JavaFX-CSS：如何“移动”孩子的父母风格？ [英] JavaFX-CSS: How to "move" style of parent to a child?

问题描述

触发此操作的是一个快速实验来解决 TreeItem选择宽度：要求是仅突出显示文本，不是整个树细胞。没有什么比这更容易了（Frederik :)：

The trigger for this was a quick experiment to solve TreeItem selection width: the requirement is to highlight only the text, not the whole tree cell. Nothing easier than that (said Frederik :)

• 实现一个自定义TreeCell，标签为图形（并根据需要配置标签） ）


• 删除选择样式（主要是单元格中的高亮背景）


• 将高亮样式添加到标签

类似的东西（使用它的可运行示例在最后）：

Something like (a runnable example using this is at the end):

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背景


• 文本自动调整其填充

实际行为：

• 使用语义（？）突出显示颜色选择栏，背景颜色为标签未更改为高亮颜色，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，甚至是重音如上所述）更改标签的背景但文本填充没有更新

显而易见的问题：如何让它按预期工作？

The obvious question: How to make it work as expected?

为方便起见，一个可运行的例子：

For convenience, a runnable example:

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);
    }
}

推荐答案

之所以不起作用，是因为 .label 没有适用 -fx-background 的规则，因此分配给它的任何值都不会影响任何 Label 属性。

The reason why it doesn't work is because .label doesn't have a rule where -fx-background is applied, so any value assigned to it won't affect any of the Label properties.

更重要的是，标签不使用 -fx-background-color property。

What's more, Label doesn't use a -fx-background-color property.

所以一个简单的解决方案就是添加它：

So an easy solution would be adding it:

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

现在，您可以仅使用此语义颜色应用所有样式。

Now you can apply all the style using only this "semantic" colors.

注意我还添加了控件没有焦点的情况：

Note I've added also the case where the control doesn't have the focus:

/* 
 * 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; 
}

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