Function msDrawLayer

mapdraw.c:664–780

* Generic function to render a layer object. */

 * Generic function to render a layer object.
*/
int msDrawLayer(mapObj *map, layerObj *layer, imageObj *image)
{
  imageObj *image_draw = image;
  outputFormatObj *altFormat=NULL;
  int retcode=MS_SUCCESS;
  int originalopacity = layer->opacity;
  const char *alternativeFomatString = NULL;

  if(!msLayerIsVisible(map, layer))
    return MS_SUCCESS;  

  if(layer->opacity == 0) return MS_SUCCESS; /* layer is completely transparent, skip it */

  /* conditions may have changed since this layer last drawn, so set
     layer->project true to recheck projection needs (Bug #673) */
  layer->project = MS_TRUE;

  /* inform the rendering device that layer draw is starting. */
  msImageStartLayer(map, layer, image);

  /*check if an alternative renderer should be used for this layer*/
  alternativeFomatString = msLayerGetProcessingKey( layer, "RENDERER");
  if (MS_RENDERER_PLUGIN(image_draw->format) && alternativeFomatString!=NULL && 
      (altFormat=  msSelectOutputFormat(map, alternativeFomatString)))
  {
      rendererVTableObj *renderer=NULL; 
      msInitializeRendererVTable(altFormat);

      image_draw = msImageCreate(image->width, image->height,
                                 altFormat, image->imagepath, image->imageurl, map->resolution, map->defresolution, &map->imagecolor);
      renderer = MS_IMAGE_RENDERER(image_draw);
      renderer->startLayer(image_draw,map,layer);
  }
  else if (MS_RENDERER_PLUGIN(image_draw->format)) {
	    rendererVTableObj *renderer = MS_IMAGE_RENDERER(image_draw);
		if (layer->opacity > 0 && layer->opacity < 100) {
			if (!renderer->supports_transparent_layers) {
				image_draw = msImageCreate(image->width, image->height,
						image->format, image->imagepath, image->imageurl, map->resolution, map->defresolution, NULL);
				if (!image_draw) {
					msSetError(MS_MISCERR, "Unable to initialize temporary transparent image.",
							"msDrawLayer()");
					return (MS_FAILURE);
				}
				/* set opacity to full, as the renderer should be rendering a fully opaque image */
				layer->opacity=100;
				renderer->startLayer(image_draw,map,layer);
			} 
		}
  }
  /* 
  ** redirect procesing of some layer types. 
  */
  if(layer->connectiontype == MS_WMS) {
#ifdef USE_WMS_LYR
    retcode = msDrawWMSLayer(map, layer, image_draw);
#else  
    retcode = MS_FAILURE;