异步的ShowDialog [英] Async ShowDialog

问题描述

我使用异步/伺机异步从数据库，并在加载过程中加载我的数据，我想弹出一个装载形式，它只是一个简单的形式与运行进度条，表明有一个正在运行的进程。数据被加载后，对话框会自动关闭。我怎样才能做到这一点？下面是我目前的code：

I'm using async/await to asynchronously load my data from database and during the loading process, I want to popup a loading form, it's just a simple form with running progress bar to indicate that there's a running process. After data has been loaded, the dialog will automatically be closed. How can I achieve that ? Below is my current code:

 protected async void LoadData() 
    {
       ProgressForm _progress = new ProgressForm();  
       _progress.ShowDialog()  // not working
       var data = await GetData();          
       _progress.Close();
    }

更新：

我设法得到它的工作通过改变code：

I managed to get it working by changing the code:

 protected async void LoadData() 
        {
           ProgressForm _progress = new ProgressForm();  
           _progress.BeginInvoke(new System.Action(()=>_progress.ShowDialog()));
           var data = await GetData();          
           _progress.Close();
        }

这是正确的做法或有任何更好的方法？

Is this the correct way or there's any better ways ?

感谢您的帮助。

推荐答案

这很容易与 Task.Yield 来实现，就像这样（的WinForms，没有异常处理简单）

It's easy to implement with Task.Yield, like this (WinForms, no exception handling for simplicity):

namespace WinFormsApp
{
    public partial class MainForm : Form
    {
        public MainForm()
        {
            InitializeComponent();
        }

        async Task<int> LoadDataAsync()
        {
            await Task.Delay(2000);
            return 42;
        }

        private async void button1_Click(object sender, EventArgs e)
        {
            var progressForm = new Form() { 
                Width = 300, Height = 100, Text = "Please wait... " };

            var progressFormTask = progressForm.ShowDialogAsync();

            var data = await LoadDataAsync();

            progressForm.Close();
            await progressFormTask;

            MessageBox.Show(data.ToString());
        }
    }

    internal static class DialogExt
    {
        public static async Task<DialogResult> ShowDialogAsync(this Form @this)
        {
            await Task.Yield();
            if (@this.IsDisposed)
                return DialogResult.OK;
            return @this.ShowDialog();
        }
    }
}

要了解这里的执行流程如何跳转到一个新的嵌套的消息循环（即模态对话框），然后又回到了原来的消息循环（这就是等待progressFormTask 是）。

It's important to understand here how the execution flow jumps over to a new nested message loop (that of the modal dialog) and then goes back to the original message loop (that's what await progressFormTask is for).

这篇关于异步的ShowDialog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！