实现了界面可以像QQ一样像上伸缩

#region 类似QQ的往上伸缩的功能
/*
* 可以做一个像QQ一样往上收的功能
* 使用说明:
* 在窗体加载的事件中添加两句话
*  intOriHeight = this.Height;
*  JudgeWinMouPosition.Enabled = true;
*/
//实现类似QQ可以伸缩到屏幕上方
#region 声明本程序中用到的API函数
//获取当前鼠标下可视化控件的函数
[System.Runtime.InteropServices.DllImport("user32.dll")]
public static extern int WindowFromPoint(int xPoint, int yPoint);
//获取指定句柄的父级函数
[System.Runtime.InteropServices.DllImport("user32.dll", ExactSpelling = true, CharSet = System.Runtime.InteropServices.CharSet.Auto)]
public static extern IntPtr GetParent(IntPtr hWnd);
//获取屏幕的大小
[System.Runtime.InteropServices.DllImport("user32.dll", EntryPoint = "GetSystemMetrics")]
private static extern int GetSystemMetrics(int mVal);
#endregion

#region 运行本程序需要声明的变量
private IntPtr CurrentHandle;//记录鼠标当前状态下控件的句柄
private int WindowFlag;//标记是否对窗体进行拉伸操作
private int intOriHeight;
#endregion

#region 获取鼠标当前状态下控件的句柄
/// <summary>
/// 获取鼠标当前状态下控件的句柄
/// </summary>
/// <param name="x">当前鼠标的X坐标</param>
/// <param name="y">当前鼠标的Y坐标</param>
/// <returns></returns>
public IntPtr MouseNowPosition(int x, int y)
{
IntPtr OriginalHandle;//声明保存原始句柄的变量
OriginalHandle = ((IntPtr)WindowFromPoint(x, y));//获取包含鼠标原始位置的窗口的句柄
CurrentHandle = OriginalHandle;//设置当前句柄
while (OriginalHandle != ((IntPtr)0))//循环判断鼠标是否移动
{
CurrentHandle = OriginalHandle;//记录当前的句柄
OriginalHandle = GetParent(CurrentHandle);//更新原始句柄
}
return CurrentHandle;  //返回当前的句柄
}
#endregion

public int OriHeight
{
get { return intOriHeight; }
}

private void JudgeWinMouPosition_Tick(object sender, EventArgs e)
{
if (this.Top < 3)                       //当本窗体距屏幕的上边距小于3px时
{
if (this.Handle == MouseNowPosition(Cursor.Position.X, Cursor.Position.Y))//当鼠标在该窗体上时
{
WindowFlag = 1;                //设定当前的窗体状态
HideWindow.Enabled = false;     //设定计时器HideWindow为不可用状态
this.Top = 0;                 //设定窗体上边缘与容器工作区上边缘之间的距离
}
else                              //当鼠标没在窗体上时
{
WindowFlag = 1;                //设定当前的窗体状态
HideWindow.Enabled = true;      //启动计时器HideWindow

}
}                                     //当本窗体距屏幕的上边距大于3px时
else
{
//当本窗体在屏幕的最左端或者最右端、最下端时
if (this.Left < 3 || (this.Left + this.Width) > (GetSystemMetrics(0) - 3) || (this.Top + this.Height) > (Screen.AllScreens[0].Bounds.Height - 3))
{
if (this.Left < 3)              //当窗体处于屏幕左侧时
{
if (this.Handle == MouseNowPosition(Cursor.Position.X, Cursor.Position.Y))    //当鼠标在该窗体上时
{
this.Height = Screen.AllScreens[0].Bounds.Height - 40;
this.Top = 3;
WindowFlag = 2;        //设定当前的窗体状态
HideWindow.Enabled = false;//设定计时器HideWindow为不可用状态
this.Left = 0;         //设定窗体的左边缘与容器工作区的左边缘之间的距离
}
else                      //当鼠标没在该窗体上时
{
WindowFlag = 2;        //设定当前的窗体状态
HideWindow.Enabled = true;//设定计时器HideWindow为可用状态

}
}
if ((this.Left + this.Width) > (GetSystemMetrics(0) - 3)) //当窗体处于屏幕的最右侧时
{
if (this.Handle == MouseNowPosition(Cursor.Position.X, Cursor.Position.Y))//当鼠标处于窗体上时
{
this.Height = Screen.AllScreens[0].Bounds.Height - 40;
this.Top = 3;
WindowFlag = 3;        //设定当前的窗体状态
HideWindow.Enabled = false; //设定计时器HideWindow为不可用状态
this.Left = GetSystemMetrics(0) - this.Width;//设定该窗体与容器工作区左边缘之间的距离
}
else                          //当鼠标离开窗体时
{
WindowFlag = 3;            //设定当前的窗体状态
HideWindow.Enabled = true;  //设定计时器HideWindow为可用状态
}
}
//当窗体距屏幕最下端的距离小于3px时
if ((this.Top + this.Height) > (Screen.AllScreens[0].Bounds.Height - 3))
{
if (this.Handle == MouseNowPosition(Cursor.Position.X, Cursor.Position.Y)) //当鼠标在该窗体上时
{
WindowFlag = 4;           //设定当前的窗体状态
HideWindow.Enabled = false;//设定计时器HideWindow为不可用状态
this.Top = Screen.AllScreens[0].Bounds.Height - this.Height;//设定该窗体与容器工作区上边缘之间的距离
}
else
{
if ((this.Left > this.Width + 3) && (GetSystemMetrics(0) - this.Right) > 3)
{
WindowFlag = 4;           //设定当前的窗体状态
HideWindow.Enabled = true; //设定计时器HideWindow为可用状态
}
}
}
}
}
}

private void HideWindow_Tick(object sender, EventArgs e)
{
switch (Convert.ToInt32(WindowFlag.ToString())) //判断当前窗体处于那个状态
{
case 1:             //当窗体处于最上端时
if (this.Top < 3)   //当窗体与容器工作区的上边缘的距离小于5px时
this.Top = -(this.Height - 2);  //设定当前窗体距容器工作区上边缘的值
break;
case 2:              //当窗体处于最左端时
if (this.Left < 3)//当窗体与容器工作区的左边缘的距离小于5px时
this.Left = -(this.Width - 2); //设定当前窗体据容器工作区左边缘的值
break;
case 3:             //当窗体处于最右端时
if ((this.Left + this.Width) > (GetSystemMetrics(0) - 3))  //当窗体与容器工作区的右边缘的距离小于5px时
this.Left = GetSystemMetrics(0) - 2;    //设定当前窗体距容器工作区左边缘的值
break;
case 4:             //当窗体处于最低端时
if (this.Bottom > Screen.AllScreens[0].Bounds.Height - 3)//当窗体与容器工作区的下边缘的距离小于5px时
this.Top = Screen.AllScreens[0].Bounds.Height - 5;   //设定当前窗体距容器工作区上边缘之间的距离
break;
}
}

//当窗体离开左右隐藏区域时，窗体回复原有高度
private void MyQQMain_LocationChanged(object sender, EventArgs e)
{
if (this.Left > 3 && this.Right < (GetSystemMetrics(0) - 3))
{
if (this.Height == Screen.AllScreens[0].Bounds.Height - 40)
{
this.Height = OriHeight;
}
}
}

#endregion