Winform 限制窗体只能在屏幕内, 不能拖拽到屏幕外面

198366809 · 发表于 2021-8-19 19:27:44

添加一个类文件"BaseForm.cs"

代码如下：

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Forms;
using System.Drawing;
using System.Runtime.InteropServices;

namespace WindowsFormsApp3
{
public class BaseForm : Form
{
      private Point _mouseDownPos;
      private bool _move;

      protected override void WndProc(ref Message m)
      {
         RECT nativeRect;
         switch (m.Msg)
         {
            case 0x20:
                  int lp = m.LParam.ToInt32();
                  if ((lp & 0xFFFF) == 2 &&
                  ((lp >> 0x10) & 0xFFFF) == 0x201)
                  {
                     _mouseDownPos = Control.MousePosition;
                     _move = true;
                  }
                  break;
            case 0x231:
                  if (_move)
                  {
                     Rectangle rect = Screen.GetWorkingArea(this);
                     nativeRect = new RECT(
                     _mouseDownPos.X - Location.X,
                     _mouseDownPos.Y - Location.Y,
                     rect.Right - (Bounds.Right - _mouseDownPos.X),
                     rect.Bottom - (Bounds.Bottom - _mouseDownPos.Y));
                     ClipCursor(ref nativeRect);
                  }
                  break;
            case 0x0232:
                  if (_move)
                  {
                     nativeRect = new RECT(Screen.GetWorkingArea(this));
                     ClipCursor(ref nativeRect);
                     _move = false;
                  }
                  break;
         }
         base.WndProc(ref m);
      }

      [DllImport("user32.dll")]
      public static extern bool ClipCursor(ref RECT lpRect);

      [StructLayout(LayoutKind.Sequential)]
      public struct RECT
      {
         public int Left;
         public int Top;
         public int Right;
         public int Bottom;

         public RECT(int left, int top, int right, int bottom)
         {
            Left = left;
            Top = top;
            Right = right;
            Bottom = bottom;
         }

         public RECT(Rectangle rect)
         {
            Left = rect.Left;
            Top = rect.Top;
            Right = rect.Right;
            Bottom = rect.Bottom;
         }

         public Rectangle Rect
         {
            get
            {
                  return new Rectangle(
                  Left,
                  Top,
                  Right - Left,
                  Bottom - Top);
            }
         }

         public Size Size
         {
            get
            {
                  return new Size(Right - Left, Bottom - Top);
            }
         }

         public static RECT FromXYWH(int x, int y, int width, int height)
         {
            return new RECT(x,
               y,
               x + width,
               y + height);
         }

         public static RECT FromRectangle(Rectangle rect)
         {
            return new RECT(rect.Left,
               rect.Top,
               rect.Right,
               rect.Bottom);
         }
      }
}
}

新建应用窗体"Form1.cs"，继承"BaseForm"

public partial class Form1 : BaseForm
{
public Form1()
{
      InitializeComponent();
}
}
调试运行，窗体只能在屏幕内部来回拖动，无法拖拽到屏幕外。

来源：C#社区

原文：https://www.hicsharp.com/a/0c2ee4aded234c8fa023c9f751a57061