784867 - Copy WebGL frames to gralloc for B2G

Status: RESOLVED WONTFIX

(Core :: Graphics: CanvasWebGL, defect)

Description

[Kelsey Gilbert [:jgilbert]]

Until we get better in bug 716859, we should extend what we do for OMTC WebGL publishing to work with gralloc on B2G.

Comment 1

[Kelsey Gilbert [:jgilbert]]

Attachment: wip

A WIP based on a conversation with cjones.

Comment 2

[Kelsey Gilbert [:jgilbert]]

Attachment: hack it into the existing (maybe) gralloc code

Comment 3

[Chris Jones [:cjones] inactive; ni?/f?/r? if you need me]

Comment on attachment 654450 [details] [diff] [review]
hack it into the existing (maybe) gralloc code

This doesn't compile.

Comment 4

[Kelsey Gilbert [:jgilbert]]

Attachment: buildable patch

I can't seem to flash my phone today. All I get is 'mozilla' in the bottom-right of the screen, and it doesn't seem to do anything. (with or without this patch)

Comment 5

[Kelsey Gilbert [:jgilbert]]

Attachment: Use BlitFramebufferToTexture to do the copy instead of ReadPixels

So on my Nexus S, this is slightly slower. On this device, we don't save any copy (or upload) by doing this, because we currently ReadPixels into a Gralloc buffer we later sample from as a texture.

This patch will generally use CopyTexSubImage, unless you flip the pref |gl.blit-draw-not-copy| to true. (default: false) If true, it'll do a RTT of the screen texture onto the Gralloc buffer, which (for me) is slower-still.

So, for the Nexus S, it seems that this doesn't win us anything. It's possible that there is some device where it does, but I think it's relatively unlikely. (No harm in trying, though)

Comment 6

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

I think given that we have bug 716859 landed now, and the remaining gralloc stuff being done in bug 843599, this is probably wontfix.