8346281: [Windows] RenderScale doesn't update to HiDPI changes

[jperedadnr]

This PR adds the missing native implementation for Windows GlassWindow::HandleDPIEvent, to notify the (Java) window when there is a DPI change event, which can happen when the user changes the resolution of the screen (via Settings -> System -> Display -> scale), while the JavaFX application is running.

When such WM_DPICHANGED event happens, GlassWindow::HandleDPIEvent notifies the (Java) window, which changes its platform scale via Window::notifyScaleChanged, and GlassScreen::HandleDisplayChange(); is needed too, to update the platform scale of the screen where the window is at as well.

There are no tests added to this PR, since these would require manual intervention to change the display. In any case, the test case added to the issue runs fine now when the app runs on a given screen and the user changes its resolution.

There is a follow-up issue after this PR, that might require a more complex fix, for the case where the user changes the resolution of a different screen that is placed before the one that has the application (as location coordinates of the latter depend on the former), because there is no WM_DPICHANGED event in this case.

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Progress

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Issue

• JDK-8346281: [Windows] RenderScale doesn't update to HiDPI changes (Bug - P4)(⚠️ The fixVersion in this issue is [jfx25] but the fixVersion in .jcheck/conf is jfx24, a new backport will be created when this pr is integrated.)

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[bridgekeeper]

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[openjdk]

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[andy-goryachev-oracle]

/reviewers 2

[openjdk]

@andy-goryachev-oracle
The total number of required reviews for this PR (including the jcheck configuration and the last /reviewers command) is now set to 2 (with at least 1 Reviewer, 1 Author).

[andy-goryachev-oracle]

shouldn't this value come from some windows header?

[andy-goryachev-oracle]

please add the test case to https://bugs.openjdk.org/browse/JDK-8346281

[andy-goryachev-oracle]

Does not seem to work. Here is my scenario:

1. win11 with two monitors, the built-in laptop screen at scale 100%, the external monitor at 225% (located "above" the build-in one).
2. the monkey tester opens up on the external monitor (since it remembers its position between launches)
3. when the user clicks on the menu, the menu pops up in the wrong location (way outside of the main window in fact)
4. change resolution to 200%
5. click on the menu, the menu also appears in the wrong location
6. it's only after I drag the window to the main monitor the menus start appearing at the right location. drag it back to the external monitor, the menu appears at the correct location again.
7. change external scale back to 225%, the menu opens up at the right location.

[jperedadnr]

I've added the test case to the JBS issue (sorry about that, I thought I did when I created it).

About the test case scenario:

• you have a JavaFX application already running in a given monitor
• without changing resolution, the label shows the current output scale, and the menu popup shows up in the correct position (if it doesn't, this is a different issue than this one).
• Then, after showing the menu at least once, you change the screen resolution (the screen that has the app, that is)

With this PR you should see:

• the label showing the correct output scale once you change the resolution (this doesn't happen without the PR),
• and the menu popup showing up at the correct position (this doesn't happen without the PR).

[andy-goryachev-oracle]

hmm, not sure where the disconnect is.

• before I launch the monkey tester, there is no fx app running anywhere
• the monkey tester appears on the external monitor, it's status bar shows scale 2.25
• the menu appears in the wrong location

let me try attaching the screenshot:

[jperedadnr]

Do you have the same issue (unexpected offset for the popup) as well without this PR?

[andy-goryachev-oracle]

I think the difference between your scenario and mine is that the monkey tester appears on the external monitor instead of the main one.

If I close the monkey tester while it is on the primary laptop screen and restart it, the menu shows up at the right location from the start.

Maybe you can change your test app to open one window on each screen?

[andy-goryachev-oracle]

Do you have the same issue (unexpected offset for the popup) as well without this PR?

The behavior is different. With the MT showing up on the external monitor, the initial location of the menus is correct. Once I change the scale, the menus pop up in two wrong location above and to the left (the change in scale was 2.25 -> 1.5)

[andy-goryachev-oracle]

attached an updated SCCE to the ticket. the initial scale value seems to be incorrect in this PR.