JavaFX-CSS:如何将父级的 "move"样式传递给子级？

Question

触发这个的是一个快速实验来解决 TreeItem selection width :要求是只突出显示文本，而不是整个树单元格。没有比这更容易的了(弗雷德里克说:)

• 使用 Label 作为图形实现自定义 TreeCell(并根据需要使用项目配置标签)
• 移除选择样式(主要是单元格的高亮背景
• 给标签添加高亮样式

类似的东西(使用它的可运行示例在最后):

public static class MyTreeCell extends TreeCell<String> {

    private Label label;

    public MyTreeCell() {
        getStyleClass().add("tree-text-only");
    }
    @Override
    public void updateItem(String item, boolean empty) {
        super.updateItem(item, empty);
        if (empty) {
            setText(null);
            setGraphic(null);
        } else {
            if (label == null) {
                label = new Label();
            }
            label.setText(item);
            setGraphic(label);
        }
    }
}

CSS:

/* remove the highlight from cell as a whole, 
   c&p'd the unselected style from modena */
.tree-text-only:filled:selected {
    -fx-background: -fx-control-inner-background; 
    -fx-background-color: -fx-background;
}
/* c&p'd selected style */
/* using > doesn't make a different to the behaviour */ 
/* .tree-text-only:filled:selected > .label { */

.tree-text-only:filled:selected .label {
    /* following is the selection color from themes, doesn't show */
    -fx-background: -fx-selection-bar; 
    /* hard-coded color does show */
    /*   -fx-background-color: -fx-accent ; */
    /* auto-adjust text fill */
    /* no effect for hard-coded color, showing nothing for selection bar */
    -fx-text-fill: -fx-text-background-color;
}

预期行为

• 标签在使用选择栏时突出显示了背景
• 文本自动调整填充

实际行为:

• 使用“语义”(？)高亮颜色选择栏，标签的背景颜色没有更改为高亮颜色，但文本填充更改为“白色”，因此文本不显示
• 使用硬编码颜色(任何颜色，甚至是上面的重音)会更改标签的背景，但不会更新文本填充

显而易见的问题:如何使其按预期工作？

为方便起见，一个可运行的例子:

public class TreeCellExample extends Application {

    public static class MyTreeCell extends TreeCell<String> {

        private Label label;

        public MyTreeCell() {
            getStyleClass().add("tree-text-only");
        }
        @Override
        public void updateItem(String item, boolean empty) {
            super.updateItem(item, empty);
            if (empty) {
                setText(null);
                setGraphic(null);
            } else {
                if (label == null) {
                    label = new Label();
                }
                label.setText(item);
                setGraphic(label);
            }
        }
    }

    private Parent getContent() {
        TreeItem root = createSubTree("root");
        root.setExpanded(true);
        TreeView tree = new TreeView(root);
        tree.getStylesheets().add(
                getClass().getResource("treetextonly.css").toExternalForm());
        tree.setCellFactory(p -> new MyTreeCell());
        BorderPane pane = new BorderPane(tree);
        return pane;
    }

    ObservableList rawItems = FXCollections.observableArrayList(
            "9-item", "8-item", "7-item", "6-item", 
            "5-item", "4-item", "3-item", "2-item", "1-item");

    protected TreeItem createSubTree(Object value) {
        TreeItem child = new TreeItem(value);
        child.getChildren().setAll((List<TreeItem>) rawItems.stream()
                .map(TreeItem::new)
                .collect(Collectors.toList()));
        return child;
    }

    @Override
    public void start(Stage primaryStage) throws Exception {
        Scene scene = new Scene(getContent());
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
}

Answer 1

它不起作用的原因是因为 .label 没有应用 -fx-background 的规则，所以分配给它的任何值都会' 影响任何 Label 属性。

此外，Label 不使用 -fx-background-color 属性。

所以一个简单的解决方案是添加它:

.tree-text-only > .label {
    -fx-background-color: -fx-background; 
}

现在您可以仅使用这种“语义”颜色来应用所有样式。

请注意，我还添加了控件没有焦点的情况:

/* 
 * remove the highlight from cell as a whole 
 */

/* Selected rows */
.tree-view:focused > .virtual-flow > .clipped-container > .sheet > .tree-text-only:filled:selected {
    -fx-background: -fx-control-inner-background; 
}
/* Selected when control is not focused */
.tree-text-only:filled:selected {
    -fx-background: -fx-control-inner-background; 
}
/* focused cell (keyboard navigation) */
.tree-view:focused > .virtual-flow > .clipped-container > .sheet > .tree-text-only:focused {
    -fx-cell-focus-inner-border: -fx-control-inner-background; 
}

/* 
 * highlight only the label
 */

// Add background color rule
.tree-text-only > .label {
    -fx-background-color: -fx-background; 
}
/* Selected rows */
.tree-view:focused > .virtual-flow > .clipped-container > .sheet > .tree-text-only:filled:selected > .label {
    -fx-background: -fx-selection-bar; 
}
/* Selected when control is not focused */
.tree-text-only:filled:selected > .label {
    -fx-background: -fx-selection-bar-non-focused;
}
/* focused cell (keyboard navigation) */
.tree-view:focused > .virtual-flow > .clipped-container > .sheet > .tree-text-only:focused > .label {
    -fx-background: -fx-selection-bar; 
}