private void palyBtn_Click(object sender, EventArgs e) { if (touchlessMgr.Markers.Count == 0) { MessageBox.Show("请先设置一个Marker。"); return; } if (drawDemo == null) { drawDemo = new DrawPicture(touchlessMgr, pictureBoxDisplay.Bounds, imgBox.Text); palyBtn.Text = "停止"; } else { drawDemo.Dispose(); drawDemo = null; palyBtn.Text = "开始"; } }