c# - WPF:截取屏幕截图的方法

Question

希望修改以下内容以截取所有监视器的屏幕截图。我试过调整它，但我的图像是空白的。写到 test.png 是为了测试。 byte[] 将被发送到接收应用。

public byte[] Take()
{
    int screenWidth = Convert.ToInt32(SystemParameters.VirtualScreenWidth);
    int screenHeight = Convert.ToInt32(SystemParameters.VirtualScreenHeight);
    int screenLeft = Convert.ToInt32(SystemParameters.VirtualScreenLeft);
    int screenTop = Convert.ToInt32(SystemParameters.VirtualScreenTop);

    RenderTargetBitmap renderTarget = new RenderTargetBitmap(screenWidth, screenHeight, 96, 96, PixelFormats.Pbgra32);
    VisualBrush sourceBrush = new VisualBrush();

    DrawingVisual drawingVisual = new DrawingVisual();
    DrawingContext drawingContext = drawingVisual.RenderOpen();

    using (drawingContext)
    {
        drawingContext.PushTransform(new ScaleTransform(1, 1));
        drawingContext.DrawRectangle(sourceBrush, null, new Rect(new Point(0, 0), new Point(screenWidth, screenHeight)));
    }
    renderTarget.Render(drawingVisual);

    PngBitmapEncoder pngEncoder = new PngBitmapEncoder();
    pngEncoder.Frames.Add(BitmapFrame.Create(renderTarget));

    Byte[] _imageArray;

    using (MemoryStream outputStream = new MemoryStream())
    {
        pngEncoder.Save(outputStream);
        _imageArray = outputStream.ToArray();
    }

    using (FileStream stream = new FileStream(@"c:\test.png", FileMode.Create, FileAccess.ReadWrite))
    {
        using (BinaryWriter writer = new BinaryWriter(stream))
        {
            writer.Write(_imageArray);
        }
    }

    return _imageArray;
}

Answer 1

首先，您需要为以下命名空间添加引用:

using System.Drawing;
using System.Drawing.Imaging;
using System.Windows.Forms;

然后枚举您的监视器以获取所有显示表面的边界矩形并将其传递给 Graphics.CopyFromScreen() 方法调用:

private static BitmapSource CopyScreen()
{
    var left = Screen.AllScreens.Min(screen => screen.Bounds.X);
    var top = Screen.AllScreens.Min(screen => screen.Bounds.Y);
    var right = Screen.AllScreens.Max(screen => screen.Bounds.X + screen.Bounds.Width);
    var bottom = Screen.AllScreens.Max(screen => screen.Bounds.Y + screen.Bounds.Height);
    var width = right - left;
    var height = bottom - top;

    using (var screenBmp = new Bitmap(width, height, System.Drawing.Imaging.PixelFormat.Format32bppArgb))
    {
        using (var bmpGraphics = Graphics.FromImage(screenBmp))
        {
            bmpGraphics.CopyFromScreen(left, top, 0, 0, new System.Drawing.Size(width, height));
            return Imaging.CreateBitmapSourceFromHBitmap(
                screenBmp.GetHbitmap(),
                IntPtr.Zero,
                Int32Rect.Empty,
                BitmapSizeOptions.FromEmptyOptions());
        }
    }
}

请记住，虽然显示器通常不能整齐地放入一个矩形中，尤其是当它们具有不同的分辨率等时，因此您最好对各个屏幕进行快照。无论哪种方式，您的问题的解决方案是更改您传递给 Graphics.CopyFromScreen() 方法调用的坐标。

编辑:请参阅下面 Demetris Leptos 的评论，我在此答案中发布的代码应该在 screenBmp.GetHbitmap() 返回的位图上调用 DeleteObject 以避免内存泄漏，因为在 MSDN 文档中指定。