using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Windows.Forms;
using System.Drawing;namespace WindowsApplication2{class ResizeAction{bool IsMoving = false;int ctrlLastWidth = 0;int ctrlLastHeight = 0;int ctrlWidth;int ctrlHeight;int ctrlLeft;int ctrlTop;int cursorL;int cursorT;int ctrlLastLeft;int ctrlLastTop;int Htap;int Wtap;bool ctrlIsResizing = false;System.Drawing.Rectangle ctrlRectangle = new System.Drawing.Rectangle();private Control ctrl;private Form frm;public ResizeAction(Control c, Form frm){ctrl = c;this.frm = frm;this.Htap = this.frm.Height - this.frm.ClientRectangle.Height;this.Wtap = this.frm.Width - this.frm.ClientRectangle.Width;ctrl.MouseDown += new MouseEventHandler(MouseDown);ctrl.MouseMove += new MouseEventHandler(MouseMove);ctrl.MouseUp += new MouseEventHandler(MouseUp);}public void MouseMove(object sender, MouseEventArgs e){if (frm == null)return;if (e.Button == MouseButtons.Left){if (this.IsMoving){if (ctrlLastLeft == 0)ctrlLastLeft = ctrlLeft;if (ctrlLastTop == 0)ctrlLastTop = ctrlTop;int locationX = (Cursor.Position.X - this.cursorL + this.frm.DesktopLocation.X + this.Wtap + this.ctrl.Location.X);int locationY = (Cursor.Position.Y - this.cursorT + this.frm.DesktopLocation.Y + this.Htap + this.ctrl.Location.Y);if (locationX < this.frm.DesktopLocation.X + this.Wtap)locationX = this.frm.DesktopLocation.X + this.Wtap;if (locationY < this.frm.DesktopLocation.Y + this.Htap)locationY = this.frm.DesktopLocation.Y + this.Htap;this.ctrlLeft = locationX;this.ctrlTop = locationY;ctrlRectangle.Location = new System.Drawing.Point(this.ctrlLastLeft, this.ctrlLastTop);ctrlRectangle.Size = new System.Drawing.Size(ctrlWidth, ctrlHeight);ControlPaint.DrawReversibleFrame(ctrlRectangle, Color.Empty, System.Windows.Forms.FrameStyle.Dashed);ctrlLastLeft = ctrlLeft;ctrlLastTop = ctrlTop;ctrlRectangle.Location = new System.Drawing.Point(ctrlLeft, ctrlTop);ctrlRectangle.Size = new System.Drawing.Size(ctrlWidth, ctrlHeight);ControlPaint.DrawReversibleFrame(ctrlRectangle, Color.Empty, System.Windows.Forms.FrameStyle.Dashed);return;}int sizeageX = (Cursor.Position.X - this.frm.DesktopLocation.X - this.Wtap - this.ctrl.Location.X);int sizeageY = (Cursor.Position.Y - this.frm.DesktopLocation.Y - this.Htap - this.ctrl.Location.Y);if (sizeageX < 2)sizeageX = 1;if (sizeageY < 2)sizeageY = 1;ctrlWidth = sizeageX;ctrlHeight = sizeageY;if (ctrlLastWidth == 0)ctrlLastWidth = ctrlWidth;if (ctrlLastHeight == 0)ctrlLastHeight = ctrlHeight;if (ctrlIsResizing){ctrlRectangle.Location = new System.Drawing.Point(this.frm.DesktopLocation.X + this.ctrl.Left + this.Wtap, this.frm.DesktopLocation.Y + this.Htap + this.ctrl.Top);ctrlRectangle.Size = new System.Drawing.Size(ctrlLastWidth, ctrlLastHeight);}ctrlIsResizing = true;ControlPaint.DrawReversibleFrame(ctrlRectangle, Color.Empty, System.Windows.Forms.FrameStyle.Dashed);ctrlLastWidth = ctrlWidth;ctrlLastHeight = ctrlHeight;ctrlRectangle.Location = new System.Drawing.Point(this.frm.DesktopLocation.X + this.Wtap + this.ctrl.Left, this.frm.DesktopLocation.Y + this.Htap + this.ctrl.Top);ctrlRectangle.Size = new System.Drawing.Size(ctrlWidth, ctrlHeight);ControlPaint.DrawReversibleFrame(ctrlRectangle, Color.Empty, System.Windows.Forms.FrameStyle.Dashed);}}public void MouseDown(object sender, MouseEventArgs e){if (frm == null)return;if (e.X < this.ctrl.Width - 10 || e.Y < this.ctrl.Height - 10){this.IsMoving = true;this.ctrlLeft = this.frm.DesktopLocation.X + this.Wtap + this.ctrl.Left;this.ctrlTop = this.frm.DesktopLocation.Y + this.Htap + this.ctrl.Top;this.cursorL = Cursor.Position.X;this.cursorT = Cursor.Position.Y;this.ctrlWidth = this.ctrl.Width;this.ctrlHeight = this.ctrl.Height;}ctrlRectangle.Location = new System.Drawing.Point(this.ctrlLeft, this.ctrlTop);ctrlRectangle.Size = new System.Drawing.Size(ctrlWidth, ctrlHeight);ControlPaint.DrawReversibleFrame(ctrlRectangle, Color.Empty, System.Windows.Forms.FrameStyle.Dashed);}public void MouseUp(object sender, MouseEventArgs e){if (frm == null)return;ctrlIsResizing = false;if (this.IsMoving){ctrlRectangle.Location = new System.Drawing.Point(this.ctrlLeft, this.ctrlTop);ctrlRectangle.Size = new System.Drawing.Size(ctrlWidth, ctrlHeight);ControlPaint.DrawReversibleFrame(ctrlRectangle, Color.Empty, System.Windows.Forms.FrameStyle.Dashed);this.ctrl.Left = this.ctrlLeft - this.frm.DesktopLocation.X - this.Wtap;this.ctrl.Top = this.ctrlTop - this.frm.DesktopLocation.Y - this.Htap;this.IsMoving = false;this.ctrl.Refresh();return;}ctrlRectangle.Location = new System.Drawing.Point(this.frm.DesktopLocation.X + this.Wtap + this.ctrl.Left, this.frm.DesktopLocation.Y + this.Htap + this.ctrl.Top);ctrlRectangle.Size = new System.Drawing.Size(ctrlWidth, ctrlHeight);ControlPaint.DrawReversibleFrame(ctrlRectangle, Color.Empty, System.Windows.Forms.FrameStyle.Dashed);this.ctrl.Width = ctrlWidth;this.ctrl.Height = ctrlHeight;this.ctrl.Refresh();}}
}调用:private void Form1_Load(object sender, EventArgs e){//WindowsApplication2.ResizeAction rs = new WindowsApplication2.ResizeAction(this.label1,this);WindowsApplication2.ResizeAction rs = new WindowsApplication2.ResizeAction(this.button1, this);   }
参考：http://www.cnblogs.com/DS-CzY/archive/2007/06/30/801377.aspx