Requires: GfaWinx.lg32
Ensure Dialog boxes are centered on top of their owner.
DlgCenter
Set Obj = DlgCenterHook()
| Obj | : a local Object variable |
These commands will center all of GFA-BASIC’s dialog boxes of the current thread on top of their owner.
DlgCenter only works for the program’s main thread. DlgCenterHook is used in additional threads the program creates. The dialogs that are centered include all dialogs that have an owner, like MsgBox (but not MsgBox0), Alert, Prompt, Dlg Open/Save and others, and the CommDlg Ocx dialogs.
DlgCenter installs a thread-local hook to intercept the creation of dialogs for the main thread. It creates a hidden global AutoFreePtr Object that unhooks the thread’s hook when the object variable goes out of scope (after the application is closed). DlgCenter calls DlgCenterHook to obtain the object and stores it in the hidden global variable.
To center dialogs created in an additional thread use DlgCenterHook. The object returned by DlgCenterHook must be stored in a thread local variable. The local object variable must be declared in the ThreadProc and is then assigned the object returned from DlgCenterHook. When the thread ends the local thread object variable is freed and the thread’s hook is unhooked.
Example 1 - Single thread
$Library "gfawinx"
$Library "UpdateRT"
UpdateRuntime ' Patches GfaWin23.Ocx
OpenW 1, 0, 0, 300, 300
DlgCenter
Alert 1, "Centered AlertBox", 1, "Ok|Cancel"
CloseW 1
Example 2 - Multiple threads
$Library "gfawinx"
$Library "UpdateRT"
UpdateRuntime ' Patches GfaWin23.Ocx
OpenW 1
DlgCenter ' for main thread
Local threadID As Long
Global hThread As Handle, oThread As Object
Global Handle hThread = CreateThread(Null, 0, ProcAddr(ThreadProc), 0, 0, V:threadID)
Set oThread = AutoFreePtr(hThread, AfpCloseHandle) ' API function, handle must be closed when finished
Do
Sleep
Until Me Is Nothing
Procedure ThreadProc(lp%)
Local Object oDlgCtrHk ' Local!!
Set oDlgCtrHk = DlgCenterHook() ' center dialogs in this thread
// Code for new thread
EndProcedure ' unhooks the hook saved in oDlgCtrHk
MsgBox, Message, Alert, Prompt, CommDlg.
{Created by Sjouke Hamstra; Last updated: 23/02/2022 by James Gaite}