Bug 307431 – Navigating with the Layers inspector tab open breaks the visualization

• Status: RESOLVED
• Resolution: FIXED
• Component: Web Inspector

[Adrian Perez]

Steps to reproduce:

  1. run-minibrowser --wpe https://blogs.igalia.com/webkit/
  2. Open the Inspector with Ctrl+Shift+I
  3. In the inspector window, open the “Layers” tab
  4. Click the “About” link at the top of the page

Expected outcome:

  The “Layers” tab updates itself with the contents of the newly loaded page.

Actual outcome:

  The “Layers” tab remains empty and no longer updates. The following errors
  are written to the standard error stream:

  resource:///org/webkit/inspector/UserInterface/Controllers/ConsoleManager.js:241:27: CONSOLE ASSERT ERROR
  resource:///org/webkit/inspector/UserInterface/Base/Main.js:3131:22: CONSOLE ERROR Error: Layer has zero size

This affects both the “main” branch and the “webkitglib/2.50” one.

[Adrian Perez]

(In reply to Adrian Perez from comment #0)

> This affects both the “main” branch and the “webkitglib/2.50” one.

This should read: the “main” branch and the “webkitglib/2.52” one.

[Adrian Perez]

As a workaround, if the “Layers” tab gets stuck like this, closing the inspector and reopening it again works (but it's an annoyance).

[Adrian Perez]

The empty size error comes from InspectorLayerTreeAgent::requestContent(), defined in Source/WebCore/inspector/agents/InspectorLayerTreeAgent.cpp:

Inspector::CommandResult<String> InspectorLayerTreeAgent::requestContent(const Inspector::Protocol::LayerTree::LayerId& layerId)
{
    // ...

    FloatSize layerSize = graphicsLayer->size();
    if (layerSize.isEmpty())
        return makeUnexpected("Layer has zero size"_s);

    // ...
}

[Radar WebKit Bug Importer]

<rdar://problem/170836910>

[Razvan Caliman]

This affects the macOS build of Web Inspector as well. It's not isolated to GTK/WPE. 

The root cause is a race condition during page reload/navigation.

[Razvan Caliman]

Pull request: https://github.com/WebKit/WebKit/pull/63972

[EWS]

Committed 312435@main (95810670932e): <https://commits.webkit.org/312435@main>

Reviewed commits have been landed. Closing PR #63972 and removing active labels.