RFR: 8354943: [Linux] Simplify and update glass gtk backend: window sizing, positioning, and state management issues [v12]

[Lukasz Kostyra]

On Thu, 1 May 2025 14:50:15 GMT, Thiago Milczarek Sayao <tsayao at openjdk.org> wrote:

>> This is a continuation to [JDK-8236651](https://bugs.openjdk.org/browse/JDK-8236651) and it aims to stabilize the linux glass gtk backend.
>> 
>> 
>> Overall, it has been made more robust within its scope, particularly in terms of sizing, positioning, and state management.
>> 
>> List of changes:
>> 1. Use GDK for creating Windows. Since we paint directly to the underlying XWindow, creating a GtkWidget for the window is unnecessary and results in unused GTK resources. Additionally, avoiding the use of a GtkWidget eliminates the need for workarounds caused by conflicting GTK behavior—such as setting the initial window state, position, or size.
>> 2. It aligns with X11's asynchronous behavior by reporting geometry changes only upon receiving a configure event, since requests to the window manager aren't guaranteed to be honored. However, changes are still reported immediately in special cases, such as before the window is realized. For example, a request to move the window to (0, 0) might be overridden by the window manager, placing it in the top-right corner instead.
>> 3. States (fullscreen, maximized and iconify) are now reported back to Java when it actually happens rather than immediately (except when not realized);
>> 4. When a window is maximized, it will ignore geometry changes and restore to the geometry it had prior to being maximized. After some testing, I believe this is the best behavior for platform compatibility;
>> 5. Unifies the WindowContext class: previously, there were three separate classes—two of which (for applets and Java Web Start) were removed, leaving only one. However, the supporting infrastructure was still there partially. [Unify WindowContext in glass-gtk](https://bugs.openjdk.org/browse/JDK-8305768)
>> 6. Tests were added and re-enabled to ensure everything works correctly. The stage tests now cover various StageStyle configurations, as I found that `DECORATED` stages often behave differently from `UNDECORATED` or `UTILITY` stages;
>> 7. Added Logs for debugging. Enable it with ` -PCONF=DebugNative`;
>> 8. Old work-arounds dating back to Ubuntu 16.04 with Compiz were removed. 
>> 
>> A simple manual test is provided:
>> `java @build/run.args tests/manual/stage/TestStage.java `
>> 
>> 
>> List of fixed issues:
>> 
>> 1. [[Linux] Stage.setMaximized() before show() does not persist](https://bugs.openjdk.org/browse/JDK-8316425)
>> 3. [[Linux] Intermittent test failure in IconifyTest.canIconifyDecoratedStage](https://bugs.openjdk.org/browse/JDK-831689...
>
> Thiago Milczarek Sayao has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix test on SizingTest

modules/javafx.graphics/src/main/native-glass/gtk/GlassApplication.cpp line 486:

> 484:                 case GDK_PROPERTY_NOTIFY:
> 485:                     ctx->process_property_notify(&event->property);
> 486:                     gtk_main_do_event(event);

Some event types first call respective `ctx->process` and then `gtk_main_do_event`, while others do it the other way around. Is there a specific reason why?

modules/javafx.graphics/src/main/native-glass/gtk/GlassRobot.cpp line 22:

> 20:  *
> 21:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
> 22:  * or visit www.oracle.com if you need additiFonal information or have any

Coincidental change in copyright header

modules/javafx.graphics/src/main/native-glass/gtk/glass_general.h line 251:

> 249: #define LOG5(msg, param1, param2, param3, param4, param5) {printf(msg, param1, param2, param3, param4, param5);fflush(stdout);}
> 250: #define LOG6(msg, param1, param2, param3, param4, param5, param6) {printf(msg, param1, param2, param3, param4, param5, param6);fflush(stdout);}
> 251: #define LOG10(msg, param1, param2, param3, param4, param5, param6, param7, param8, param9, param10) \

Instead of adding more `LOG*` macros consider replacing them with `#define LOG(...) { printf(__VA_ARGS__); fflush(stdout); }`

Eventually I would accept filing a separate change for improving this if we don't have one already. Seems like the `ERROR` macros below could also be improved in this way.

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PR Review Comment: https://git.openjdk.org/jfx/pull/1789#discussion_r2071271567
PR Review Comment: https://git.openjdk.org/jfx/pull/1789#discussion_r2071440205
PR Review Comment: https://git.openjdk.org/jfx/pull/1789#discussion_r2071479393