Small cleanups and documentation improvements for QgsRenderContext

Author: nyalldawson

src/core/qgsrendercontext.cpp

@@ -25,15 +25,6 @@
 
 QgsRenderContext::QgsRenderContext()
     : mFlags( DrawEditingInfo | UseAdvancedEffects | DrawSelection | UseRenderingOptimization )
-    , mPainter( nullptr )
-    , mRenderingStopped( false )
-    , mScaleFactor( 1.0 )
-    , mRendererScale( 1.0 )
-    , mLabelingEngine( nullptr )
-    , mGeometry( nullptr )
-    , mFeatureFilterProvider( nullptr )
-    , mSegmentationTolerance( M_PI_2 / 90 )
-    , mSegmentationToleranceType( QgsAbstractGeometry::MaximumAngle )
 {
   mVectorSimplifyMethod.setSimplifyHints( QgsVectorSimplifyMethod::NoSimplification );
 }
@@ -73,18 +64,12 @@ QgsRenderContext&QgsRenderContext::operator=( const QgsRenderContext & rh )
   mVectorSimplifyMethod = rh.mVectorSimplifyMethod;
   mExpressionContext = rh.mExpressionContext;
   mGeometry = rh.mGeometry;
-  mFeatureFilterProvider = rh.mFeatureFilterProvider ? rh.mFeatureFilterProvider->clone() : nullptr;
+  mFeatureFilterProvider.reset( rh.mFeatureFilterProvider ? rh.mFeatureFilterProvider->clone() : nullptr );
   mSegmentationTolerance = rh.mSegmentationTolerance;
   mSegmentationToleranceType = rh.mSegmentationToleranceType;
   return *this;
 }
 
-QgsRenderContext::~QgsRenderContext()
-{
-  delete mFeatureFilterProvider;
-  mFeatureFilterProvider = nullptr;
-}
-
 QgsRenderContext QgsRenderContext::fromQPainter( QPainter* painter )
 {
   QgsRenderContext context;
@@ -209,11 +194,17 @@ void QgsRenderContext::setUseRenderingOptimization( bool enabled )
 
 void QgsRenderContext::setFeatureFilterProvider( const QgsFeatureFilterProvider* ffp )
 {
-  delete mFeatureFilterProvider;
-  mFeatureFilterProvider = nullptr;
-
   if ( ffp )
   {
-    mFeatureFilterProvider = ffp->clone();
+    mFeatureFilterProvider.reset( ffp->clone() );
+  }
+  else
+  {
+    mFeatureFilterProvider.reset( nullptr );
   }
 }
+
+const QgsFeatureFilterProvider* QgsRenderContext::featureFilterProvider() const
+{
+  return mFeatureFilterProvider.data();
+}

src/core/qgsrendercontext.h

@@ -27,13 +27,12 @@
 #include "qgsrectangle.h"
 #include "qgsvectorsimplifymethod.h"
 #include "qgsexpressioncontext.h"
+#include "qgsfeaturefilterprovider.h"
 
 class QPainter;
-
 class QgsAbstractGeometry;
 class QgsLabelingEngine;
 class QgsMapSettings;
-class QgsFeatureFilterProvider;
 
 
 /** \ingroup core
@@ -50,8 +49,6 @@ class CORE_EXPORT QgsRenderContext
     QgsRenderContext( const QgsRenderContext& rh );
     QgsRenderContext& operator=( const QgsRenderContext& rh );
 
-    ~QgsRenderContext();
-
     /** Enumeration of flags that affect rendering operations.
      * @note added in QGIS 2.14
      */
@@ -103,6 +100,10 @@ class CORE_EXPORT QgsRenderContext
 
     //getters
 
+    /**
+     * Returns the destination QPainter for the render operation.
+     * @see setPainter()
+    */
     QPainter* painter() {return mPainter;}
     const QPainter* constPainter() const { return mPainter; }
 
@@ -115,6 +116,12 @@ class CORE_EXPORT QgsRenderContext
 
     const QgsMapToPixel& mapToPixel() const {return mMapToPixel;}
 
+    /**
+     * Returns the scaling factor for the render to convert painter units
+     * to physical sizes. This is usually equal to the number of pixels
+     * per millimeter.
+     * @see setScaleFactor()
+     */
     double scaleFactor() const {return mScaleFactor;}
 
     bool renderingStopped() const {return mRenderingStopped;}
@@ -131,6 +138,11 @@ class CORE_EXPORT QgsRenderContext
 
     bool drawEditingInformation() const;
 
+    /**
+     * Returns the renderer map scale. This will match the desired scale denominator
+     * for the rendered map, eg 1000.0 for a 1:1000 map render.
+     * @see setRendererScale()
+     */
     double rendererScale() const {return mRendererScale;}
 
     //! Get access to new labeling engine (may be nullptr)
@@ -157,8 +169,28 @@ class CORE_EXPORT QgsRenderContext
     void setDrawEditingInformation( bool b );
 
     void setRenderingStopped( bool stopped ) {mRenderingStopped = stopped;}
+
+    /**
+     * Sets the scaling factor for the render to convert painter units
+     * to physical sizes. This should usually be equal to the number of pixels
+     * per millimeter.
+     * @see scaleFactor()
+     */
     void setScaleFactor( double factor ) {mScaleFactor = factor;}
+
+    /**
+     * Sets the renderer map scale. This should match the desired scale denominator
+     * for the rendered map, eg 1000.0 for a 1:1000 map render.
+     * @see rendererScale()
+     */
     void setRendererScale( double scale ) {mRendererScale = scale;}
+
+    /**
+     * Sets the destination QPainter for the render operation. Ownership of the painter
+     * is not transferred and the QPainter destination must stay alive for the duration
+     * of any rendering operations.
+     * @see painter()
+     */
     void setPainter( QPainter* p ) {mPainter = p;}
 
     void setForceVectorOutput( bool force );
@@ -225,7 +257,7 @@ class CORE_EXPORT QgsRenderContext
      * @note added in QGIS 2.14
      * @see setFeatureFilterProvider()
      */
-    const QgsFeatureFilterProvider* featureFilterProvider() const { return mFeatureFilterProvider; }
+    const QgsFeatureFilterProvider* featureFilterProvider() const;
 
     /** Sets the segmentation tolerance applied when rendering curved geometries
     @param tolerance the segmentation tolerance*/
@@ -244,7 +276,7 @@ class CORE_EXPORT QgsRenderContext
     Flags mFlags;
 
     //! Painter for rendering operations
-    QPainter* mPainter;
+    QPainter* mPainter = nullptr;
 
     //! For transformation between coordinate systems. Can be invalid if on-the-fly reprojection is not used
     QgsCoordinateTransform mCoordTransform;
@@ -254,16 +286,16 @@ class CORE_EXPORT QgsRenderContext
     QgsMapToPixel mMapToPixel;
 
     //! True if the rendering has been canceled
-    bool mRenderingStopped;
+    bool mRenderingStopped = false;
 
     //! Factor to scale line widths and point marker sizes
-    double mScaleFactor;
+    double mScaleFactor = 1.0;
 
     //! Map scale
-    double mRendererScale;
+    double mRendererScale = 1.0;
 
     //! Newer labeling engine implementation (can be nullptr)
-    QgsLabelingEngine* mLabelingEngine;
+    QgsLabelingEngine* mLabelingEngine = nullptr;
 
     //! Color used for features that are marked as selected
     QColor mSelectionColor;
@@ -275,14 +307,14 @@ class CORE_EXPORT QgsRenderContext
     QgsExpressionContext mExpressionContext;
 
     //! Pointer to the (unsegmentized) geometry
-    const QgsAbstractGeometry* mGeometry;
+    const QgsAbstractGeometry* mGeometry = nullptr;
 
     //! The feature filter provider
-    const QgsFeatureFilterProvider* mFeatureFilterProvider;
+    QScopedPointer< QgsFeatureFilterProvider > mFeatureFilterProvider;
 
-    double mSegmentationTolerance;
+    double mSegmentationTolerance = M_PI_2 / 90;
 
-    QgsAbstractGeometry::SegmentationToleranceType mSegmentationToleranceType;
+    QgsAbstractGeometry::SegmentationToleranceType mSegmentationToleranceType = QgsAbstractGeometry::MaximumAngle;
 };
 
 Q_DECLARE_OPERATORS_FOR_FLAGS( QgsRenderContext::Flags )