RFR: 8358450: Viewport characteristics media features [v20]

[Markus Mack]

On Fri, 9 Jan 2026 02:51:10 GMT, Michael Strauß <mstrauss at openjdk.org> wrote:

>> Implementation of [viewport characteristics media features](https://www.w3.org/TR/mediaqueries-5/#mf-viewport-characteristics):
>> * `width`
>> * `height`
>> * `aspect-ratio`: width / height
>> * `orientation`: `portrait`, `landscape`
>> * `display-mode`: `fullscreen`, `standalone` (note: `browser` and `minimal-ui` are not supported in JavaFX)
>> 
>> Here's a small example how the new media features can be used:
>> 
>>     @Override
>>     public void start(Stage stage) {
>>         var button = new Button("Toggle full-screen");
>>         button.setOnAction(_ -> stage.setFullScreen(!stage.isFullScreen()));
>>         var label = new Label();
>>         var root = new BorderPane(button, null, null, label, null);
>>         var scene = new Scene(root, 650, 200);
>>         BorderPane.setAlignment(label, Pos.CENTER);
>>         label.textProperty().bind(scene.widthProperty().map(v -> String.format("Width: %.2f", v.doubleValue())));
>>         scene.getStylesheets().add("data:text/css;base64," + Base64.getEncoder().encodeToString("""
>>             @media (max-width: 500) {
>>                 .button {
>>                     -fx-background-color: red;
>>                 }
>>             }
>> 
>>             @media (600 < width <= 700) {
>>                 .button {
>>                     -fx-background-color: green;
>>                 }
>>             }
>> 
>>             @media (min-width: 800) {
>>                 .button {
>>                     -fx-background-color: yellow;
>>                 }
>>             }
>> 
>>             @media (display-mode: fullscreen) {
>>                 .button {
>>                     -fx-background-color: black !important;
>>                 }
>>             }
>>             """.getBytes(StandardCharsets.UTF_8)));
>> 
>>         stage.initStyle(StageStyle.DECORATED);
>>         stage.setScene(scene);
>>         stage.show();
>>     }
>
> Michael Strauß has updated the pull request incrementally with one additional commit since the last revision:
> 
>   update copyright years

I reviewed this PR's code and left some minor comments. The largest part is an implementation of complex media query expressions, which looks very solid and well-maintainable.

Manual testing on Windows 11 looks good as well as long as there are no CSS transitions.

In combination with CSS transitions I see some irregularities, e.g. consider this in a resizable window with two buttons:

.button {
  transition: -fx-scale-x 2s;
}

@media (width > 300px) {
  .button {
    -fx-scale-x: 2;
  }
}

When horizontally resizing the window around the width threshold, sometimes the transition jumps or even affects one of the buttons differently than the other.
Is such a configuration supposed to be supported?

modules/javafx.graphics/src/main/docs/javafx/scene/doc-files/cssref.html line 880:

> 878:                 operators and two values. For example:<br>
> 879:                 <code>
> 880:                     (400px >= width >= 600px)<br>

This should be `(400px <= width <= 600px)`

modules/javafx.graphics/src/main/java/com/sun/javafx/css/media/MediaQuery.java line 55:

> 53:      * @return the context awareness flags
> 54:      */
> 55:     int getContextAwareness();

Have you considered using an EnumSet here for stronger typing?

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

PR Review: https://git.openjdk.org/jfx/pull/1844#pullrequestreview-3643179694
PR Review Comment: https://git.openjdk.org/jfx/pull/1844#discussion_r2675525845
PR Review Comment: https://git.openjdk.org/jfx/pull/1844#discussion_r2675527995