1042536 - Enable ImageLayer optimization for clipped backgrounds

Status: RESOLVED FIXED

(Core :: Layout, defect)

Description

[Matt Woodrow (:mattwoodrow)]

Attachment: image-layerize

Now that we clip background images using DisplayItemClip (bug 1042423), we can optimize more images into ImageLayers.

https://tbpl.mozilla.org/?tree=Try&rev=f2427af4e3c6

Comment 1

[Markus Stange [:mstange]]

Attachment: subimage sampling testcase

With this patch, does this testcase correctly show solid white squares with black borders? (You'll need to enable layout.css.will-change.enabled to get an image layer in the bottom square.)

We talked about this optimization in Taipei and the subimage sampling requirement was what put me off doing this sooner. jrmuizel suggested adding a sampling rect property to ImageLayers and using a shader that clamps the texture sample positions to this rect.

Comment 2

[Matt Woodrow (:mattwoodrow)]

Yes, becaause we still don't get an ImageLayer for this case. We patch should only let us have an ImageLayer when the destination is clipped, not when we need source clipping for the image.

Comment 3

[Markus Stange [:mstange]]

Oh because you're not removing the "if (!state.mDestArea.IsEqualEdges(state.mFillArea)) {" further down in the function. Good, I missed that.

Comment 4

[Markus Stange [:mstange]]

Comment on attachment 8460770 [details] [diff] [review]
image-layerize

Can I steal this review?

Comment 5

[Matt Woodrow (:mattwoodrow)]

Fine with me!

https://treeherder.mozilla.org/#/jobs?repo=try&revision=1881c681b497

Comment 6

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/e26240900b5a

Comment 7

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/e26240900b5a