C# ScreenCapture

Question

I am trying to capture the screen using Visual Studio 12 (sorry, we have to use 12) cand C#. I found an algorithm here: Capture screenshot of active window?

 ScreenCapture sc = new ScreenCapture();

I tried this and got an error message that the type or namespace is not found. This is not unexpected. I figured I just need another "using..." statement up at the top. I tried to do a search for which package to do a "using" on to get ScreenCapture() but I come up empty handed. Does anyone know?

Answer 1

According to the documentation you need to use Windows.Media.Capture. Please note that

Important

The ScreenCapture feature is only supported for mobile devices running Windows Phone 8.1. This API is not supported on Windows 10.

You can check this answer which works on all windows desktop platforms.

Answer 2

I think it is probably giving you an error around using System.Runtime.InteropServices;

You need to add the reference of the DLL System.Runtime.InteropServices

Answer 3

This lib doesn't seem to exist on NuGet. However, you can find it at Developer Fusion.

The downloads section only includes a zip file with the following class, that you can copy-paste in your VS Project

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

namespace ScreenShotDemo
{
    /// <summary>
    /// Provides functions to capture the entire screen, or a particular window, and save it to a file.
    /// </summary>
    public class ScreenCapture
    {
        /// <summary>
        /// Creates an Image object containing a screen shot of the entire desktop
        /// </summary>
        /// <returns></returns>
        public Image CaptureScreen() 
        {
            return CaptureWindow( User32.GetDesktopWindow() );
        }

        /// <summary>
        /// Creates an Image object containing a screen shot of a specific window
        /// </summary>
        /// <param name="handle">The handle to the window. (In windows forms, this is obtained by the Handle property)</param>
        /// <returns></returns>
        public Image CaptureWindow(IntPtr handle)
        {
            // get te hDC of the target window
            IntPtr hdcSrc = User32.GetWindowDC(handle);
            // get the size
            User32.RECT windowRect = new User32.RECT();
            User32.GetWindowRect(handle,ref windowRect);
            int width = windowRect.right - windowRect.left;
            int height = windowRect.bottom - windowRect.top;
            // create a device context we can copy to
            IntPtr hdcDest = GDI32.CreateCompatibleDC(hdcSrc);
            // create a bitmap we can copy it to,
            // using GetDeviceCaps to get the width/height
            IntPtr hBitmap = GDI32.CreateCompatibleBitmap(hdcSrc,width,height); 
            // select the bitmap object
            IntPtr hOld = GDI32.SelectObject(hdcDest,hBitmap);
            // bitblt over
            GDI32.BitBlt(hdcDest,0,0,width,height,hdcSrc,0,0,GDI32.SRCCOPY);
            // restore selection
            GDI32.SelectObject(hdcDest,hOld);
            // clean up 
            GDI32.DeleteDC(hdcDest);
            User32.ReleaseDC(handle,hdcSrc);

            // get a .NET image object for it
            Image img = Image.FromHbitmap(hBitmap);
            // free up the Bitmap object
            GDI32.DeleteObject(hBitmap);

            return img;
        }

        /// <summary>
        /// Captures a screen shot of a specific window, and saves it to a file
        /// </summary>
        /// <param name="handle"></param>
        /// <param name="filename"></param>
        /// <param name="format"></param>
        public void CaptureWindowToFile(IntPtr handle, string filename, ImageFormat format) 
        {
            Image img = CaptureWindow(handle);
            img.Save(filename,format);
        }

        /// <summary>
        /// Captures a screen shot of the entire desktop, and saves it to a file
        /// </summary>
        /// <param name="filename"></param>
        /// <param name="format"></param>
        public void CaptureScreenToFile(string filename, ImageFormat format) 
        {
            Image img = CaptureScreen();
            img.Save(filename,format);
        }

        /// <summary>
        /// Helper class containing Gdi32 API functions
        /// </summary>
        private class GDI32
        {

            public const int SRCCOPY = 0x00CC0020; // BitBlt dwRop parameter

            [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);
        }

        /// <summary>
        /// Helper class containing User32 API functions
        /// </summary>
        private class User32
        {
            [StructLayout(LayoutKind.Sequential)]
            public struct RECT
            {
                public int left;
                public int top;
                public int right;
                public int bottom;
            }

            [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 ReleaseDC(IntPtr hWnd,IntPtr hDC);
            [DllImport("user32.dll")]
            public static extern IntPtr GetWindowRect(IntPtr hWnd,ref RECT rect);

        }


    }
}