抓取屏幕，分析屏幕上的目标小图片位置，代码犀利，速度很快

原文：http://www.codeproject.com/Articles/25025/Screen-Scraper-in-Managed-Code

Screen Scraper in Managed Code

核心代码：

public List<Point> findImages()
{
    Bitmap bm = getDesktopBitmap();
    BitmapData bmd = bm.LockBits(new Rectangle(0, 0, bm.Width, bm.Height),
                                ImageLockMode.ReadOnly, bm.PixelFormat);
    List<Point> results = new List<Point>();
    foundRects = new List<Rectangle>();

    for (int y = 0; y < bmd.Height; y++)
    {
        byte* scanline = (byte*)bmd.Scan0 + (y * bmd.Stride);

        for (int x = 0; x < bmd.Width; x++)
        {
            int xo = x * PIXLESIZE;
            byte[] buff = { scanline[xo], scanline[xo + 1], 
                            scanline[xo + 2], 0xff };
            int val = BitConverter.ToInt32(buff, 0);

            // Pixle value from subimage in desktop image
            if (pixels.ContainsKey(val) && notFound(x, y))
            {
                Point loc = (Point)pixels[val];

                int sx = x - loc.X; 
                int sy = y - loc.Y;
                // Subimage occurs in desktop image 
                if (imageThere(bmd, sx, sy))
                {
                    Point p = new Point(x - loc.X, y - loc.Y);
                    results.Add(p);
                    foundRects.Add(new Rectangle(x, y, bmImage.Width, 
                                                       bmImage.Height));
                }
            }
        }
    }

    return results;
}

private bool imageThere(BitmapData bmd, int sx, int sy)
{
    int ix;

    for (int iy = 0; iy < bmImage.Height; iy++)
    {
        // Horizontal line of pixles in the bitmap data
        byte* scanline = (byte*)bmd.Scan0 + ((sy + iy) * bmd.Stride);

        for (ix = 0; ix < bmImage.Width; ix++)
        {
            // Offset into the scan line
            int xo = (sx + ix) * PIXLESIZE;
            // Convert PixelFormat.Format24bppRgb
            // to PixelFormat.Format32bppArgb
            byte[] buff = { scanline[xo], scanline[xo + 1], 
                            scanline[xo + 2], 0xff };
            // Pixle value
            int val = BitConverter.ToInt32(buff, 0);

            if (val != image[ix, iy])
                return false;
        }
        ix = 0;
    }

    return true;
}

private bool notFound(int x, int y)
{
    Point p = new Point(x, y);
    foreach (Rectangle r in foundRects)
    {
        if (r.Contains(p))
            return false;
    }

    return true;
}

获取屏幕图片

private static Bitmap getDesktopBitmap()
{
    SendKeys.SendWait("^{PRTSC}");
    Bitmap bm = new Bitmap(Clipboard.GetImage());
    Clipboard.Clear();
    return bm;
}

demo：
桌面



我从右侧的广告上截了个小图：



用工具查找下：



很是牛B吧，作者本来打算用来分析网页源码的，这么搞也是很有想法。

几点注意的地方：

There are a couple of things to keep in mind when using this program:

Requires the images loaded are in 32 bit ARGB format

The time it takes to run is dependent on the existence of a good unique pixel value

On a 2 GHz Athelon with a 15.4'' screen, about .5 sec. for most images

About 30 sec. for small white images and white screen background

The Print Screen functionality was only tested on Windows XP, and may not work the same on Vista, etc.