[fix #17773] fix HiDPI in map canvas on mac

For system introducing pixel device ratio, the image rendered by the canvas is actually scaled up to match the physical size of the canvas"
qgis · Oct 19, 2018 · ea982fe · ea982fe
1 parent 7ad0dcf
commit ea982fe
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Showing 8 changed files with 86 additions and 14 deletions.
diff --git a/python/core/auto_generated/qgsmapsettings.sip.in b/python/core/auto_generated/qgsmapsettings.sip.in
@@ -58,6 +58,29 @@ Returns the size of the resulting map image
     void setOutputSize( QSize size );
 %Docstring
 Sets the size of the resulting map image
+%End
+
+    int devicePixelRatio() const;
+%Docstring
+Returns device pixel ratio
+
+.. versionadded:: 3.4
+%End
+
+    void setDevicePixelRatio( int dpr );
+%Docstring
+Sets the device pixel ratio
+
+.. versionadded:: 3.4
+%End
+
+    QSize physicalSize() const;
+%Docstring
+Returns the physical size of the map canvas
+This is equivalent to the output size multiplicated
+by the device pixel ratio
+
+.. versionadded:: 3.4
 %End
 
     double rotation() const;

diff --git a/src/core/qgsmaprenderercustompainterjob.cpp b/src/core/qgsmaprenderercustompainterjob.cpp
@@ -60,14 +60,17 @@ void QgsMapRendererCustomPainterJob::start()
   prepareTime.start();
 
   // clear the background
-  mPainter->fillRect( 0, 0, mSettings.outputSize().width(), mSettings.outputSize().height(), mSettings.backgroundColor() );
+  mPainter->fillRect( 0, 0, mSettings.physicalSize().width(), mSettings.physicalSize().height(), mSettings.backgroundColor() );
 
   mPainter->setRenderHint( QPainter::Antialiasing, mSettings.testFlag( QgsMapSettings::Antialiasing ) );
 
 #ifndef QT_NO_DEBUG
   QPaintDevice *paintDevice = mPainter->device();
-  QString errMsg = QStringLiteral( "pre-set DPI not equal to painter's DPI (%1 vs %2)" ).arg( paintDevice->logicalDpiX() ).arg( mSettings.outputDpi() );
-  Q_ASSERT_X( qgsDoubleNear( paintDevice->logicalDpiX(), mSettings.outputDpi() ), "Job::startRender()", errMsg.toLatin1().data() );
+  QString errMsg = QStringLiteral( "pre-set DPI not equal to painter's DPI (%1 vs %2)" )
+                   .arg( paintDevice->logicalDpiX() )
+                   .arg( mSettings.outputDpi() );
+  Q_ASSERT_X( qgsDoubleNear( paintDevice->logicalDpiX(), mSettings.outputDpi() ),
+              "Job::startRender()", errMsg.toLatin1().data() );
 #endif
 
   mLabelingEngineV2.reset();

diff --git a/src/core/qgsmaprendererjob.cpp b/src/core/qgsmaprendererjob.cpp
@@ -313,6 +313,7 @@ LayerRenderJobs QgsMapRendererJob::prepareJobs( QPainter *painter, QgsLabelingEn
       job.cached = true;
       job.imageInitialized = true;
       job.img = new QImage( mCache->cacheImage( ml->id() ) );
+      job.img->setDevicePixelRatio( mSettings.devicePixelRatio() );
       job.renderer = nullptr;
       job.context.setPainter( nullptr );
       continue;
@@ -324,10 +325,9 @@ LayerRenderJobs QgsMapRendererJob::prepareJobs( QPainter *painter, QgsLabelingEn
     if ( mCache || !painter || needTemporaryImage( ml ) )
     {
       // Flattened image for drawing when a blending mode is set
-      QImage *mypFlattenedImage = nullptr;
-      mypFlattenedImage = new QImage( mSettings.outputSize().width(),
-                                      mSettings.outputSize().height(),
-                                      mSettings.outputImageFormat() );
+      QImage *mypFlattenedImage = new QImage( mSettings.physicalSize(),
+                                              mSettings.outputImageFormat() );
+      mypFlattenedImage->setDevicePixelRatio( mSettings.devicePixelRatio() );
       if ( mypFlattenedImage->isNull() )
       {
         mErrors.append( Error( ml->id(), tr( "Insufficient memory for image %1x%2" ).arg( mSettings.outputSize().width() ).arg( mSettings.outputSize().height() ) ) );
@@ -366,6 +366,7 @@ LabelRenderJob QgsMapRendererJob::prepareLabelingJob( QPainter *painter, QgsLabe
     job.cached = true;
     job.complete = true;
     job.img = new QImage( mCache->cacheImage( LABEL_CACHE_ID ) );
+    Q_ASSERT( job.img->devicePixelRatio() == 2 );
     job.context.setPainter( nullptr );
   }
   else
@@ -374,9 +375,9 @@ LabelRenderJob QgsMapRendererJob::prepareLabelingJob( QPainter *painter, QgsLabe
     {
       // Flattened image for drawing labels
       QImage *mypFlattenedImage = nullptr;
-      mypFlattenedImage = new QImage( mSettings.outputSize().width(),
-                                      mSettings.outputSize().height(),
+      mypFlattenedImage = new QImage( mSettings.physicalSize(),
                                       mSettings.outputImageFormat() );
+      mypFlattenedImage->setDevicePixelRatio( mSettings.devicePixelRatio() );
       if ( mypFlattenedImage->isNull() )
       {
         mErrors.append( Error( QStringLiteral( "labels" ), tr( "Insufficient memory for label image %1x%2" ).arg( mSettings.outputSize().width() ).arg( mSettings.outputSize().height() ) ) );
@@ -447,7 +448,8 @@ void QgsMapRendererJob::cleanupLabelJob( LabelRenderJob &job )
 
 QImage QgsMapRendererJob::composeImage( const QgsMapSettings &settings, const LayerRenderJobs &jobs, const LabelRenderJob &labelJob )
 {
-  QImage image( settings.outputSize(), settings.outputImageFormat() );
+  QImage image( settings.physicalSize(), settings.outputImageFormat() );
+  image.setDevicePixelRatio( settings.devicePixelRatio() );
   image.fill( settings.backgroundColor().rgba() );
 
   QPainter painter( &image );

diff --git a/src/core/qgsmaprenderersequentialjob.cpp b/src/core/qgsmaprenderersequentialjob.cpp
@@ -25,7 +25,8 @@ QgsMapRendererSequentialJob::QgsMapRendererSequentialJob( const QgsMapSettings &
 {
   QgsDebugMsgLevel( QStringLiteral( "SEQUENTIAL construct" ), 5 );
 
-  mImage = QImage( mSettings.outputSize(), mSettings.outputImageFormat() );
+  mImage = QImage( mSettings.physicalSize(), mSettings.outputImageFormat() );
+  mImage.setDevicePixelRatio( mSettings.devicePixelRatio() );
   mImage.setDotsPerMeterX( 1000 * settings.outputDpi() / 25.4 );
   mImage.setDotsPerMeterY( 1000 * settings.outputDpi() / 25.4 );
   mImage.fill( Qt::transparent );

diff --git a/src/core/qgsmapsettings.cpp b/src/core/qgsmapsettings.cpp
@@ -146,8 +146,8 @@ void QgsMapSettings::updateDerived()
     }
   }
 
-  double myHeight = mSize.height();
-  double myWidth = mSize.width();
+  double myHeight = mSize.height() * mDevicePixelRatio;
+  double myWidth = mSize.width() * mDevicePixelRatio;
 
   if ( !myWidth || !myHeight )
   {
@@ -230,6 +230,21 @@ void QgsMapSettings::setOutputSize( QSize size )
   updateDerived();
 }
 
+int QgsMapSettings::devicePixelRatio() const
+{
+  return mDevicePixelRatio;
+}
+
+void QgsMapSettings::setDevicePixelRatio( int dpr )
+{
+  mDevicePixelRatio = dpr;
+}
+
+QSize QgsMapSettings::physicalSize() const
+{
+  return outputSize() * mDevicePixelRatio;
+}
+
 double QgsMapSettings::outputDpi() const
 {
   return mDpi;

diff --git a/src/core/qgsmapsettings.h b/src/core/qgsmapsettings.h
@@ -81,6 +81,26 @@ class CORE_EXPORT QgsMapSettings
     //! Sets the size of the resulting map image
     void setOutputSize( QSize size );
 
+    /**
+     * Returns device pixel ratio
+     * \since QGIS 3.4
+     */
+    int devicePixelRatio() const;
+
+    /**
+     * Sets the device pixel ratio
+     * \since QGIS 3.4
+     */
+    void setDevicePixelRatio( int dpr );
+
+    /**
+     * Returns the physical size of the map canvas
+     * This is equivalent to the output size multiplicated
+     * by the device pixel ratio
+     * \since QGIS 3.4
+     */
+    QSize physicalSize() const;
+
     /**
      * Returns the rotation of the resulting map image, in degrees clockwise.
      * \see setRotation()
@@ -403,6 +423,7 @@ class CORE_EXPORT QgsMapSettings
     double mDpi;
 
     QSize mSize;
+    int mDevicePixelRatio = 1;
 
     QgsRectangle mExtent;
 

diff --git a/src/gui/qgsmapcanvas.cpp b/src/gui/qgsmapcanvas.cpp
@@ -163,6 +163,7 @@ QgsMapCanvas::QgsMapCanvas( QWidget *parent )
 
   QSize s = viewport()->size();
   mSettings.setOutputSize( s );
+  mSettings.setDevicePixelRatio( devicePixelRatio() );
   setSceneRect( 0, 0, s.width(), s.height() );
   mScene->setSceneRect( QRectF( 0, 0, s.width(), s.height() ) );
 
@@ -682,7 +683,8 @@ QgsRectangle QgsMapCanvas::imageRect( const QImage &img, const QgsMapSettings &m
   // expects (encoding of position and size of the item)
   const QgsMapToPixel &m2p = mapSettings.mapToPixel();
   QgsPointXY topLeft = m2p.toMapCoordinates( 0, 0 );
-  double res = m2p.mapUnitsPerPixel();
+  Q_ASSERT( img.devicePixelRatio() == mapSettings.devicePixelRatio() );
+  double res = m2p.mapUnitsPerPixel() / img.devicePixelRatioF();
   QgsRectangle rect( topLeft.x(), topLeft.y(), topLeft.x() + img.width()*res, topLeft.y() - img.height()*res );
   return rect;
 }

diff --git a/src/gui/qgsmapcanvasmap.cpp b/src/gui/qgsmapcanvasmap.cpp
@@ -83,7 +83,12 @@ void QgsMapCanvasMap::paint( QPainter *painter )
     painter->drawImage( QRectF( ul.x(), ul.y(), lr.x() - ul.x(), lr.y() - ul.y() ), imIt->first, QRect( 0, 0, imIt->first.width(), imIt->first.height() ) );
   }
 
+  qDebug() << "map painter: " << w << h << mImage.size() << mImage.devicePixelRatioF();
   painter->drawImage( QRect( 0, 0, w, h ), mImage );
+  //Q_ASSERT(mImage.isNull() || mImage.devicePixelRatio()==2);
+  //QImage img = mImage;
+  //img.setDevicePixelRatio(2);
+  //painter->drawImage( 0,0, img );
 
   // For debugging:
 #if 0