从C#WinForm应用程序中的循环更改标签背景颜色

Question

我的应用程序中有一系列标签 -

    Label[] labels = new Label[8];      

我想按顺序改变循环中那些的背景颜色 -

    private void btnPrepare_Click(object sender, EventArgs e)
    {
        Application.DoEvents();
        for (int i = 0; i < 8; i++)
        {
           labels[i].BackColor = System.Drawing.Color.Red;
           System.Threading.Thread.Sleep(2000);
        }
    }

但所有变化都是一起出现的,而不是顺序出现的.

有帮助吗？

Answer 1

就像这样(快速修正):

private void btnPrepare_Click(object sender, EventArgs e) { 
  //DONE: foreach - no magic numbers (8)
  foreach (var lbl in labels) {
    lbl.BackColor = System.Drawing.Color.Red;
    lbl.Update(); // <- Update == force label repainting

    System.Threading.Thread.Sleep(2000);
  }
}

Application.DoEvents()是邪恶的:当你想要画画时,它会翻译所有事件,例如,形式关闭.

一个更好的办法是使用Task,而不是Thread:

// async: we're going to put await in the method
private async void btnPrepare_Click(object sender, EventArgs e) { 
  //DONE: foreach - no magic numbers (8)
  foreach (var lbl in labels) {
    lbl.BackColor = System.Drawing.Color.Red;

    // await: No need in force repainting, messages translating etc.
    await Task.Delay(2000);
  }
}