您如何通过 .Net 代码截取网站截图？

Question

是否可以使用 .Net 代码截取任何给定 URL 的屏幕截图？

最简单的方法是什么？

Answer 1

偶然发现：http://pietschsoft.com/post/2008/07/C-Generate-WebPage-Thumbmail-Screenshot-Image.aspx

也许你可以使用一些东西？

Answer 2

我建议为此使用第三方方法，而不是自己做。不过，如果你坚持，那么强硬的方法是使用System.Diagnostics.Process 启动浏览器，然后使用GetDesktopImage 获取屏幕截图。

我确信有一个更简单的方法，但看起来像这样：

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;

public class PlatformInvokeGDI32
{
    public  const int SRCCOPY = 13369376;

    [DllImport("gdi32.dll",EntryPoint="DeleteDC")]
    public static extern IntPtr DeleteDC(IntPtr hDc);

    [DllImport("gdi32.dll",EntryPoint="DeleteObject")]
    public static extern IntPtr DeleteObject(IntPtr hDc);

    [DllImport("gdi32.dll",EntryPoint="BitBlt")]
    public static extern bool BitBlt(IntPtr hdcDest, int xDest, int yDest, int wDest, int hDest, IntPtr hdcSource, int xSrc, int ySrc, int RasterOp);

    [DllImport ("gdi32.dll",EntryPoint="CreateCompatibleBitmap")]
    public static extern IntPtr CreateCompatibleBitmap(IntPtr hdc,int nWidth, int nHeight);

    [DllImport ("gdi32.dll",EntryPoint="CreateCompatibleDC")]
    public static extern IntPtr CreateCompatibleDC(IntPtr hdc);

    [DllImport ("gdi32.dll",EntryPoint="SelectObject")]
    public static extern IntPtr SelectObject(IntPtr hdc,IntPtr bmp);
}

public class PlatformInvokeUSER32
{
    public const int SM_CXSCREEN = 0;
    public const int SM_CYSCREEN = 1;

    [DllImport("user32.dll", EntryPoint="GetDesktopWindow")]
    public static extern IntPtr GetDesktopWindow();

    [DllImport("user32.dll",EntryPoint="GetDC")]
    public static extern IntPtr GetDC(IntPtr ptr);

    [DllImport("user32.dll",EntryPoint="GetSystemMetrics")]
    public static extern int GetSystemMetrics(int abc);

    [DllImport("user32.dll",EntryPoint="GetWindowDC")]
    public static extern IntPtr GetWindowDC(Int32 ptr);

    [DllImport("user32.dll",EntryPoint="ReleaseDC")]
    public static extern IntPtr ReleaseDC(IntPtr hWnd,IntPtr hDc);
}

public class CaptureScreen
{
    public static Bitmap GetDesktopImage()
    {
        //In size variable we shall keep the size of the screen.
        SIZE size;

        //Variable to keep the handle to bitmap.
        IntPtr hBitmap;

        //Here we get the handle to the desktop device context.
        IntPtr  hDC = PlatformInvokeUSER32.GetDC(PlatformInvokeUSER32.GetDesktopWindow());

        //Here we make a compatible device context in memory for screen device context.
        IntPtr hMemDC = PlatformInvokeGDI32.CreateCompatibleDC(hDC);

        //We pass SM_CXSCREEN constant to GetSystemMetrics to get the
        //X coordinates of the screen.
        size.cx = PlatformInvokeUSER32.GetSystemMetrics(PlatformInvokeUSER32.SM_CXSCREEN);

        //We pass SM_CYSCREEN constant to GetSystemMetrics to get the Y coordinates of the screen.
        size.cy = PlatformInvokeUSER32.GetSystemMetrics (PlatformInvokeUSER32.SM_CYSCREEN);

        //We create a compatible bitmap of the screen size and using the screen device context.
        hBitmap = PlatformInvokeGDI32.CreateCompatibleBitmap(hDC, size.cx, size.cy);

        //As hBitmap is IntPtr, we cannot check it against null.
        //For this purpose, IntPtr.Zero is used.
        if(hBitmap != IntPtr.Zero)
        {
            //Here we select the compatible bitmap in the memeory device
            //context and keep the refrence to the old bitmap.
            IntPtr hOld = (IntPtr) PlatformInvokeGDI32.SelectObject(hMemDC, hBitmap);

            //We copy the Bitmap to the memory device context.
            PlatformInvokeGDI32.BitBlt(hMemDC, 0, 0, size.cx, size.cy, hDC, 0, 0, PlatformInvokeGDI32.SRCCOPY);

            //We select the old bitmap back to the memory device context.
            PlatformInvokeGDI32.SelectObject(hMemDC, hOld);

            //We delete the memory device context.
            PlatformInvokeGDI32.DeleteDC(hMemDC);

            //We release the screen device context.
            PlatformInvokeUSER32.ReleaseDC(PlatformInvokeUSER32.GetDesktopWindow(), hDC);

            //Image is created by Image bitmap handle and stored in local variable.
            Bitmap bmp = System.Drawing.Image.FromHbitmap(hBitmap);

            //Release the memory to avoid memory leaks.
            PlatformInvokeGDI32.DeleteObject(hBitmap);

            //This statement runs the garbage collector manually.
            GC.Collect();

            //Return the bitmap
            return bmp;
        }

        //If hBitmap is null, retun null.
        return null;
    }
}

//This structure shall be used to keep the size of the screen.
public struct SIZE
{
  public int cx;
  public int cy;
}

Answer 3

有几个 3rd 方组件可以做到这一点。显然这不是微不足道的，因为 Flash 之类的东西并不容易捕捉，例如。

我过去使用过HTMLSnapshot，对它很满意（它不是免费的，但很便宜）。

我衷心建议您不要浪费太多时间自行实施，因为您最终必然会重做这些 3rd 方解决方案已经处理的许多最终案例。

Answer 4

我进行了广泛搜索以找到解决此问题的方法，而使用 WebBrowser 和其他建议的问题是您需要大量访问该框。

迄今为止，这是我能找到的最好的第三方工具：

http://www.websitesscreenshot.com/

他们的 SEO 很糟糕，但我相信我是在论坛甚至 Stack 上找到他们的……我确实拥有许可证，而你得到的只是一个可供参考的 DLL。将许可证传递给构造函数会删除它们的水印。

在快速浏览 ILSpy 之后，我相信它的作用是解释 HTML 并转储图像以供您查看。

用法

保存网址

WebsitesScreenshot.WebsitesScreenshot  _Obj;
_Obj = new WebsitesScreenshot.WebsitesScreenshot ();
WebsitesScreenshot.WebsitesScreenshot.Result _Result;
_Result = _Obj.CaptureWebpage("http://www.google.com");
if (_Result == WebsitesScreenshot.WebsitesScreenshot.Result.Captured)
{
    _Obj.ImageFormat = WebsitesScreenshot.
        WebsitesScreenshot.ImageFormats.PNG;
    _Obj.SaveImage ("c:\\google.png");
}            
_Obj.Dispose();

保存原始 HTML 字符串

WebsitesScreenshot.WebsitesScreenshot _Obj;
_Obj=new WebsitesScreenshot.WebsitesScreenshot();
WebsitesScreenshot.WebsitesScreenshot.Result _Result;
_Result = _Obj.CaptureHTML(
"<html><body><h1> Hello world </h1></body></html>");
if (_Result == WebsitesScreenshot.WebsitesScreenshot.Result.Captured)
{
    _Obj.ImageFormat = WebsitesScreenshot.
        WebsitesScreenshot.ImageFormats.GIF;
    _Obj.SaveImage("c:\\test.gif");
}
_Obj.Dispose();

您可以在他们的使用页面上找到更多信息。在这里找到：

http://www.websitesscreenshot.com/Usage.html

希望这会有所帮助！

干杯！！