RFR: 8304831: TextFlow.hitTest.insertionIndex incorrect with surrogate pairs [v8]

[Kevin Rushforth]

On Mon, 22 May 2023 14:21:33 GMT, Karthik P K <kpk at openjdk.org> wrote:

>> Since surrogate pairs are internally considered as 2 characters and text field is null in `HitInfo` when `getInsertionIndex` is invoked from `TextFlow`, wrong insertion index was returned.
>> 
>> Updated code to calculate insertion index in `getHitInfo` method of `PrismTextLayout` class when `hitTest` of trailing side of surrogate pair is requested. Since text runs are processed in this method already, calculating the insertion index in this method looks better than calculating in `getInsertionIndex` of `HitInfo` method.
>> The latter approach also requires the text to be sent to `HitInfo` as parameter from the `hitTest` method of `TextFlow`. If the number of `Text` nodes in `TextFlow` are very large, processing all the `Text` nodes on each `hitTest` method invocation might cause performance issue. Hence implemented first approach.
>> 
>> Added system test to validate the fix.
>
> Karthik P K has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains eight commits:
> 
>  - Merge master to resolve merge conflict
>  - Stabilizing the system tests
>  - Add new test. Optimizations to make the tests robust
>  - Change insertion index initialization approach. Add additional test
>  - Initialize insertion index in PrismTextLayout
>  - Address code review
>  - Fix insertion index calculation issue with emojis. Add additional test cases
>  - Fix insertion index calculation issue in TextFlow

@prrace Would you be willing to take a  look?

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PR Comment: https://git.openjdk.org/jfx/pull/1091#issuecomment-1557495583