<Swing Dev> [9] Review request for 8142966 Wrong cursor position in text components on HiDPI display

[Phil Race]

On 5/31/2016 1:36 PM, Alexandr Scherbatiy wrote:
> On 5/31/2016 10:54 PM, Phil Race wrote:
>>
>>
>> This looks reasonable except I am not sure when gc would be null here :-
>>
>> 1062     private static FontRenderContext getFRCProperty(JComponent c) {
>> 1063         if (c != null) {
>> 1064
>> 1065             GraphicsConfiguration gc = 
>> c.getGraphicsConfiguration();
>> 1066             AffineTransform tx = (gc == null) ? null : 
>> gc.getDefaultTransform();
>>
>>
>> if it is only in some case such as where Swing is rendering in 
>> headless mode that should be OK
>     It happens when a size of a component is requested but the 
> component has not been added to a frame yet. This is a case where a 
> text component size can differ before it is added to a frame and after 
> that.

I do not know the flow here but it seems like you need to be careful 
that anything
dependent on this needs to be updated once the component is added to a 
parent.


-phil.

>
>   Thanks,
>   Alexandr.
>>
>> -phil.
>>
>> On 05/04/2016 10:42 PM, Alexandr Scherbatiy wrote:
>>>
>>> Hello,
>>>
>>> Could you review the fix:
>>>   bug: https://bugs.openjdk.java.net/browse/JDK-8142966
>>>   webrev: http://cr.openjdk.java.net/~alexsch/8142966/webrev.02
>>>
>>>   Swing uses a font rendering context which does not take the 
>>> graphics configuration transform into account.
>>>   This lead to the situation when text size is measured by one font 
>>> rendering context and drawn by another. As the result the calculated 
>>> text size can differ from the drawn text size.
>>>
>>>   For this issue it means that a cursor position can be farther away 
>>> from the char position.
>>>
>>>   This is the initial fix where graphics configuration transform is 
>>> included into the Swing font rendering context.
>>>
>>>   There is one more issue related to the fact that glyph advances 
>>> are calculated in dev space and then transformed to the user space. 
>>> Char width can have fractional value in user space if dev transform 
>>> is not identity.
>>>   It means that Swing should be able to draw a cursor at or select a 
>>> text from a fractional position.
>>>   These issues will be considered in separated fixes.
>>>
>>>  Thanks,
>>>  Alexandr.
>>>
>>
>