Preview Bitmap before PDF is drawn

Hi,
is there any function yet, to draw a bitmap instead of a pdf?

use-case would be for example:
a pdf is currently downloading, meanwhile you're seeing a low-res jpg (with all the functions, zoom, swipe, etc...). this low-res jpg will be replaced with the pdf when download is finished.

thanks,
lukas

not supportted directly, you shall develop view class by yourself.