JavaFx:当Treeitem不在View中时，在TreeView中仅需要滚动到索引号 [英] JavaFx: In TreeView Need Only Scroll to Index number when treeitem is out of View

问题描述

我需要做一个简单的事情.我有一个大的TreeView.以及菜单项下一个和上一个.在下一步，我必须选择下一个树项.树形列表看起来像这样

I need to do a simple thing. I have a large TreeView. and a menu item Next and Previous. on Next I have to select next Tree Item. Tree List Look like this

-Root(set visible hide is true for root)
 --Parent 1
 ----Child 1
 ----Child 2
 ----Child 3
 --Parent 2
 ----Child 1
 ----Child 2

现在，通过按下一个"或上一个"菜单项，我呼叫

Now By pressing Next or previous menu item i call

myTreeView.getSelectionModel().clearAndSelect(newIndex);

通过此操作，我设法选择了下一项，并通过

By This I have manage to select next item and by

myTreeView.getSelectionModel().scrollTo(newIndex) 

我设法滚动到选定的树项.

i have manage to scroll to selected treeitem.

让我手动选择第一项.在此之后，我按下一步按钮.现在，这会导致一个奇怪的行为，即它总是在新选定的树状对象在视图中(可查看区域的边界)或视图外滚动时滚动.假设我有很多树木项目.而我的要求是，我只希望仅在新选择的树项不可见时才发生滚动.任何人都可以建议如何实现这一目标吗?

Let I select the first item manually. after this i press next button. Now This cause a weird behavior that it always scrolls weather new selected treeitem is in view (bounds of view able area) or out of view. let assume i have large list of tree items. and my requirement is just i only want scroll happened only when new selected tree item go out of view. can any body suggest how to achieve this??

谢谢.

推荐答案

这个简单的事情并不是那么简单.这是JavaFX中的一个已知问题.参见问题RT-18965 .

This simple thing is not so simple. It is a known issue in JavaFX; see issue RT-18965.

基于问题中的评论，我使其与我自己的TreeView一起使用.请注意，正如问题注释中所述，我依靠JavaFX中的内部类来获得最终结果.无法保证这些内部类将继续存在.

Based on the comment in the issue, I have made it work with my own TreeView. Please note that - as in the issue comment - I have relied on internal classes within JavaFX to get my end result. There is no guarantee that these internal classes will continue to be.

首先，创建一个从内部类派生的新外观(同样:危险):

First, create a new Skin that is derived from an internal class (again: dangerous):

import javafx.scene.control.TreeView;
import com.sun.javafx.scene.control.skin.TreeViewSkin;
import com.mycompany.mymodel.DataNode;

/**
 * Only done as a workaround until https://javafx-jira.kenai.com/browse/RT-18965
 * is resolved.
 */
public class FolderTreeViewSkin extends TreeViewSkin<DataNode>
{
    public FolderTreeViewSkin(TreeView<DataNode> treeView)
    {
        super(treeView);
    }

    public boolean isIndexVisible(int index)
    {
        if (flow.getFirstVisibleCell() != null &&
            flow.getLastVisibleCell() != null &&
            flow.getFirstVisibleCell().getIndex() <= index &&
            flow.getLastVisibleCell().getIndex() >= index)
            return true;
        return false;
    }
}

第二，将该皮肤应用于您关注的TreeView实例.

Second, apply that skin to the TreeView instance you are concerned about.

myTreeView.setSkin(new FolderTreeViewSkin(myTreeView));

最后，将新方法用作scrollTo之前的条件:

Finally, use the new method as a condition before scrollTo:

if (!((FolderTreeViewSkin) myTreeView.getSkin()).isIndexVisible( intThePositionToShow ))
    myTreeView.scrollTo( intThePositionToShow );

这就是对我有用的东西；我希望它可以帮助您或其他任何人.

This is what worked for me; I hope it can help you or anyone else.

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