我有一堆要加载到表单中的 ElementHost。发生这种情况时,元素主机都显示为黑色背景。如果我将另一个控件放在前面,然后关闭另一个控件,则 ElementHosts 将正常重新绘制。经过一番谷歌搜索,我发现如果我将 ElementHost 子类化并在构造函数中执行此操作
using (CreateGraphics()) { }
ElementHosts 都是用良好的背景绘制的……但是,每个元素主机大约需要 300 毫秒才能出现在表单上……而且它们是按顺序出现的……所以就像看着表单布局一样……我有,当然手动调用了 SuspendLayout 和 ResumeLayout,但这不会改变结果。
这只是 Windows 窗体集成错误吗?或者我可以做些什么来使控件以合理的速度正确显示?
谢谢。
更新:我可以用非常简单的代码重现问题:
public partial class TestControl2 : UserControl
{
public TestControl2()
{
InitializeComponent();
}
protected override void OnLoad(EventArgs e)
{
base.OnLoad(e);
// deferring load with the BackgroundWorker seems to be related to the problem here...
var bw = new BackgroundWorker();
bw.DoWork += delegate { Thread.Sleep(2000); };
bw.RunWorkerCompleted += delegate
{
int x = 0;
int y = 0;
for (int i = 0; i < 20; i++)
{
var control = new Panel();
control.Width = 200;
control.Height = 80;
control.Controls.Add(new ElementHost { Child = new System.Windows.Controls.Label { Content = @"Hello" }, Dock = DockStyle.Left, Size = new System.Drawing.Size(75, 23) });
control.Controls.Add(new ElementHost { Child = new System.Windows.Controls.Button { Content = @"button" }, Dock = DockStyle.Fill });
var uc2 = new UserControl();
uc2.Controls.Add(control);
control.Dock = DockStyle.Fill;
uc2.Left = x;
uc2.Top = y;
x += control.Width + 10;
// adding using (uc2.CreateGraphics()) {} fixes the problem but slows down the load so it looks like each UserControl is being added one at a time
panel1.Controls.Add(uc2);
}
};
bw.RunWorkerAsync();
}
}