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Par2: Check for multiple instances of a program 2000-01-16 -- Alexey Solovjev Far ago I posted an example of the program which uses mutex objects to
find another its instance. Attached one is its extension which uses
SetProp/GetProp functions to get a handle of first instance's window
from another program instance (really, in this way mutex objects become
unnecessary).
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PROGRAM
OMIT ('=== 16 bit', _WIDTH32_)
This program uses 32 bit specific API calls
! === 16 bit
HANDLE EQUATE(UNSIGNED)
HWND EQUATE(HANDLE)
DWORD EQUATE(LONG)
BOOL EQUATE(SIGNED)
LPARAM EQUATE(LONG)
SW_RESTORE EQUATE(9)
ERROR_ALREADY_EXISTS EQUATE(183)
MAP
MODULE('')
CreateMutex (<*DWORD>, BOOL, <*CSTRING>),HANDLE,RAW,PASCAL,NAME('CreateMutexA')
CloseHandle (HANDLE),BOOL,PROC,PASCAL,NAME('CloseHandle')
GetLastError (),DWORD,PASCAL,NAME('GetLastError')
GetDesktopWindow (),HWND,PASCAL,NAME('GetDesktopWindow')
GetWindowText (HWND,*CSTRING,SIGNED),SIGNED,RAW,PROC,PASCAL,NAME('GetWindowTextA')
SetProp (HWND,*CSTRING,HANDLE),BOOL,RAW,PROC,PASCAL,NAME('SetPropA')
GetProp (HWND,*CSTRING),HANDLE,RAW,PASCAL,NAME('GetPropA')
RemoveProp (HWND,*CSTRING),HANDLE,RAW,PROC,PASCAL,NAME('RemovePropA')
IsIconic (HWND),BOOL,PASCAL,NAME('IsIconic')
ShowWindow (HWND,SIGNED),BOOL,PROC,PASCAL,NAME('ShowWindow')
SetForegroundWindow (HWND),BOOL,PROC,PASCAL,NAME('SetForegroundWindow')
END
ShutProc()
Main()
TestInst(),BOOL
SwitchToOther(),BOOL
END
IDString CSTRING('00000ABC000') ! Some program ID string
AppMutexH HANDLE(0)
PropSet BOOL(FALSE)
CODE
SHUTDOWN (ShutProc)
IF NOT TestInst()
IF SwitchToOther()
RETURN
END
END
Main()
RETURN
! ===================================================================
ShutProc PROCEDURE()
CODE
IF AppMutexH <> 0
CloseHandle (AppMutexH)
AppMutexH = 0
END
IF PropSet
RemoveProp (GetDesktopWindow(), IDString)
PropSet = FALSE
END
! ===================================================================
TestInst PROCEDURE()
CODE
AppMutexH = CreateMutex (, FALSE, IDString)
RETURN CHOOSE (GetLastError() <> ERROR_ALREADY_EXISTS)
! ===================================================================
SwitchToOther PROCEDURE()
OtherInstFrame HWND,AUTO
Info CSTRING(128),AUTO
CODE
OtherInstFrame = GetProp (GetDesktopWindow(), IDString)
IF OtherInstFrame = 0
MESSAGE ('Property is FALSE')
RETURN FALSE
END
GetWindowText (OtherInstFrame, Info, SIZE (Info))
MESSAGE (Info, OtherInstFrame)
SetForegroundWindow (OtherInstFrame)
IF IsIconic (OtherInstFrame)
ShowWindow (OtherInstFrame, SW_RESTORE)
END
RETURN TRUE
! ===================================================================
Main PROCEDURE()
W0 APPLICATION('One Instance Test Program'),AT(,,280,100),FONT('MS Sans Serif',8,,FONT:regular),SYSTEM,
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RESIZE,ICON(ICON:Application),MAX
TOOLBAR,AT(0,0,,30)
BUTTON('&Close'),AT(8,7,45,14),USE(?Close),STD(STD:Close)
END
END
hWnd HWND,AUTO
CODE
OPEN (W0)
hWnd = W0 {PROP:Handle}
SetProp (GetDesktopWindow(), IDString, hWnd)
PropSet = TRUE
W0 {PROP:Text} = W0 {PROP:Text} & ' - ' & hWnd
ACCEPT
END
CLOSE (W0)
Today is April 23, 2024, 4:17 am This article has been viewed 35114 times.
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