Create a better fake rendercontext for symbol previews

mhugent · mhugent · commit ebee6cf19f70 · 2010-01-14T21:36:35.000Z
git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@12763 c8812cc2-4d05-0410-92ff-de0c093fc19c
diff --git a/src/core/symbology-ng/qgssymbollayerv2utils.cpp b/src/core/symbology-ng/qgssymbollayerv2utils.cpp
@@ -660,3 +660,19 @@ double QgsSymbolLayerV2Utils::pixelSizeScaleFactor( QgsRenderContext& c, QgsSymb
     return c.rasterScaleFactor() / c.mapToPixel().mapUnitsPerPixel();
   }
 }
+
+QgsRenderContext QgsSymbolLayerV2Utils::createRenderContext( QPainter* p )
+{
+  QgsRenderContext context;
+  context.setPainter( p );
+  context.setRasterScaleFactor( 1.0 );
+  if ( p && p->device() )
+  {
+    context.setScaleFactor( p->device()->logicalDpiX() / 25.4 );
+  }
+  else
+  {
+    context.setScaleFactor( 3.465 ); //assume 88 dpi as standard value
+  }
+  return context;
+}
diff --git a/src/core/symbology-ng/qgssymbollayerv2utils.h b/src/core/symbology-ng/qgssymbollayerv2utils.h
@@ -73,6 +73,8 @@ class CORE_EXPORT QgsSymbolLayerV2Utils
     static double lineWidthScaleFactor( QgsRenderContext& c, QgsSymbolV2::OutputUnit u );
     /**Returns scale factor painter units -> pixel dimensions*/
     static double pixelSizeScaleFactor( QgsRenderContext& c, QgsSymbolV2::OutputUnit u );
+    /**Creates a render context for a pixel based device*/
+    static QgsRenderContext createRenderContext( QPainter* p );
 };
 
 class QPolygonF;
diff --git a/src/core/symbology-ng/qgssymbolv2.cpp b/src/core/symbology-ng/qgssymbolv2.cpp
@@ -160,8 +160,7 @@ QColor QgsSymbolV2::color()
 
 void QgsSymbolV2::drawPreviewIcon( QPainter* painter, QSize size )
 {
-  QgsRenderContext context;
-  context.setPainter( painter );
+  QgsRenderContext context = QgsSymbolLayerV2Utils::createRenderContext( painter );
   QgsSymbolV2RenderContext symbolContext( context, mOutputUnit );
   for ( QgsSymbolLayerV2List::iterator it = mLayers.begin(); it != mLayers.end(); ++it )
   {
@@ -186,9 +185,7 @@ QImage QgsSymbolV2::bigSymbolPreviewImage()
     p.drawLine( 50, 0, 50, 100 );
   }
 
-  QgsRenderContext context;
-  context.setPainter( &p );
-
+  QgsRenderContext context = QgsSymbolLayerV2Utils::createRenderContext( &p );
   startRender( context );
 
   if ( mType == QgsSymbolV2::Line )
@@ -248,7 +245,7 @@ QgsSymbolLayerV2List QgsSymbolV2::cloneLayers() const
 ////////////////////
 
 QgsSymbolV2RenderContext::QgsSymbolV2RenderContext( QgsRenderContext& c, QgsSymbolV2::OutputUnit u )
-  : mRenderContext( c ), mOutputUnit( u )
+    : mRenderContext( c ), mOutputUnit( u )
 {
 
 }
@@ -258,12 +255,12 @@ QgsSymbolV2RenderContext::~QgsSymbolV2RenderContext()
 
 }
 
-double QgsSymbolV2RenderContext::outputLineWidth(double width) const
+double QgsSymbolV2RenderContext::outputLineWidth( double width ) const
 {
   return width * QgsSymbolLayerV2Utils::lineWidthScaleFactor( mRenderContext, mOutputUnit );
 }
 
-double QgsSymbolV2RenderContext::outputPixelSize(double size) const
+double QgsSymbolV2RenderContext::outputPixelSize( double size ) const
 {
   return size * QgsSymbolLayerV2Utils::pixelSizeScaleFactor( mRenderContext, mOutputUnit );
 }

Original file line number	Diff line number	Diff line change
`@@ -160,8 +160,7 @@ QColor QgsSymbolV2::color()`
`160`	`160`
`161`	`161`	`void QgsSymbolV2::drawPreviewIcon( QPainter* painter, QSize size )`
`162`	`162`	`{`
`163`		`- QgsRenderContext context;`
`164`		`- context.setPainter( painter );`
	`163`	`+ QgsRenderContext context = QgsSymbolLayerV2Utils::createRenderContext( painter );`
`165`	`164`	`QgsSymbolV2RenderContext symbolContext( context, mOutputUnit );`
`166`	`165`	`for ( QgsSymbolLayerV2List::iterator it = mLayers.begin(); it != mLayers.end(); ++it )`
`167`	`166`	`{`
`@@ -186,9 +185,7 @@ QImage QgsSymbolV2::bigSymbolPreviewImage()`
`186`	`185`	`p.drawLine( 50, 0, 50, 100 );`
`187`	`186`	`}`
`188`	`187`
`189`		`- QgsRenderContext context;`
`190`		`- context.setPainter( &p );`
`191`		`-`
	`188`	`+ QgsRenderContext context = QgsSymbolLayerV2Utils::createRenderContext( &p );`
`192`	`189`	`startRender( context );`
`193`	`190`
`194`	`191`	`if ( mType == QgsSymbolV2::Line )`
`@@ -248,7 +245,7 @@ QgsSymbolLayerV2List QgsSymbolV2::cloneLayers() const`
`248`	`245`	`////////////////////`
`249`	`246`
`250`	`247`	`QgsSymbolV2RenderContext::QgsSymbolV2RenderContext( QgsRenderContext& c, QgsSymbolV2::OutputUnit u )`
`251`		`- : mRenderContext( c ), mOutputUnit( u )`
	`248`	`+ : mRenderContext( c ), mOutputUnit( u )`
`252`	`249`	`{`
`253`	`250`
`254`	`251`	`}`
`@@ -258,12 +255,12 @@ QgsSymbolV2RenderContext::~QgsSymbolV2RenderContext()`
`258`	`255`
`259`	`256`	`}`
`260`	`257`
`261`		`-double QgsSymbolV2RenderContext::outputLineWidth(double width) const`
	`258`	`+double QgsSymbolV2RenderContext::outputLineWidth( double width ) const`
`262`	`259`	`{`
`263`	`260`	`return width * QgsSymbolLayerV2Utils::lineWidthScaleFactor( mRenderContext, mOutputUnit );`
`264`	`261`	`}`
`265`	`262`
`266`		`-double QgsSymbolV2RenderContext::outputPixelSize(double size) const`
	`263`	`+double QgsSymbolV2RenderContext::outputPixelSize( double size ) const`
`267`	`264`	`{`
`268`	`265`	`return size * QgsSymbolLayerV2Utils::pixelSizeScaleFactor( mRenderContext, mOutputUnit );`
`269`	`266`	`}`