Josh Smith 关于 MVVM、WPF、C# 的文章：如何关闭特定选项卡？

Question

我一直在我自己的应用程序中改编 Josh Smith 关于 C#/WPF 中的 MVVM 的示例，到目前为止，对于 C#-WPF 初学者来说相对成功。但现在还有一个障碍即将到来：

如果用户在特定选项卡上进行了任何内容更改，并且用户在该选项卡关闭按钮之后单击，则应显示一个消息框并通知/询问用户：“对选项卡内容的更改”示例-Tab" 已创建，但未保存。提示：如果关闭，任何内容更改都将丢失！您真的要关闭此选项卡吗？"如果他然后单击消息框的“确定”按钮，则应禁用/删除该选项卡，并且不应触发任何保存命令或类似的东西。如果他或者单击“取消”按钮，则应该只关闭消息框并显示源选项卡。

1) 消息框交互逻辑不是魔法。

2) 但是我怎样才能实现关闭特定选项卡？关闭选项卡时，适当的视图/视图模型在哪里注册或存放？我在所有不同的 TabViewModels 中都有一个布尔静态方法 IsContentOfTextboxesChanged，它返回 如果对一个或多个文本框进行了任何内容更改，则为 true；如果对任何文本框内容未进行任何内容更改，则为 false。

不幸的是，我不知道如何关闭特定标签！ ：/

Answer 1

好的，我有办法了。

更改：

void OnWorkspacesChanged(object sender, NotifyCollectionChangedEventArgs e)
{
    if (e.NewItems != null && e.NewItems.Count != 0)
        foreach (WorkspaceViewModel workspace in e.NewItems)
        {
            if (tab.GetType() == typeof(Tab01ViewModel))
                workspace.RequestClose += this.OnWorkspaceRequestCloseTab01;

            if (tab.GetType() == typeof(Tab02ViewModel))
                workspace.RequestClose += this.OnWorkspaceRequestCloseTab02;

            if (tab.GetType() == typeof(Tab03ViewModel))
                workspace.RequestClose += this.OnWorkspaceRequestCloseTab03;

            // and so on ...
        }


    if (e.OldItems != null && e.OldItems.Count != 0)
        foreach (WorkspaceViewModel workspace in e.OldItems)
        {
            if (tab.GetType() == typeof(Tab01ViewModel))
                workspace.RequestClose -= this.OnWorkspaceRequestCloseTab01;

            if (tab.GetType() == typeof(Tab02ViewModel))
                workspace.RequestClose -= this.OnWorkspaceRequestCloseTab02;

            if (tab.GetType() == typeof(Tab03ViewModel))
                workspace.RequestClose -= this.OnWorkspaceRequestCloseTab03;

            // and so on ...
        }
}



/// <summary>
/// Closes and removes a tab of type Tab01ViewModel
/// </summary>
void OnWorkspaceRequestCloseTab01(object sender, EventArgs e)
{
    WorkspaceViewModel workspace = sender as WorkspaceViewModel;

     if(Tab01ViewModel.IsContentOfTextboxesChanged) 
    {
        var result = System.Windows.Forms.MessageBox.Show(
            "Changes to the tab-content »" + Tab01ViewModel.TabTitle +
            "« were made, without setting them." + 
            "\n\nHint: If closing, any content changes will be lost!" + 
            "\n\nDo you really want to close this tab?",
            "MessageboxTitle", MessageBoxButtons.OKCancel, 
            MessageBoxIcon.Question);

        if (result == DialogResult.OK)
        {
            workspace.Dispose();
            this.Workspaces.Remove(workspace);
        }
    }

    else 
    {
        workspace.Dispose();
        this.Workspaces.Remove(workspace);
    }
}



/// <summary>
/// Closes and removes a tab of type Tab02ViewModel
/// </summary>
void OnWorkspaceRequestCloseTab02(object sender, EventArgs e)
{
    WorkspaceViewModel workspace = sender as WorkspaceViewModel;

     if(Tab02ViewModel.IsContentOfTextboxesChanged) 
    {
        var result = System.Windows.Forms.MessageBox.Show(
            "Changes to the tab-content »" + Tab02ViewModel.TabTitle +
            "« were made, without setting them." + 
            "\n\nHint: If closing, any content changes will be lost!" + 
            "\n\nDo you really want to close this tab?",
            "MessageboxTitle", MessageBoxButtons.OKCancel, 
            MessageBoxIcon.Question);


        if (result == DialogResult.OK)
        {
            workspace.Dispose();
            this.Workspaces.Remove(workspace);
        }
    }

    else 
    {
        workspace.Dispose();
        this.Workspaces.Remove(workspace);
    }
}



/// <summary>
/// Closes and removes a tab of type Tab03ViewModel
/// </summary>
void OnWorkspaceRequestCloseTab03(object sender, EventArgs e)
{
    WorkspaceViewModel workspace = sender as WorkspaceViewModel;

     if(Tab03ViewModel.IsContentOfTextboxesChanged) 
    {
        var result = System.Windows.Forms.MessageBox.Show(
            "Changes to the tab-content »" + Tab03ViewModel.TabTitle +
            "« were made, without setting them." + 
            "\n\nHint: If closing, any content changes will be lost!" + 
            "\n\nDo you really want to close this tab?",
            "MessageboxTitle", MessageBoxButtons.OKCancel, 
            MessageBoxIcon.Question);


        if (result == DialogResult.OK)
        {
            workspace.Dispose();
            this.Workspaces.Remove(workspace);
        }
    }

    else 
    {
        workspace.Dispose();
        this.Workspaces.Remove(workspace);
    }
}