C#窗体程序实现全屏及取消全屏步骤

private Int16 zoom = -1;//用来控制点击此button4的时候，是需要全屏还是取消全屏
 //视频窗口的缩放代码
  private void button4_Click(object sender, EventArgs e)
  {
   if(zoom<0)
   {
    float w = this.Width - 210; //为了保证左边的控件不被挡上减了一个210
    float h = this.Height - 50;//为了底下的按钮不被挡上，因为还要用到，因此减了50
    this.VideoPlayWnd.Size = Size.Ceiling(new SizeF(w, h));//重新部署视频框即这个picturebox空间的长宽
    VideoPlayWnd.Location = new System.Drawing.Point(210, 0);//视频框的左上角坐标，会发现与我上边减去的210一致（大家肯定都理解为什么我就不说了）
    button4.Location = new System.Drawing.Point(795, 0);//不能只有picturebox变了，这个button的位置也要保证和视频框同步，所以需要重设坐标
    // button4.BackgroundImage = Image.FromFile(@"E:\lwj\addpersoninfo\addpersoninfo\Resources\退出全屏.png");//绝对路径（这是我测试的时候用的）
    button4.BackgroundImage = Image.FromFile(AppDomain.CurrentDomain.BaseDirectory + @"退出全屏.png");//AppDomain.CurrentDomain.BaseDirectory语句可以获取到你当前项目的bin目录，所以需要把图片放到对应目录下
    zoom = 1;//全屏之后，再点击需要取消全屏，因此要改变zoom的值
   }
   else
   { //以下为取消全屏，即还原自己的视频框和按钮，具体操作类似全屏，就不细致注释了
    VideoPlayWnd.Location = new System.Drawing.Point(495, 360);
    this.VideoPlayWnd.Size = Size.Ceiling(new SizeF(323, 271));
    button4.Location = new System.Drawing.Point(795, 360);
    button4.BackgroundImage = Image.FromFile(AppDomain.CurrentDomain.BaseDirectory + @"全屏.png");
    zoom = -1;//取消全屏后再点击就要进行全屏，因此继续设为-1（保证小于0，以满足全屏操作的if条件）
   }
  }

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
 
namespace CvNetVideo.Play
{
 class FullScreenHelper
 {
  bool m_bFullScreen = false;
  IntPtr m_OldWndParent = IntPtr.Zero;
  WINDOWPLACEMENT m_OldWndPlacement = new WINDOWPLACEMENT();
  Control m_control = null;
 
  public FullScreenHelper(Control c)
  {
   m_control = c;
  }
  struct POINT
  {
   int x;
   int y;
  };
  struct RECT
  {
   public int left;
   public int top;
   public int right;
   public int bottom;
  };
  //锁定指定窗口，禁止它更新。同时只能有一个窗口处于锁定状态。锁定指定窗口，禁止它更新。同时只能有一个窗口处于锁定状态
  [DllImport("User32.dll")]
  public static extern bool LockWindowUpdate(IntPtr hWndLock);
 
  //函数来设置弹出式窗口，层叠窗口或子窗口的父窗口。新的窗口与窗口必须属于同一应用程序
  [DllImport("User32.dll")]
  public static extern IntPtr SetParent(IntPtr hWndChild, IntPtr hWndNewParent);
 
  //函数设置指定窗口的显示状态和恢复，最大化，最小化位置。函数功能： 函及原型 
  [DllImport("User32.dll")]
  public static extern bool SetWindowPlacement(IntPtr hWnd, ref WINDOWPLACEMENT lpwndpl);
 
  //函数将创建指定窗口的线程设置到前台，并且激活该窗口。键盘输入转向该窗口，并为用户改各种可视的记号
  [DllImport("User32.dll")]
  public static extern bool SetForegroundWindow(IntPtr hWnd);
 
  //该函数返回桌面窗口的句柄。桌面窗口覆盖整个屏幕。桌面窗口是一个要在其上绘制所有的图标和其他窗口的区域
  [DllImport("User32.dll")]
  public static extern IntPtr GetDesktopWindow();
 
  //函数名。该函数返回指定窗口的显示状态以及被恢复的、最大化的和最小化的窗口位置
  [DllImport("User32.dll")]
  public static extern bool GetWindowPlacement(IntPtr hWnd, ref WINDOWPLACEMENT lpwndpl);
 
  //是用于得到被定义的系统数据或者系统配置信息的一个专有名词 
  [DllImport("User32.dll")]
  public static extern int GetSystemMetrics(int nIndex); 
 
  [DllImport("user32.dll", EntryPoint = "GetParent", SetLastError = true)]
  public static extern IntPtr GetParent(IntPtr hWnd);
  [DllImport("user32.dll", CharSet = CharSet.Auto)]
  public static extern int SetWindowPos(IntPtr hWnd, int hWndInsertAfter, int x, int y, int Width, int Height, int flags);
  [DllImport("user32.dll", CharSet = CharSet.Auto)]
  public static extern System.IntPtr GetForegroundWindow();
  [DllImport("user32")]
  public static extern bool GetWindowRect(IntPtr hwnd, out RECT lpRect);
  [DllImport("user32.dll")]
  public static extern uint ScreenToClient(IntPtr hwnd, ref POINT p);
   public void FullScreen(bool flag)
  {
   m_bFullScreen = flag;
   if (!m_bFullScreen)
   {
    LockWindowUpdate(m_control.Handle);
    SetParent(m_control.Handle, m_OldWndParent);
    SetWindowPlacement(m_control.Handle, ref m_OldWndPlacement);
    SetForegroundWindow(m_OldWndParent);
    LockWindowUpdate(IntPtr.Zero);
   }
   else
   {
    GetWindowPlacement(m_control.Handle, ref m_OldWndPlacement);
    int nScreenWidth = GetSystemMetrics(0);
    int nScreenHeight = GetSystemMetrics(1);
    m_OldWndParent = GetParent(m_control.Parent.Handle);
    SetParent(m_control.Handle, GetDesktopWindow());
    WINDOWPLACEMENT wp1 = new WINDOWPLACEMENT();
    wp1.length = (uint)Marshal.SizeOf(wp1);
    wp1.showCmd = 1;
    wp1.rcNormalPosition.left = 0;
    wp1.rcNormalPosition.top = 0;
    wp1.rcNormalPosition.right = nScreenWidth;
    wp1.rcNormalPosition.bottom = nScreenHeight;
    SetWindowPlacement(m_control.Handle, ref wp1);
    SetForegroundWindow(GetDesktopWindow());
    SetForegroundWindow(m_control.Handle);
   }
   m_bFullScreen = !m_bFullScreen;
  }
  struct WINDOWPLACEMENT
  {
   public uint length;
   public uint flags;
   public uint showCmd;
   public POINT ptMinPosition;
   public POINT ptMaxPosition;
   public RECT rcNormalPosition;
  };
 }
}

 /// <summary>
  /// 全屏事件
  /// </summary>
  /// <param name="sender"></param>
  /// <param name="e"></param>
  private void UCVideo_DoubleClick(object sender, EventArgs e)
  {
   //全屏设置
   //sdlVideo.SDL_MaximizeWindow();
   fullScreenHelper = new CvNetVideo.Play.FullScreenHelper(this);
   fullScreenHelper.FullScreen(true);
   Console.WriteLine("Entrance FullScreen Mode");
  }
  /// <summary>
  /// 按键弹起事件
  /// </summary>
  private void UCVideo_KeyUp(object sender, KeyEventArgs e)
  {
   // ESC 退出全屏
   if (e.KeyCode == Keys.Escape&& fullScreenHelper!=null)
   {
    fullScreenHelper.FullScreen(false);
    fullScreenHelper = null;
    Console.WriteLine("Exit FullScreen Mode");
   }   
  }

public void SDL_MaximizeWindow()
  {
   Console.WriteLine("设置全屏");
 
   SDL.SDL_MaximizeWindow(screen);
   SDL.SDL_SetWindowFullscreen(screen, SDL.SDL_GetWindowFlags(screen));
   SDL.SDL_ShowWindow(screen);
 
   //int width, height;
    获取最大窗口值
   //SDL2.SDL.SDL_GetWindowMaximumSize(screen, out width, out height);
    设置最大窗口值
   //if (width>0&&height>0)
   //{
   // SDL2.SDL.SDL_SetWindowMaximumSize(screen, width, height);
   // Console.WriteLine("设置全屏......成功!width=" + width + ",height=" + height);
   /