Feature #8725: Fast rendering of geom (v-OGR)

Implements fast rendering of LineStrings and Polygons pre-applying a
view threshold filter to the geometries to render in qgis. Also disable
'Antialiasing' when it is possible.

View Table of test results in 'http://hub.qgis.org/issues/8725'

(This version of branch implements the improvement in vector-providers)

Author: ahuarte47

python/core/symbology-ng/qgssymbollayerv2.sip

@@ -202,5 +202,5 @@ class QgsFillSymbolLayerV2 : QgsSymbolLayerV2
   protected:
     QgsFillSymbolLayerV2( bool locked = false );
     /**Default method to render polygon*/
-    void _renderPolygon( QPainter* p, const QPolygonF& points, const QList<QPolygonF>* rings );
+    void _renderPolygon( QPainter* p, const QPolygonF& points, const QList<QPolygonF>* rings, QgsSymbolV2RenderContext& context );
 };

src/core/CMakeLists.txt

@@ -81,6 +81,7 @@ SET(QGIS_CORE_SRCS
   qgslabelattributes.cpp
   qgslabelsearchtree.cpp
   qgslogger.cpp
+  qgsmaprequest.cpp
   qgsmaplayer.cpp
   qgsmaplayerregistry.cpp
   qgsmaprenderer.cpp

src/core/qgsclipper.cpp

@@ -45,6 +45,9 @@ const unsigned char* QgsClipper::clippedLineWKB( const unsigned char* wkb, const
 
   bool hasZValue = ( wkbType == QGis::WKBLineString25D );
 
+  int sizeOfDoubleX = sizeof(double);
+  int sizeOfDoubleY = hasZValue ? 2*sizeof(double) : sizeof(double);
+
   double p0x, p0y, p1x = 0.0, p1y = 0.0; //original coordinates
   double p1x_c, p1y_c; //clipped end coordinates
   double lastClipX = 0.0, lastClipY = 0.0; //last successfully clipped coords
@@ -56,29 +59,18 @@ const unsigned char* QgsClipper::clippedLineWKB( const unsigned char* wkb, const
   {
     if ( i == 0 )
     {
-      memcpy( &p1x, wkb, sizeof( double ) );
-      wkb += sizeof( double );
-      memcpy( &p1y, wkb, sizeof( double ) );
-      wkb += sizeof( double );
-      if ( hasZValue ) // ignore Z value
-      {
-        wkb += sizeof( double );
-      }
+      memcpy( &p1x, wkb, sizeof( double ) ); wkb += sizeOfDoubleX;
+      memcpy( &p1y, wkb, sizeof( double ) ); wkb += sizeOfDoubleY;
+
       continue;
     }
     else
     {
       p0x = p1x;
       p0y = p1y;
 
-      memcpy( &p1x, wkb, sizeof( double ) );
-      wkb += sizeof( double );
-      memcpy( &p1y, wkb, sizeof( double ) );
-      wkb += sizeof( double );
-      if ( hasZValue ) // ignore Z value
-      {
-        wkb += sizeof( double );
-      }
+      memcpy( &p1x, wkb, sizeof( double ) ); wkb += sizeOfDoubleX;
+      memcpy( &p1y, wkb, sizeof( double ) ); wkb += sizeOfDoubleY;
 
       p1x_c = p1x; p1y_c = p1y;
       if ( clipLineSegment( clipExtent.xMinimum(), clipExtent.xMaximum(), clipExtent.yMinimum(), clipExtent.yMaximum(),

src/core/qgsfeaturerequest.cpp

@@ -56,6 +56,8 @@ QgsFeatureRequest::QgsFeatureRequest( const QgsFeatureRequest &rh )
 
 QgsFeatureRequest& QgsFeatureRequest::operator=( const QgsFeatureRequest & rh )
 {
+  QgsMapRequest::operator=( rh );
+
   mFlags = rh.mFlags;
   mFilter = rh.mFilter;
   mFilterRect = rh.mFilterRect;

src/core/qgsfeaturerequest.h

@@ -17,6 +17,7 @@
 
 #include <QFlags>
 
+#include "qgsmaprequest.h"
 #include "qgsfeature.h"
 #include "qgsrectangle.h"
 #include "qgsexpression.h"
@@ -53,15 +54,16 @@ typedef QList<int> QgsAttributeList;
  *     QgsFeatureRequest().setFilterFid(45)
  *
  */
-class CORE_EXPORT QgsFeatureRequest
+class CORE_EXPORT QgsFeatureRequest : public QgsMapRequest
 {
   public:
     enum Flag
     {
       NoFlags            = 0,
       NoGeometry         = 1,  //!< Geometry is not required. It may still be returned if e.g. required for a filter condition.
       SubsetOfAttributes = 2,  //!< Fetch only a subset of attributes (setSubsetOfAttributes sets this flag)
-      ExactIntersect     = 4   //!< Use exact geometry intersection (slower) instead of bounding boxes
+      ExactIntersect     = 4,  //!< Use exact geometry intersection (slower) instead of bounding boxes
+      SimplifyGeometries = 8   //!< Simplify the geometry using the current map2pixel context
     };
     Q_DECLARE_FLAGS( Flags, Flag )
 

src/core/qgsmaprenderer.cpp

@@ -278,6 +278,10 @@ void QgsMapRenderer::render( QPainter* painter, double* forceWidthScale )
   //so must be false at every new render operation
   mRenderContext.setRenderingStopped( false );
 
+  // Gets the configured Tolerance for simplify transformations between map coordinates and device coordinates
+  QSettings mySettings2;
+  mRenderContext.setMapToPixelTol( mySettings2.value( "Map/map2pixelTol", 1.0f ).toFloat() );
+
   // set selection color
   QgsProject* prj = QgsProject::instance();
   int myRed = prj->readNumEntry( "Gui", "/SelectionColorRedPart", 255 );