RFR: 8299968: Second call to Stage.setScene() create sizing issue with uiScale > 1.0 [v2]

[Kevin Rushforth]

On Tue, 7 Mar 2023 15:20:50 GMT, Lukasz Kostyra <lkostyra at openjdk.org> wrote:

>> Issue happened during setting a new Scene - updating a new View was done while the Window reference it kept was null. This caused it to default scaling values to 1.0f (or 100%) while processing a resize notification, which for high DPI screens with scaling different than 100% caused UI issues.
>> 
>> Resolved by splitting `_setView()` native call into two parts - first one sets the view, then back in JVM side we set a correct Window reference, then we trigger the notification. It has to be triggered from native side, because Windows backend of Glass sends back new width/height pulled from WinAPI `::GetClientRect()` call.
>> 
>> In process of working on this issue I also found another scenario causing the same problem - calling `Stage.setScene()` after `Stage.show()`. The patch fixed that case as well.
>> 
>> Added a system test which is supposed to check for above issues. I didn't limit it to run only on platforms with UI scaling enabled because it also serves as a good sanity check in case there are some other changes to code that might move/scale the UI unwantingly. I tested this patch both on macOS Ventura and Windows 11, with `d9c091f` all tests pass while without `d9c091f` on Windows tests `testShowAndSetScene` and `testSecondSetScene` fail as expected.
>
> Lukasz Kostyra has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Move SetSceneScalingTest to robot test directory

The fix looks good to me, although I want to test on a dual screen setup. I doubt there will be any difference in behavior, since the fix looks independent of the screen. I did leave one minor suggestion on a comment you added.

The test fails for me intermittently, which suggests that there is a timing issue. You will likely need to use a latch to wait for the button to be clicked (or a sleep of around 1/2 sec) rather than immediately testing `wasClicked`.

modules/javafx.graphics/src/main/java/com/sun/glass/ui/Window.java line 374:

> 372:             this.view = view;
> 373:             this.view.setWindow(this);
> 374:             // JDK-8299968: View size update (especially notifyResize event) have to happen

Minor: we generally don't put a bug ID in comments in the implementation when fixing a bug.

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PR: https://git.openjdk.org/jfx/pull/1054