I'd Cap That

A buddy suggested I do a Vim how-to.  The only problem I have is that, on Windows, I don't have an animated window capture utility to provide proof of the power of this programmer's editor.  So, in preparation, I decided to see if I could build one.  Here's how.

Google-Fu

Darn skippy I copied all of this -- and in just three queries:

https://www.google.com/search?q=.net+screenshot

https://www.google.com/search?q=get+window+by+title

https://www.google.com/search?q=pinvoke+FindWindow

Thank you, information super-highway. Now, on to what I found...

Copy-Pasta

The relevant pages I found were:

http://stackoverflow.com/questions/1163761/capture-screenshot-of-active-window

http://www.developerfusion.com/code/4630/capture-a-screen-shot/

http://msdn.microsoft.com/en-us/library/windows/desktop/ms633499%28v=vs.85%29.aspx

http://www.pinvoke.net/default.aspx/user32.findwindow

I reviewed the code at developerfusion.com, found it to be straightforward, and incorporated it into a C# program.  Then I wrote this code to go with it:

 public class Cap
 {
  // http://www.pinvoke.net/default.aspx/user32.findwindow
  // Find window by Caption only. Note you must pass IntPtr.Zero as the first parameter.
  [DllImport("user32.dll", EntryPoint="FindWindow", SetLastError = true)]
  static public extern IntPtr FindWindowByCaption(IntPtr ZeroOnly, string lpWindowName);

  static public int Main(string [] args)
  {
   if (args.Length != 3)
   {
    Console.WriteLine("Usage: cap windowtitle gifbasename delayms");
    return 1;
   }

   IntPtr hWnd = FindWindowByCaption(IntPtr.Zero, args[0]);

   if (hWnd == IntPtr.Zero)
   {
    Console.WriteLine("No window by the title - {0}", args[0]);
    return 1;
   }

   Console.WriteLine("Capturing...");

   // stackoverflow.com/questions/1163761/capture-screenshot-of-active-window
   ScreenCapture sc = new ScreenCapture();

   int i = 0;
   StringBuilder sb = new StringBuilder();

   while (true)
   {
    sb.Clear();
    sb.AppendFormat("{0}{1}.gif", args[1], i.ToString("D8"));
    sc.CaptureWindowToFile(hWnd, sb.ToString(), ImageFormat.Gif);
    Thread.Sleep(Convert.ToInt32(args[2]));
    i++;
   }

   return 0;
  }
 }

I saved the 171-line file as screenshot.cs, and then wrote a compiler script:

@ECHO OFF
%WINDIR%\Microsoft.NET\Framework\v4.0.30319\csc.exe *.cs
PAUSE

Then, I double-clicked that, sifted through some warnings, and came up with an executable.

Next, I built a script to use ImageMagick's convert.exe to stitch those gifs into an animation:

@ECHO OFF

IF "%3" == "" GOTO Usage

:Start
 convert -loop 0 -delay %3 -resize %4 %1 %2
 GOTO :EOF

:Usage
 ECHO Usage: %~nx0 fileswildcard outfile dly reduce%%
 ECHO.
 ECHO Note: fileswildcard ought not match outfile, else: Inception!
 ECHO Note: dly in units of msec / 10
 GOTO :EOF

I saved that as makegif.cmd.  Finally, I decided to test it:

Now I'm ready to do that Vim demo.  Tomorrow, that is.

'nite ;-)