新建投影Form窗口“FormProjector”，添加pictureBox控件

在主窗口“FormMain”，添加代码

   //投影窗口FormProjector fProjector = new FormProjector();private void timerProjectorState_Tick(object sender, EventArgs e){Screen[] sc;sc = Screen.AllScreens;//判断连接为两个显示器则认为投影仪已经连接if (sc.Length > 1){labelProjectorState.Text = "状态：已连接";labelProjectorState.ForeColor = Color.Blue;if (fProjector.WindowState != FormWindowState.Maximized){fProjector.Left = Screen.AllScreens[1].Bounds.X + 10;fProjector.Top = Screen.AllScreens[1].Bounds.Y;fProjector.StartPosition = FormStartPosition.Manual;fProjector.Location = new System.Drawing.Point(sc[1].Bounds.Left, sc[1].Bounds.Top);fProjector.WindowState = FormWindowState.Maximized;fProjector.Show();}}else{labelProjectorState.Text = "状态：未连接";labelProjectorState.ForeColor = Color.Red;if (fProjector.WindowState == FormWindowState.Maximized){fProjector.WindowState = FormWindowState.Normal;fProjector.Hide();}}}private void proImg(){Image img = new Bitmap(@"J:\ref0.bmp");timerProjectorState.Enabled = true;//投影图片fProjector.pictureBoxShowImage.Image = img;}