Enhanced FindWindow for variable window class names

Author: Comm@nder21 (talk, contrib)

Introduction

Sometimes, you want to send messages to a window, that you don't know the full window class name (wcn) of, or it contains variables and you know the constant part. So you can't use FindWindow because it doesn't support wildcars. This function doesn't too. But you can get the handle of any window, with only one known part of the wcn.

Usage

Push  0   # the starting offset of the push below
Push  "Application"   # the known part of the class name
Call  EnhancedFindWindow
Pop  $0   # will contain the window's handle
Pop  $1   # will contain the full wcn
          # both will contain "failed", if no matching class name was found

The Function

Function  EnhancedFindWindow
  ; input, save variables
  Exch  $0   # part of the class name to search for
  Exch
  Exch  $1   # starting offset
  Push  $2   # length of $0
  Push  $3   # window handle
  Push  $4   # class name
  Push  $5   # temp
 
  ; set up the variables
  StrCpy  $4  0
  StrLen  $2  $0
 
 ; loop to search for open windows
 search_loop:
  FindWindow  $3  ""  ""  0  $3
   IntCmp  $3  0  search_failed
    IsWindow  $3  0  search_loop
     System::Call 'user32.dll::GetClassName(i r3, t .r4, i ${NSIS_MAX_STRLEN}) i .n'
     StrCmp  $4  0  search_loop
     StrCpy  $5  $4  $2  $1
     StrCmp  $0  $5  search_end  search_loop
 
 ; no matching class-name found, return "failed"
 search_failed:
  StrCpy  $3  "failed"
  StrCpy  $4  "failed"
 
 ; search ended, output and restore variables
 search_end:
  StrCpy  $1  $3
  StrCpy  $0  $4
  Pop  $5
  Pop  $4
  Pop  $3
  Pop  $2
  Exch  $1
  Exch
  Exch  $0
FunctionEnd

Feedback

Any suggestions, feature requests or even bug reports? Feel free to send me an email or a private message.

Please post any other question, e.g. about usage and customization at the NSIS forums. Remember: You're not alone ...

Further Reading

See this topic for more information about the function itself and alternatives. See the msdn for more information about the user32 api call "GetClassName".