在线程 c# 中打开 Windows 窗体（MDI）

Question

我有一个 MDI 表单，现在单击 MDI 表单中的菜单，我在 PnlView（面板）中打开其他表单，这充当表单的容器。

我在想的是，当应用程序加载时，它会打开一个默认表单。 此时我想打开所有表单，但是由于一次打开所有表单会影响性能，因此其他表单打开应该在不同的线程中运行。然后如果所有表单都打开了，那么用户可以在表单之间快速切换。

   private bool IsFormAlreadyOpen(ControlItem _item)
    {
       bool reutrnValue = false;
       foreach (Control ctrl in PnlView.Controls)
       {
          if (ctrl.Name.ToLower() == _item.Control.Name.ToLower())
          {
             reutrnValue = true;
             break;
          }
       }
       return reutrnValue;
    }


This is the function which checks if form is already opened or not. So this will get all the forms open and will just bring that form to front.

Can anyone helps me with opening form in thread so that it will not impact the performance.  
I hope this makes sense.

---------------------------------------------------------------------

     private void MdiForm1_Load(object sender, EventArgs e)
    {
  OpenFirstForm(); //This ospens a default form, form name frmDefault
         bw.WorkerReportsProgress = true;
                bw.WorkerSupportsCancellation = true;
                bw.DoWork += new DoWorkEventHandler(bw_DoWork);
                bw.ProgressChanged += new ProgressChangedEventHandler(bw_ProgressChanged);
                bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bw_RunWorkerCompleted);
                bw.RunWorkerAsync();
            }

            private void bw_ProgressChanged(object sender, ProgressChangedEventArgs e)
            {
                //this.tbProgress.Text = (e.ProgressPercentage.ToString() + "%");
            }

            private void bw_DoWork(object sender, DoWorkEventArgs e)
            {
                BackgroundWorker worker = sender as BackgroundWorker;

                for (int i = 1; (i <= 2); i++)
                {
                    if ((worker.CancellationPending == true))
                    {
                        e.Cancel = true;
                        break;
                    }
                    else
                    {
                        // Perform a time consuming operation and report progress.
                        //System.Threading.Thread.Sleep(500);
                       OpenForms(form1);
                       OpenForms(form2);
                        worker.ReportProgress((i * 10));
                    }
                }
            }

抛出异常，

跨线程操作无效：控件''从创建它的线程以外的线程访问

遇到异常， 没有重载 'OpenForm' 匹配委托 MethodInvoker

       this.Invoke(new MethodInvoker(OpenForm),new object[] { Keys.F12, Keys.Alt });

    private void OpenForm(Keys keyPressed, Keys modifier)
    {
---------------------------
}

Answer 1

问题是您正试图从另一个线程访问在一个线程中实例化的控件。使用以下代码 sn-p 来解决您手头的问题：

// Paste this snippet in the beginning of your method
if (InvokeRequired)
{
   this.Invoke(new MethodInvoker(/*Enter the name of your method here*/));
   return;
}
// Method code goes here ......

/*
    Example:
    private void SomeMethod(object sender, EventArgs e) {
       if (InvokeRequired)
       {
         this.Invoke(new MethodInvoker(SomeMethod)); // Name of current method is 'SomeMethod'
         return;
       }
       // Code continues here
       int x,y,z;
       // Do something .....
    }
*/

希望这会有所帮助。