[map canvas] Fix preview jobs for rotated map canvas

qgis · Mar 3, 2025 · 866c3ca · 866c3ca
1 parent 9036541
commit 866c3ca
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Showing 2 changed files with 27 additions and 22 deletions.
diff --git a/src/gui/qgsmapcanvas.cpp b/src/gui/qgsmapcanvas.cpp
@@ -1006,7 +1006,7 @@ void QgsMapCanvas::previewJobFinished()
 
   if ( mMap )
   {
-    mMap->addPreviewImage( job->renderedImage(), job->mapSettings().extent() );
+    mMap->addPreviewImage( job->renderedImage(), job->mapSettings().visibleExtent() );
     mPreviewJobs.removeAll( job );
 
     int number = job->property( "number" ).toInt();
@@ -3517,37 +3517,40 @@ const QgsLabelingEngineSettings &QgsMapCanvas::labelingEngineSettings() const
 void QgsMapCanvas::startPreviewJobs()
 {
   stopPreviewJobs(); //just in case still running
-
-  //canvas preview jobs aren't compatible with rotation
-  // TODO fix this
-  if ( !qgsDoubleNear( mSettings.rotation(), 0.0 ) )
-    return;
-
   schedulePreviewJob( 0 );
 }
 
 void QgsMapCanvas::startPreviewJob( int number )
 {
-  QgsRectangle mapRect = mSettings.visibleExtent();
-
   if ( number == 4 )
     number += 1;
 
   int j = number / 3;
   int i = number % 3;
 
+  QgsMapSettings mapSettings = mSettings;
+  mapSettings.setRotation( 0 );
+  const QgsRectangle mapRect = mapSettings.visibleExtent();
+  QgsPointXY jobCenter = mapRect.center();
+  const double dx = ( i - 1 ) * mapRect.width();
+  const double dy = ( 1 - j ) * mapRect.height();
+  if ( !qgsDoubleNear( mSettings.rotation(), 0.0 ) )
+  {
+    const double radians = mSettings.rotation() * M_PI / 180;
+    const double rdx = dx * cos( radians ) - dy * sin( radians );
+    const double rdy = dy * cos( radians ) + dx * sin( radians );
+    jobCenter.setX( jobCenter.x() + rdx );
+    jobCenter.setY( jobCenter.y() + rdy );
+  }
+  else
+  {
+    jobCenter.setX( jobCenter.x() + dx );
+    jobCenter.setY( jobCenter.y() + dy );
+  }
+  const QgsRectangle jobExtent = QgsRectangle::fromCenterAndSize( jobCenter, mapRect.width(), mapRect.height() );
+
   //copy settings, only update extent
   QgsMapSettings jobSettings = mSettings;
-
-  double dx = ( i - 1 ) * mapRect.width();
-  double dy = ( 1 - j ) * mapRect.height();
-  QgsRectangle jobExtent = mapRect;
-
-  jobExtent.setXMaximum( jobExtent.xMaximum() + dx );
-  jobExtent.setXMinimum( jobExtent.xMinimum() + dx );
-  jobExtent.setYMaximum( jobExtent.yMaximum() + dy );
-  jobExtent.setYMinimum( jobExtent.yMinimum() + dy );
-
   jobSettings.setExtent( jobExtent );
   jobSettings.setFlag( Qgis::MapSettingsFlag::DrawLabeling, false );
   jobSettings.setFlag( Qgis::MapSettingsFlag::RenderPreviewJob, true );

diff --git a/src/gui/qgsmapcanvasmap.cpp b/src/gui/qgsmapcanvasmap.cpp
@@ -83,9 +83,11 @@ void QgsMapCanvasMap::paint( QPainter *painter )
   QList<QPair<QImage, QgsRectangle>>::const_iterator imIt = mPreviewImages.constBegin();
   for ( ; imIt != mPreviewImages.constEnd(); ++imIt )
   {
-    const QPointF ul = toCanvasCoordinates( QgsPoint( imIt->second.xMinimum() + offsetX, imIt->second.yMaximum() + offsetY ) );
-    const QPointF lr = toCanvasCoordinates( QgsPoint( imIt->second.xMaximum() + offsetX, imIt->second.yMinimum() + offsetY ) );
-    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() ) );
+    const QgsPointXY extentCenter = imIt->second.center();
+    const QPointF canvasCenter = toCanvasCoordinates( QgsPoint( extentCenter.x() + offsetX, extentCenter.y() + offsetY ) );
+    const double imageWidth = imIt->first.width();
+    const double imageHeight = imIt->first.height();
+    painter->drawImage( QRectF( canvasCenter.x() - imageWidth / 2, canvasCenter.y() - imageHeight / 2, imageWidth, imageHeight ), imIt->first, QRect( 0, 0, imIt->first.width(), imIt->first.height() ) );
   }
 
   if ( scale )