1604280 - Get the APZ minimap to work with WebRender

Status: RESOLVED FIXED

(Core :: Panning and Zooming, task, P3)

Description

[Botond Ballo [:botond]]

The APZ minimap is currently drawn by ContainerLayerComposite and therefore not drawn if WebRender is enabled.

It's a useful diagnostic tool, so we should keep it working with WebRender.

Comment 1

[Botond Ballo [:botond]]

This came up today as a tool that would make it easier to diagnose checkerboarding bugs like bug 1818967.

Comment 2

[Botond Ballo [:botond]]

A possible approach for implementing this to be:

• In RenderBackend::update_document(), when sampling async scroll offsets from APZ here, also query APZ for information that would be displayed in the minimap (e.g. the scrollable rect, viewport rects, and displayport rect)
• Propagate the minimap information to build_frame() and FrameBuilder::build(), which can append the rects we want to draw to Frame::debug_items here

Comment 3

[Botond Ballo [:botond]]

I would like to give this a try, it should help with checkerboarding-related investigations such as the one in bug 1781007.

Comment 4

[Botond Ballo [:botond]]

Posting for my own reference: a link to the old Layers implementation of the minimap.

Comment 5

[Botond Ballo [:botond]]

Attachment: Bug 1604280 - Implement an APZ minimap for WebRender. r=dlrobertson!,gw!

Comment 6

[Botond Ballo [:botond]]

Attachment: Bug 1604280 - Fix a bug in SpatialTree::get_world_transform_impl(). r=gw

The first branch (where the node is in the root coordinate system)
was not handling the TransformScroll::Unscrolled case.

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/f3656d44c967
Fix a bug in SpatialTree::get_world_transform_impl(). r=gw
https://hg.mozilla.org/integration/autoland/rev/872d8cd8e16c
Implement an APZ minimap for WebRender. r=dlrobertson,gw

Comment 8

[Natalia Csoregi [:nataliaCs]]

https://hg.mozilla.org/mozilla-central/rev/f3656d44c967
https://hg.mozilla.org/mozilla-central/rev/872d8cd8e16c