Fix for embedding legend and scalebar if pixel buffer is not supported with the selected output format (MapServer#4618)

Author: szekerest

maplegend.c

@@ -632,15 +632,10 @@ int msEmbedLegend(mapObj *map, imageObj *img)
   pointObj point;
   imageObj *image = NULL;
   symbolObj *legendSymbol;
+  char* imageType = NULL;
 
   rendererVTableObj *renderer;
 
-  if(!MS_RENDERER_PLUGIN(map->outputformat) || !MS_MAP_RENDERER(map)->supports_pixel_buffer) {
-    msSetError(MS_MISCERR, "unsupported output format", "msEmbedLegend()");
-    return MS_FAILURE;
-  }
-  renderer = MS_MAP_RENDERER(map);
-
   s = msGetSymbolIndex(&(map->symbolset), "legend", MS_FALSE);
   if(s != -1)
     msRemoveSymbol(&(map->symbolset), s); /* solves some caching issues in AGG with long-running processes */
@@ -652,10 +647,26 @@ int msEmbedLegend(mapObj *map, imageObj *img)
   map->symbolset.numsymbols++;
   initSymbol(legendSymbol);
 
+  if(!MS_RENDERER_PLUGIN(map->outputformat) || !MS_MAP_RENDERER(map)->supports_pixel_buffer) {
+    imageType = msStrdup(map->imagetype); /* save format */
+    if MS_DRIVER_CAIRO(map->outputformat)
+      map->outputformat = msSelectOutputFormat( map, "cairopng" );
+    else
+      map->outputformat = msSelectOutputFormat( map, "png" );
+    
+    msInitializeRendererVTable(map->outputformat);
+  }
+  renderer = MS_MAP_RENDERER(map);
+
   /* render the legend. */
   image = msDrawLegend(map, MS_FALSE);
   if( image == NULL ) return -1;
 
+  if (imageType) {
+    map->outputformat = msSelectOutputFormat( map, imageType ); /* restore format */
+    msFree(imageType);
+  }
+
   /* copy renderered legend image into symbol */
   legendSymbol->pixmap_buffer = calloc(1,sizeof(rasterBufferObj));
   MS_CHECK_ALLOC(legendSymbol->pixmap_buffer, sizeof(rasterBufferObj), MS_FAILURE);

mapscale.c

@@ -339,24 +339,39 @@ int msEmbedScalebar(mapObj *map, imageObj *img)
   int l,index,s;
   pointObj point;
   imageObj *image = NULL;
-  rendererVTableObj *renderer = MS_MAP_RENDERER(map);
+  rendererVTableObj *renderer;
   symbolObj *embededSymbol;
+  char* imageType = NULL;
 
-  if( ! renderer ) {
-    msSetError(MS_MISCERR,"unsupported outputformat","msEmbedScalebar()");
-    return MS_FAILURE;
-  }
   index = msGetSymbolIndex(&(map->symbolset), "scalebar", MS_FALSE);
   if(index != -1)
     msRemoveSymbol(&(map->symbolset), index); /* remove cached symbol in case the function is called multiple
                       times with different zoom levels */
 
   if((embededSymbol=msGrowSymbolSet(&map->symbolset)) == NULL)
     return MS_FAILURE;
+
   s = map->symbolset.numsymbols;
   map->symbolset.numsymbols++;
 
+  if(!MS_RENDERER_PLUGIN(map->outputformat) || !MS_MAP_RENDERER(map)->supports_pixel_buffer) {
+    imageType = msStrdup(map->imagetype); /* save format */
+    if MS_DRIVER_CAIRO(map->outputformat)
+      map->outputformat = msSelectOutputFormat( map, "cairopng" );
+    else
+      map->outputformat = msSelectOutputFormat( map, "png" );
+    
+    msInitializeRendererVTable(map->outputformat);
+  }
+  renderer = MS_MAP_RENDERER(map);
+
   image = msDrawScalebar(map);
+
+  if (imageType) {
+    map->outputformat = msSelectOutputFormat( map, imageType ); /* restore format */
+    msFree(imageType);
+  }
+
   if(!image) {
     return MS_FAILURE;
   }