RFR: 8345538: Robot.mouseMove doesn't clamp bounds on macOS when trying to move mouse off screen [v3]

[Alexey Ivanov]

On Tue, 17 Dec 2024 18:48:43 GMT, Phil Race <prr at openjdk.org> wrote:

>> src/java.desktop/share/classes/java/awt/Robot.java line 225:
>> 
>>> 223: //        peer.mouseMove(x, y);
>>> 224:         peer.mouseMove(Math.min(Math.max(x, screenBounds.x), screenBounds.x + screenBounds.width),
>>> 225:                 Math.min(Math.max(y, screenBounds.y), screenBounds.y + screenBounds.height));
>> 
>> But that will limit current robot's functionality on the multi-monitor setups. Right now i can move mouse using robot from one screen to another, With your change it seems to be impossible?
>
> Robot is already created with a screen .. ie GraphicsDevice .. the bounds are from that .. and it is already used elsewhere in Robot
> If that can be across physical screens it will still work.
> If screens are separate then Robot is constrained to that anyway.
> 
> Can you show a specific case where this is a problem ?

I agree with Alex. Currently, it's possible to use a Robot instance to move mouse across all the screens in a multi-monitor environment.

According to the specification of [`Robot(GraphicsDevice screen)`](https://docs.oracle.com/en/java/javase/23/docs/api/java.desktop/java/awt/Robot.html#%3Cinit%3E(java.awt.GraphicsDevice)), <q cite="https://docs.oracle.com/en/java/javase/23/docs/api/java.desktop/java/awt/Robot.html#%3Cinit%3E(java.awt.GraphicsDevice)">Coordinates passed to `Robot` method calls like `mouseMove`, `getPixelColor` and `createScreenCapture` will be interpreted as being in the same coordinate system as the specified screen.</q>

I understand this statement correctly, it means that if I create a Robot instance with a screen that's not the main one, `Robot.mouse(0, 0)` should move the mouse to `(screenBounds.x, screenBounds.y)`.

However, if “share the same coordinate system to form a combined virtual screen”, `Robot` is expected to move mouse within the bounds of the virtual screen, isn't it?

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PR Review Comment: https://git.openjdk.org/jdk/pull/22781#discussion_r1893970251