RFR: 8304831: TextFlow.hitTest.insertionIndex incorrect with surrogate pairs [v9]

[Andy Goryachev]

On Mon, 5 Jun 2023 11:16:52 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 incrementally with one additional commit since the last revision:
> 
>   Add out of bound check for insertion index

FYI, I've added "Enter Text" button to Text/TextFlow pages in the Monkey Tester
https://github.com/andy-goryachev-oracle/MonkeyTest

it might be easier to test various emojis and text strings with it.

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PR Comment: https://git.openjdk.org/jfx/pull/1091#issuecomment-1577172797