desktop-shell: How to enable really alpha blending of weston background?

YoungJun Jo dtoartist at
Tue Feb 23 01:11:39 UTC 2016


Thanks for your reply.

What i want is alpha blending for my chips.
As i mentioned, My chips have four independent H/W overlays.

For example,
H/W Overlay 1 => Weston, Applications, etc..
H/W Overlay 2 => Video play.
H/W Overlay 3 = > Empty.
H/W Overlay 4 = > Empty.

I also know that weston don't know H/W Overlays above mentioned.

1. If i click play button on my video application, it will be call alpha
blending API.
2. When weston receives alpha blending api, weston background will be
3. And i could see video playing from H/W Layer 2.(Still H/W Layer1 shows
GUI of video control buttons)

So i want really alpha blending of weston background.

I'm sorry to describe it difficult to understand.


2016-02-22 21:36 GMT+09:00 YoungJun Jo <dtoartist at>:

> Environment
> OS : Linux kernel 3.10
> Version : Weston 1.8.0
> H/W spec : embedded soc based on ARM
> Hello, All
> I have a question about weston background.
> I want enable alpha blending to background, so i have typed
> 'background-color=0x00ffffff' on weston.ini.
> But that's not really alpha blending. Because alpha value of pixel is a
> 'ff'.
> My chips have four H/W layers, top of the layer is UI layer and second
> layer is video layer.
> I reviewed source code of 'desktop-shell.c' but i can't find any hints.
> Need some additional ideas to solve this problem. Any feedback is
> appreciated.
> Thanks.
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