8273743: KeyCharacterCombination for "+" does not work on US QWERTY keyboard layout

[beldenfox]

On Linux getKeyCodeForChar does not consult the current keyboard layout. For example, it assumes the “+” character is on KeyCode.PLUS even on layouts which don’t generate KeyCode.PLUS. The result is that most KeyCharacterCombinations don’t work.

This PR fixes this using the same approach that Mac glass uses. When the user types a key we lookup all the characters that key might generate and put them in a map. getKeyCodeForChar then consults the map to find the Java key code. This ensures that we only pay attention to keys that are on the user’s physical keyboard.

(Some Linux layout maps are expansive and include entries for keys that may be on the user’s keyboard but probably aren’t, like “(“ and “)” on the numeric keypad. If we simply ask for all entries that generate a given character we can get multiple hits with no good way to determine which ones are physically present.)

This PR also contains fixes to the Robot to enable testing. When Glass consults the GdkKeymap to determine which keys might generate a keyval GDK returns a list covering every installed layout and shift level. The old Glass code simply picked the first entry in the list. This PR iterates through the list looking for one that works for the current layout and correct shift level.

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Progress

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Issue

• JDK-8273743: KeyCharacterCombination for "+" does not work on US QWERTY keyboard layout (Bug - P3)

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[bridgekeeper]

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[mlbridge]

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[kevinrushforth]

/reviewers 2

[openjdk]

@kevinrushforth
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).

[openjdk]

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[beldenfox]

Comment added to keep the bots at bay.

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[beldenfox]

I've updated to the latest master. This will probably be the last time I refresh this pull request; I can only hold off the bots for so long.

[andy-goryachev-oracle]

In the context of the recent discussion on the mailing list, would it be possible to actually detect the keyboard layout? There is a limited number of layouts, so in theory that should be possible.

Another question - I recall on Windows there is a way to enter certain key using Alt codes. Does this method exist on Linux?

[beldenfox]

In the context of the recent discussion on the mailing list, would it be possible to actually detect the keyboard layout?

I answered this question in full on the mailing list but will provide a summary here. There's no documented way of doing this on Windows. The Mac organizes layouts based on language (for example, English), Linux organizes them based on country (so Australia, Great Britain, and the U.S. are all distinct). On all platforms there are more layouts than you think (the Mac has 5 German layouts and Linux has 20 Germany layouts) and there's no standard on how the variants are designated.

Another question - I recall on Windows there is a way to enter certain key using Alt codes. Does this method exist on Linux?

I'm not that familiar with this feature but here's my understanding. The feature isn't universal but tied to the input method system you're using. With IBus you can press Shift+Ctrl+U followed by the Unicode value followed by Enter. But if you want to use an IME with JavaFX you have to use the obsolete XIM framework instead which doesn't support this.