Panic when trying to show window on GLX display with femtovg and Skia/OpenGL renderers

[ngocnha]

(edited by @tronical )

Running with the FemtoVG or Skia OpenGL renderers against a GLX accelerated display panics.

The backtrace below is from an earlier symptom.

Acceptance criteria:

• [x] The FemtoVG renderer can be used with the winit backend on GLX displays.
• [ ] Skia OpenGL renderer also works with the winit backend on GLX displays.

RUST_BACKTRACE=1 target/debug/slint-app
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Error { raw_code: Some(160), raw_os_message: Some("GLXBadDrawable"), kind: BadSurface }', /home/whiteseed/.cargo/registry/src/github.com-1ecc6299db9ec823/i-slint-backend-winit-0.3.5/renderer/femtovg/glcontext.rs:172:75
stack backtrace:
   0: rust_begin_unwind
             at /rustc/d5a82bbd26e1ad8b7401f6a718a9c57c96905483/library/std/src/panicking.rs:575:5
   1: core::panicking::panic_fmt
             at /rustc/d5a82bbd26e1ad8b7401f6a718a9c57c96905483/library/core/src/panicking.rs:64:14
   2: core::result::unwrap_failed
             at /rustc/d5a82bbd26e1ad8b7401f6a718a9c57c96905483/library/core/src/result.rs:1791:5
   3: core::result::Result<T,E>::unwrap
             at /rustc/d5a82bbd26e1ad8b7401f6a718a9c57c96905483/library/core/src/result.rs:1113:23
   4: i_slint_backend_winit::renderer::femtovg::glcontext::OpenGLContext::new_context
             at /home/whiteseed/.cargo/registry/src/github.com-1ecc6299db9ec823/i-slint-backend-winit-0.3.5/renderer/femtovg/glcontext.rs:172:29
   5: <i_slint_backend_winit::renderer::femtovg::FemtoVGRenderer as i_slint_backend_winit::renderer::WinitCompatibleRenderer>::show
             at /home/whiteseed/.cargo/registry/src/github.com-1ecc6299db9ec823/i-slint-backend-winit-0.3.5/renderer/femtovg.rs:58:30
   6: <i_slint_backend_winit::glwindow::GLWindow<Renderer> as i_slint_core::window::WindowAdapterSealed>::show::{{closure}}
             at /home/whiteseed/.cargo/registry/src/github.com-1ecc6299db9ec823/i-slint-backend-winit-0.3.5/glwindow.rs:545:13
   7: core::ops::function::FnOnce::call_once
             at /rustc/d5a82bbd26e1ad8b7401f6a718a9c57c96905483/library/core/src/ops/function.rs:507:5
   8: i_slint_backend_winit::glwindow::GLWindow<Renderer>::call_with_event_loop
             at /home/whiteseed/.cargo/registry/src/github.com-1ecc6299db9ec823/i-slint-backend-winit-0.3.5/glwindow.rs:175:9
   9: <i_slint_backend_winit::glwindow::GLWindow<Renderer> as i_slint_core::window::WindowAdapterSealed>::show
             at /home/whiteseed/.cargo/registry/src/github.com-1ecc6299db9ec823/i-slint-backend-winit-0.3.5/glwindow.rs:390:9
  10: i_slint_core::window::WindowInner::show
             at /home/whiteseed/.cargo/registry/src/github.com-1ecc6299db9ec823/i-slint-core-0.3.5/window.rs:615:9
  11: i_slint_core::api::Window::show
             at /home/whiteseed/.cargo/registry/src/github.com-1ecc6299db9ec823/i-slint-core-0.3.5/api.rs:346:9
  12: <slint_app::slint_generatedAppWindow::AppWindow as i_slint_core::api::ComponentHandle>::show
             at ./target/debug/build/slint-app-952588998e8ffc3d/out/appwindow.rs:1417:14
  13: <slint_app::slint_generatedAppWindow::AppWindow as i_slint_core::api::ComponentHandle>::run
             at ./target/debug/build/slint-app-952588998e8ffc3d/out/appwindow.rs:1412:14
  14: slint_app::main
             at ./src/main.rs:12:5
  15: core::ops::function::FnOnce::call_once
             at /rustc/d5a82bbd26e1ad8b7401f6a718a9c57c96905483/library/core/src/ops/function.rs:507:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

[tronical]

I suspect that somehow the window is not created to be suitable for GLX rendering :(

[ogoffart]

Under what condition is this triggered?

We should be able to give a better error message at least when this happen.

[ngocnha]

Maybe the issue occurred while I was using the NVIDIA graphics mode. When I switched to Hybrid mode today, it started working again.

---

Hardware Model: Micro-Star International Co., Ltd. GF63 Thin 8RCS Memory: 16.0 GiB Processor: Intel® Core™ i7-8750H CPU @ 2.20GHz × 12 Graphics: NVIDIA Corporation GP107M [GeForce GTX 1050 Mobile] / Mesa Intel® UHD Graphic

OS Name: Pop!_OS 22.04 LTS OS Type: 64-bit GNOME Version: 42.5 Windowing System: X11

NVDIA Driver: 525.85.05

[jeandudey]

Getting the same error using the same same driver version on a RTX 3070, may be related to NVIDIA X11 implementation.

[tronical]

I can reproduce this error locally (yay)

[tronical]

I think this is somewhat related to https://github.com/rust-windowing/winit/issues/2681 . Until winit can tell us what visual it picked, we need have two code paths:

1. On WGL, create the Window first, then select a window-compatible GL config.
2. On GLX select the GL config first, retrieve the x11 visual info and pass it to the winit window builder with with_x11_visual - that way the visuals match and this error should go away.

[tronical]

I made a fix for this that works with FemtoVG. With Skia the situation is a little more complicated, because the internal Skia renderer API is built on two assumptions:

1. The renderer does not depend on winit (for use in experimental C++ platform API).
2. The window exists before calling show() on the renderer.

So the "easy" fix, adding WindowBuilder to the API and using glutin-winit doesn't quite work.

I tried to fix this by creating the corresponding glutin config that can provide the x11 visual in the skia renderer constructor (only on x11), then pass the visual to the window builder, and then continue as normal. Unfortunately this crashes in the Skia GL code. Branch is at https://github.com/slint-ui/slint/tree/simon/wip/skia-glx

[tronical]

We should not panic anymore since https://github.com/slint-ui/slint/pull/2907