Fix crash when changing viewport settings #4862

pm100 · 2024-07-22T01:39:53Z

Fixes Crash when changing a viewport aspect, that requires window recreation #3959

There are two bugs racing each other here, which is why it sometimes crashes and sometimes the app just silently exists

Bug 1
When the window is recreated a Destroyed event arrives (due to the Drop of the old window). The code that receives this event does not look to see if its the main viewport or a secondary one and unconditionally closes the app. The code path for other platforms is slightly different and does check.

I have moved the code that handles the destroy to be in the same place and have the same behavior as the other platforms.

Bug 2

At recreate time the window and winit entries of the viewport are set to None (forcin g them to be recreated). But the surface is still bound to the old window, this causes the next context switch to fail. So I simply added a viewport.gl_surface = None too,

This is my first egui PR so I hope I have not broken anything. If nothing else I understand a little better how egui works.

pm100 · 2024-07-22T22:09:56Z

fix works on mac - it showed the same behavior as bug1, immediate exit when recreating secondary viewport. Did no exhibit bug 2

I cannot get egui to build on linux so cannot test

emilk · 2024-07-31T07:49:27Z

crates/eframe/src/native/glow_integration.rs

+            winit::event::WindowEvent::Destroyed => {
+                log::debug!(
+                    "Received WindowEvent::Destroyed for viewport {:?}",
+                    viewport_id
+                );
+                if viewport_id == Some(ViewportId::ROOT) {
+                    return EventResult::Exit;
+                } else {
+                    return EventResult::Wait;
+                }
+            }
+


You probably need to add the same code to wgpu_integration.rs.

We just merged the update to latest winit (#4849), so please merge that into this branch and then test this PR with:

cargo r -p test_viewports

cargo r -p test_viewports -F wgpu

cargo r -p serial_windows

will do, note that I found this #4894

@emilk Am I reading this correctly. That clicking the close box on a child viewport does nothing unless I actually have code that checks for CloseRequested? And that you have to set the vp as not visible in order to destroy it . Thats not at all obvious. (Was trying to work out why the bug reporters app was not closing the child VP after I fixed the bugs I could find)

@emilk I added to wgpu the equivalent release of the drawing surface, in wgpu not releasing this resulted in the recreate of the vp leaving the original in place (rather than crashing as in glow).

Tested on windows and mac,

Note the wgpu has very strange defferred vp close behavior (also meaning that I did not need to add any close logic to wpgpu_integration). Because there is no close option only the option to no longer request its presence there is some very odd stuff happening. I worried that it was my bad but the current master shows the same thing. After CloseRequest is received you have to stop drawing secondary vp in update, BUT, this means you need another main window draw before the window disappears. I filed a bug on this #4894 . I tried to add the necessary code to the original reports code but could not - I thought it was simply a matter of doing request_repaint but I could not make that work. And the fact that the test_viewports app shows the same bug shows that its not simple.

I think it would be really ice to have an explicit vp.close call (even though that goes again the immediate model VPs are really not transient, the OS knows them (unlike stuff drawn on the gl surfaces). I will investigate and make a separate PR

Also I have not tested on linux becasue I cannot make it build on linux, it complains about a lot of pkg errors.

I will do a separate PR to add vp calls the need window recreation to test_viewports. Done #4907

In summary - I think this PR is complete, apart from not being tested on Linux.

emilk · 2024-08-26T06:47:09Z

crates/eframe/src/native/glow_integration.rs

+            winit::event::WindowEvent::Destroyed => {
+                log::debug!(
+                    "Received WindowEvent::Destroyed for viewport {:?}",
+                    viewport_id
+                );
+                if viewport_id == Some(ViewportId::ROOT) {
+                    return EventResult::Exit;
+                } else {
+                    return EventResult::Wait;
+                }
+            }
+


This make the test excercise the window recreation logic, that resulted in several bugs - see #4862 Adds a check box that turns the close button on and off for child windows

This make the test excercise the window recreation logic, that resulted in several bugs - see emilk#4862 Adds a check box that turns the close button on and off for child windows

* Fixes emilk#3959 There are two bugs racing each other here, which is why it sometimes crashes and sometimes the app just silently exists Bug 1 When the window is recreated a Destroyed event arrives (due to the Drop of the old window). The code that receives this event does not look to see if its the main viewport or a secondary one and unconditionally closes the app. The code path for other platforms is slightly different and does check. I have moved the code that handles the destroy to be in the same place and have the same behavior as the other platforms. Bug 2 At recreate time the window and winit entries of the viewport are set to None (forcin g them to be recreated). But the surface is still bound to the old window, this causes the next context switch to fail. So I simply added a viewport.gl_surface = None too, This is my first egui PR so I hope I have not broken anything. If nothing else I understand a little better how egui works.

This make the test excercise the window recreation logic, that resulted in several bugs - see emilk#4862 Adds a check box that turns the close button on and off for child windows

* Fixes emilk#3959 There are two bugs racing each other here, which is why it sometimes crashes and sometimes the app just silently exists Bug 1 When the window is recreated a Destroyed event arrives (due to the Drop of the old window). The code that receives this event does not look to see if its the main viewport or a secondary one and unconditionally closes the app. The code path for other platforms is slightly different and does check. I have moved the code that handles the destroy to be in the same place and have the same behavior as the other platforms. Bug 2 At recreate time the window and winit entries of the viewport are set to None (forcin g them to be recreated). But the surface is still bound to the old window, this causes the next context switch to fail. So I simply added a viewport.gl_surface = None too, This is my first egui PR so I hope I have not broken anything. If nothing else I understand a little better how egui works.

pm100 added 2 commits July 21, 2024 18:31

init fix

1cd39cf

fix accidental delete of line

c1e9bfc

emilk changed the title ~~Fix for #3959~~ Fix crash when changing viewport settings Jul 30, 2024

emilk reviewed Jul 31, 2024

View reviewed changes

pm100 added 2 commits July 31, 2024 09:33

Merge branch 'emilk:master' into fixwindestroy

858a08d

fix wgpu recreate vp bug

645f061

pm100 mentioned this pull request Aug 3, 2024

Add close_button option to test_viewports #4907

Merged

emilk approved these changes Aug 26, 2024

View reviewed changes

emilk added bug Something is broken eframe Relates to epi and eframe viewports multiple viewports, viewports API labels Aug 26, 2024

emilk merged commit 0c528fb into emilk:master Aug 26, 2024
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Fix crash when changing viewport settings #4862

Fix crash when changing viewport settings #4862

pm100 commented Jul 22, 2024 •

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pm100 commented Jul 22, 2024

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emilk Aug 26, 2024

emilk Aug 26, 2024

Fix crash when changing viewport settings #4862

Fix crash when changing viewport settings #4862

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