<Swing Dev> [9] Review request for 8162350 RepaintManager shifts repainted region when the floating point UI scale is used

Wed Nov 30 23:57:32 UTC 2016

On 29.11.16 20:46, Alexandr Scherbatiy wrote:
>   The result of running SwingMark 2 with the following JDK is:
>   1. without the fix
>     1st test run [1]: 92373
>     2nd test run [2]: 92156
>
>    average: (92373 + 92156) / 2 = 92264.5
>
>   2. paintDoubleBufferedImp() method is always used
>     1st test run [3]: 92476    // (92476 - 92264.5) / 92264.5 / 100 =
> 0.000023%
>     2nd test run [4]: 90800  // (90800 - 92264.5) / 92264.5 / 100 =
> -0.000159%
>
>   3.paintDoubleBufferedFPScales () method is always used
>     1st test run [5]: 91053    // (91053 - 92264.5) / 92264.5 / 100 =
> -0.000131%
>     2nd test run [6]: 92900    // (92900 - 92264.5) / 92264.5 / 100 =
> 0.000069%

So it seems we can simplify the this codepath and always use the new 
method? Do we have some arguments against it?

> [1]
> http://cr.openjdk.java.net/~alexsch/8162350/swingmark2/repaint-manager-fp-scale-base_00.txt
>
> [2]
> http://cr.openjdk.java.net/~alexsch/8162350/swingmark2/repaint-manager-fp-scale-base_01.txt
>
> [3]
> http://cr.openjdk.java.net/~alexsch/8162350/swingmark2/repaint-manager-fp-scale-int_00.txt
>
> [4]http://cr.openjdk.java.net/~alexsch/8162350/swingmark2/repaint-manager-fp-scale-int_01.txt
>
> [5]
> http://cr.openjdk.java.net/~alexsch/8162350/swingmark2/repaint-manager-fp-scale-fp_00.txt
>
> [6]
> http://cr.openjdk.java.net/~alexsch/8162350/swingmark2/repaint-manager-fp-scale-fp_01.txt
>
>>
>> On 21.11.16 16:59, Alexandr Scherbatiy wrote:
>>>
>>> Hello,
>>>
>>> Could you review the updated fix:
>>>   http://cr.openjdk.java.net/~alexsch/8162350/webrev.04
>>>
>>>  - isFloatingPointScale(AffineTransform) is moved from the SunGraphics2D
>>> to the SwingUtilities2 class.
>>>
>>>   Thanks,
>>>   Alexandr.
>>>
>>> On 11/18/2016 11:23 PM, Jim Graham wrote:
>>>> Hi ALexandr,
>>>>
>>>> This looks great.
>>>>
>>>> BTW, when I suggested moving the FPscale test into SG2D I was
>>>> suggesting that to avoid having to copy the transform out of it via
>>>> getTransform(), but you've found a different solution to that issue
>>>> (i.e. the new getTransform(g) method) so it no longer matters where
>>>> that utility static function is located.  You can move it back to one
>>>> of the Swing classes.
>>>>
>>>> In terms of the logic of choosing which repaint function to use, it
>>>> looks like you use the old-style function if the scales don't match,
>>>> but won't that cause rendering anomalies?  The new code is still an
>>>> improvement for the standard HiDPI case, and I'm guessing that
>>>> mismatched scales probably never tends to happen, but we might want to
>>>> flag it for further investigation.
>>>>
>>>> +1 relative to whether you want to move the FPscale test back out of
>>>> SG2D or not...
>>>>
>>>>             ...jim
>>>>
>>>> On 11/18/16 1:44 AM, Alexandr Scherbatiy wrote:
>>>>>
>>>>> Thank you. I see that using the integer device-pixel translations
>>>>> preserves the component painting in the same way for
>>>>> floating point scales.
>>>>>
>>>>> Could you review the updated fix:
>>>>>   http://cr.openjdk.java.net/~alexsch/8162350/webrev.03
>>>>>
>>>>>   - translation adjustment is removed
>>>>>   - Region.clipRound() is used for pixels coordinates rounding.
>>>>>
>>>>>   Thanks,
>>>>>   Alexandr.
>>>>>
>>>>> On 11/16/2016 1:52 AM, Jim Graham wrote:
>>>>>> Let me clarify something...
>>>>>>
>>>>>> On 11/15/16 2:49 AM, Alexandr Scherbatiy wrote:
>>>>>>>   Let's consider the following use case:
>>>>>>>   scale = 1.5
>>>>>>>   A component calls fillRect(1, 1, 1, 1).
>>>>>>>   This is (1.5, 1.5, 3.0, 3.0) in the device space
>>>>>>>   which fills  (1, 1, 3, 3) and covers 2x2 pixels
>>>>>>
>>>>>> Agreed.
>>>>>>
>>>>>>>   Now the area (1, 1, 1, 1) needs to be repainted
>>>>>>>     create a backbuffer
>>>>>>>     translate(-1, -1) // move the top left corner of the area to
>>>>>>> the zero point
>>>>>>>     draw the component into the backbuffer:
>>>>>>>       fillRect(1, 1, 1, 1) -> after translation fillRect(0, 0, 1,
>>>>>>> 1) -> after scaling  (0.0, 0.0, 1.5, 1.5 ) in the
>>>>>>> device space
>>>>>>>       which fills (0, 0, 1, 1) and covers 1x1 pixels
>>>>>>
>>>>>> If you did g.setTransform(identity), g.translate(-1, -1), (then
>>>>>> restore the scale) then the analysis is as follows:
>>>>>>
>>>>>> g.setTransform(identity) => [1 0 0] [0 1 0]
>>>>>> g.translate(-1, -1) => [1 0 -1] [0 1 -1]
>>>>>> g.scale(1.5, 1.5) => [1.5 0 -1] [0 1.5 -1]
>>>>>> g.fillRect(1, 1, 1, 1)
>>>>>>     => coordinates are (1.5-1, 1.5-1, 3-1, 3-1)
>>>>>>     => (.5, .5, 2, 2)
>>>>>>     => fills (0, 0, 2, 2)
>>>>>>     => which covers 2x2 pixels
>>>>>>
>>>>>> If you did g.translate(-1, -1) on the scaled transform then the
>>>>>> analysis is as follows:
>>>>>>
>>>>>> g.transform is [1.5 0 0] [0 1.5 0]
>>>>>> g.translate(-1, -1) is [1.5 0 -1.5] [0 1.5 -1.5]
>>>>>> g.fillRect(1, 1, 1, 1)
>>>>>>     => coordinates are (1.5-1.5, 1.5-1.5, 3-1.5, 3-1.5)
>>>>>>     => (0, 0, 1.5, 1.5)
>>>>>>     => fill (0, 0, 1, 1)
>>>>>>     => covers 1x1 pixels
>>>>>>
>>>>>> The second operation is what you are describing above and that would
>>>>>> be an inappropriate way to perform damage repair
>>>>>> because you used a scaled translation which did not result in an
>>>>>> integer coordinate translation.
>>>>>>
>>>>>> Please re-read my previous analysis that shows what happens when you
>>>>>> use integer device-pixel translations which are
>>>>>> translations that happen using integers on a non-scaled transform.
>>>>>> Note that you can add a scale *AFTER* you apply
>>>>>> the integer device pixel translation and it will not affect the
>>>>>> integer-ness of the translation.  You can see above
>>>>>> that the difference in how the translate command is issues affects
>>>>>> where the translation components of the matrix end
>>>>>> up being -1,-1 or -1.5,-1.5...
>>>>>>
>>>>>>             ...jim
>>>>>
>>>
>>
>>
>

-- 
Best regards, Sergey.