如何避免在javafx组合框中单击鼠标时关闭弹出菜单？ [英] How to avoid closing popup menu on mouse clicking in javafx combobox?

问题描述

我有一个带有自定义ListCell的组合框：

I have combobox with custom ListCell:

private class SeverityCell extends ListCell<CustomItem> {
    private final CustomBox custombox;

    {
        setContentDisplay(ContentDisplay.GRAPHIC_ONLY); 
        custombox = new CustomBox();
    }

    @Override 
    protected void updateItem(CustomItem item, boolean empty) {         
        super.updateItem(item, empty);
        if (null != item) {
            //...
        }
        setGraphic(custombox);
    }
}

和

combobox.setCellFactory(new Callback<ListView<CustomItem>, ListCell<CustomItem>>() {
    @Override public ListCell<CustomItem> call(ListView<CustomItem> p) {
        return new SeverityCell();
    }
});

当我单击mu时，自定义组件弹出窗口关闭，但我想避免这种情况。我需要覆盖哪个方法/事件？

When I click on mu custom component popup closes, but I want to avoid it. Which method/event I need to override?

推荐答案

ComboBox 内部使用 ListView 用于呈现其项目。同样，它的皮肤类是 ComboBoxListViewSkin 。在此类的源代码中，有一个布尔标志来控制弹出窗口的隐藏行为：

ComboBox internally utilizes ListView for rendering its items. Also its skin class is ComboBoxListViewSkin. In a source code of this class there is boolean flag to control popup hiding behavior:

// Added to allow subclasses to prevent the popup from hiding when the
// ListView is clicked on (e.g when the list cells have checkboxes).
protected boolean isHideOnClickEnabled() {
    return true;
}

用于列表视图：

       _listView.addEventFilter(MouseEvent.MOUSE_RELEASED, t -> {
            // RT-18672: Without checking if the user is clicking in the
            // scrollbar area of the ListView, the comboBox will hide. Therefore,
            // we add the check below to prevent this from happening.
            EventTarget target = t.getTarget();
            if (target instanceof Parent) {
                List<String> s = ((Parent) target).getStyleClass();
                if (s.contains("thumb")
                        || s.contains("track")
                        || s.contains("decrement-arrow")
                        || s.contains("increment-arrow")) {
                    return;
                }
            }

            if (isHideOnClickEnabled()) {
                comboBox.hide();
            }
        });

因此，您可以（并且可能应该）使用自定义外观来实现所需的行为。但是，解决方法可以是

So the behavior you want can be (and probably should be) implemented with custom skin. However, the workaround can be

combobox.setSkin( new ComboBoxListViewSkin<CustomItem>( combobox )
{
    @Override
    protected boolean isHideOnClickEnabled()
    {
        return false;
    }
} );

，并在例如更改值时手动隐藏弹出窗口：

and manually hide the popup, when the value is changed for instance:

combobox.valueProperty().addListener( new ChangeListener()
{
    @Override
    public void changed( ObservableValue observable, Object oldValue, Object newValue )
    {
        combobox.hide();
    }
});

请注意，我没有完全测试这种匿名的内部皮肤方法。

Note please, I didn't fully test this anonymous inner skin approach.

这篇关于如何避免在javafx组合框中单击鼠标时关闭弹出菜单？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！