因为近来想写个类似于远程桌面监控的程序,该程序中要用到屏幕捕捉.为实现该程序的一部分功能,做了个小DEMO.程序很简单，用到的技术也不多，只能实现类似qq的截图功能(方法虽然很笨)
程序流程如下：

1.截取整个屏幕并保存
2.新开一个全屏窗口,将保存的屏幕作为背景
3.鼠标拖动改变截取范围,右键取消
4.双击截取,保存在粘贴板,全屏窗口关闭

好了,下面的是代码部分

首先新建一个项目ScreenCutter(VS2005),将窗体名改为MainForm,再新建一个窗体ScreenBody.
添加一个按钮btnCutter到ScreenCutter并添加按钮事件:
        private void btnCutter_Click(object sender, EventArgs e)
        {
            Image img = new Bitmap(Screen.AllScreens[0].Bounds.Width, Screen.AllScreens[0].Bounds.Height);
            Graphics g = Graphics.FromImage(img);
            g.CopyFromScreen(new Point(0, 0), new Point(0, 0), Screen.AllScreens[0].Bounds.Size);
            ScreenBody body = new ScreenBody();
            body.BackgroundImage = img;
            body.Show();
        }Screen.AllScreens[0]是获取当前所有设备窗口的第一个,我这里只有一个显示器,当然我就是第一个.
利用Graphics的CopyFromScreen函数获取当前屏幕.

好了,现在按下按钮全屏窗口就会出来了.

下面讲全屏窗口ScreenBody,首先设置窗体的FormBorderStyle为None,然后声明以下变量
private Graphics MainPainter;  //主画笔
private Pen pen;               //就是笔咯
private bool isDowned;         //判断鼠标是否按下
private bool RectReady;         //矩形是否绘制完成
private Image baseImage;       //基本图形(原来的画面)
private Rectangle Rect;        //就是要保存的矩形
private Point downPoint;        //鼠标按下的点
int tmpx;                    
int tmpy;
之后就是窗体的鼠标函数了,里面很多代码都没有作出整理,看了一下,整理后的代码应该会更少更精简的

private void ScreenBody_DoubleClick(object sender, EventArgs e)
{
    if (((MouseEventArgs)e).Button == MouseButtons.Left &&Rect.Contains(((MouseEventArgs)e).X, ((MouseEventArgs)e).Y))
    {
        //保存的时候有很多种方法的......我这里只用了这种
        Image memory = new Bitmap(Rect.Width, Rect.Height);
        Graphics g = Graphics.FromImage(memory);
        g.CopyFromScreen(Rect.X + 1, Rect.Y + 1, 0, 0, Rect.Size);
        Clipboard.SetImage(memory);
        this.Close();
    }
}

private void ScreenBody_MouseDown(object sender, MouseEventArgs e)
{
    if (e.Button == MouseButtons.Left)
    {
        isDowned = true;
       
        if (RectReady == false)
        {
            Rect.X = e.X;
            Rect.Y = e.Y;
            downPoint = new Point(e.X, e.Y);
        }
        if (RectReady == true)
        {
            tmpx = e.X;
            tmpy = e.Y;
        }
    }
    if (e.Button == MouseButtons.Right)
    {
        if (RectReady != true)
        {
            this.Close();
            return;
        }
        MainPainter.DrawImage(baseImage, 0, 0);
        RectReady = false;
    }

}

private void ScreenBody_MouseUp(object sender, MouseEventArgs e)
{
    if (e.Button == MouseButtons.Left)
    {
        isDowned = false;
        RectReady = true;
    }
}

private void ScreenBody_MouseMove(object sender, MouseEventArgs e)
{

    if (RectReady == false)
    {
        if (isDowned == true)
        {
            Image New = DrawScreen((Image)baseImage.Clone(), e.X, e.Y);
            MainPainter.DrawImage(New, 0, 0);
            New.Dispose();
        }
    }
    if (RectReady == true)
    {
        if (Rect.Contains(e.X, e.Y))
        {
            //this.Cursor = Cursors.Hand;
            if (isDowned == true)
            {
                //和上一次的位置比较获取偏移量
                Rect.X = Rect.X + e.X - tmpx;
                Rect.Y = Rect.Y + e.Y - tmpy;
                //记录现在的位置
                tmpx = e.X;
                tmpy = e.Y;
                MoveRect((Image)baseImage.Clone(), Rect);
            }
        }
    }
   
}

private void ScreenBody_Load(object sender, EventArgs e)
{
    this.WindowState = FormWindowState.Maximized;
    MainPainter = this.CreateGraphics();
    pen = new Pen(Brushes.Blue);
    isDowned = false;
    baseImage = this.BackgroundImage;
    Rect = new Rectangle();
    RectReady = false;
}

辅助函数
本来应该写更多的辅助函数的,将窗体响应函数里面的代码放到里面来,不过本人很懒,就这样将就了.呵呵

private void DrawRect(Graphics Painter, int Mouse_x, int Mouse_y)
{
    int width = 0;
    int heigth = 0;
    if (Mouse_y < Rect.Y)
    {
        Rect.Y = Mouse_y;
        heigth = downPoint.Y - Mouse_y;
    }
    else
    {
        heigth = Mouse_y - downPoint.Y;
    }
    if (Mouse_x < Rect.X)
    {
        Rect.X = Mouse_x;
        width = downPoint.X - Mouse_x;
    }
    else
    {
        width = Mouse_x - downPoint.X;
    }
    Rect.Size = new Size(width, heigth);
    Painter.DrawRectangle(pen, Rect);
}

private Image DrawScreen(Image back, int Mouse_x, int Mouse_y)
{
    Graphics Painter = Graphics.FromImage(back);
    DrawRect(Painter, Mouse_x, Mouse_y);
    return back;
}
private void MoveRect(Image image, Rectangle Rect)
{
    Graphics Painter = Graphics.FromImage(image);
    Painter.DrawRectangle(pen, Rect.X, Rect.Y, Rect.Width, Rect.Height);
    DrawRects(Painter);
    MainPainter.DrawImage(image, 0, 0);
    image.Dispose();
}

到这里,代码就算是写完了,运行
http://www.cnblogs.com/kevin-wu/archive/2006/12/24/601989.html