Capture screenshot of active window

Question

I am making a screen capturing application and everything is going fine   All I need to do is capture the active window and take a screenshot of this active window   Does anyone know how I can do this

User · Answer

You can use the code from this question  How can I save a screenshot directly to a file in Windows   Just change WIN32 API GetDesktopWindow   to the Handle property of the window you want to capture

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Works if the Desktop scaling is set  public class ScreenCapture        DllImport  quot user32 dll quot        private static extern IntPtr GetForegroundWindow          DllImport  quot user32 dll quot   CharSet   CharSet Auto  ExactSpelling   true       public static extern IntPtr GetDesktopWindow          StructLayout LayoutKind Sequential       private struct Rect               public int Left          public int Top          public int Right          public int Bottom              DllImport  quot user32 dll quot        private static extern IntPtr GetWindowRect IntPtr hWnd  ref Rect rect        public static Image CaptureDesktop                 return CaptureWindow GetDesktopWindow                public static Bitmap CaptureActiveWindow                 return CaptureWindow GetForegroundWindow                public static Bitmap CaptureWindow IntPtr handle                var rect   new Rect            GetWindowRect handle  ref rect           GetScale getScale   new GetScale            var bounds   new Rectangle rect Left  rect Top   int   rect Right - rect Left   getScale getScalingFactor      int   rect Bottom - rect Top    getScale getScalingFactor              var result   new Bitmap bounds Width  bounds Height            using  var graphics   Graphics FromImage result                         graphics CopyFromScreen new Point bounds Left  bounds Top   Point Empty  bounds Size                      return result

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Here is a snippet to capture either the desktop or the active window  It has no reference to Windows Forms   public class ScreenCapture        DllImport  user32 dll        private static extern IntPtr GetForegroundWindow          DllImport  user32 dll   CharSet   CharSet Auto  ExactSpelling   true       public static extern IntPtr GetDesktopWindow          StructLayout LayoutKind Sequential       private struct Rect               public int Left          public int Top          public int Right          public int Bottom                 DllImport  user32 dll        private static extern IntPtr GetWindowRect IntPtr hWnd  ref Rect rect        public static Image CaptureDesktop                 return CaptureWindow GetDesktopWindow                public static Bitmap CaptureActiveWindow                 return CaptureWindow GetForegroundWindow                public static Bitmap CaptureWindow IntPtr handle                var rect   new Rect            GetWindowRect handle  ref rect           var bounds   new Rectangle rect Left  rect Top  rect Right - rect Left  rect Bottom - rect Top           var result   new Bitmap bounds Width  bounds Height            using  var graphics   Graphics FromImage result                         graphics CopyFromScreen new Point bounds Left  bounds Top   Point Empty  bounds Size                      return result            How to capture the whole screen   var image   ScreenCapture CaptureDesktop    image Save   C  temp snippetsource jpg   ImageFormat Jpeg     How to capture the active window   var image   ScreenCapture CaptureActiveWindow    image Save   C  temp snippetsource jpg   ImageFormat Jpeg     Originally found here  http   www snippetsource net Snippet 158 capture-screenshot-in-c

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Use the following code                    Shot size   screen size             Size shotSize   Screen PrimaryScreen Bounds Size                  the upper left point in the screen to start shot                0 0 to get the shot from upper left point             Point upperScreenPoint   new Point 0  0                   the upper left point in the image to put the shot             Point upperDestinationPoint   new Point 0  0                   create image to get the shot in it             Bitmap shot   new Bitmap shotSize Width  shotSize Height                   new Graphics instance              Graphics graphics   Graphics FromImage shot                   get the shot by Graphics class              graphics CopyFromScreen upperScreenPoint  upperDestinationPoint  shotSize                   return the image             pictureBox1 Image   shot

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I suggest next solution for capturing any current active window  not only our C  application  or entire screen with cursor position determination relative to left-top corner of window or screen respectively        public enum enmScreenCaptureMode       Screen      Window    class ScreenCapturer        DllImport  user32 dll        private static extern IntPtr GetForegroundWindow          DllImport  user32 dll        private static extern IntPtr GetWindowRect IntPtr hWnd  ref Rect rect         StructLayout LayoutKind Sequential       private struct Rect               public int Left          public int Top          public int Right          public int Bottom             public Bitmap Capture enmScreenCaptureMode screenCaptureMode   enmScreenCaptureMode Window                Rectangle bounds           if  screenCaptureMode    enmScreenCaptureMode Screen                        bounds   Screen GetBounds Point Empty               CursorPosition   Cursor Position                    else                       var foregroundWindowsHandle   GetForegroundWindow                var rect   new Rect                GetWindowRect foregroundWindowsHandle  ref rect               bounds   new Rectangle rect Left  rect Top  rect Right - rect Left  rect Bottom - rect Top               CursorPosition   new Point Cursor Position X - rect Left  Cursor Position Y - rect Top                      var result   new Bitmap bounds Width  bounds Height            using  var g   Graphics FromImage result                         g CopyFromScreen new Point bounds Left  bounds Top   Point Empty  bounds Size                      return result             public Point CursorPosition               get          protected set

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A little tweak to method static void ImageSave   will grant you the option where to save it  Credit goes to Microsoft  http   msdn microsoft com en-us library sfezx97z aspx   static void ImageSave string filename  ImageFormat format  Image image  SaveFileDialog saveFileDialog1                 saveFileDialog1 Filter    JPeg Image   jpg Bitmap Image   bmp Gif Image   gif           saveFileDialog1 Title    Enregistrer un image           saveFileDialog1 ShowDialog                If the file name is not an empty string open it for saving          if  saveFileDialog1 FileName                                 Saves the Image via a FileStream created by the OpenFile method              System IO FileStream fs                   System IO FileStream saveFileDialog1 OpenFile                   Saves the Image in the appropriate ImageFormat based upon the                File type selected in the dialog box                 NOTE that the FilterIndex property is one-based              switch  saveFileDialog1 FilterIndex                                case 1                      image Save fs                         System Drawing Imaging ImageFormat Jpeg                       break                   case 2                      image Save fs                         System Drawing Imaging ImageFormat Bmp                       break                   case 3                      image Save fs                         System Drawing Imaging ImageFormat Gif                       break                             fs Close                         Your button click event should be coded something like this     private void btnScreenShot Click object sender  EventArgs e                 SaveFileDialog saveFileDialog1   new SaveFileDialog              ScreenCapturer CaptureAndSave filename  mode  format  saveFileDialog1

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ScreenCapture sc   new ScreenCapture       capture entire screen  and save it to a file Image img   sc CaptureScreen       display image in a Picture control named imageDisplay this imageDisplay Image   img     capture this window  and save it sc CaptureWindowToFile this Handle  C   temp2 gif  ImageFormat Gif     http   www developerfusion com code 4630 capture-a-screen-shot

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Rectangle bounds   Screen GetBounds Point Empty   using Bitmap bitmap   new Bitmap bounds Width  bounds Height         using Graphics g   Graphics FromImage bitmap                  g CopyFromScreen Point Empty  Point Empty  bounds Size             bitmap Save  test jpg   ImageFormat Jpeg       for capturing current window use   Rectangle bounds   this Bounds   using  Bitmap bitmap   new Bitmap bounds Width  bounds Height          using  Graphics g   Graphics FromImage bitmap                 g CopyFromScreen new Point bounds Left bounds Top   Point Empty  bounds Size             bitmap Save  C   test jpg   ImageFormat Jpeg

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KvanTTT s code worked great   I extended it a bit to allow a little more flexibility on save format  as well as the ability to save by hWnd   NET Control Form   You can get a bitmap or save to file  with a few options     using System  using System Drawing  using System Drawing Imaging  using System IO  using System Runtime InteropServices  using System Windows Forms   namespace MosaiqPerformanceMonitor        public enum CaptureMode             Screen  Window              public static class ScreenCapturer              DllImport  user32 dll              private static extern IntPtr GetForegroundWindow                DllImport  user32 dll              private static extern IntPtr GetWindowRect IntPtr hWnd  ref Rect rect               StructLayout LayoutKind Sequential             private struct Rect                   public int Left                  public int Top                  public int Right                  public int Bottom                          DllImport  user32 dll   CharSet   CharSet Auto  ExactSpelling   true             public static extern IntPtr GetDesktopWindow                    lt summary gt  Capture Active Window  Desktop  Window or Control by hWnd or  NET Contro Form and save it to a specified file    lt  summary gt                 lt param name  filename  gt Filename                 lt para gt   If extension is omitted  it s calculated from the type of file lt  para gt                 lt para gt   If path is omitted  defaults to  TEMP  lt  para gt                 lt para gt   Use  NOW  to put a timestamp in the filename lt  para gt  lt  param gt                 lt param name  mode  gt Optional  The default value is CaptureMode Window  lt  param gt                 lt param name  format  gt Optional file save mode   Default is PNG lt  param gt            public static void CaptureAndSave string filename  CaptureMode mode   CaptureMode Window  ImageFormat format   null                    ImageSave filename  format  Capture mode                                lt summary gt  Capture a specific window  or control  and save it to a specified file    lt  summary gt                 lt param name  filename  gt Filename                 lt para gt   If extension is omitted  it s calculated from the type of file lt  para gt                 lt para gt   If path is omitted  defaults to  TEMP  lt  para gt                 lt para gt   Use  NOW  to put a timestamp in the filename lt  para gt  lt  param gt                 lt param name  handle  gt hWnd  handle  of the window to capture lt  param gt                 lt param name  format  gt Optional file save mode   Default is PNG lt  param gt            public static void CaptureAndSave string filename  IntPtr handle  ImageFormat format   null                    ImageSave filename  format  Capture handle                                lt summary gt  Capture a specific window  or control  and save it to a specified file    lt  summary gt                 lt param name  filename  gt Filename                 lt para gt   If extension is omitted  it s calculated from the type of file lt  para gt                 lt para gt   If path is omitted  defaults to  TEMP  lt  para gt                 lt para gt   Use  NOW  to put a timestamp in the filename lt  para gt  lt  param gt                 lt param name  c  gt Object to capture lt  param gt                 lt param name  format  gt Optional file save mode   Default is PNG lt  param gt            public static void CaptureAndSave string filename  Control c  ImageFormat format   null                    ImageSave filename  format  Capture c                               lt summary gt  Capture the active window  default  or the desktop and return it as a bitmap  lt  summary gt                 lt param name  mode  gt Optional  The default value is CaptureMode Window  lt  param gt            public static Bitmap Capture CaptureMode mode   CaptureMode Window                    return Capture mode    CaptureMode Screen   GetDesktopWindow     GetForegroundWindow                                 lt summary gt  Capture a  NET Control  Form  UserControl  etc   lt  summary gt                 lt param name  c  gt Object to capture lt  param gt                 lt returns gt  Bitmap of control s area  lt  returns gt            public static Bitmap Capture Control c                    return Capture c Handle                                lt summary gt  Capture a specific window and return it as a bitmap  lt  summary gt                 lt param name  handle  gt hWnd  handle  of the window to capture lt  param gt            public static Bitmap Capture IntPtr handle                    Rectangle bounds                  var rect   new Rect                    GetWindowRect handle  ref rect                   bounds   new Rectangle rect Left  rect Top  rect Right - rect Left  rect Bottom - rect Top                   CursorPosition   new Point Cursor Position X - rect Left  Cursor Position Y - rect Top                    var result   new Bitmap bounds Width  bounds Height                   using  var g   Graphics FromImage result                        g CopyFromScreen new Point bounds Left  bounds Top   Point Empty  bounds Size                    return result                              lt summary gt  Position of the cursor relative to the start of the capture  lt  summary gt            public static Point CursorPosition                   lt summary gt  Save an image to a specific file  lt  summary gt                 lt param name  filename  gt Filename                 lt para gt   If extension is omitted  it s calculated from the type of file lt  para gt                 lt para gt   If path is omitted  defaults to  TEMP  lt  para gt                 lt para gt   Use  NOW  to put a timestamp in the filename lt  para gt  lt  param gt                 lt param name  format  gt Optional file save mode   Default is PNG lt  param gt                 lt param name  image  gt Image to save   Usually a BitMap  but can be any               Image  lt  param gt            static void ImageSave string filename  ImageFormat format  Image image                    format   format    ImageFormat Png                  if   filename Contains                            filename   filename Trim           format ToString   ToLower                     if   filename Contains                             filename   Path Combine Environment GetEnvironmentVariable  TEMP        C  Temp   filename                    filename   filename Replace   NOW    DateTime Now ToString  yyyy-MM-dd hh mm ss                     image Save filename  format

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Based on ArsenMkrt s reply  but this one allows you to capture a control in your form  I m writing a tool for example that has a WebBrowser control in it and want to capture just its display   Note the use of PointToScreen method     Project  WebCapture   Filename  ScreenshotUtils cs   Author  George Birbilis  http   zoomicon com    Version  20130820  using System Drawing  using System Windows Forms   namespace WebCapture     public static class ScreenshotUtils          public static Rectangle Offseted this Rectangle r  Point p              r Offset p         return r             public static Bitmap GetScreenshot this Control c              return GetScreenshot new Rectangle c PointToScreen Point Empty   c Size               public static Bitmap GetScreenshot Rectangle bounds              Bitmap bitmap   new Bitmap bounds Width  bounds Height         using  Graphics g   Graphics FromImage bitmap           g CopyFromScreen new Point bounds Left  bounds Top   Point Empty  bounds Size         return bitmap             public const string DEFAULT IMAGESAVEFILEDIALOG TITLE    Save image       public const string DEFAULT IMAGESAVEFILEDIALOG FILTER    PNG Image    png    png JPEG Image    jpg    jpg Bitmap Image    bmp    bmp GIF Image    gif    gif        public const string CUSTOMPLACES COMPUTER    0AC0837C-BBF8-452A-850D-79D08E667CA7       public const string CUSTOMPLACES DESKTOP    B4BFCC3A-DB2C-424C-B029-7FE99A87C641       public const string CUSTOMPLACES DOCUMENTS    FDD39AD0-238F-46AF-ADB4-6C85480369C7       public const string CUSTOMPLACES PICTURES    33E28130-4E1E-4676-835A-98395C3BC3BB       public const string CUSTOMPLACES PUBLICPICTURES    B6EBFB86-6907-413C-9AF7-4FC2ABF07CC5       public const string CUSTOMPLACES RECENT    AE50C081-EBD2-438A-8655-8A092E34987A        public static SaveFileDialog GetImageSaveFileDialog        string title   DEFAULT IMAGESAVEFILEDIALOG TITLE         string filter   DEFAULT IMAGESAVEFILEDIALOG FILTER              SaveFileDialog dialog   new SaveFileDialog           dialog Title   title        dialog Filter   filter               this seems to throw error on Windows Server 2008 R2  must be for Windows Vista only       dialog CustomPlaces Add CUSTOMPLACES COMPUTER         dialog CustomPlaces Add CUSTOMPLACES DESKTOP         dialog CustomPlaces Add CUSTOMPLACES DOCUMENTS         dialog CustomPlaces Add CUSTOMPLACES PICTURES         dialog CustomPlaces Add CUSTOMPLACES PUBLICPICTURES         dialog CustomPlaces Add CUSTOMPLACES RECENT                   return dialog             public static void ShowSaveFileDialog this Image image  IWin32Window owner   null              using  SaveFileDialog dlg   GetImageSaveFileDialog            if  dlg ShowDialog owner     DialogResult OK            image Save dlg FileName                  Having the Bitmap object you can just call Save on it  private void btnCapture Click object sender  EventArgs e      webBrowser GetScreenshot   Save  C   test jpg   ImageFormat Jpeg       The above assumes the GC will grab the bitmap  but maybe it s better to assign the result of someControl getScreenshot   to a Bitmap variable  then dispose that variable manually when finished with each image  especially if you re doing this grabbing often  say you have a list of webpages you want to load and save screenshots of them    private void btnCapture Click object sender  EventArgs e      Bitmap bitmap   webBrowser GetScreenshot      bitmap ShowSaveFileDialog      bitmap Dispose      release bitmap resources     Even better  could employ a using clause  which has the added benefit of releasing the bitmap resources even in case of an exception occuring inside the using  child  block   private void btnCapture Click object sender  EventArgs e      using Bitmap bitmap   webBrowser GetScreenshot        bitmap ShowSaveFileDialog        exit from using block will release bitmap resources even if exception occured     Update   Now WebCapture tool is ClickOnce-deployed  http   gallery clipflair net WebCapture  from the web  also has nice autoupdate support thanks to ClickOnce  and you can find its source code at https   github com Zoomicon ClipFlair tree master Server Tools WebCapture

User · Answer

I assume you use Graphics CopyFromScreen to get the screenshot   You can use P Invoke to GetForegroundWindow  and then get its position and size  to determine which region you need to copy from

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If you want to use managed code  This will capture any window via the ProcessId   I used the following to make the window active   Microsoft VisualBasic Interaction AppActivate ProcessId   Threading Thread Sleep 20     I used the print screen to capture a window   SendKeys SendWait    PRTSC     Threading Thread Sleep 40   IDataObject objData   Clipboard GetDataObject

[c#] Capture screenshot of active window?

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