窗体截屏(含遮挡截屏)

using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
using System.Runtime.InteropServices;
using System.Windows.Forms;

class PicCompress
{
    public byte[] GetPictureData(string imagepath)
    {
        FileStream file = new FileStream(imagepath, FileMode.Open);
        byte[] by = new byte[file.Length];
        file.Read(by, 0, by.Length);
        file.Close();
        return by;
    }

    public byte[] GetPictureData(Image imgPhoto)
    {
        //将Image转换成流数据，并保存为byte[]
        MemoryStream mstream = new MemoryStream();
        imgPhoto.Save(mstream, System.Drawing.Imaging.ImageFormat.Bmp);
        byte[] byData = new Byte[mstream.Length];
        mstream.Position = 0;
        mstream.Read(byData, 0, byData.Length);
        mstream.Close();
        return byData;
    }


    /// <summary>
    /// 无损压缩图片
    /// </summary>
    /// <param name="sFile">原图片</param>
    /// <param name="dFile">压缩后保存位置</param>
    /// <param name="dHeight">高度</param>
    /// <param name="dWidth">宽度</param>
    /// <param name="flag">压缩质量 1-100</param>
    /// <returns></returns>
    public bool CompressImage(Image iSource, string dFile, int dHeight, int dWidth, int flag)
    {
        if (File.Exists(dFile))
        {
            File.Delete(dFile);
        }


        ImageFormat tFormat = iSource.RawFormat;
        int sW = 0, sH = 0;
        //按比例缩放
        Size tem_size = new Size(iSource.Width, iSource.Height);

        if (tem_size.Width > dHeight || tem_size.Width > dWidth)
        {
            if ((tem_size.Width * dHeight) > (tem_size.Height * dWidth))
            {
                sW = dWidth;
                sH = (dWidth * tem_size.Height) / tem_size.Width;
            }
            else
            {
                sH = dHeight;
                sW = (tem_size.Width * dHeight) / tem_size.Height;
            }
        }
        else
        {
            sW = tem_size.Width;
            sH = tem_size.Height;
        }
        Bitmap ob = new Bitmap(sW, sH);
        Graphics g = Graphics.FromImage(ob);
        g.Clear(Color.WhiteSmoke);
        g.CompositingQuality = CompositingQuality.HighQuality;
        g.SmoothingMode = SmoothingMode.HighQuality;
        g.InterpolationMode = InterpolationMode.HighQualityBicubic;
        g.DrawImage(iSource, new Rectangle(0, 0, sW, sH), 0, 0, iSource.Width, iSource.Height, GraphicsUnit.Pixel);
        g.Dispose();
        //以下代码为保存图片时，设置压缩质量
        EncoderParameters ep = new EncoderParameters();
        long[] qy = new long[1];
        qy[0] = flag;//设置压缩的比例1-100
        EncoderParameter eParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, qy);
        ep.Param[0] = eParam;
        try
        {
            ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders();
            ImageCodecInfo jpegICIinfo = null;
            for (int x = 0; x < arrayICI.Length; x++)
            {
                if (arrayICI[x].FormatDescription.Equals("JPEG"))
                {
                    jpegICIinfo = arrayICI[x];
                    break;
                }
            }
            if (jpegICIinfo != null)
            {
                ob.Save(dFile, jpegICIinfo, ep);//dFile是压缩后的新路径
            }
            else
            {
                ob.Save(dFile, tFormat);
            }
            return true;
        }
        catch
        {
            return false;
        }
        finally
        {
            iSource.Dispose();
            ob.Dispose();
        }

    }
    /// <summary>
    /// 有遮挡截屏
    /// </summary>
    /// <param name="fc"></param>
    /// <returns></returns>
    public Image CaptureScreen(Form fc)
    {
        Image MyImage = new Bitmap(fc.Width, fc.Height);
        Graphics g = Graphics.FromImage(MyImage);
        g.CopyFromScreen(fc.Location.X, fc.Location.Y, 0, 0, fc.Size);
        return MyImage;
    }

    /// <summary>
    /// 无遮挡截屏
    /// </summary>
    public Image CaptureScreen2(Form fc)
    {
        Image MyImage = null;
        IntPtr hdc = GetWindowDC(fc.Handle);
        LPPOINT lphook = new LPPOINT();
        lphook.x = 0;
        lphook.y = 0;

        ClientToScreen(fc.Handle, ref lphook);
        ScreenToClient(fc.Handle, ref lphook);
        Rectangle rect = new Rectangle(lphook.x, lphook.y, fc.Width, fc.Height);
        if (hdc != IntPtr.Zero)
        {
            IntPtr hdcMem = CreateCompatibleDC(hdc);
            if (hdcMem != IntPtr.Zero)
            {
                IntPtr hbitmap = CreateCompatibleBitmap(hdc, fc.Width, fc.Height);
                if (hbitmap != IntPtr.Zero)
                {
                    IntPtr ip = SelectObject(hdcMem, hbitmap);
                    if (ip != IntPtr.Zero)
                    {
                        bool a = PrintWindow(fc.Handle, hdcMem, 0);
                        DeleteObject(hbitmap);
                        Image tempImg = Image.FromHbitmap(hbitmap);
                        Bitmap b = new Bitmap(tempImg);
                        MyImage = b.Clone(rect, b.PixelFormat);
                    }
                }
            }
        }
        return MyImage;
    }



    [System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
    private static extern bool BitBlt(
          IntPtr hdcDest, // 目标 DC的句柄  
          int nXDest,
        int nYDest,
        int nWidth,
        int nHeight,
        IntPtr hdcSrc,  // 源DC的句柄  
          int nXSrc,
        int nYSrc,
        System.Int32 dwRop  // 光栅的处理数值  
          );

    [System.Runtime.InteropServices.DllImportAttribute("User32.dll")]
    private static extern IntPtr GetWindowDC(
         IntPtr hwnd
         );

    [System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
    private static extern IntPtr CreateCompatibleDC(
         IntPtr hdc
         );

    [System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
    private static extern IntPtr CreateCompatibleBitmap(
        IntPtr hdc,
        int nWidth,     // width of bitmap, in pixels  
        int nHeight // height of bitmap, in pixels  
         );

    [System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
    private static extern IntPtr SelectObject(
        IntPtr hdc,// handle to DC  
        IntPtr hgdiobj   // handle to object  
         );

    [System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
    private static extern bool DeleteObject(
        IntPtr hObject  // handle to graphic object  
         );

    [System.Runtime.InteropServices.DllImportAttribute("User32.dll")]
    private static extern bool PrintWindow(
          IntPtr hwnd,               // Window to copy  
          IntPtr hdcBlt,             // HDC to print into  
          int nFlags              // Optional flags  
         );

    [System.Runtime.InteropServices.DllImportAttribute("User32.dll")]
    private static extern int ReleaseDC(
          IntPtr hWnd,  // handle to window  
          IntPtr hDC     // handle to DC  
         );

    [System.Runtime.InteropServices.DllImportAttribute("User32.dll")]
    private static extern bool ScreenToClient(
            IntPtr hWnd,        // handle to window  
            ref LPPOINT lpPoint   // screen coordinates  
         );

    [System.Runtime.InteropServices.DllImportAttribute("User32.dll")]
    private static extern bool ClientToScreen(
            IntPtr hWnd,        // handle to window  
            ref LPPOINT lpPoint   // screen coordinates  
         );

    [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
    public struct LPPOINT
    {
        public int x;
        public int y;
    }
}

调用方法:

            PicCompress pc = new PicCompress();

            //无遮挡截屏

            Image memory = pc.CaptureScreen(this);

            //有遮挡截屏
            Image memory = pc.CaptureScreen2(this);
            //改路径
            string path = FilePath_PIC + "ABC.jpeg";

            //图像压缩
            pc.CompressImage(memory, path, this.Height, this.Width, 80);
            memory.Dispose();
            GC.Collect();