在Windows窗体应用程序中显示进度条 [英] Show progress bar in windows forms application

问题描述

嗨



i想在我的Windows窗体应用程序中使用进度条。



i尝试使用< b> BackgroundWorker 来自此链接 http://eclipsed4utoo.com/blog/windows-form-progressbar/ [ ^ ]。



在我的表单上点击按钮，它将数据从SQL数据库下载到XML文件，数据下载需要8到10秒。在那个时候我想显示进度条。

这里问题是从SQL下载到XML后代码显示进度条。



这里是下面的代码

hi

i want to use progress bar in my windows form application.

i tried using BackgroundWorker from this link http://eclipsed4utoo.com/blog/windows-form-progressbar/[^].

In my form on button click it downloads data from SQL database to XML file, it takes 8 to 10 sec for data downloading.in that time i would like to show progress bar.
here problem is progress bar is showing after code downloaded from SQL to XML.

here is the code below

bgw = new BackgroundWorker();
     bgw.WorkerReportsProgress = true;
     bgw.ProgressChanged += new ProgressChangedEventHandler(bgw_ProgressChanged);
     bgw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bgw_RunWorkerCompleted);
     bgw.DoWork += new DoWorkEventHandler(bgw_DoWork);

       private void btnSubmitEventId_Click(object sender, EventArgs e)
        {
 
        bgw.RunWorkerAsync();  // called RunWorkerAsync in my button click

       // here my code for data downloading

        }



    void bgw_DoWork(object sender, DoWorkEventArgs e)
   {
    for (int i = 0; i < 10; i++)
    {
        bgw.ReportProgress((i + 1) * 10);
        Thread.Sleep(1000);
    }
   }

      void bgw_ProgressChanged(object sender, ProgressChangedEventArgs e)
     {
        progressBar1.Value = e.ProgressPercentage;
     }

     void bgw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
     {
     MessageBox.Show("Finished");
     }


here i understand that ReportProgress raises the bgw_ProgressChanged and assigned progress ercentage to  progressBar1.Value that is fine but here  ReportProgress raises bgw_ProgressChanged method after my data downloading is completed.

plz help me to find this out. 

推荐答案

解决方案可能类似于：

Solution may be something like:

void bgw_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
   progressBar1.BeginInvoke(new MethodInvoker(pb => pb.Value = e.ProgressPercentage));
}

由于您尝试从与创建它的线程不同的线程更新UI元素（您的ProgressBar），您必须使用BeginInvoke （）方法。



希望这会有所帮助。



[edit]更新以构建委托作为参数for BeginInvoke（）[/ edit]

Since you are trying to update an UI element (your ProgressBar) from a different thread than the one which has created it, you have to use BeginInvoke() method.

Hope this helps.

[edit] Updated to construct a delegate as parameter for BeginInvoke() [/edit]

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