RFR: 8345538: Robot.mouseMove doesn't clamp bounds on macOS when trying to move mouse off screen [v6]

[Alexey Ivanov]

On Tue, 28 Jan 2025 18:39:44 GMT, Alisen Chung <achung at openjdk.org> wrote:

>> src/java.desktop/share/classes/java/awt/Robot.java line 175:
>> 
>>> 173:         for (int i = 0; i < gs.length; i++) {
>>> 174:             allScreenBounds[i] = gs[i].getDefaultConfiguration().getBounds();
>>> 175:         }
>> 
>> This doesn't look right to me… `init` is an instance method, yet it initialises `allScreenBounds` which is shared among all instances.
>> 
>> In a way it makes sense to share the graphics environment / configuration. On the other hand how much would it affect the operation of robot if the bounds are fetched from `GraphicsEnvironment` only when needed?
>> 
>> What happens if the graphics configuration changes? Does the user need to create a new instance of the `Robot` class?
>
> I did consider this and thought it would be too expensive to fetch the bounds on every mouseMove action, so i thought it would be better to reinitialize robot when the graphics configuration changes. Do you have a better idea for where/when to cache the bounds?

The first question to answer: _Is it expensive to get screen data from GraphicsEnvironment?_ It shouldn't be, the data is already there, you just fetch the data.

> it would be better to reinitialize robot when the graphics configuration changes

But I see no code which re-initialises the cached graphics configuration if anything changes.

Do I miss anything?

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PR Review Comment: https://git.openjdk.org/jdk/pull/22781#discussion_r1932687868