On Mon, 1 Dec 2025 22:08:27 GMT, Michael Strauß <[email protected]> wrote:
>> When a `Scene` or `SubScene` has its width or height set to 0, coordinate
>> transformations stop working because the transformation matrix contains
>> NaNs. This is a consequence of divisions by zero in both parallel and
>> perspective projections.
>>
>> Even though a 0x0 scene is mathematically degenerate, it is still desirable
>> for coordinate transformation APIs to remain numerically well-behaved and
>> return finite results whenever possible, rather than being poisoned by
>> NaN/Infinity.
>>
>> Here is an application that demonstrates the failing coordinate
>> transformations. Click on the buttons to resize the SubScene and observe the
>> console output. After applying the patch in this PR, you should observe that
>> `localToScreen()` no longer returns NaN.
>>
>>
>> public class ZeroSizeSubScene extends Application {
>>
>> @Override
>> public void start(Stage stage) {
>> var rect = new Rectangle(50, 50, Color.RED);
>> var subScene = new SubScene(new Group(rect), 100, 100);
>> subScene.setFill(Color.GRAY);
>>
>> // Also try a perspective camera:
>> //
>> // var camera = new PerspectiveCamera();
>> // camera.setRotate(45);
>> // camera.setTranslateX(-20);
>> // camera.setRotationAxis(new Point3D(0, 1, 0));
>> // subScene.setCamera(camera);
>>
>> class MyButton extends Button {
>> public MyButton(String text, double width, double height) {
>> super(text);
>> setOnAction(_ -> {
>> var timeline = new Timeline(
>> new KeyFrame(Duration.seconds(1), new
>> KeyValue(subScene.widthProperty(), width)),
>> new KeyFrame(Duration.seconds(1), new
>> KeyValue(subScene.heightProperty(), height)));
>>
>> timeline.setOnFinished(_ -> {
>> Point2D p0 = rect.localToScreen(0, 0);
>> System.out.println("rect.localToScreen(0, 0) = " +
>> p0);
>> });
>>
>> timeline.play();
>> });
>> }
>> }
>>
>> VBox.setMargin(subScene, new Insets(0, 0, 20, 0));
>>
>> var root = new VBox(5,
>> subScene,
>> new CheckBox("Rotate SubScene") {{ setOnAction(_ ->
>> subScene.setRotate(isSelected() ? 45 : 0)); }},
>> new MyButton("Size: 100x100", 100, 100),
>> new MyButton("Size: 10x10", 10, 10),
>> new MyButton("Size: 100x0", 100, 0),
>> ne...
>
> Michael Strauß has updated the pull request incrementally with one additional
> commit since the last revision:
>
> review comments
Marked as reviewed by angorya (Reviewer).
@lukostyra could you please take a look at this on Windows with fractional
scale?
-------------
PR Review: https://git.openjdk.org/jfx/pull/1992#pullrequestreview-3527333662
PR Comment: https://git.openjdk.org/jfx/pull/1992#issuecomment-3599261316
