<Swing Dev> review request for 6899434: Add affine transform support to JLayer

[Piet Blok]

Hi Artem,

The problem with making existing methods public is that it solves only half 
of the problem at hand:

1) Locate the correct component (can be solved)

2) Recalculating the mouse point from rendered space to layout space is not 
solved because the locating methods only return a component. Recalculation 
is needed to correctly set a mouse point in the new events, relative to the 
target component.

In my proposed implementation the shift caused by transformations is stored 
when looking up the target (for future use: creating new events from the 
original event). This future is quite an immediate future because creating a 
new event from an existing event will always be directly preceded by looking 
up that target event.

An alternative would be to again iterate through the hierarchy and do the 
transformations. This must be done in LightweightDispatcher in the methods:

1) retargetMouseEvent (an inverse transform is needed, so the new Container 
method getConvertedPoint can be used)

2) eventDispatched. Unfortunately here an ordinary transform is needed, so a 
second new Container method must be defined that does an ordinary transform.

But.... a completely different approach is also possible. I did this in an 
earlier version, so I know that it works. With this approach no new public 
or protected methods need to be introduced and no existing methods need to 
go public or protected. All remains private or package private.

That approach is as follows:

1) Define the AffineTransform as a private field in Component.

2) Use the AWTAccessor pattern to make the transform available in Container 
and LightweightDispatcher and in swing classes.

3) In Container and LightweightDispatcher, get the transform and do 
transformations when needed.

In my opinion, the solution with the AWTAccessor pattern is the cleanest. 
However, it requires Component and AWTAccessor to be touched.

Please let me know what you think.

Piet



> Hi, Piet,
>
> I haven't looked through the entire webrev and inspected mostly an AWT 
> part of the fix. A question is whether it's possible to get rid of the new 
> "conversionShift" field in Container, to make transformations support 
> really stateless?
>
> Another option to consider is to make some of the existing methods (e.g. 
> getMouseEventTargetImpl()) public instead of introducing new ones.
>
> Thanks,
>
> Artem
>
> On 1/28/2010 8:21 PM, Piet Blok wrote:
>> Hello all,
>>
>> review request for 6899434: Add affine transform support to JLayer
>>
>> The webrev: http://www.pbjar.org/OpenJDK/6899434/webrev/
>>
>> The patch covers all the requested functionality. It is concentrated in
>> JLayer class, keeping in mind to affect the library as little as 
>> possible.
>>
>> 1) A setter and getter for the transform in JLayer
>>
>> 2) The paint method in JLayer has been adapted to use the transform
>>
>> 3) RepaintManager has been adapted to propagate repaint requests from
>> the view or any of its children to the top level JLayer and have the
>> dirty region transformed.
>>
>> 4) java.awt.Container and java.awt.LightweightDispatcher (both in the
>> same source) have been adapted to redispatch MouseEvents to the intended
>> target component. The lookup for the component that provides a custon
>> cursor has also been adapted.
>>
>> 5) To enable Container to do necessary reculculations, a protected
>> method has been introduced that will be overridden by JLayer:
>> protected Point getConvertedPoint(Point point).
>> (If someone can suggest a better name for this method I'm glad to hear)
>>
>> 6) A package private method in SwingUtilities has been added that helps
>> JPopupMenu and ToolTipManager to find the correct popup location.
>> JPopupMenu and ToolTipManager have been changed to use this new method
>> in their calculations.
>>
>> 7) Two jtreg tests have been added.
>>
>> Looking forward for comments.
>>
>> Thanks,
>> Piet
>>
>>
>>
>