支持异步操作的组件用法

 

using System;

using System.ComponentModel;

using System.Windows.Forms;

 

namespace AsyncComponent

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

            pictureBox1.LoadCompleted += new AsyncCompletedEventHandler(pictureBox1_LoadCompleted);

        }

 

        //调用 LoadAsync 方法时，您的应用程序将继续运行，而下载操作将在另一个线程上

        //（“在后台”）继续。图像加载操作完成时，将会调用您的事件处理程序，您的事件

        //处理程序可以检查 AsyncCompletedEventArgs 参数以确定下载是否已成功完成。

 

        private void pictureBox1_LoadCompleted(object sender, AsyncCompletedEventArgs e)

        {

            if (e.Error != null)

            {

                MessageBox.Show(e.Error.Message, "Load Error");

            }

            else if (e.Cancelled)

            {

                MessageBox.Show("Load canceled", "Canceled");

            }

            else

            {

                MessageBox.Show("Load completed", "Completed");

            }

        }

 

        private void Form1_Load(object sender, EventArgs e)

        {

        }

 

        private void loadButton_Click(object sender, EventArgs e)

        {

            //希望应用程序在加载图像时保持运行，可以调用 LoadAsync 方法

            pictureBox1.LoadAsync("D:""桌面.jpg");

        }

 

        private void cancleLoadButton_Click(object sender, EventArgs e)

        {

            pictureBox1.CancelAsync();

        }

    }

}