1920058 - Add a debug view clearly showing layerization

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, task, P3)

Description

[Nicolas Silva [:nical]]

I find myself missing the gfx.layers.show-borders view from the pre-webrender era. We have a debug overlay for picture cache slices which is useful to observe the behavior of the invalidation logic, but it is too hard to read the layerization breakdown, and it does not show child pictures.

Without this, I have to load wrench replays in renderdoc to observe the layerization while prototyping the view-transitions work which is too time consuming.

The debug view would overlay borders on top of the rendered frames for picture cache slices, tiles and, child pictures with different colors.

Comment 1

[Nicolas Silva [:nical]]

Attachment: Bug 1920058 - Add a debug pref to show picture borders. r=#gfx-reviewers

This patch moves the logic to draw the tiled picture overlay out of the entirely too large take_context into a separate function, and add a separate option to draw only the borders of all pictures (non-tiled ones included) and tiles. This new overlay is enabled via the pref gfx.webrender.debug.picture-borders and is useful when trying to observe the breakdown of the page into pictures.
It does not quite do what I want it to: borders for non-tiled pictures seem to only appear on the frame they are drawn and aren't shown in subsequent frames unles the containing tile cache is invalidated. So there will probably be followup adjustments, but the functionality is already useful in its current state.

Comment 2

[Nicolas Silva [:nical]]

Attachment: Bug 1920058 - Support drawing debug rects with a thickness. r=#gfx-reviewers

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/c57bdb9e97a0
Add a debug pref to show picture borders. r=gfx-reviewers,lsalzman
https://hg.mozilla.org/integration/autoland/rev/2c20d0704d4e
Support drawing debug rects with a thickness. r=gfx-reviewers,lsalzman

Comment 4

[Cristina Horotan [:chorotan]]

https://hg.mozilla.org/mozilla-central/rev/c57bdb9e97a0
https://hg.mozilla.org/mozilla-central/rev/2c20d0704d4e