[layouts] Respect XYZ output zoom level when previewing map items in …

…the layout designer
qgis · May 3, 2021 · 8d1371f · 8d1371f
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Showing 15 changed files with 125 additions and 14 deletions.
diff --git a/python/core/auto_generated/qgsmapsettings.sip.in b/python/core/auto_generated/qgsmapsettings.sip.in
@@ -191,6 +191,22 @@ The default value is 96 dpi.
 Sets the ``dpi`` (dots per inch) used for conversion between real world units (e.g. mm) and pixels.
 
 .. seealso:: :py:func:`outputDpi`
+%End
+
+    double dpiTarget() const;
+%Docstring
+Returns the target DPI (dots per inch) to be taken into consideration when rendering.
+
+The default value is -1, which states no DPI target is provided.
+
+.. seealso:: :py:func:`setDpiTarger`
+%End
+
+    void setDpiTarget( double dpi );
+%Docstring
+Sets the target ``dpi`` (dots per inch) to be taken into consideration when rendering.
+
+.. seealso:: :py:func:`dpiTarget`
 %End
 
     void setMagnificationFactor( double factor, const QgsPointXY *center = 0 );

diff --git a/python/core/auto_generated/qgsrendercontext.sip.in b/python/core/auto_generated/qgsrendercontext.sip.in
@@ -278,6 +278,16 @@ to physical sizes. This is usually equal to the number of pixels
 per millimeter.
 
 .. seealso:: :py:func:`setScaleFactor`
+%End
+
+    double dpiTarget() const;
+%Docstring
+Returns the targeted DPI for rendering.
+scale.
+
+.. seealso:: :py:func:`setDpiTarget`
+
+.. versionadded:: 3.20
 %End
 
     bool renderingStopped() const;
@@ -425,6 +435,15 @@ to physical sizes. This should usually be equal to the number of pixels
 per millimeter.
 
 .. seealso:: :py:func:`scaleFactor`
+%End
+
+    void setDpiTarget( double dpi );
+%Docstring
+Sets the targeted ``dpi`` for rendering.
+
+.. seealso:: :py:func:`dpiTarget`
+
+.. versionadded:: 3.20
 %End
 
     void setRendererScale( double scale );

diff --git a/python/core/auto_generated/raster/qgsrasterdataprovider.sip.in b/python/core/auto_generated/raster/qgsrasterdataprovider.sip.in
@@ -77,7 +77,8 @@ Base class for raster data providers.
       WriteLayerMetadata,
       ProviderHintBenefitsFromResampling,
       ProviderHintCanPerformProviderResampling,
-      ReloadData
+      ReloadData,
+      PixelDependentRendering,
     };
 
     typedef QFlags<QgsRasterDataProvider::ProviderCapability> ProviderCapabilities;

diff --git a/python/core/auto_generated/raster/qgsrasterdrawer.sip.in b/python/core/auto_generated/raster/qgsrasterdrawer.sip.in
@@ -20,7 +20,7 @@ The drawing pipe for raster layers.
 #include "qgsrasterdrawer.h"
 %End
   public:
-    QgsRasterDrawer( QgsRasterIterator *iterator );
+    QgsRasterDrawer( QgsRasterIterator *iterator, double dpiTarget = -1.0 );
 
     void draw( QPainter *p, QgsRasterViewPort *viewPort, const QgsMapToPixel *qgsMapToPixel, QgsRasterBlockFeedback *feedback = 0 );
 %Docstring

diff --git a/src/core/layout/qgslayoutitemmap.cpp b/src/core/layout/qgslayoutitemmap.cpp
@@ -1484,6 +1484,8 @@ QgsMapSettings QgsLayoutItemMap::mapSettings( const QgsRectangle &extent, QSizeF
   jobMapSettings.setExtent( extent );
   jobMapSettings.setOutputSize( size.toSize() );
   jobMapSettings.setOutputDpi( dpi );
+  if ( layout()->renderContext().isPreviewRender() )
+    jobMapSettings.setDpiTarget( layout()->renderContext().dpi() );
   jobMapSettings.setBackgroundColor( Qt::transparent );
   jobMapSettings.setRotation( mEvaluatedMapRotation );
   if ( mLayout )

diff --git a/src/core/qgsmaprendererjob.cpp b/src/core/qgsmaprendererjob.cpp
@@ -408,6 +408,7 @@ LayerRenderJobs QgsMapRendererJob::prepareJobs( QPainter *painter, QgsLabelingEn
     job.estimatedRenderingTime = mLayerRenderingTimeHints.value( ml->id(), 0 );
     job.renderingTime = -1;
 
+
     job.context = QgsRenderContext::fromMapSettings( mSettings );
     job.context.expressionContext().appendScope( QgsExpressionContextUtils::layerScope( ml ) );
     job.context.setPainter( painter );

diff --git a/src/core/qgsmapsettings.cpp b/src/core/qgsmapsettings.cpp
@@ -272,6 +272,15 @@ void QgsMapSettings::setOutputDpi( double dpi )
   updateDerived();
 }
 
+double QgsMapSettings::dpiTarget() const
+{
+  return mDpiTarget;
+}
+
+void QgsMapSettings::setDpiTarget( double dpi )
+{
+  mDpiTarget = dpi;
+}
 
 QStringList QgsMapSettings::layerIds() const
 {

diff --git a/src/core/qgsmapsettings.h b/src/core/qgsmapsettings.h
@@ -204,6 +204,22 @@ class CORE_EXPORT QgsMapSettings : public QgsTemporalRangeObject
      */
     void setOutputDpi( double dpi );
 
+    /**
+     * Returns the target DPI (dots per inch) to be taken into consideration when rendering.
+     *
+     * The default value is -1, which states no DPI target is provided.
+     *
+     * \see setDpiTarger()
+     */
+    double dpiTarget() const;
+
+    /**
+     * Sets the target \a dpi (dots per inch) to be taken into consideration when rendering.
+     *
+     * \see dpiTarget()
+     */
+    void setDpiTarget( double dpi );
+
     /**
      * Set the magnification factor.
      * \param factor the factor of magnification
@@ -773,7 +789,8 @@ class CORE_EXPORT QgsMapSettings : public QgsTemporalRangeObject
 
   protected:
 
-    double mDpi;
+    double mDpi = 96.0;
+    double mDpiTarget = -1;
 
     QSize mSize;
     float mDevicePixelRatio = 1.0;

diff --git a/src/core/qgsrendercontext.cpp b/src/core/qgsrendercontext.cpp
@@ -51,6 +51,7 @@ QgsRenderContext::QgsRenderContext( const QgsRenderContext &rh )
   , mMapToPixel( rh.mMapToPixel )
   , mRenderingStopped( rh.mRenderingStopped )
   , mScaleFactor( rh.mScaleFactor )
+  , mDpiTarget( rh.mDpiTarget )
   , mRendererScale( rh.mRendererScale )
   , mLabelingEngine( rh.mLabelingEngine )
   , mSelectionColor( rh.mSelectionColor )
@@ -88,6 +89,7 @@ QgsRenderContext &QgsRenderContext::operator=( const QgsRenderContext &rh )
   mMapToPixel = rh.mMapToPixel;
   mRenderingStopped = rh.mRenderingStopped;
   mScaleFactor = rh.mScaleFactor;
+  mDpiTarget = rh.mDpiTarget;
   mRendererScale = rh.mRendererScale;
   mLabelingEngine = rh.mLabelingEngine;
   mSelectionColor = rh.mSelectionColor;
@@ -220,6 +222,7 @@ QgsRenderContext QgsRenderContext::fromMapSettings( const QgsMapSettings &mapSet
   ctx.setFlag( LosslessImageRendering, mapSettings.testFlag( QgsMapSettings::LosslessImageRendering ) );
   ctx.setFlag( Render3DMap, mapSettings.testFlag( QgsMapSettings::Render3DMap ) );
   ctx.setScaleFactor( mapSettings.outputDpi() / 25.4 ); // = pixels per mm
+  ctx.setDpiTarget( mapSettings.dpiTarget() >= 0.0 ? mapSettings.dpiTarget() : -1.0 );
   ctx.setRendererScale( mapSettings.scale() );
   ctx.setExpressionContext( mapSettings.expressionContext() );
   ctx.setSegmentationTolerance( mapSettings.segmentationTolerance() );

diff --git a/src/core/qgsrendercontext.h b/src/core/qgsrendercontext.h
@@ -333,6 +333,15 @@ class CORE_EXPORT QgsRenderContext : public QgsTemporalRangeObject
      */
     double scaleFactor() const {return mScaleFactor;}
 
+    /**
+     * Returns the targeted DPI for rendering.
+     * scale.
+     *
+     * \see setDpiTarget()
+     * \since QGIS 3.20
+     */
+    double dpiTarget() const {return mDpiTarget;}
+
     /**
      * Returns TRUE if the rendering operation has been stopped and any ongoing
      * rendering should be canceled immediately.
@@ -476,6 +485,14 @@ class CORE_EXPORT QgsRenderContext : public QgsTemporalRangeObject
      */
     void setScaleFactor( double factor ) {mScaleFactor = factor;}
 
+    /**
+     * Sets the targeted \a dpi for rendering.
+     *
+     * \see dpiTarget()
+     * \since QGIS 3.20
+     */
+    void setDpiTarget( double dpi ) {mDpiTarget = dpi;}
+
     /**
      * 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.
@@ -928,6 +945,9 @@ class CORE_EXPORT QgsRenderContext : public QgsTemporalRangeObject
     //! Factor to scale line widths and point marker sizes
     double mScaleFactor = 1.0;
 
+    //! Targeted DPI
+    double mDpiTarget = -1.0;
+
     //! Map scale
     double mRendererScale = 1.0;
 

diff --git a/src/core/raster/qgsrasterdataprovider.h b/src/core/raster/qgsrasterdataprovider.h
@@ -102,7 +102,8 @@ class CORE_EXPORT QgsRasterDataProvider : public QgsDataProvider, public QgsRast
       WriteLayerMetadata = 1 << 2, //!< Provider can write layer metadata to the data store. Since QGIS 3.0. See QgsDataProvider::writeLayerMetadata()
       ProviderHintBenefitsFromResampling = 1 << 3, //!< Provider benefits from resampling and should apply user default resampling settings (since QGIS 3.10)
       ProviderHintCanPerformProviderResampling = 1 << 4, //!< Provider can perform resampling (to be opposed to post rendering resampling) (since QGIS 3.16)
-      ReloadData = 1 << 5 //!< Is able to force reload data / clear local caches. Since QGIS 3.18, see QgsDataProvider::reloadProviderData()
+      ReloadData = 1 << 5, //!< Is able to force reload data / clear local caches. Since QGIS 3.18, see QgsDataProvider::reloadProviderData()
+      PixelDependentRendering = 1 << 6, //! Provider's rendering is dependent on requested pixel size of the viewport
     };
 
     //! Provider capabilities

diff --git a/src/core/raster/qgsrasterdrawer.cpp b/src/core/raster/qgsrasterdrawer.cpp
@@ -29,7 +29,9 @@
 #include <QPrinter>
 #endif
 
-QgsRasterDrawer::QgsRasterDrawer( QgsRasterIterator *iterator ): mIterator( iterator )
+QgsRasterDrawer::QgsRasterDrawer( QgsRasterIterator *iterator, double dpiTarget )
+  : mIterator( iterator )
+  , mDpiTarget( dpiTarget )
 {
 }
 
@@ -115,28 +117,29 @@ void QgsRasterDrawer::draw( QPainter *p, QgsRasterViewPort *viewPort, const QgsM
   }
 }
 
+#include <QDebug>
 void QgsRasterDrawer::drawImage( QPainter *p, QgsRasterViewPort *viewPort, const QImage &img, int topLeftCol, int topLeftRow, const QgsMapToPixel *qgsMapToPixel ) const
 {
   if ( !p || !viewPort )
   {
     return;
   }
 
+  const double dpiScaleFactor = mDpiTarget >= 0.0 ? mDpiTarget / p->device()->logicalDpiX() : 1.0;
   //top left position in device coords
-  QPoint tlPoint = QPoint( viewPort->mTopLeftPoint.x() + topLeftCol, viewPort->mTopLeftPoint.y() + topLeftRow );
+  QPoint tlPoint = QPoint( viewPort->mTopLeftPoint.x() + topLeftCol / dpiScaleFactor, viewPort->mTopLeftPoint.y() + topLeftRow / dpiScaleFactor );
+
   QgsScopedQPainterState painterState( p );
   p->setRenderHint( QPainter::Antialiasing, false );
 
   // Blending problem was reported with PDF output if background color has alpha < 255
   // in #7766, it seems to be a bug in Qt, setting a brush with alpha 255 is a workaround
   // which should not harm anything
   p->setBrush( QBrush( QColor( Qt::white ), Qt::NoBrush ) );
-
+  int w = qgsMapToPixel->mapWidth();
+  int h = qgsMapToPixel->mapHeight();
   if ( qgsMapToPixel )
   {
-    int w = qgsMapToPixel->mapWidth();
-    int h = qgsMapToPixel->mapHeight();
-
     double rotation = qgsMapToPixel->mapRotation();
     if ( rotation )
     {
@@ -149,7 +152,7 @@ void QgsRasterDrawer::drawImage( QPainter *p, QgsRasterViewPort *viewPort, const
     }
   }
 
-  p->drawImage( tlPoint, img );
+  p->drawImage( tlPoint, dpiScaleFactor != 1.0 ? img.scaledToWidth( img.width() / dpiScaleFactor ) : img );
 
 #if 0
   // For debugging:

diff --git a/src/core/raster/qgsrasterdrawer.h b/src/core/raster/qgsrasterdrawer.h
@@ -37,7 +37,7 @@ class QgsRasterIterator;
 class CORE_EXPORT QgsRasterDrawer
 {
   public:
-    QgsRasterDrawer( QgsRasterIterator *iterator );
+    QgsRasterDrawer( QgsRasterIterator *iterator, double dpiTarget = -1.0 );
 
     /**
      * Draws raster data.
@@ -64,6 +64,7 @@ class CORE_EXPORT QgsRasterDrawer
 
   private:
     QgsRasterIterator *mIterator = nullptr;
+    double mDpiTarget = -1.0;
 };
 
 #endif // QGSRASTERDRAWER_H
diff --git a/src/core/raster/qgsrasterlayerrenderer.cpp b/src/core/raster/qgsrasterlayerrenderer.cpp
@@ -58,7 +58,7 @@ void QgsRasterLayerRendererFeedback::onNewData()
   feedback.setPreviewOnly( true );
   feedback.setRenderPartialOutput( true );
   QgsRasterIterator iterator( mR->mPipe->last() );
-  QgsRasterDrawer drawer( &iterator );
+  QgsRasterDrawer drawer( &iterator, mR->renderContext()->dpiTarget() );
   drawer.draw( mR->renderContext()->painter(), mR->mRasterViewPort, &mR->renderContext()->mapToPixel(), &feedback );
   mR->mReadyToCompose = true;
   QgsDebugMsgLevel( QStringLiteral( "total raster preview time: %1 ms" ).arg( t.elapsed() ), 3 );
@@ -201,6 +201,19 @@ QgsRasterLayerRenderer::QgsRasterLayerRenderer( QgsRasterLayer *layer, QgsRender
   mRasterViewPort->mWidth = static_cast<qgssize>( std::abs( mRasterViewPort->mBottomRightPoint.x() - mRasterViewPort->mTopLeftPoint.x() ) );
   mRasterViewPort->mHeight = static_cast<qgssize>( std::abs( mRasterViewPort->mBottomRightPoint.y() - mRasterViewPort->mTopLeftPoint.y() ) );
 
+
+  if ( mProviderCapabilities & QgsRasterDataProvider::PixelDependentRendering
+       && rendererContext.dpiTarget() >= 0.0 )
+  {
+    const double dpiScaleFactor = rendererContext.dpiTarget() / rendererContext.painter()->device()->logicalDpiX();
+    mRasterViewPort->mWidth *= dpiScaleFactor;
+    mRasterViewPort->mHeight *= dpiScaleFactor;
+  }
+  else
+  {
+    rendererContext.setDpiTarget( -1.0 );
+  }
+
   //the drawable area can start to get very very large when you get down displaying 2x2 or smaller, this is because
   //mapToPixel.mapUnitsPerPixel() is less then 1,
   //so we will just get the pixel data and then render these special cases differently in paintImageToCanvas()
@@ -322,7 +335,7 @@ bool QgsRasterLayerRenderer::render()
 
   // Drawer to pipe?
   QgsRasterIterator iterator( mPipe->last() );
-  QgsRasterDrawer drawer( &iterator );
+  QgsRasterDrawer drawer( &iterator, renderContext()->dpiTarget() );
   drawer.draw( renderContext()->painter(), mRasterViewPort, &renderContext()->mapToPixel(), mFeedback );
 
   if ( restoreOldResamplingStage )

diff --git a/src/providers/wms/qgswmsprovider.cpp b/src/providers/wms/qgswmsprovider.cpp
@@ -2024,6 +2024,11 @@ int QgsWmsProvider::capabilities() const
     // capability |= Capability::Prefetch;
   }
 
+  if ( mSettings.mTiled && mSettings.mXyz )
+  {
+    capability |= PixelDependentRendering;
+  }
+
   QgsDebugMsgLevel( QStringLiteral( "capability = %1" ).arg( capability ), 2 );
   return capability;
 }