动态修改大小的Panel用户控件

定义一个透明的可以使用鼠标拖动，改变大小的透明Panel用户控件，可以显示黑色边框。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Drawing;

namespace CRectCtl
{
public class TransPannel :Panel
{
public TransPannel()
{
InitializeComponent();
initProperty();
}

//1、定义一个枚举类型，描述光标状态
private enum EnumMousePointPosition
{
MouseSizeNone = 0, //'无
MouseSizeRight = 1, //'拉伸右边框
MouseSizeLeft = 2, //'拉伸左边框
MouseSizeBottom = 3, //'拉伸下边框
MouseSizeTop = 4, //'拉伸上边框
MouseSizeTopLeft = 5, //'拉伸左上角
MouseSizeTopRight = 6, //'拉伸右上角
MouseSizeBottomLeft = 7, //'拉伸左下角
MouseSizeBottomRight = 8, //'拉伸右下角
MouseDrag = 9 // '鼠标拖动
}

//2、定义几个变量
const int Band = 5;
const int MinWidth = 10;
const int MinHeight = 10;
private EnumMousePointPosition m_MousePointPosition;
private Point p, p1;
//3、定义自己的MyMouseDown事件
private void MyMouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
{
p.X = e.X;
p.Y = e.Y;
p1.X = e.X;
p1.Y = e.Y;
}
//4、定义自己的MyMouseLeave事件
private void MyMouseLeave(object sender, System.EventArgs e)
{
m_MousePointPosition = EnumMousePointPosition.MouseSizeNone;
this.Cursor = Cursors.Arrow;
}
//5、设计一个函数，确定光标在控件不同位置的样式
private EnumMousePointPosition MousePointPosition(Size size, System.Windows.Forms.MouseEventArgs e)
{
if ((e.X >= -1 * Band) | (e.X <= size.Width) | (e.Y >= -1 * Band) | (e.Y <= size.Height))
{
if (e.X < Band)
{
if (e.Y < Band) {
Console.WriteLine("MouseSizeTopLeft");
return EnumMousePointPosition.MouseSizeTopLeft; }
else
{
if (e.Y > -1 * Band + size.Height)
{ return EnumMousePointPosition.MouseSizeBottomLeft; }
else
{ return EnumMousePointPosition.MouseSizeLeft; }
}
}
else
{
if (e.X > -1 * Band + size.Width)
{
if (e.Y < Band)
{ return EnumMousePointPosition.MouseSizeTopRight; }
else
{
if (e.Y > -1 * Band + size.Height)
{ return EnumMousePointPosition.MouseSizeBottomRight; }
else
{ return EnumMousePointPosition.MouseSizeRight; }
}
}
else
{
if (e.Y < Band)
{ return EnumMousePointPosition.MouseSizeTop; }
else
{
if (e.Y > -1 * Band + size.Height)
{ return EnumMousePointPosition.MouseSizeBottom; }
else
{ return EnumMousePointPosition.MouseDrag; }
}
}
}
}
else
{ return EnumMousePointPosition.MouseSizeNone; }
}

//6、定义自己的MyMouseMove事件，在这个事件里，会使用上面设计的函数
private void MyMouseMove(object sender, System.Windows.Forms.MouseEventArgs e)
{
Control lCtrl = (sender as Control);
if (e.Button == MouseButtons.Left)
{
switch (m_MousePointPosition)
{
case EnumMousePointPosition.MouseDrag:
lCtrl.Left = lCtrl.Left + e.X - p.X;
lCtrl.Top = lCtrl.Top + e.Y - p.Y;
break;
case EnumMousePointPosition.MouseSizeBottom:
lCtrl.Height = lCtrl.Height + e.Y - p1.Y;
p1.X = e.X;
p1.Y = e.Y; //'记录光标拖动的当前点
break;
case EnumMousePointPosition.MouseSizeBottomRight:
lCtrl.Width = lCtrl.Width + e.X - p1.X;
lCtrl.Height = lCtrl.Height + e.Y - p1.Y;
p1.X = e.X;
p1.Y = e.Y; //'记录光标拖动的当前点
break;
case EnumMousePointPosition.MouseSizeRight:
lCtrl.Width = lCtrl.Width + e.X - p1.X;
// lCtrl.Height = lCtrl.Height + e.Y - p1.Y;
p1.X = e.X;
p1.Y = e.Y; //'记录光标拖动的当前点
break;
case EnumMousePointPosition.MouseSizeTop:
lCtrl.Top = lCtrl.Top + (e.Y - p.Y);
lCtrl.Height = lCtrl.Height - (e.Y - p.Y);
break;
case EnumMousePointPosition.MouseSizeLeft:
lCtrl.Left = lCtrl.Left + e.X - p.X;
lCtrl.Width = lCtrl.Width - (e.X - p.X);
break;
case EnumMousePointPosition.MouseSizeBottomLeft:
lCtrl.Left = lCtrl.Left + e.X - p.X;
lCtrl.Width = lCtrl.Width - (e.X - p.X);
lCtrl.Height = lCtrl.Height + e.Y - p1.Y;
p1.X = e.X;
p1.Y = e.Y; //'记录光标拖动的当前点
break;
case EnumMousePointPosition.MouseSizeTopRight:
lCtrl.Top = lCtrl.Top + (e.Y - p.Y);
lCtrl.Width = lCtrl.Width + (e.X - p1.X);
lCtrl.Height = lCtrl.Height - (e.Y - p.Y);
p1.X = e.X;
p1.Y = e.Y; //'记录光标拖动的当前点
break;
case EnumMousePointPosition.MouseSizeTopLeft:
lCtrl.Left = lCtrl.Left + e.X - p.X;
lCtrl.Top = lCtrl.Top + (e.Y - p.Y);
lCtrl.Width = lCtrl.Width - (e.X - p.X);
lCtrl.Height = lCtrl.Height - (e.Y - p.Y);
break;
default:
break;
}
if (lCtrl.Width < MinWidth) lCtrl.Width = MinWidth;
if (lCtrl.Height < MinHeight) lCtrl.Height = MinHeight;
}
else
{
m_MousePointPosition = MousePointPosition(lCtrl.Size, e); //'判断光标的位置状态
switch (m_MousePointPosition) //'改变光标
{
case EnumMousePointPosition.MouseSizeNone:
this.Cursor = Cursors.Arrow; //'箭头
break;
case EnumMousePointPosition.MouseDrag:
this.Cursor = Cursors.SizeAll; //'四方向
break;
case EnumMousePointPosition.MouseSizeBottom:
this.Cursor = Cursors.SizeNS; //'南北
break;
case EnumMousePointPosition.MouseSizeTop:
this.Cursor = Cursors.SizeNS; //'南北
break;
case EnumMousePointPosition.MouseSizeLeft:
this.Cursor = Cursors.SizeWE; //'东西
break;
case EnumMousePointPosition.MouseSizeRight:
this.Cursor = Cursors.SizeWE; //'东西
break;
case EnumMousePointPosition.MouseSizeBottomLeft:
this.Cursor = Cursors.SizeNESW; //'东北到南西
break;
case EnumMousePointPosition.MouseSizeBottomRight:
this.Cursor = Cursors.SizeNWSE; //'东南到西北
break;
case EnumMousePointPosition.MouseSizeTopLeft:
this.Cursor = Cursors.SizeNWSE; //'东南到西北
break;
case EnumMousePointPosition.MouseSizeTopRight:
this.Cursor = Cursors.SizeNESW; //'东北到南西
break;
default:
break;
}
}
}

//7、制作一个初始化过程，将界面panel1上的所有控件都绑定MyMouseDown、MyMouseLeave、MyMouseMove事件，记得在Form初始化或者Form_Load时先执行它。
private void initProperty()
{

this.MouseDown += new System.Windows.Forms.MouseEventHandler(MyMouseDown);
this.MouseLeave += new System.EventHandler(MyMouseLeave);
this.MouseMove += new System.Windows.Forms.MouseEventHandler(MyMouseMove);

}

private void InitializeComponent()
{
this.SuspendLayout();
//
// TransPannel
//

SetStyle(ControlStyles.UserPaint, true);
SetStyle(ControlStyles.SupportsTransparentBackColor, true);
this.BackColor = Color.Transparent;

this.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
this.ResumeLayout(false);

}
}
}