How to update the value of a control in a WinForm child thread

1. How to set the value of the control in the WinForm sub-thread?

In WinForm, child threads cannot directly operate UI controls, but the value of the control can be updated in the child thread through the following methods:

1. Use the Invoke method:

   • In the child thread, call the delegate through the control's Invoke method to perform the update operation on the UI thread. Sample code:

   private void UpdateControlValue(string value)
   {
       if (control.InvokeRequired)
       {
           control.Invoke(new Action(() => { control.Text = value; }));
       }
       else
       {
           control.Text = value;
       }
   }

2. Using BeginInvoke method:

   • Similar to Invoke , but BeginInvoke is asynchronous and will not block child threads. Sample code:

   private void UpdateControlValue(string value)
   {
       if (control.InvokeRequired)
       {
           control.BeginInvoke(new Action(() => { control.Text = value; }));
       }
       else
       {
           control.Text = value;
       }
   }

With the above method, you can safely update the control value in WinForm in the child thread.

2. How to display some pictures in a loop at the bottom of a WinForm form when it is running?

To cycle through some pictures at the bottom of the WinForm form, you can use the Timer control to achieve this. The following are the detailed steps:

1. Add a Timer control:

   • In WinForm, drag a from the toolbox Timer control to the form.

2. Set the Timer property:

   • Set the Interval of Timer Property, indicating the time interval (milliseconds) for image switching.

3. Add a PictureBox control:

   • Add a PictureBox control in the bottom area for display image.

4. Load the picture list:

   • Create a picture list in the code, and then use TimerTick events cycle to switch pictures.

   List<Image> imageList = new List<Image>(); // 存储图片的列表
   int currentIndex = 0; // 当前显示的图片索引
   
   private void LoadImages()
   {
       // 加载图片到imageList中
       imageList.Add(Properties.Resources.Image1);
       imageList.Add(Properties.Resources.Image2);
       // 添加更多图片...
   
       // 初始化PictureBox显示第一张图片
       pictureBox.Image = imageList[currentIndex];
   }

5. Timer Tick event:

   • Tick## at Timer #Update the picture displayed in PictureBox in the event.

   private void timer_Tick(object sender, EventArgs e)
   {
       // 循环切换图片
       currentIndex = (currentIndex + 1) % imageList.Count;
       pictureBox.Image = imageList[currentIndex];
   }

6. Start Timer:

   Start
   • Timer in the form load event.

   private void Form_Load(object sender, EventArgs e)
   {
       LoadImages(); // 加载图片
       timer.Start(); // 启动Timer
   }

Through the above steps, you can display some pictures in a loop at the bottom of the WinForm form.

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