On Mon, 21 Oct 2024 15:32:28 GMT, Michael Strauß <mstra...@openjdk.org> wrote:
> When the initial value of a styleable property is not specified in a
> stylesheet, no transition is started:
>
> .button {
> transition: -fx-opacity 1s;
> }
>
> .button:hover {
> -fx-opacity: 0.5;
> }
>
> The expected behavior is that a transition is started in this case, since the
> default value of `-fx-opacity` is 1.
>
> The reason for this bug is that `StyleableProperty` implementations do not
> start a CSS transition when the value is applied for the first time. The
> intention behind this is that a node that is added to the scene graph should
> not start transitions. CSS transitions should only be started _after_ the
> node has been shown for the first time.
>
> The logic to detect this situation is currently as follows:
>
> // If this.origin == null, we're setting the value for the first time.
> // No transition should be started in this case.
> TransitionDefinition transition = this.origin != null && getBean()
> instanceof Node node ?
> NodeHelper.findTransitionDefinition(node, getCssMetaData()) : null;
>
>
> However, this does not work. When no initial style is specified in the
> stylesheet, `this.origin` will not be set, and thus no transition will be
> started even after the node has been shown. The new logic works like this:
>
> A `Node.initialCssState` flag is added. Initially, this is `true`. Manually
> calling `applyCss` or similar methods will not clear this flag, as we
> consider all manual CSS processing to be part of the "initial CSS state".
> Only at the end of `Scene.doCSSPass` will this flag be cleared on all nodes
> that have expressed their interest. This mechanism ensures that a node will
> be eligible for CSS transitions only after the following conditions have been
> satisfied:
> 1. The node was added to a scene graph
> 2. CSS processing was completed for a scene pulse
modules/javafx.graphics/src/main/java/javafx/scene/Scene.java line 607:
> 605: * CSS state (see {@link Node#initialCssState}.
> 606: */
> 607: private final Set<Node> clearInitialCssStateNodes =
> Collections.newSetFromMap(new IdentityHashMap<>());
why not use a normal `HashSet`? What advantage has this approach?
-------------
PR Review Comment: https://git.openjdk.org/jfx/pull/1607#discussion_r1856527311
