Category : C++ Source Code
Archive   : C_ALL.ZIP
Filename : TI869.ASC

PRODUCT : Borland C++ NUMBER : 869
VERSION : All
OS : WIN
DATE : August 12, 1992 PAGE : 1/3

TITLE : How To Center A Dialog Box On Its Parent Window




It is often necessary to center a dialog box on top of its parent
window for aesthetic reasons. Who would one do this? Simple,
use the function provided below when the dialog box that needs
centering receives a WM_INITDIALOG message.

Below is a sample dialog box procedure that shows the use of the
function UICenterDialog as well as the source for UICenterDialog
itself.

Note: If the dialog box would not be 100% visible by centering
it on top of its parent window, this code then centers it on the
Windows desktop. If this behavior is not necessary simply remove
the last if statement.

// CNTRDLG.C
// Copyright (C) 1992 Borland Internationa, Inc.
// All Rights Reserved

// Function to show the use of UICenterDialog
//...............................................................

BOOL FAR PASCAL MyDialogProc(HWND hDlg, WORD msg, WORD wParam,
LONG lParam)
{
switch(msg)
{
case WM_INITDIALOG:
UICenterDialog(hDlg);
break;

default:
return TRUE;
}
return FALSE;
}

// Source for the UICenterDialog function
//...............................................................

void UICenterDialog(HWND hDlg)
{
int cxWin, // Delta X for parent window
cyWin, // Delta Y for parent window













PRODUCT : Borland C++ NUMBER : 869
VERSION : All
OS : WIN
DATE : August 12, 1992 PAGE : 2/3

TITLE : How To Center A Dialog Box On Its Parent Window




xDlg, // New X coordinate for dialog box
yDlg, // New Y coordinate for dialog box
cxDlg, // Delta X for dialog box
cyDlg, // Delta Y for dialog box
cxScreen, // Delta X for screen
cyScreen; // Delta Y for screen
RECT rcDlg, // Rectangle for dialog box
rcPrnt; // Rectangle for parent window
HWND hWndParent; // Handle the parent window

// Determine the width and height of the screen.
cxScreen = GetSystemMetrics(SM_CXSCREEN);
cyScreen = GetSystemMetrics(SM_CYSCREEN);

// Determine rectangle for parent window of dialog box.
hWndParent = GetWindowWord(hDlg, GWW_HWNDPARENT);
if(IsWindow(hWndParent))
{
// Use parent coordinates (rect) to determine where the
// dialog needs to be on the Windows desktop
GetWindowRect(hWndParent, &rcPrnt);
cxWin = rcPrnt.right - rcPrnt.left;
cyWin = rcPrnt.bottom - rcPrnt.top;
}
else
{
// We were unable to determine who the parent is,
// therefore centering the dialog is pointless! Place
// it in the upper left corner of the Windows desktop.
cxWin = 0; // Force the centering calculation to
cyWin = 0; // think that the dialog is centered on
// the Windows desktop
}

// Determine rectangle for dialog box itself.
GetWindowRect(hDlg, &rcDlg);
cxDlg = rcDlg.right - rcDlg.left;
cyDlg = rcDlg.bottom - rcDlg.top;

// Determine new dialog X and Y coordinate
xDlg = (cxWin - cxDlg) / 2;
xDlg += rcPrnt.left;
yDlg = (cyWin - cyDlg) / 2;













PRODUCT : Borland C++ NUMBER : 869
VERSION : All
OS : WIN
DATE : August 12, 1992 PAGE : 3/3

TITLE : How To Center A Dialog Box On Its Parent Window




yDlg += rcPrnt.top;

// Center the dialog using new coordinates
if ((xDlg < 0) || (yDlg < 0) || (xDlg+cxDlg > cxScreen) ||
(yDlg+cyDlg > cyScreen))
{
// If by centering the dialog on top of its parent it
// would not be 100% visible, then center it on the
// Windows desktop instead.
xDlg = (cxScreen - cxDlg) / 2;
yDlg = (cyScreen - cyDlg) / 2;
}

// Move the dialog box to its new home on the desktop
MoveWindow(hDlg, xDlg, yDlg, cxDlg, cyDlg, TRUE);
}

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