Add new map settings/render context flag for high quality image trans…

…forms which is opt in, and consistently respect this for better quality raster image markers, svg/raster fills when set We don't set this by default (keep things light for server), but do use it in the map canvas and layout exports whenever antialiasing is enabled.
qgis · Nov 7, 2021 · 294282c · 294282c
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diff --git a/python/core/auto_additions/qgis.py b/python/core/auto_additions/qgis.py
@@ -825,7 +825,10 @@
 QgsMapSettings.Render3DMap = Qgis.MapSettingsFlag.Render3DMap
 QgsMapSettings.Render3DMap.is_monkey_patched = True
 QgsMapSettings.Render3DMap.__doc__ = "Render is for a 3D map"
-Qgis.MapSettingsFlag.__doc__ = 'Flags which adjust the way maps are rendered.\n\n.. versionadded:: 3.22\n\n' + '* ``Antialiasing``: ' + Qgis.MapSettingsFlag.Antialiasing.__doc__ + '\n' + '* ``DrawEditingInfo``: ' + Qgis.MapSettingsFlag.DrawEditingInfo.__doc__ + '\n' + '* ``ForceVectorOutput``: ' + Qgis.MapSettingsFlag.ForceVectorOutput.__doc__ + '\n' + '* ``UseAdvancedEffects``: ' + Qgis.MapSettingsFlag.UseAdvancedEffects.__doc__ + '\n' + '* ``DrawLabeling``: ' + Qgis.MapSettingsFlag.DrawLabeling.__doc__ + '\n' + '* ``UseRenderingOptimization``: ' + Qgis.MapSettingsFlag.UseRenderingOptimization.__doc__ + '\n' + '* ``DrawSelection``: ' + Qgis.MapSettingsFlag.DrawSelection.__doc__ + '\n' + '* ``DrawSymbolBounds``: ' + Qgis.MapSettingsFlag.DrawSymbolBounds.__doc__ + '\n' + '* ``RenderMapTile``: ' + Qgis.MapSettingsFlag.RenderMapTile.__doc__ + '\n' + '* ``RenderPartialOutput``: ' + Qgis.MapSettingsFlag.RenderPartialOutput.__doc__ + '\n' + '* ``RenderPreviewJob``: ' + Qgis.MapSettingsFlag.RenderPreviewJob.__doc__ + '\n' + '* ``RenderBlocking``: ' + Qgis.MapSettingsFlag.RenderBlocking.__doc__ + '\n' + '* ``LosslessImageRendering``: ' + Qgis.MapSettingsFlag.LosslessImageRendering.__doc__ + '\n' + '* ``Render3DMap``: ' + Qgis.MapSettingsFlag.Render3DMap.__doc__
+QgsMapSettings.HighQualityImageTransforms = Qgis.MapSettingsFlag.HighQualityImageTransforms
+QgsMapSettings.HighQualityImageTransforms.is_monkey_patched = True
+QgsMapSettings.HighQualityImageTransforms.__doc__ = "Enable high quality image transformations, which results in better appearance of scaled or rotated raster components of a map (since QGIS 3.24)"
+Qgis.MapSettingsFlag.__doc__ = 'Flags which adjust the way maps are rendered.\n\n.. versionadded:: 3.22\n\n' + '* ``Antialiasing``: ' + Qgis.MapSettingsFlag.Antialiasing.__doc__ + '\n' + '* ``DrawEditingInfo``: ' + Qgis.MapSettingsFlag.DrawEditingInfo.__doc__ + '\n' + '* ``ForceVectorOutput``: ' + Qgis.MapSettingsFlag.ForceVectorOutput.__doc__ + '\n' + '* ``UseAdvancedEffects``: ' + Qgis.MapSettingsFlag.UseAdvancedEffects.__doc__ + '\n' + '* ``DrawLabeling``: ' + Qgis.MapSettingsFlag.DrawLabeling.__doc__ + '\n' + '* ``UseRenderingOptimization``: ' + Qgis.MapSettingsFlag.UseRenderingOptimization.__doc__ + '\n' + '* ``DrawSelection``: ' + Qgis.MapSettingsFlag.DrawSelection.__doc__ + '\n' + '* ``DrawSymbolBounds``: ' + Qgis.MapSettingsFlag.DrawSymbolBounds.__doc__ + '\n' + '* ``RenderMapTile``: ' + Qgis.MapSettingsFlag.RenderMapTile.__doc__ + '\n' + '* ``RenderPartialOutput``: ' + Qgis.MapSettingsFlag.RenderPartialOutput.__doc__ + '\n' + '* ``RenderPreviewJob``: ' + Qgis.MapSettingsFlag.RenderPreviewJob.__doc__ + '\n' + '* ``RenderBlocking``: ' + Qgis.MapSettingsFlag.RenderBlocking.__doc__ + '\n' + '* ``LosslessImageRendering``: ' + Qgis.MapSettingsFlag.LosslessImageRendering.__doc__ + '\n' + '* ``Render3DMap``: ' + Qgis.MapSettingsFlag.Render3DMap.__doc__ + '\n' + '* ``HighQualityImageTransforms``: ' + Qgis.MapSettingsFlag.HighQualityImageTransforms.__doc__
 # --
 QgsMapSettings.Flags = Qgis.MapSettingsFlags
 Qgis.MapSettingsFlag.baseClass = Qgis
@@ -882,7 +885,10 @@
 QgsRenderContext.RenderingSubSymbol = Qgis.RenderContextFlag.RenderingSubSymbol
 QgsRenderContext.RenderingSubSymbol.is_monkey_patched = True
 QgsRenderContext.RenderingSubSymbol.__doc__ = "Set whenever a sub-symbol of a parent symbol is currently being rendered. Can be used during symbol and symbol layer rendering to determine whether the symbol being rendered is a subsymbol. (Since QGIS 3.24)"
-Qgis.RenderContextFlag.__doc__ = 'Flags which affect rendering operations.\n\n.. versionadded:: 3.22\n\n' + '* ``DrawEditingInfo``: ' + Qgis.RenderContextFlag.DrawEditingInfo.__doc__ + '\n' + '* ``ForceVectorOutput``: ' + Qgis.RenderContextFlag.ForceVectorOutput.__doc__ + '\n' + '* ``UseAdvancedEffects``: ' + Qgis.RenderContextFlag.UseAdvancedEffects.__doc__ + '\n' + '* ``UseRenderingOptimization``: ' + Qgis.RenderContextFlag.UseRenderingOptimization.__doc__ + '\n' + '* ``DrawSelection``: ' + Qgis.RenderContextFlag.DrawSelection.__doc__ + '\n' + '* ``DrawSymbolBounds``: ' + Qgis.RenderContextFlag.DrawSymbolBounds.__doc__ + '\n' + '* ``RenderMapTile``: ' + Qgis.RenderContextFlag.RenderMapTile.__doc__ + '\n' + '* ``Antialiasing``: ' + Qgis.RenderContextFlag.Antialiasing.__doc__ + '\n' + '* ``RenderPartialOutput``: ' + Qgis.RenderContextFlag.RenderPartialOutput.__doc__ + '\n' + '* ``RenderPreviewJob``: ' + Qgis.RenderContextFlag.RenderPreviewJob.__doc__ + '\n' + '* ``RenderBlocking``: ' + Qgis.RenderContextFlag.RenderBlocking.__doc__ + '\n' + '* ``RenderSymbolPreview``: ' + Qgis.RenderContextFlag.RenderSymbolPreview.__doc__ + '\n' + '* ``LosslessImageRendering``: ' + Qgis.RenderContextFlag.LosslessImageRendering.__doc__ + '\n' + '* ``ApplyScalingWorkaroundForTextRendering``: ' + Qgis.RenderContextFlag.ApplyScalingWorkaroundForTextRendering.__doc__ + '\n' + '* ``Render3DMap``: ' + Qgis.RenderContextFlag.Render3DMap.__doc__ + '\n' + '* ``ApplyClipAfterReprojection``: ' + Qgis.RenderContextFlag.ApplyClipAfterReprojection.__doc__ + '\n' + '* ``RenderingSubSymbol``: ' + Qgis.RenderContextFlag.RenderingSubSymbol.__doc__
+QgsRenderContext.HighQualityImageTransforms = Qgis.RenderContextFlag.HighQualityImageTransforms
+QgsRenderContext.HighQualityImageTransforms.is_monkey_patched = True
+QgsRenderContext.HighQualityImageTransforms.__doc__ = "Enable high quality image transformations, which results in better appearance of scaled or rotated raster components of a map (since QGIS 3.24)"
+Qgis.RenderContextFlag.__doc__ = 'Flags which affect rendering operations.\n\n.. versionadded:: 3.22\n\n' + '* ``DrawEditingInfo``: ' + Qgis.RenderContextFlag.DrawEditingInfo.__doc__ + '\n' + '* ``ForceVectorOutput``: ' + Qgis.RenderContextFlag.ForceVectorOutput.__doc__ + '\n' + '* ``UseAdvancedEffects``: ' + Qgis.RenderContextFlag.UseAdvancedEffects.__doc__ + '\n' + '* ``UseRenderingOptimization``: ' + Qgis.RenderContextFlag.UseRenderingOptimization.__doc__ + '\n' + '* ``DrawSelection``: ' + Qgis.RenderContextFlag.DrawSelection.__doc__ + '\n' + '* ``DrawSymbolBounds``: ' + Qgis.RenderContextFlag.DrawSymbolBounds.__doc__ + '\n' + '* ``RenderMapTile``: ' + Qgis.RenderContextFlag.RenderMapTile.__doc__ + '\n' + '* ``Antialiasing``: ' + Qgis.RenderContextFlag.Antialiasing.__doc__ + '\n' + '* ``RenderPartialOutput``: ' + Qgis.RenderContextFlag.RenderPartialOutput.__doc__ + '\n' + '* ``RenderPreviewJob``: ' + Qgis.RenderContextFlag.RenderPreviewJob.__doc__ + '\n' + '* ``RenderBlocking``: ' + Qgis.RenderContextFlag.RenderBlocking.__doc__ + '\n' + '* ``RenderSymbolPreview``: ' + Qgis.RenderContextFlag.RenderSymbolPreview.__doc__ + '\n' + '* ``LosslessImageRendering``: ' + Qgis.RenderContextFlag.LosslessImageRendering.__doc__ + '\n' + '* ``ApplyScalingWorkaroundForTextRendering``: ' + Qgis.RenderContextFlag.ApplyScalingWorkaroundForTextRendering.__doc__ + '\n' + '* ``Render3DMap``: ' + Qgis.RenderContextFlag.Render3DMap.__doc__ + '\n' + '* ``ApplyClipAfterReprojection``: ' + Qgis.RenderContextFlag.ApplyClipAfterReprojection.__doc__ + '\n' + '* ``RenderingSubSymbol``: ' + Qgis.RenderContextFlag.RenderingSubSymbol.__doc__ + '\n' + '* ``HighQualityImageTransforms``: ' + Qgis.RenderContextFlag.HighQualityImageTransforms.__doc__
 # --
 QgsRenderContext.Flags = Qgis.RenderContextFlags
 Qgis.RenderContextFlag.baseClass = Qgis

diff --git a/python/core/auto_generated/qgis.sip.in b/python/core/auto_generated/qgis.sip.in
@@ -575,6 +575,7 @@ The development version
       RenderBlocking,
       LosslessImageRendering,
       Render3DMap,
+      HighQualityImageTransforms,
     };
     typedef QFlags<Qgis::MapSettingsFlag> MapSettingsFlags;
 
@@ -598,6 +599,7 @@ The development version
       Render3DMap,
       ApplyClipAfterReprojection,
       RenderingSubSymbol,
+      HighQualityImageTransforms,
     };
     typedef QFlags<Qgis::RenderContextFlag> RenderContextFlags;
 

diff --git a/src/analysis/processing/qgsalgorithmrasterize.cpp b/src/analysis/processing/qgsalgorithmrasterize.cpp
@@ -197,6 +197,7 @@ QVariantMap QgsRasterizeAlgorithm::processAlgorithm( const QVariantMap &paramete
   mapSettings.setOutputImageFormat( QImage::Format_ARGB32 );
   mapSettings.setDestinationCrs( context.project()->crs() );
   mapSettings.setFlag( Qgis::MapSettingsFlag::Antialiasing, true );
+  mapSettings.setFlag( Qgis::MapSettingsFlag::HighQualityImageTransforms, true );
   mapSettings.setFlag( Qgis::MapSettingsFlag::RenderMapTile, true );
   mapSettings.setFlag( Qgis::MapSettingsFlag::UseAdvancedEffects, true );
   mapSettings.setTransformContext( context.transformContext() );

diff --git a/src/app/qgsanimationexportdialog.cpp b/src/app/qgsanimationexportdialog.cpp
@@ -241,6 +241,7 @@ void QgsAnimationExportDialog::applyMapSettings( QgsMapSettings &mapSettings )
   const QgsSettings settings;
 
   mapSettings.setFlag( Qgis::MapSettingsFlag::Antialiasing, settings.value( QStringLiteral( "qgis/enable_anti_aliasing" ), true ).toBool() );
+  mapSettings.setFlag( Qgis::MapSettingsFlag::HighQualityImageTransforms, settings.value( QStringLiteral( "qgis/enable_anti_aliasing" ), true ).toBool() );
   mapSettings.setFlag( Qgis::MapSettingsFlag::DrawEditingInfo, false );
   mapSettings.setFlag( Qgis::MapSettingsFlag::DrawSelection, false );
   mapSettings.setSelectionColor( mMapCanvas->mapSettings().selectionColor() );

diff --git a/src/app/qgsmapsavedialog.cpp b/src/app/qgsmapsavedialog.cpp
@@ -319,10 +319,12 @@ void QgsMapSaveDialog::applyMapSettings( QgsMapSettings &mapSettings )
   {
     case Pdf:
       mapSettings.setFlag( Qgis::MapSettingsFlag::Antialiasing, true ); // hardcode antialiasing when saving as PDF
+      mapSettings.setFlag( Qgis::MapSettingsFlag::HighQualityImageTransforms, true ); // hardcode antialiasing when saving as PDF
       break;
 
     case Image:
       mapSettings.setFlag( Qgis::MapSettingsFlag::Antialiasing, settings.value( QStringLiteral( "qgis/enable_anti_aliasing" ), true ).toBool() );
+      mapSettings.setFlag( Qgis::MapSettingsFlag::HighQualityImageTransforms, settings.value( QStringLiteral( "qgis/enable_anti_aliasing" ), true ).toBool() );
       break;
   }
   mapSettings.setFlag( Qgis::MapSettingsFlag::ForceVectorOutput, true ); // force vector output (no caching of marker images etc.)

diff --git a/src/core/layout/qgslayoutitemmap.cpp b/src/core/layout/qgslayoutitemmap.cpp
@@ -1531,6 +1531,7 @@ QgsMapSettings QgsLayoutItemMap::mapSettings( const QgsRectangle &extent, QSizeF
   // layout-specific overrides of flags
   jobMapSettings.setFlag( Qgis::MapSettingsFlag::ForceVectorOutput, true ); // force vector output (no caching of marker images etc.)
   jobMapSettings.setFlag( Qgis::MapSettingsFlag::Antialiasing, mLayout->renderContext().flags() & QgsLayoutRenderContext::FlagAntialiasing );
+  jobMapSettings.setFlag( Qgis::MapSettingsFlag::HighQualityImageTransforms, mLayout->renderContext().flags() & QgsLayoutRenderContext::FlagAntialiasing );
   jobMapSettings.setFlag( Qgis::MapSettingsFlag::LosslessImageRendering, mLayout->renderContext().flags() & QgsLayoutRenderContext::FlagLosslessImageRendering );
   jobMapSettings.setFlag( Qgis::MapSettingsFlag::DrawEditingInfo, false );
   jobMapSettings.setSelectionColor( mLayout->renderContext().selectionColor() );

diff --git a/src/core/layout/qgslayoutrendercontext.cpp b/src/core/layout/qgslayoutrendercontext.cpp
@@ -63,7 +63,10 @@ Qgis::RenderContextFlags QgsLayoutRenderContext::renderContextFlags() const
 {
   Qgis::RenderContextFlags flags = Qgis::RenderContextFlags();
   if ( mFlags & FlagAntialiasing )
+  {
     flags = flags | Qgis::RenderContextFlag::Antialiasing;
+    flags = flags | Qgis::RenderContextFlag::HighQualityImageTransforms;
+  }
   if ( mFlags & FlagUseAdvancedEffects )
     flags = flags | Qgis::RenderContextFlag::UseAdvancedEffects;
   if ( mFlags & FlagLosslessImageRendering )

diff --git a/src/core/maprenderer/qgsmaprenderercustompainterjob.cpp b/src/core/maprenderer/qgsmaprenderercustompainterjob.cpp
@@ -40,6 +40,7 @@ void QgsMapRendererAbstractCustomPainterJob::preparePainter( QPainter *painter,
   painter->fillRect( 0, 0, mSettings.deviceOutputSize().width(), mSettings.deviceOutputSize().height(), backgroundColor );
 
   painter->setRenderHint( QPainter::Antialiasing, mSettings.testFlag( Qgis::MapSettingsFlag::Antialiasing ) );
+  painter->setRenderHint( QPainter::SmoothPixmapTransform, mSettings.testFlag( Qgis::MapSettingsFlag::HighQualityImageTransforms ) );
 #if QT_VERSION >= QT_VERSION_CHECK(5, 13, 0)
   painter->setRenderHint( QPainter::LosslessImageRendering, mSettings.testFlag( Qgis::MapSettingsFlag::LosslessImageRendering ) );
 #endif

diff --git a/src/core/maprenderer/qgsmaprendererjob.cpp b/src/core/maprenderer/qgsmaprendererjob.cpp
@@ -390,6 +390,7 @@ QPainter *QgsMapRendererJob::allocateImageAndPainter( QString layerId, QImage *&
   {
     painter = new QPainter( image );
     painter->setRenderHint( QPainter::Antialiasing, mSettings.testFlag( Qgis::MapSettingsFlag::Antialiasing ) );
+    painter->setRenderHint( QPainter::SmoothPixmapTransform, mSettings.testFlag( Qgis::MapSettingsFlag::HighQualityImageTransforms ) );
 #if QT_VERSION >= QT_VERSION_CHECK(5, 13, 0)
     painter->setRenderHint( QPainter::LosslessImageRendering, mSettings.testFlag( Qgis::MapSettingsFlag::LosslessImageRendering ) );
 #endif

diff --git a/src/core/qgis.h b/src/core/qgis.h
@@ -933,6 +933,7 @@ class CORE_EXPORT Qgis
       RenderBlocking           = 0x800, //!< Render and load remote sources in the same thread to ensure rendering remote sources (svg and images). WARNING: this flag must NEVER be used from GUI based applications (like the main QGIS application) or crashes will result. Only for use in external scripts or QGIS server.
       LosslessImageRendering   = 0x1000, //!< Render images losslessly whenever possible, instead of the default lossy jpeg rendering used for some destination devices (e.g. PDF). This flag only works with builds based on Qt 5.13 or later.
       Render3DMap              = 0x2000, //!< Render is for a 3D map
+      HighQualityImageTransforms = 0x4000, //!< Enable high quality image transformations, which results in better appearance of scaled or rotated raster components of a map (since QGIS 3.24)
     };
     //! Map settings flags
     Q_DECLARE_FLAGS( MapSettingsFlags, MapSettingsFlag ) SIP_MONKEYPATCH_FLAGS_UNNEST( QgsMapSettings, Flags )
@@ -962,6 +963,7 @@ class CORE_EXPORT Qgis
       Render3DMap              = 0x4000, //!< Render is for a 3D map
       ApplyClipAfterReprojection = 0x8000, //!< Feature geometry clipping to mapExtent() must be performed after the geometries are transformed using coordinateTransform(). Usually feature geometry clipping occurs using the extent() in the layer's CRS prior to geometry transformation, but in some cases when extent() could not be accurately calculated it is necessary to clip geometries to mapExtent() AFTER transforming them using coordinateTransform().
       RenderingSubSymbol       = 0x10000, //!< Set whenever a sub-symbol of a parent symbol is currently being rendered. Can be used during symbol and symbol layer rendering to determine whether the symbol being rendered is a subsymbol. (Since QGIS 3.24)
+      HighQualityImageTransforms = 0x20000, //!< Enable high quality image transformations, which results in better appearance of scaled or rotated raster components of a map (since QGIS 3.24)
     };
     //! Render context flags
     Q_DECLARE_FLAGS( RenderContextFlags, RenderContextFlag ) SIP_MONKEYPATCH_FLAGS_UNNEST( QgsRenderContext, Flags )

diff --git a/src/core/qgsrendercontext.cpp b/src/core/qgsrendercontext.cpp
@@ -145,6 +145,8 @@ QgsRenderContext QgsRenderContext::fromQPainter( QPainter *painter )
 
   if ( painter && painter->renderHints() & QPainter::Antialiasing )
     context.setFlag( Qgis::RenderContextFlag::Antialiasing, true );
+  if ( painter && painter->renderHints() & QPainter::SmoothPixmapTransform )
+    context.setFlag( Qgis::RenderContextFlag::HighQualityImageTransforms, true );
 
 #if QT_VERSION >= QT_VERSION_CHECK(5, 13, 0)
   if ( painter && painter->renderHints() & QPainter::LosslessImageRendering )
@@ -166,6 +168,7 @@ void QgsRenderContext::setPainterFlagsUsingContext( QPainter *painter ) const
 #if QT_VERSION >= QT_VERSION_CHECK(5, 13, 0)
   painter->setRenderHint( QPainter::LosslessImageRendering, mFlags & Qgis::RenderContextFlag::LosslessImageRendering );
 #endif
+  painter->setRenderHint( QPainter::SmoothPixmapTransform, mFlags & Qgis::RenderContextFlag::HighQualityImageTransforms );
 }
 
 QgsCoordinateTransformContext QgsRenderContext::transformContext() const
@@ -241,6 +244,7 @@ QgsRenderContext QgsRenderContext::fromMapSettings( const QgsMapSettings &mapSet
   ctx.setFlag( Qgis::RenderContextFlag::RenderBlocking, mapSettings.testFlag( Qgis::MapSettingsFlag::RenderBlocking ) );
   ctx.setFlag( Qgis::RenderContextFlag::LosslessImageRendering, mapSettings.testFlag( Qgis::MapSettingsFlag::LosslessImageRendering ) );
   ctx.setFlag( Qgis::RenderContextFlag::Render3DMap, mapSettings.testFlag( Qgis::MapSettingsFlag::Render3DMap ) );
+  ctx.setFlag( Qgis::RenderContextFlag::HighQualityImageTransforms, mapSettings.testFlag( Qgis::MapSettingsFlag::HighQualityImageTransforms ) );
   ctx.setScaleFactor( mapSettings.outputDpi() / 25.4 ); // = pixels per mm
   ctx.setDpiTarget( mapSettings.dpiTarget() >= 0.0 ? mapSettings.dpiTarget() : -1.0 );
   ctx.setRendererScale( mapSettings.scale() );

diff --git a/src/core/symbology/qgsfillsymbollayer.cpp b/src/core/symbology/qgsfillsymbollayer.cpp
@@ -3711,10 +3711,6 @@ void QgsPointPatternFillSymbolLayer::applyPattern( const QgsSymbolRenderContext
     pointRenderContext.setPainter( &p );
     pointRenderContext.setScaleFactor( context.renderContext().scaleFactor() );
 
-    if ( context.renderContext().flags() & Qgis::RenderContextFlag::Antialiasing )
-      pointRenderContext.setFlag( Qgis::RenderContextFlag::Antialiasing, true );
-    pointRenderContext.setFlag( Qgis::RenderContextFlag::LosslessImageRendering, context.renderContext().flags() & Qgis::RenderContextFlag::LosslessImageRendering );
-
     context.renderContext().setPainterFlagsUsingContext( &p );
     QgsMapToPixel mtp( context.renderContext().mapToPixel().mapUnitsPerPixel() );
     pointRenderContext.setMapToPixel( mtp );

diff --git a/src/core/symbology/qgslinesymbollayer.cpp b/src/core/symbology/qgslinesymbollayer.cpp
@@ -2956,8 +2956,7 @@ void QgsAbstractBrushedLineSymbolLayer::renderLine( const QPolygonF &points, Qgs
   // prepare temporary image
   QPainter imagePainter;
   imagePainter.begin( &temporaryImage );
-  imagePainter.setRenderHint( QPainter::Antialiasing, true );
-  imagePainter.setRenderHint( QPainter::SmoothPixmapTransform, true );
+  context.renderContext().setPainterFlagsUsingContext( &imagePainter );
   imagePainter.translate( -minX + lineThickness + ANTIALIAS_ALLOWANCE_PIXELS, -minY + lineThickness + ANTIALIAS_ALLOWANCE_PIXELS );
 
   imagePainter.setClipPath( stroke, Qt::IntersectClip );

diff --git a/src/core/symbology/qgsmarkersymbollayer.cpp b/src/core/symbology/qgsmarkersymbollayer.cpp
@@ -2972,10 +2972,7 @@ void QgsRasterMarkerSymbolLayer::renderPoint( QPointF point, QgsSymbolRenderCont
     if ( context.selected() )
       QgsImageOperation::adjustHueSaturation( img, 1.0, context.renderContext().selectionColor(), 1.0, context.renderContext().feedback() );
 
-    const bool prevSmoothTransform = p->testRenderHint( QPainter::RenderHint::SmoothPixmapTransform );
-    p->setRenderHint( QPainter::RenderHint::SmoothPixmapTransform, true );
     p->drawImage( -img.width() / 2.0, -img.height() / 2.0, img );
-    p->setRenderHint( QPainter::RenderHint::SmoothPixmapTransform, prevSmoothTransform );
   }
 }
 

diff --git a/src/core/symbology/qgssymbol.cpp b/src/core/symbology/qgssymbol.cpp
@@ -683,6 +683,7 @@ QImage QgsSymbol::asImage( QSize size, QgsRenderContext *customContext )
 
   QPainter p( &image );
   p.setRenderHint( QPainter::Antialiasing );
+  p.setRenderHint( QPainter::SmoothPixmapTransform );
 
   drawPreviewIcon( &p, size, customContext );
 
@@ -708,6 +709,9 @@ QImage QgsSymbol::bigSymbolPreviewImage( QgsExpressionContext *expressionContext
 
   QgsRenderContext context = QgsRenderContext::fromQPainter( &p );
   context.setFlag( Qgis::RenderContextFlag::RenderSymbolPreview );
+  context.setFlag( Qgis::RenderContextFlag::Antialiasing );
+  context.setFlag( Qgis::RenderContextFlag::HighQualityImageTransforms );
+  context.setPainterFlagsUsingContext( &p );
   if ( expressionContext )
     context.setExpressionContext( *expressionContext );