[Pixman] How to modify image opacity?

Jonathan Meson jona at visualblasters.com
Sat Aug 22 13:38:08 PDT 2015

Ah, never mind I resolved this by using a mask!

I did notice a particular bug with using a PIXMAN_a8  mask on images of
sizes not divisible by 4 such as a width 854.  The alpha of the mask was
completely ignored. I was using composite with PIXMAN_OP_OVER and running
an arm build neon disabled.

On Fri, Aug 21, 2015 at 11:39 AM, Jonathan Meson <jona at visualblasters.com>

> Hey guys, I'm new to the list. I'm very excited about this powerful
> library and slowly understanding how to use it properly.
> So, I'm looking to modify the opacity of an image but I'm not sure how. I
> attempted to do some research and try some things but it was a bit hard
> finding documentation or samples.
> The simple formula to set opacity at 50% is:
> float alpha = 0.5f;
> C = c*alpha;
> A = a*alpha;
> However, I'm not sure how to achieve this using pixman_image_composite or
> any other method from the pixman library.
> Thanks for any details or guidance with respect to this.
> --
> *Jonathan Meson*
> *CEO and Lead Engineer*
> Visual Blasters LLC
> 717-813-4287

*Jonathan Meson*
*CEO and Lead Engineer*
Visual Blasters LLC
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/pixman/attachments/20150822/4a56b823/attachment.html>

More information about the Pixman mailing list