I would love to be able to do this.
Dirk
> Am 11.02.2025 um 23:47 schrieb John Hendrikx <john.hendr...@gmail.com>:
>
> Hi list,
>
> I've done a little proof of concept where I've made some minor modifications
> to CssStyleHelper to allow the CSS engine to offer styleable properties on
> children, but defined by the container class.
>
> What this means is that we can make it appear that direct children of a
> container like GridPane, HBox and VBox have properties like: `vgrow`,
> `hgrow`, `column-index`, `margin`, `halignment`, `fill-width` etc. The exact
> names can be chosen by the container in question. For example, I could style
> a child of an HBox like this:
>
> .text-field {
> -fx-background-color: yellow;
> -fx-hbox-hgrow: ALWAYS;
> -fx-hbox-margin: 5px;
> }
>
> This will make it possible to do far more visual styling directly in CSS. As
> usual, unrecognized properties are ignored, so if you put this text field in
> a VBox, nothing will happen.
>
> How does it work?
>
> - Containers that wish to add additional styleable properties to their direct
> descendants implement this interface:
>
> public interface ChildStyleProvider {
> List<CssMetaData<Styleable, ?>> getChildCssMetaData(Node child);
> }
> - The CssMetaData they provide for these properties looks like this for
> example:
>
>
> new CssMetaData<>("-fx-hbox-hgrow",
> StyleConverter.getEnumConverter(Priority.class)) {
> @Override
> public boolean isSettable(Styleable styleable) {
> return true;
> }
>
> @Override
> public StyleableProperty<Priority>
> getStyleableProperty(Styleable styleable) {
> return ChildStyleProvider.createProp(this, "hbox-hgrow",
> child);
> }
> }
> - A special StyleableProperty is created as the "receiver" of CSS styling
> that will store the value in the Node#getProperties map (where normally these
> values are already stored when using the static methods like
> HBox.setHGrow(Node, Priority) type methods). This property is cached as part
> of the same getProperties map, so it is only created once.
>
> - The CssStyleHelper will see if the parent of the Node being styled
> implements ChildStyleProvider, and if so will also process these additional
> CssMetaData properties when any are present; this seems to be fairly safe to
> do, as changing a Node's parent will reset all its styling already. Some more
> tests are needed here, if moving this forward.
>
> That is basically the change in a nutshell. Not only does setting a property
> like `-fx-hbox-hgrow` on a child now act as if you called `HBox.setHGrow`,
> changing the style of the child can also change these settings and HBox will
> instantly respond to the change. When the style is completely removed, it
> will also null the hgrow value which is translated as removing that key from
> the Node#getProperties map.
>
> If people think this proposal has some merit, I can flesh it out further and
> make it into a PR.
>
> --John
>
>
>
>
>
>
