在用VS的窗体设计器时，我们可以发现控件都是可以拖动的，并且还可以调整大小。怎么在自己的程序中可以使用上述功能呢？ 下面的方法值得借鉴！
using System;
using System.Windows.Forms;
using System.Drawing;
namespace ControlSizeChangeEx
{
/// <summary>
/// This class implements sizing and moving functions for
/// runtime editing of graphic controls
/// </summary>
public class PickBox
{
//////////////////////////////////////////////////////////////////
// PRIVATE CONSTANTS AND VARIABLES
//////////////////////////////////////////////////////////////////
private const int BOX_SIZE = 8;
private Color BOX_COLOR = Color.White;
private ContainerControl m_container;
private Control m_control;
private Label[] lbl = new Label[8];
private int startl;
private int startt;
private int startw;
private int starth;
private int startx;
private int starty;
private bool dragging;
private Cursor[] arrArrow = new Cursor[] {Cursors.SizeNWSE, Cursors.SizeNS,
Cursors.SizeNESW, Cursors.SizeWE, Cursors.SizeNWSE, Cursors.SizeNS,
Cursors.SizeNESW, Cursors.SizeWE};
private Cursor oldCursor;
private const int MIN_SIZE = 20;
//
// Constructor creates 8 sizing handles & wires mouse events
// to each that implement sizing functions
//
public PickBox()
{
for (int i = 0; i < 8; i++)
{
lbl[i] = new Label();
lbl[i].TabIndex = i;
lbl[i].FlatStyle = 0;
lbl[i].BorderStyle = BorderStyle.FixedSingle;
lbl[i].BackColor = BOX_COLOR;
lbl[i].Cursor = arrArrow[i];
lbl[i].Text = "";
lbl[i].BringToFront();
lbl[i].MouseDown += new MouseEventHandler(this.lbl_MouseDown);
lbl[i].MouseMove += new MouseEventHandler(this.lbl_MouseMove);
lbl[i].MouseUp += new MouseEventHandler(this.lbl_MouseUp);
}
}
//////////////////////////////////////////////////////////////////
// PUBLIC METHODS
//////////////////////////////////////////////////////////////////
//
// Wires a Click event handler to the passed Control
// that attaches a pick box to the control when it is clicked
//
public void WireControl(Control ctl)
{
ctl.Click += new EventHandler(this.SelectControl);
}
/////////////////////////////////////////////////////////////////
// PRIVATE METHODS
/////////////////////////////////////////////////////////////////
//
// Attaches a pick box to the sender Control
//
private void SelectControl(object sender, EventArgs e)
{
if (m_control is Control)
{
m_control.Cursor = oldCursor;
//Remove event any pre-existing event handlers appended by this class
m_control.MouseDown -= new MouseEventHandler(this.ctl_MouseDown);
m_control.MouseMove -= new MouseEventHandler(this.ctl_MouseMove);
m_control.MouseUp -= new MouseEventHandler(this.ctl_MouseUp);
m_control = null;
}
m_control = (Control)sender;
//Add event handlers for moving the selected control around
m_control.MouseDown += new MouseEventHandler(this.ctl_MouseDown);
m_control.MouseMove += new MouseEventHandler(this.ctl_MouseMove);
m_control.MouseUp += new MouseEventHandler(this.ctl_MouseUp);
//Add sizing handles to Control's <a href="http://lib.csdn.net/base/docker" class='replace_word' title="Docker知识库" target='_blank' style='color:#df3434; font-weight:bold;'>Container</a> (Form or PictureBox)
for (int i = 0; i < 8; i++)
{
m_control.Parent.Controls.Add(lbl[i]);
lbl[i].BringToFront();
}
//Position sizing handles around Control
MoveHandles();
//Display sizing handles
ShowHandles();
oldCursor = m_control.Cursor;
m_control.Cursor = Cursors.SizeAll;
}
public void Remove()
{
HideHandles();
m_control.Cursor = oldCursor;
}
private void ShowHandles()
{
if (m_control != null)
{
for (int i = 0; i < 8; i++)
{
lbl[i].Visible = true;
}
}
}
private void HideHandles()
{
for (int i = 0; i < 8; i++)
{
lbl[i].Visible = false;
}
}
private void MoveHandles()
{
int sX = m_control.Left - BOX_SIZE;
int sY = m_control.Top - BOX_SIZE;
int sW = m_control.Width + BOX_SIZE;
int sH = m_control.Height + BOX_SIZE;
int hB = BOX_SIZE / 2;
int[] arrPosX = new int[] {sX+hB, sX + sW / 2, sX + sW-hB, sX + sW-hB,
sX + sW-hB, sX + sW / 2, sX+hB, sX+hB};
int[] arrPosY = new int[] {sY+hB, sY+hB, sY+hB, sY + sH / 2, sY + sH-hB,
sY + sH-hB, sY + sH-hB, sY + sH / 2};
for (int i = 0; i < 8; i++)
lbl[i].SetBounds(arrPosX[i], arrPosY[i], BOX_SIZE, BOX_SIZE);
}
/////////////////////////////////////////////////////////////////
// MOUSE EVENTS THAT IMPLEMENT SIZING OF THE PICKED CONTROL
/////////////////////////////////////////////////////////////////
//
// Store control position and size when mouse button pushed over
// any sizing handle
//
private void lbl_MouseDown(object sender, MouseEventArgs e)
{
dragging = true;
startl = m_control.Left;
startt = m_control.Top;
startw = m_control.Width;
starth = m_control.Height;
HideHandles();
}
//
// Size the picked control in accordance with sizing handle being dragged
// 0 1 2
// 7 3
// 6 5 4
//
private void lbl_MouseMove(object sender, MouseEventArgs e)
{
int l = m_control.Left;
int w = m_control.Width;
int t = m_control.Top;
int h = m_control.Height;
if (dragging)
{
switch (((Label)sender).TabIndex)
{
case 0: // Dragging top-left sizing box
l = startl + e.X < startl + startw - MIN_SIZE ? startl + e.X : startl + startw - MIN_SIZE;
t = startt + e.Y < startt + starth - MIN_SIZE ? startt + e.Y : startt + starth - MIN_SIZE;
w = startl + startw - m_control.Left;
h = startt + starth - m_control.Top;
break;
case 1: // Dragging top-center sizing box
t = startt + e.Y < startt + starth - MIN_SIZE ? startt + e.Y : startt + starth - MIN_SIZE;
h = startt + starth - m_control.Top;
break;
case 2: // Dragging top-right sizing box
w = startw + e.X > MIN_SIZE ? startw + e.X : MIN_SIZE;
t = startt + e.Y < startt + starth - MIN_SIZE ? startt + e.Y : startt + starth - MIN_SIZE;
h = startt + starth - m_control.Top;
break;
case 3: // Dragging right-middle sizing box
w = startw + e.X > MIN_SIZE ? startw + e.X : MIN_SIZE;
break;
case 4: // Dragging right-bottom sizing box
w = startw + e.X > MIN_SIZE ? startw + e.X : MIN_SIZE;
h = starth + e.Y > MIN_SIZE ? starth + e.Y : MIN_SIZE;
break;
case 5: // Dragging center-bottom sizing box
h = starth + e.Y > MIN_SIZE ? starth + e.Y : MIN_SIZE;
break;
case 6: // Dragging left-bottom sizing box
l = startl + e.X < startl + startw - MIN_SIZE ? startl + e.X : startl + startw - MIN_SIZE;
w = startl + startw - m_control.Left;
h = starth + e.Y > MIN_SIZE ? starth + e.Y : MIN_SIZE;
break;
case 7: // Dragging left-middle sizing box
l = startl + e.X < startl + startw - MIN_SIZE ? startl + e.X : startl + startw - MIN_SIZE;
w = startl + startw - m_control.Left;
break;
}
l = (l < 0) ? 0 : l;
t = (t < 0) ? 0 : t;
m_control.SetBounds(l, t, w, h);
}
}
//
// Display sizing handles around picked control once sizing has completed
//
private void lbl_MouseUp(object sender, MouseEventArgs e)
{
dragging = false;
MoveHandles();
ShowHandles();
}
/////////////////////////////////////////////////////////////////
// MOUSE EVENTS THAT MOVE THE PICKED CONTROL AROUND THE FORM
/////////////////////////////////////////////////////////////////
//
// Get mouse pointer starting position on mouse down and hide sizing handles
//
private void ctl_MouseDown(object sender, MouseEventArgs e)
{
dragging = true;
startx = e.X;
starty = e.Y;
HideHandles();
}
//
// Reposition the dragged control
//
private void ctl_MouseMove(object sender, MouseEventArgs e)
{
if (dragging)
{
int l = m_control.Left + e.X - startx;
int t = m_control.Top + e.Y - starty;
int w = m_control.Width;
int h = m_control.Height;
l = (l < 0) ? 0 : ((l + w > m_control.Parent.ClientRectangle.Width) ?
m_control.Parent.ClientRectangle.Width - w : l);
t = (t < 0) ? 0 : ((t + h > m_control.Parent.ClientRectangle.Height) ?
m_control.Parent.ClientRectangle.Height - h : t);
m_control.Left = l;
m_control.Top = t;
}
}
//
// Display sizing handles around picked control once dragging has completed
//
private void ctl_MouseUp(object sender, MouseEventArgs e)
{
dragging = false;
MoveHandles();
ShowHandles();
}
}
}
创建一个PickBox对象 , 调用此对象的WireControl(你希望改变的控件);方法就行了。