Winform软件，不要在线程里操作UI

Posted 2020-08-19 zeroone

对于Winform软件，不要在线程里操作UI，不要相信：StartForm.CheckForIllegalCrossThreadCalls = false;

于是，把所有的代码都改成主线程委托调用的方式

private delegate void SetTextHandle(string id, string value);

        private void ThreadSetText(string id, string value)
        {
            this.Controls.Find(id, true)[0].Text = value;
        }
        private void SetText(string id, string value)
        {
            if (this.InvokeRequired)
            {
                this.Invoke(new SetTextHandle(ThreadSetText), new object[] { id, value });
            }
            else
            {
                ThreadSetText(id, value);
            }
        }

2

// the canonical form (C# consumer)

public delegate void ControlStringConsumer(Control control, string text);  // defines a delegate type

public void SetText(Control control, string text) {
    if (control.InvokeRequired) {
        control.Invoke(new ControlStringConsumer(SetText), new object[]{control, text});  // invoking itself
    } else {
        control.Text=text;      // the "functional part", executing only on the main thread
    }
}

 3

public static class ControlHelpers
{
    public static void InvokeIfRequired<T>(this T control, Action<T> action) where T : ISynchronizeInvoke
    {
        if (control.InvokeRequired)
        {
            control.Invoke(new Action(() => action(control)), null);
        }
        else
        {
            action(control);
        }
    }
}

 

Use it like this:

private void UpdateSummary(string text)
{
    summary.InvokeIfRequired(s => { s.Text = text });
}

3

theLabel.Invoke(new Action(() => theLabel.Text = "hello world from worker thread!"));

 4

public static void InvokeIfRequired(this Control control, MethodInvoker action)
{
    if (control.InvokeRequired) {
        control.Invoke(action);
    } else {
        action();
    }
}

 调用：

richEditControl1.InvokeIfRequired(() =>
{
    // Do anything you want with the control here
    richEditControl1.RtfText = value;
    RtfHelpers.AddMissingStyles(richEditControl1);
});

 更新为:

public static void InvokeIfRequired(this ISynchronizeInvoke obj,
                                         MethodInvoker action)
{
    if (obj.InvokeRequired) {
        var args = new object[0];
        obj.Invoke(action, args);
    } else {
        action();
    }
}

 考虑仍出现异常时：

while (!control.Visible)
{
    System.Threading.Thread.Sleep(50);
}


5

public static void InvokeIfRequired(this Control c, Action<Control> action)
{
    if(c.InvokeRequired)
    {
        c.Invoke(new Action(() => action(c)));
    }
    else
    {
        action(c);
    }
}

 变更为：

public static void InvokeIfRequired<T>(this T c, Action<T> action) 
    where T : Control

 调用方法：

object1.InvokeIfRequired(c => { c.Visible = true; });