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Mono GTK#Nodeview Nodestore始终获取空引用_Mono_Gtk#_Visual Studio Mac - Fatal编程技术网

Mono GTK#Nodeview Nodestore始终获取空引用

Mono GTK#Nodeview Nodestore始终获取空引用,mono,gtk#,visual-studio-mac,Mono,Gtk#,Visual Studio Mac,我已经按照GTK#Mono教程页面中的代码创建了一个GTK#Nodeview+NodeStore!我的更改是添加一个按钮,向NodeView添加新条目,并尝试使其可交互。我的问题是NodeView 选择更改事件正在使应用程序崩溃 using System; using Gtk; public partial class MainWindow : Window { Button button; NodeView nodeview; NodeStore nodestore;

我已经按照GTK#Mono教程页面中的代码创建了一个GTK#Nodeview+NodeStore!我的更改是添加一个按钮,向NodeView添加新条目,并尝试使其可交互。我的问题是NodeView 选择更改事件正在使应用程序崩溃

using System;
using Gtk;

public partial class MainWindow : Window
{
    Button button;
    NodeView nodeview;
    NodeStore nodestore;

    [TreeNode(ListOnly = true)]
    public class MyTreeNode : TreeNode
    {
        public MyTreeNode(string artist)
        {
            Artist = artist;
        }

        [TreeNodeValue(Column = 0)]
        public string Artist;
    }


    public MainWindow() : base(WindowType.Toplevel)
    {
        Build();

        var vbox = new VBox();
        nodeview = new NodeView();
        // Create a column with title Artist and bind its renderer to model column 0
        nodeview.AppendColumn("Artist", new CellRendererText(), "text", 0);

        nodestore = new NodeStore(typeof(MyTreeNode));
        nodestore.AddNode(new MyTreeNode("temp"));
        nodeview.NodeStore = nodestore;

        nodeview.Selection.Changed += Selection_Changed;

        button = new Button("Add New!!");
        button.Clicked += Button_Clicked;

        vbox.PackStart(nodeview, true, true, 0);
        vbox.PackStart(button, false, true, 0);

        Add(vbox);
        ShowAll();
    }

    void Button_Clicked(object sender, EventArgs e)
    {
        nodestore.AddNode(new MyTreeNode("temp"));
    }

    void Selection_Changed(object sender, EventArgs e)
    {
        NodeSelection selection = (NodeSelection)sender;
        if (selection != null)
        {
            MyTreeNode node = (MyTreeNode)selection.SelectedNode;
            var a = node.Artist;
        }
    }

    protected void OnDeleteEvent(object sender, DeleteEventArgs a)
    {
        Application.Quit();
        a.RetVal = true;


    }
}
当我在NodeView中选择一个节点时,应用程序会在没有任何通知的情况下崩溃。然后通过一些调试,我意识到当输入NodeSelection_时,Nodeview中的NodeStore变量总是空的。即使它正在向其中添加节点。。(它们正在呈现给nodeview)。

这似乎是一个新版本,但在Mono 5.8及更旧版本中没有

解决方法是使用反射在NodeView类中设置“store”字段

typeof (NodeView).GetField ("store", BindingFlags.Instance | BindingFlags.NonPublic).SetValue (nodeview, nodestore);
如果在NodeView上设置nodestore的行之后添加上面的行,那么这将修复NodeView.nodestore为空的问题

nodeview.NodeStore = nodestore;
typeof (NodeView).GetField ("store", BindingFlags.Instance | BindingFlags.NonPublic).SetValue (nodeview, nodestore);
还请注意,您在Selection_Changed事件中的代码失败,因为发送方是Gtk.TreeSelection而不是Gtk.NodeSelection。我将选择更改为以下方法,该方法有效:

void Selection_Changed(object sender, EventArgs e)
{
    NodeSelection selection = nodeview.NodeSelection;
    if (selection != null)
    {
        MyTreeNode node = (MyTreeNode)selection.SelectedNode;
        var a = node.Artist;
    }
}

你能提供一个完全有效的例子吗?我不清楚nodeStore与NodeView关联的位置/时间。在Mono GTK示例中,它被创建并传递给NodeView的构造函数。现在上传了一个完整的示例!同样的问题+如果我可以的话!bug参考和解决方法的副本都非常有用。谢谢