<Swing Dev> RFR JDK-8232243:Wrong caret position in JTextPane on Windows with a screen resolution > 100%

[Prasanta Sadhukhan]

Thanks for your review. All comments incorporated

http://cr.openjdk.java.net/~psadhukhan/8232243/webrev.1/

Regards
Prasaant
On 25-Apr-20 4:25 AM, Philip Race wrote:
> In the test
>    56         textPane.setFont(new java.awt.Font("Arial", Font.PLAIN, 12));
>
> you should use a font you know exists. If the idea is that this test is just
> for windows, then @requires windows ?
>
> And
>    94         System.setProperty( "sun.java2d.uiScale", "1.5" );
>
> should be set as a command line property to the test since that is what we do
> elsewhere, then you can have the test run several times at different scales.
>
> Also currently 1.5 is truncated to 1 except on Windows ...
>
> If you want to test on Linux or Mac you need 2.
> Another reason to use the command line way of doing it.
>
>
> -phil
>
>
> On 4/16/20, 3:16 AM, 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 JTextPane, 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.
>>
>> This issue is in continuation to the fix done for JDK-8199441 where 
>> the issue was fixed for JTextArea. 
>> [http://hg.openjdk.java.net/jdk/jdk/rev/480c2ae4d031]
>>
>> The code flow for JTextArea was
>> DefaultCaret#positionCaret=>BasicTextUI#viewToModel=>BoxView.viewToModel=>CompositeView#viewToModel=>WrappedPlainView#viewToModel=>Utilities.getTabbedOffset 
>>
>>
>> whereas for JTextPane it it is 
>> DefaultCaret#positionCaret=>BasicTextUI#viewToModel=>BoxView.viewToModel=>CompositeView#viewToModel=>GlyphPainter1#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 proper floating point getTabbedOffset 
>> API is used so that floating point calculations is done for char width.
>>
>> Bug:https://bugs.openjdk.java.net/browse/JDK-8232243
>>
>> webrev: http://cr.openjdk.java.net/~psadhukhan/8232243/webrev.0/
>>
>> Regards
>> Prasanta
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