>> The backend could take care of that through caching a high-res >> rendering and scale that to produce smaller versions. >I do not think you want to do this, you are then downsampling >a bitmap and any benefits of rendering from the vector >representation are lost. Scaling raster image, especially down scaling, does not necessarily generate horrible result if filtered. Even bi-linear filtering should give quite good enough quality for icons. With recent HW accelerators, bi-linear filtered raster image scaling should not be a burden, and can be done on the fly. As far as I know, Mac OS X's icons are bitmap and nobody questions about its quality. Simply becasue original size is large enough (128x128), and they do filtered scaling. Also, I think there's no need to limit zooming level and cache all zooming level. Just rasterize as the largest needed size and do filtered scaling blit when drawing. -- BR, Koichi Mori