RFR: 8211294: ScrollPane content is blurry with 125% scaling [v6]

[Frederic Thevenet]

On Tue, 5 Jan 2021 06:32:25 GMT, Ambarish Rapte <arapte at openjdk.org> wrote:

>>> 
>>> 
>>> Apologies for delay on this review, Change looks good but I did observe an issue with layout of TabPane header area when the header is set to be shown on Left or Right side. The last tab-header's border seems to be clipped.
>>> Please check the code below. This is a very specific scenario, If tab's label is changed from "Tab" to "tab" then the issue does not occur. I did not observe any other such scenarios yet.
>>> 
>>> ```
>>> import javafx.application.Application;
>>> import javafx.scene.Scene;
>>> import javafx.scene.control.TabPane;
>>> import javafx.scene.control.Tab;
>>> import javafx.stage.Stage;
>>> import javafx.geometry.Side;
>>> 
>>> public class TabPaneExample extends Application {
>>>     public static void main(String[] args) {
>>>         launch(args);
>>>     }
>>> 
>>>     public void start(Stage primaryStage) {
>>>         Tab tab0 = new Tab("Tab 0");
>>>         Tab tab1 = new Tab("Tab 1");
>>> 	Tab tab2 = new Tab("Tab 2");
>>> 	TabPane tabPane = new TabPane();
>>>         tabPane.getTabs().addAll(tab0, tab1, tab2);
>>> 	tabPane.setSide(Side.LEFT);
>>> 
>>>         Scene scene = new Scene(tabPane);
>>>         primaryStage.setScene(scene);
>>>         primaryStage.show();
>>>     }
>>> }
>>> ```
>>> 
>>> ![with fix](https://user-images.githubusercontent.com/11330676/103559181-bd8ef880-4edb-11eb-8b87-cc6b0045b366.png) | ![without fix](https://user-images.githubusercontent.com/11330676/103559271-deefe480-4edb-11eb-99eb-fbc354d070fe.png)
>>> Output with this fix. | Output without this fix.
>>> 
>>> Edit: Also, please note the difference of space between letter `a` and `b` in Tab's label.
>> 
>> At which screen scale did you observe this?
>
>> At which screen scale did you observe this?
> 
> Both border clip and font spacing issues are observed only at 125% scale.
> 
> 
>> Update: If I run your test program using a build directly from the target branch, I see what you are seeing with the clipped tab pane border. That is likely an unrelated bug that has since been fixed.
> 
> I also see same behavior. Border clip issue does not occur with latest code but the difference in font spacing is observed(only at 125%)

I'm suspecting that the this fix might be revealing a issue related to [JDK-8199592](https://bugs.openjdk.java.net/browse/JDK-8199592).
Keeping in mind that the revision on which this fix is based does *not* include the fix for JDK-8199592, a way to confirm that would be to rebase that fix on top of the latest rev and see if the test program still exhibits the same behaviour.
 I'll try to do that later on today.

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

PR: https://git.openjdk.java.net/jfx/pull/308