@ class QgsLabelCandidate
     double cost;
 };
 
+/** \ingroup core
+  * Maintains current state of more grainular and temporal values when creating/painting
+  * component parts of an individual label (e.g. buffer, background, shadow, etc.).
+  */
+class QgsLabelComponent
+{
+%TypeHeaderCode
+#include <qgspallabeling.h>
+%End
+
+  public:
+    QgsLabelComponent();
+
+    const QString& text();
+    void setText( const QString& text );
+
+    const QgsPoint& origin();
+    void setOrigin( QgsPoint point );
+
+    bool useOrigin() const;
+    void setUseOrigin( bool use );
+
+    double rotation() const;
+    void setRotation( double rotation );
+
+    bool useRotation() const;
+    void setUseRotation( bool use );
+
+    const QgsPoint& center();
+    void setCenter( QgsPoint point );
+
+    bool useCenter() const;
+    void setUseCenter( bool use );
+
+    const QgsPoint& size();
+    void setSize( QgsPoint point );
+
+    const QgsPoint& offset();
+    void setOffset( QgsPoint point );
+
+    const QPicture* picture();
+    void setPicture( QPicture* picture );
+
+    double pictureBuffer() const;
+    void setPictureBuffer( double buffer );
+};
+
 class QgsPalLabeling : QgsLabelingEngineInterface
 {
 %TypeHeaderCode
@@ -282,6 +352,9 @@ class QgsPalLabeling : QgsLabelingEngineInterface
     void setShowingCandidates( bool showing );
     const QList<QgsLabelCandidate>& candidates();
 
+    bool isShowingShadowRectangles() const;
+    void setShowingShadowRectangles( bool showing );
+
     bool isShowingAllLabels() const;
     void setShowingAllLabels( bool showing );
 
@@ -313,14 +386,20 @@ class QgsPalLabeling : QgsLabelingEngineInterface
 /*
     void drawLabelCandidateRect( pal::LabelPosition* lp, QPainter* painter, const QgsMapToPixel* xform );
     //!drawLabel
-    void drawLabel( pal::LabelPosition* label, QgsRenderContext& context, QgsPalLayerSettings& tmplyr, DrawLabelType drawType );
+    void drawLabel( pal::LabelPosition* label, QgsRenderContext& context, QgsPalLayerSettings& tmpLyr, DrawLabelType drawType );
 */
-    static void drawLabelBuffer( QgsRenderContext& context, QString text, const QgsPalLayerSettings& tmpLyr );
+    static void drawLabelBuffer( QgsRenderContext& context,
+                                 QgsLabelComponent component,
+                                 const QgsPalLayerSettings& tmpLyr );
 
     static void drawLabelBackground( QgsRenderContext& context,
-                                     const QgsPoint& centerPt, double labelRotation, double labelWidth, double labelHeight,
+                                     QgsLabelComponent component,
                                      const QgsPalLayerSettings& tmpLyr );
 
+    static void drawLabelShadow( QgsRenderContext& context,
+                                 QgsLabelComponent component,
+                                 const QgsPalLayerSettings& tmpLyr );
+
     //! load/save engine settings to project file
     //! @note added in QGIS 1.9
     void loadEngineSettings();

python/core/symbology-ng/qgssymbollayerv2utils.sip

@@ -177,6 +177,11 @@ class QgsSymbolLayerV2Utils
     /**Multiplies opacity of image pixel values with a (global) transparency value*/
     static void multiplyImageOpacity( QImage* image, qreal alpha );
 
+    /** Blurs an image in place, e.g. creating Qt-independent drop shadows
+     * @note added in 1.9
+     */
+    static void blurImageInPlace( QImage& image, const QRect& rect, int radius, bool alphaOnly );
+
     /**Sorts the passed list in requested order*/
     static void sortVariantList( QList<QVariant>& list, Qt::SortOrder order );
     /**Returns a point on the line from startPoint to directionPoint that is a certain distance away from the starting point*/

src/app/qgslabelengineconfigdialog.cpp

@@ -39,8 +39,8 @@ QgsLabelEngineConfigDialog::QgsLabelEngineConfigDialog( QgsPalLabeling* lbl, QWi
   spinCandPolygon->setValue( candPolygon );
 
   chkShowCandidates->setChecked( mLBL->isShowingCandidates() );
-
   chkShowAllLabels->setChecked( mLBL->isShowingAllLabels() );
+  mShadowDebugRectChkBox->setChecked( mLBL->isShowingShadowRectangles() );
 
   mSaveWithProjectChkBox->setChecked( mLBL->isStoredWithProject() );
 }
@@ -56,7 +56,7 @@ void QgsLabelEngineConfigDialog::onOK()
                                   spinCandPolygon->value() );
 
   mLBL->setShowingCandidates( chkShowCandidates->isChecked() );
-
+  mLBL->setShowingShadowRectangles( mShadowDebugRectChkBox->isChecked() );
   mLBL->setShowingAllLabels( chkShowAllLabels->isChecked() );
 
   if ( mSaveWithProjectChkBox->isChecked() )
@@ -79,4 +79,5 @@ void QgsLabelEngineConfigDialog::setDefaults()
   spinCandPolygon->setValue( p.getPolyP() );
   chkShowCandidates->setChecked( false );
   chkShowAllLabels->setChecked( false );
+  mShadowDebugRectChkBox->setChecked( false );
 }

src/app/qgslabelinggui.cpp

@@ -346,8 +346,27 @@ QgsLabelingGui::QgsLabelingGui( QgsPalLabeling* lbl, QgsVectorLayer* layer, QgsM
   mShapeCollisionsChkBx->setVisible( false ); // until implemented
 
   // drop shadow
-  mShadowGrpBx->setVisible( false ); // until implemented
+  mShadowGrpBx->setChecked( lyr.shadowDraw );
+  mShadowUnderCmbBx->setCurrentIndex( lyr.shadowUnder );
 
+  connect( mShadowOffsetAngleDial, SIGNAL( valueChanged( int ) ), mShadowOffsetAngleSpnBx, SLOT( setValue( int ) ) );
+  connect( mShadowOffsetAngleSpnBx, SIGNAL( valueChanged( int ) ), mShadowOffsetAngleDial, SLOT( setValue( int ) ) );
+  mShadowOffsetAngleSpnBx->setValue( lyr.shadowOffsetAngle );
+  mShadowOffsetSpnBx->setValue( lyr.shadowOffsetDist );
+  mShadowOffsetUnitsCmbBx->setCurrentIndex( lyr.shadowOffsetUnits - 1 );
+  mShadowOffsetGlobalChkBx->setChecked( lyr.shadowOffsetGlobal );
+
+  mShadowRadiusDblSpnBx->setValue( lyr.shadowRadius );
+  mShadowRadiusUnitsCmbBx->setCurrentIndex( lyr.shadowRadiusUnits - 1 );
+  mShadowRadiusAlphaChkBx->setChecked( lyr.shadowRadiusAlphaOnly );
+
+  connect( mShadowTranspSlider, SIGNAL( valueChanged( int ) ), mShadowTranspSpnBx, SLOT( setValue( int ) ) );
+  connect( mShadowTranspSpnBx, SIGNAL( valueChanged( int ) ), mShadowTranspSlider, SLOT( setValue( int ) ) );
+  mShadowTranspSpnBx->setValue( lyr.shadowTransparency );
+  mShadowScaleSpnBx->setValue( lyr.shadowScale );
+
+  mShadowColorBtn->setColor( lyr.shadowColor );
+  mShadowBlendCmbBx->setBlendMode( lyr.shadowBlendMode );
 
   updateUi();
 
@@ -553,6 +572,20 @@ QgsPalLayerSettings QgsLabelingGui::layerSettings()
   lyr.shapeTransparency = mShapeTranspSpinBox->value();
   lyr.shapeBlendMode = mShapeBlendCmbBx->blendMode();
 
+  // drop shadow
+  lyr.shadowDraw = mShadowGrpBx->isChecked();
+  lyr.shadowUnder = ( QgsPalLayerSettings::ShadowType )mShadowUnderCmbBx->currentIndex();
+  lyr.shadowOffsetAngle = mShadowOffsetAngleSpnBx->value();
+  lyr.shadowOffsetDist = mShadowOffsetSpnBx->value();
+  lyr.shadowOffsetUnits = ( QgsPalLayerSettings::SizeUnit )( mShadowOffsetUnitsCmbBx->currentIndex() + 1 );
+  lyr.shadowOffsetGlobal = mShadowOffsetGlobalChkBx->isChecked();
+  lyr.shadowRadius = mShadowRadiusDblSpnBx->value();
+  lyr.shadowRadiusUnits = ( QgsPalLayerSettings::SizeUnit )( mShadowRadiusUnitsCmbBx->currentIndex() + 1 );
+  lyr.shadowRadiusAlphaOnly = mShadowRadiusAlphaChkBx->isChecked();
+  lyr.shadowTransparency = mShadowTranspSpnBx->value();
+  lyr.shadowScale = mShadowScaleSpnBx->value();
+  lyr.shadowColor = mShadowColorBtn->color();
+  lyr.shadowBlendMode = mShadowBlendCmbBx->blendMode();
 
   if ( chkFormattedNumbers->isChecked() )
   {

src/app/qgslabelpreview.cpp

@@ -60,6 +60,10 @@ void QgsLabelPreview::paintEvent( QPaintEvent *e )
   Q_UNUSED( e );
   QPainter p( this );
 
+  // TODO: draw all label components when this preview is an actual map canvas
+  // for now, only preview label's text and buffer
+  mTmpLyr->shadowDraw = false;
+
   p.setRenderHint( QPainter::Antialiasing );
   p.setFont( font() );
   QFontMetrics fm( font() );
@@ -77,7 +81,9 @@ void QgsLabelPreview::paintEvent( QPaintEvent *e )
   if ( mTmpLyr->bufferSize != 0 )
   {
     mContext->setPainter( &p );
-    QgsPalLabeling::drawLabelBuffer( *mContext, text(), *mTmpLyr );
+    QgsLabelComponent component;
+    component.setText( text() );
+    QgsPalLabeling::drawLabelBuffer( *mContext, component, *mTmpLyr );
   }
 
   QPainterPath path;