<Swing Dev> [11] RFR: JDK-8199441: Wrong caret position in multiline text components on Windows with a screen resolution higher than 100%

[Phil Race]

I am not sure this is the right fix.
If the intention had been to change all calls to getTabbedTextOffset() 
to use the FP
API it would have just been changed .. rather than adding a new API that 
provides
the option to specify whether to use FP.

So perhaps the problem is that internal code needs to be updated to call 
the FP
version directly ..
I'd like to read https://bugs.openjdk.java.net/browse/JDK-8168992 to see
what was said there but JBS just went down for 5 hours maintenance ..

-phil.

On 05/07/2018 11:54 PM, Prasanta Sadhukhan wrote:
> Hi Sergey,
>
> I have run javax/swing/text jtreg and jck tests and did not observe 
> any regressions.
>
> Regards
> Prasanta
> On 4/28/2018 5:38 AM, Sergey Bylokhov wrote:
>> Hi, Prasanta.
>> Please confirm that you run related jck/reg tests.
>>
>> On 26/04/2018 23:52, Prasanta Sadhukhan wrote:
>>> Hi All,
>>>
>>> Please review a fix for an issue where it is seen that,
>>>   with a screen resolution higher than 100% and then clicking in a 
>>> JTextArea having setLineWrap(true) set, the caret (insertion point) 
>>> is not aligned with the cursor.
>>>
>>> The issue seems to stem from the fact that caret position 
>>> calculation in DefaultCaret class utilises API that uses integer 
>>> calculation than floating point calculations.
>>> The code flow as seen is
>>> DefaultCaret#positionCaret=>BasicTextUI#viewToModel=>BoxView.viewToModel=>CompositeView#viewToModel=>WrappedPlainView#viewToModel=>Utilities.getTabbedOffset 
>>>
>>> Now, getTabbedOffset utilises FontMetrics.charsWidth() which uses 
>>> integer arithmetic to get the caret position.
>>> The same getTabbedOffset uses Font.getStringBounds() which uses 
>>> floating point arithmetic via Rectangle2D.Float.
>>>
>>> Proposed fix is to make sure getTabbedOffset uses floating point 
>>> calculations by using getStringBounds() instead of charsWidth() so 
>>> that it calculates
>>> the character width(s) of text present in JTextArea in floating 
>>> point to align the caret.
>>>
>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8199441
>>> webrev: http://cr.openjdk.java.net/~psadhukhan/8199441/webrev.00/
>>>
>>> Regards
>>> Prasanta
>>
>>
>