WebBrowser.DrawToBitmap()还是其他方法？

Question

我试图捕获WebBrowser控件的内容.DrawToBitmap()可以完美地工作,但WebBrowser控件的文档中不支持它.我一直试图找到另一种方法来捕获WebBrowser控件的内容并将它们保存到本地图像文件.

有没有人有任何变通办法或其他方法将WebBrowser控件的内容保存到本地图像文件？

Answer 1

Control.DrawToBitmap并不总是有效,所以我使用了以下本机API调用来提供更一致的结果:

公用事业类.调用Utilities.CaptureWindow(Control.Handle)来捕获特定控件:

public static class Utilities
{
    public static Image CaptureScreen()
    {
        return CaptureWindow(User32.GetDesktopWindow());
    }

    public static Image CaptureWindow(IntPtr handle)
    {

        IntPtr hdcSrc = User32.GetWindowDC(handle);

        RECT windowRect = new RECT();
        User32.GetWindowRect(handle, ref windowRect);

        int width = windowRect.right - windowRect.left;
        int height = windowRect.bottom - windowRect.top;

        IntPtr hdcDest = Gdi32.CreateCompatibleDC(hdcSrc);
        IntPtr hBitmap = Gdi32.CreateCompatibleBitmap(hdcSrc, width, height);

        IntPtr hOld = Gdi32.SelectObject(hdcDest, hBitmap);
        Gdi32.BitBlt(hdcDest, 0, 0, width, height, hdcSrc, 0, 0, ApiConstants.SRCCOPY);
        Gdi32.SelectObject(hdcDest, hOld);
        Gdi32.DeleteDC(hdcDest);
        User32.ReleaseDC(handle, hdcSrc);

        Image image = Image.FromHbitmap(hBitmap);
        Gdi32.DeleteObject(hBitmap);

        return image;
    }
}

Gdi32类:

public class Gdi32
{
    [DllImport("gdi32.dll")]
    public static extern bool BitBlt(IntPtr hObject, int nXDest, int nYDest, int nWidth, int nHeight, IntPtr hObjectSource, int nXSrc, int nYSrc, int dwRop);
    [DllImport("gdi32.dll")]
    public static extern IntPtr CreateCompatibleBitmap(IntPtr hDC, int nWidth, int nHeight);
    [DllImport("gdi32.dll")]
    public static extern IntPtr CreateCompatibleDC(IntPtr hDC);
    [DllImport("gdi32.dll")]
    public static extern bool DeleteDC(IntPtr hDC);
    [DllImport("gdi32.dll")]
    public static extern bool DeleteObject(IntPtr hObject);
    [DllImport("gdi32.dll")]
    public static extern IntPtr SelectObject(IntPtr hDC, IntPtr hObject);
}

User32类:

public static class User32
{
    [DllImport("user32.dll")]
    public static extern IntPtr GetDesktopWindow();
    [DllImport("user32.dll")]
    public static extern IntPtr GetWindowDC(IntPtr hWnd);
    [DllImport("user32.dll")]
    public static extern IntPtr GetWindowRect(IntPtr hWnd, ref RECT rect);
    [DllImport("user32.dll")]
    public static extern IntPtr ReleaseDC(IntPtr hWnd, IntPtr hDC);
}

使用的常数:

    public const int SRCCOPY = 13369376;

结构使用:

[StructLayout(LayoutKind.Sequential)]
public struct RECT
{
    public int left;
    public int top;
    public int right;
    public int bottom;
}

一个友好的控制扩展方法:

public static class ControlExtensions
{
    public static Image DrawToImage(this Control control)
    {
        return Utilities.CaptureWindow(control.Handle);
    }
}

这是我的CC.Utilities项目的代码片段,我专门编写它来从WebBrowser控件中截取屏幕截图.