What steps will reproduce the problem?
Create a minimal OSR app that:
- Sets CefSettings.windowless_rendering_enabled = true.
- Creates a browser with CefWindowInfo.SetAsWindowless and CefWindowInfo.external_begin_frame_enabled = true.
- Returns a fixed size from CefRenderHandler::GetViewRect and GetScreenInfo.
- Loads a static HTML file with LoadURL.
- Calls WasResized and SendExternalBeginFrame.
What is the expected output? What do you see instead?
The expected image should be delivered to the OnPaint callback. Instead, any of the following may occur:
- The OnPaint callback is never executed.
- The OnPaint callback receives a completely black image of the correct size.
What version of the product are you using? On what operating system?
The problem reproduces with CEF v78 and v79 on Windows 10 and Linux. It can occur both with GPU enabled and disabled.
The problem does not reproduce with v73 (version that added begin-frame support prior to the Viz refactoring).