Get a screenshot of a specific application

Question

I know I can get the screenshot of the entire screen using Graphics.CopyFromScreen(). However, what if I just want the screenshot of a specific application?

Answer 1

The PrintWindow win32 api will capture a window bitmap even if the window is covered by other windows or if it is off screen:

[DllImport("user32.dll")] public static extern bool GetWindowRect(IntPtr hWnd, out RECT lpRect); [DllImport("user32.dll")] public static extern bool PrintWindow(IntPtr hWnd, IntPtr hdcBlt, int nFlags);  public static Bitmap PrintWindow(IntPtr hwnd)     {            RECT rc;             GetWindowRect(hwnd, out rc);      Bitmap bmp = new Bitmap(rc.Width, rc.Height, PixelFormat.Format32bppArgb);             Graphics gfxBmp = Graphics.FromImage(bmp);             IntPtr hdcBitmap = gfxBmp.GetHdc();              PrintWindow(hwnd, hdcBitmap, 0);        gfxBmp.ReleaseHdc(hdcBitmap);                    gfxBmp.Dispose();       return bmp;    } 

The reference to RECT above can be resolved with the following class:

[StructLayout(LayoutKind.Sequential)] public struct RECT {     private int _Left;     private int _Top;     private int _Right;     private int _Bottom;      public RECT(RECT Rectangle) : this(Rectangle.Left, Rectangle.Top, Rectangle.Right, Rectangle.Bottom)     {     }     public RECT(int Left, int Top, int Right, int Bottom)     {         _Left = Left;         _Top = Top;         _Right = Right;         _Bottom = Bottom;     }      public int X {         get { return _Left; }         set { _Left = value; }     }     public int Y {         get { return _Top; }         set { _Top = value; }     }     public int Left {         get { return _Left; }         set { _Left = value; }     }     public int Top {         get { return _Top; }         set { _Top = value; }     }     public int Right {         get { return _Right; }         set { _Right = value; }     }     public int Bottom {         get { return _Bottom; }         set { _Bottom = value; }     }     public int Height {         get { return _Bottom - _Top; }         set { _Bottom = value + _Top; }     }     public int Width {         get { return _Right - _Left; }         set { _Right = value + _Left; }     }     public Point Location {         get { return new Point(Left, Top); }         set {             _Left = value.X;             _Top = value.Y;         }     }     public Size Size {         get { return new Size(Width, Height); }         set {             _Right = value.Width + _Left;             _Bottom = value.Height + _Top;         }     }      public static implicit operator Rectangle(RECT Rectangle)     {         return new Rectangle(Rectangle.Left, Rectangle.Top, Rectangle.Width, Rectangle.Height);     }     public static implicit operator RECT(Rectangle Rectangle)     {         return new RECT(Rectangle.Left, Rectangle.Top, Rectangle.Right, Rectangle.Bottom);     }     public static bool operator ==(RECT Rectangle1, RECT Rectangle2)     {         return Rectangle1.Equals(Rectangle2);     }     public static bool operator !=(RECT Rectangle1, RECT Rectangle2)     {         return !Rectangle1.Equals(Rectangle2);     }      public override string ToString()     {         return "{Left: " + _Left + "; " + "Top: " + _Top + "; Right: " + _Right + "; Bottom: " + _Bottom + "}";     }      public override int GetHashCode()     {         return ToString().GetHashCode();     }      public bool Equals(RECT Rectangle)     {         return Rectangle.Left == _Left && Rectangle.Top == _Top && Rectangle.Right == _Right && Rectangle.Bottom == _Bottom;     }      public override bool Equals(object Object)     {         if (Object is RECT) {             return Equals((RECT)Object);         } else if (Object is Rectangle) {             return Equals(new RECT((Rectangle)Object));         }          return false;     } }