Fix pixelated appearance of elevation profile chart on hidpi displays

qgis · May 23, 2023 · b99a349 · b99a349
1 parent a382930
commit b99a349
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Showing 4 changed files with 17 additions and 8 deletions.
diff --git a/python/core/auto_generated/elevation/qgsprofilerenderer.sip.in b/python/core/auto_generated/elevation/qgsprofilerenderer.sip.in
@@ -137,7 +137,7 @@ Does nothing if the generation is already in progress.
 Returns the limits of the retrieved elevation values.
 %End
 
-    QImage renderToImage( int width, int height, double distanceMin, double distanceMax, double zMin, double zMax, const QString &sourceId = QString() );
+    QImage renderToImage( int width, int height, double distanceMin, double distanceMax, double zMin, double zMax, const QString &sourceId = QString(), double devicePixelRatio = 1.0 );
 %Docstring
 Renders a portion of the profile to an image with the given ``width`` and ``height``.
 

diff --git a/src/core/elevation/qgsprofilerenderer.cpp b/src/core/elevation/qgsprofilerenderer.cpp
@@ -293,7 +293,7 @@ QgsDoubleRange QgsProfilePlotRenderer::zRange() const
   return QgsDoubleRange( min, max );
 }
 
-QImage QgsProfilePlotRenderer::renderToImage( int width, int height, double distanceMin, double distanceMax, double zMin, double zMax, const QString &sourceId )
+QImage QgsProfilePlotRenderer::renderToImage( int width, int height, double distanceMin, double distanceMax, double zMin, double zMax, const QString &sourceId, double devicePixelRatio )
 {
   QImage res( width, height, QImage::Format_ARGB32_Premultiplied );
   res.setDotsPerMeterX( 96 / 25.4 * 1000 );
@@ -305,6 +305,7 @@ QImage QgsProfilePlotRenderer::renderToImage( int width, int height, double dist
   QgsRenderContext context = QgsRenderContext::fromQPainter( &p );
   context.setFlag( Qgis::RenderContextFlag::Antialiasing, true );
   context.setPainterFlagsUsingContext( &p );
+  context.setDevicePixelRatio( devicePixelRatio );
   const double mapUnitsPerPixel = ( distanceMax - distanceMin ) / width;
   context.setMapToPixel( QgsMapToPixel( mapUnitsPerPixel ) );
 

diff --git a/src/core/elevation/qgsprofilerenderer.h b/src/core/elevation/qgsprofilerenderer.h
@@ -163,7 +163,7 @@ class CORE_EXPORT QgsProfilePlotRenderer : public QObject
      *
      * If \a sourceId is empty then all sources will be rendered, otherwise only the matching source will be rendered.
      */
-    QImage renderToImage( int width, int height, double distanceMin, double distanceMax, double zMin, double zMax, const QString &sourceId = QString() );
+    QImage renderToImage( int width, int height, double distanceMin, double distanceMax, double zMin, double zMax, const QString &sourceId = QString(), double devicePixelRatio = 1.0 );
 
     /**
      * Renders a portion of the profile using the specified render \a context.

diff --git a/src/gui/elevation/qgselevationprofilecanvas.cpp b/src/gui/elevation/qgselevationprofilecanvas.cpp
@@ -138,6 +138,8 @@ class QgsElevationProfilePlotItem : public Qgs2DPlot, public QgsPlotCanvasItem
       if ( !mRenderer )
         return;
 
+      const double pixelRatio = !scene()->views().empty() ? scene()->views().at( 0 )->devicePixelRatioF() : 1;
+
       const QStringList sourceIds = mRenderer->sourceIds();
       for ( const QString &source : sourceIds )
       {
@@ -149,10 +151,13 @@ class QgsElevationProfilePlotItem : public Qgs2DPlot, public QgsPlotCanvasItem
         }
         else
         {
-          plot = mRenderer->renderToImage( plotArea.width(), plotArea.height(), xMinimum(), xMaximum(), yMinimum(), yMaximum(), source );
+          plot = mRenderer->renderToImage( plotArea.width() * pixelRatio,
+                                           plotArea.height() * pixelRatio, xMinimum(), xMaximum(), yMinimum(), yMaximum(), source, pixelRatio );
+          plot.setDevicePixelRatio( pixelRatio );
           mCachedImages.insert( source, plot );
         }
-        rc.painter()->drawImage( plotArea.left(), plotArea.top(), plot );
+        rc.painter()->drawImage( QPointF( plotArea.left(),
+                                          plotArea.top() ), plot );
       }
     }
 
@@ -161,16 +166,19 @@ class QgsElevationProfilePlotItem : public Qgs2DPlot, public QgsPlotCanvasItem
       // cache rendering to an image, so we don't need to redraw the plot
       if ( !mImage.isNull() )
       {
-        painter->drawImage( 0, 0, mImage );
+        painter->drawImage( QPointF( 0, 0 ), mImage );
       }
       else
       {
-        mImage = QImage( mRect.width(), mRect.height(), QImage::Format_ARGB32_Premultiplied );
+        const double pixelRatio = !scene()->views().empty() ? scene()->views().at( 0 )->devicePixelRatioF() : 1;
+        mImage = QImage( mRect.width() * pixelRatio, mRect.height() * pixelRatio, QImage::Format_ARGB32_Premultiplied );
+        mImage.setDevicePixelRatio( pixelRatio );
         mImage.fill( Qt::transparent );
 
         QPainter imagePainter( &mImage );
         imagePainter.setRenderHint( QPainter::Antialiasing, true );
         QgsRenderContext rc = QgsRenderContext::fromQPainter( &imagePainter );
+        rc.setDevicePixelRatio( pixelRatio );
 
         const double mapUnitsPerPixel = ( xMaximum() - xMinimum() ) / plotArea().width();
         rc.setMapToPixel( QgsMapToPixel( mapUnitsPerPixel ) );
@@ -182,7 +190,7 @@ class QgsElevationProfilePlotItem : public Qgs2DPlot, public QgsPlotCanvasItem
         render( rc );
         imagePainter.end();
 
-        painter->drawImage( 0, 0, mImage );
+        painter->drawImage( QPointF( 0, 0 ), mImage );
       }
     }