WinForm Methods that Restrict Forms from Moving Off Screen
- 2021-07-26 08:45:56
- OfStack
This article illustrates how WinForm restricts forms from moving off-screen. Share it for your reference. The specific implementation method is as follows:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Drawing;
using System.Runtime.InteropServices;
namespace AppForm
{
/// <summary>
/// WinForm Restrict the form from moving off-screen
/// </summary>
public class FrmBase : 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);
}
}
}
}
I hope this article is helpful to everyone's C # programming.