RFR: 8264728: When use chinese IME, the candidate box isn't moved with caret of JTextArea [v2]

[柳鲲鹏]

On Wed, 28 Jun 2023 22:05:50 GMT, Nikita Provotorov <duke at openjdk.org> wrote:

> Have you tried to use just _java.awt.Component#getLocationOnScreen_?

On linux, IME need the offset position of JTextArea from focus window(frame/dialog). So we use a loop to get it.

> src/java.desktop/unix/native/libawt_xawt/awt/awt_InputMethod.c line 870:
> 
>> 868:        and block the candidate window to move with caret.
>> 869:      */
>> 870:     XIMStyle on_the_spot_styles = XIMPreeditNothing,
> 
> `XNSpotLocation` can't be used together with `XIMPreeditNothing`. Look at the [specification](https://www.x.org/releases/X11R7.6/doc/libX11/specs/libX11/libX11.html#Input_Methods) of `XNSpotLocation`:
>> When specified to any input method other than XIMPreeditPosition, this XIC value is ignored.
> 
> So even if this works with some IM on some distribution, there is no guarantee that it works more or less everywhere.

1, I tested some linux, only ubuntu has problem. Is there a macro to tell us the system is ubuntu?
2, When using XIMPreeditPosition, the XCreateIC() return NULL.
So suggest that we fix the problem first, and a comment with reason.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/13055#discussion_r1298963346
PR Review Comment: https://git.openjdk.org/jdk/pull/13055#discussion_r1298963422