WMS 1.3. compliance: distort image if width/height ratio of bbox is different to WIDTH/HEIGHT of requested image

Author: mhugent

src/server/qgswmsserver.cpp

@@ -1453,6 +1453,17 @@ QImage* QgsWMSServer::getMap( HitTest* hitTest )
   //  theImage->save( QDir::tempPath() + QDir::separator() + "lastrender.png" );
   //#endif
 
+  thePainter.end();
+
+  //test if width / height ratio of image is the same as the ratio of WIDTH / HEIGHT parameters. If not, the image has to be scaled (required by WMS spec)
+  int widthParam = mParameters.value( "WIDTH", "0" ).toInt();
+  int heightParam = mParameters.value( "HEIGHT", "0" ).toInt();
+  if ( widthParam != theImage->width() || heightParam != theImage->height() )
+  {
+    //scale image
+    *theImage = theImage->scaled( widthParam, heightParam, Qt::IgnoreAspectRatio, Qt::SmoothTransformation );
+  }
+
   return theImage;
 }
 
@@ -1574,7 +1585,6 @@ int QgsWMSServer::getFeatureInfo( QDomDocument& result, const QString& version )
   QgsRectangle mapExtent = mMapRenderer->extent();
   double scaleDenominator = scaleCalc.calculate( mapExtent, outputImage->width() );
   mConfigParser->setScaleDenominator( scaleDenominator );
-  delete outputImage; //no longer needed for feature info
 
   //read FEATURE_COUNT
   int featureCount = 1;
@@ -1614,6 +1624,16 @@ int QgsWMSServer::getFeatureInfo( QDomDocument& result, const QString& version )
     j = -1;
   }
 
+  //In case the output image is distorted (WIDTH/HEIGHT ratio not equal to BBOX width/height), I and J need to be adapted as well
+  int widthParam = mParameters.value( "WIDTH", "-1" ).toInt();
+  int heightParam = mParameters.value( "HEIGHT", "-1" ).toInt();
+  if (( i != -1 && j != -1 && widthParam != -1 && heightParam != -1 ) && ( widthParam != outputImage->width() || heightParam != outputImage->height() ) )
+  {
+    i *= ( outputImage->width() / ( double )widthParam );
+    j *= ( outputImage->height() / ( double )heightParam );
+  }
+  delete outputImage; //no longer needed for feature info
+
   //Normally, I/J or X/Y are mandatory parameters.
   //However, in order to make attribute only queries via the FILTER parameter, it is allowed to skip them if the FILTER parameter is there
 
@@ -1950,6 +1970,29 @@ QImage* QgsWMSServer::createImage( int width, int height ) const
     }
   }
 
+  //Adapt width / height if the aspect ratio does not correspond with the BBOX.
+  //Required by WMS spec. 1.3.
+  bool bboxOk;
+  QgsRectangle mapExtent = _parseBBOX( mParameters.value( "BBOX" ), bboxOk );
+  if ( bboxOk )
+  {
+    double mapWidthHeightRatio = mapExtent.width() / mapExtent.height();
+    double imageWidthHeightRatio = ( double )width / ( double )height;
+    if ( !qgsDoubleNear( mapWidthHeightRatio, imageWidthHeightRatio, 0.0001 ) )
+    {
+      if ( mapWidthHeightRatio >= imageWidthHeightRatio )
+      {
+        //decrease image height
+        height = width / mapWidthHeightRatio;
+      }
+      else
+      {
+        //decrease image width
+        width = height * mapWidthHeightRatio;
+      }
+    }
+  }
+
   if ( width < 0 || height < 0 )
   {
     return nullptr;
@@ -2032,7 +2075,7 @@ int QgsWMSServer::configureMapRender( const QPaintDevice* paintDevice ) const
     throw QgsMapServiceException( "InvalidParameterValue", "Invalid BBOX parameter" );
   }
 
-  if ( mapExtent.isEmpty() )
+  if ( mParameters.contains( "BBOX" ) && mapExtent.isEmpty() )
   {
     throw QgsMapServiceException( "InvalidParameterValue", "BBOX is empty" );
   }