RFR: JDK-8302618: [macOS] Problem typing uppercase letters with java.awt.Robot when moving mouse [v9]

[Harshitha Onkar]

On Wed, 2 Aug 2023 21:46:32 GMT, Harshitha Onkar <honkar at openjdk.org> wrote:

>> **Problem:**
>> 
>> On macOS, Robot erroneously produces lowercase letter when mouse is moved (manually) in unison with Robot's keyEvents. This issue was originally logged by a developer of an on-screen accessibility keyboard  - TouchBoard. Originally reported at https://github.com/adoptium/adoptium-support/issues/710
>> 
>> This issue is reproducible on JDK versions 22 to 11, but works fine on JDK-8. (details below) 
>> 
>> This issue is not restricted to the Shift modifier key and causes problems with other modifier keys as well and in some scenarios without any external mouse movement.
>> 
>> - This works correctly on JDK-8 up to JDK-9+129 when Accessibility APIs (AXUIElementCreateSystemWide/ AXUIElementPostKeyboardEvent) were used. Later on it was changed to CGEvents. 
>> 
>> - With the present code, the issue occurs at [CRobot.m#L295](https://github.com/openjdk/jdk/blob/ac6af6a64099c182e982a0a718bc1b780cef616e/src/java.desktop/macosx/native/libawt_lwawt/awt/CRobot.m#L295.)  The flags gets reset or cleared when mouse is moved physically in unison with Robot's key events.
>> 
>> - The physical mouse movement causes the event flags to be reset. 
>> 
>> **Impact:**
>> 
>> Modifier keys don't work as expected when using Robot with any simultaneous physical mouse movement and in case of TouchBoard, this behavior breaks the usability of the on-screen a11y keyboard. There is no known workaround for this particular use case except for reverting to JDK-8. More details on this use case [here.](https://github.com/adoptium/adoptium-support/issues/710#issuecomment-1594103280)
>> 
>> **Proposed Fix:**
>> 
>> - In order to avoid resetting of the CGEventFlags here [CRobot.m#L295](https://github.com/openjdk/jdk/blob/ac6af6a64099c182e982a0a718bc1b780cef616e/src/java.desktop/macosx/native/libawt_lwawt/awt/CRobot.m#L295.), the CGEvent flag state is obtained in `initRobot` (stored in initFlags) which is later used within `CRobot_keyEvent`.
>> 
>> - The incoming keyCode is used to determine whether it is a modifier key and the corresponding modifierFlagMask is either added or cleared from the initFlags based on whether the modifier key was pressed or released.
>> 
>> - Finally, only the required and known flag bits from initFlag are copied over to local flag which is used in `CGEventSetFlags()`.
>> 
>> **Testing:**
>> 
>> The newly added test - RobotModifierMaskTest.java tests for Shift, Caps, Control, Option and Command keys.
>> The test runs in 2 modes - as automated and manual test.
>> 
>> CASE 1 : ...
>
> Harshitha Onkar has updated the pull request incrementally with one additional commit since the last revision:
> 
>   changed allModifiersMask datatype

Changed allModifiersMask from int32 to `CGEventFlags` (uint64) as the following bit operation can produce undesired results especially (~allModifiersMask).

` flags = (initFlags & allModifiersMask) | (flags & (~allModifiersMask));`

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PR Comment: https://git.openjdk.org/jdk/pull/14744#issuecomment-1663014981