RFR: 8199592: Control labels truncated at certain DPI scaling levels

[Jeanette Winzenburg]

On Sun, 25 Oct 2020 19:27:30 GMT, Jose Pereda <jpereda at openjdk.org> wrote:

>> curious: it this expected to fix the ellipsed checkBox texts? Can verify that the test fails/passes before/after the fix, but the example in the report looks still is eclipsed: same for 1.5, slightly better (in that only the first text is eclipsed compared to the first 3 without) for 1.75 scaling. What am I missing?
>
> @kleopatra Thanks for checking. 
> 
> As discussed in the JBS issue, there is a call in `CheckBoxSkin::layoutChildren` that, probably by mistake, calls `snapSizeX` twice, and that gives different results when a different UI scale is used.
> 
> This PR applies to the snapSizeXX methods, so it is guaranteed that `snapSizeXX(snapSizeXX(a)) == snapSizeXX(a)`. With the included test, _this_ issue should now be fixed.
> 
> However, you are totally right, the CheckBox test from the JBS issue only works fine with this PR either if `Stage::sizeToScene` is called or if the Scene is created with a defined width, so we still have another issue laying around.
> 
> Running the CheckBox test on Windows with 1.75% UI scale and without calling `sizeToScene`, produces this log of width and height values: 
> 
> Scene::resizeRootOnSceneSizeChange 256.0, 33.0
> ...
> Scene::resizeRootOnSceneSizeChange 256.0, 33.0
> ...
> // WindowEvent.RESIZE event UI scale 1.75
> ...
> Scene::resizeRootOnSceneSizeChange 256.0, 33.14285659790039
> 
> Both values should be snapped, as these are generated with snap methods in HBox. However, this is not the case for height, as there are some conversions in between:  This 33.14285659790039 value comes from an int (`View`: height = (int) (33.0 x 1.75) = 58) to float (`TKSceneListener`: h = 33.142857) to double (`Scene` width = 33.14285659790039). However, the proper snapped value should be 33.14285714285714.
> 
> However, if we add a call to  `stage.sizeToScene()`, then the log is:
> 
> Scene::resizeRootOnSceneSizeChange 256.0, 33.0
> ...
> Scene::resizeRootOnSceneSizeChange 256.0, 33.0
> ...
> Scene::resizeRootOnSceneSizeChange 256.0, 33.14285659790039
> ...
> Scene::resizeRootOnSceneSizeChange 257.1428571428571, 33.14285714285714
> ...
> Scene::resizeRootOnSceneSizeChange 257.1428571428571, 33.14285714285714
> ...
> both width and height have stable snapped values, and the checkbox layout is correct.
> 
> Back to the 256.0 value of width, this value comes from margin (8.0 * 2) + controls width(54.0 * 4)  + spacing (8.0 * 3), but the value 54.0 is not properly computed, as at this point the UI scale is still 1.0. 
> Once the UI scale is set to 1.75 the checkBox width is 54.285714285714285, and the scene's width is 257.14285714285714.
> 
> So the issue can be related to the UI scale value taken into account too late, and how this change doesn't trigger an update of the scene. 
> 
> Does it make sense to address this issue with the current PR?

thanks for the additional info - good dig �� 

As you noted, there are two issues: 

- the implementation of the scaled snaps to make them stable (against nested calls) BTW, any reason snappedXXInset are not scaled?
- a timing/sequence issue with applying the scale 

So might separate them out in different issues, the first with a new one with this PR fixing it. Depends a bit on granularity of issues - personally, would prefer it, though, if only to make snapping issues more prominent.

-------------

PR: https://git.openjdk.java.net/jfx/pull/336