[Ipe-discuss] Transparency/background color and iperender -png

[Otfried Cheong]

> I would like to generate some PNG icons from IPE files using iperender.
> However, it seems that iperender always uses some kind of
> half-transparent background pattern (a mixture of transparent and white
> pixels).
>
> To reproduce, just draw a simple rectangle (stroke only, black), and use
> iperender -png rectangle.ipe rectangle.png
>
> Is there some way to get a completely transparent background?

I don't understand how you achieved a half-transparent background.  The 
background should be filled with white before drawing anything - and 
I've never seen anything transparent.

Changing this is a good idea - I'll add a flag -transparent to make the 
background transparent.

If you can recompile iperender, you can easily achieve this by changing 
the line

       *p++ = 0xffffffff;

in iperender.cpp to:

       *p++ = 0x00ffffff;

Cheers,
  Otfried