Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!husc6!huma1!fry
From: fry@huma1.HARVARD.EDU (David Fry)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Centering alerts vs. centering dialogs
Message-ID: <4800@husc6.harvard.edu>
Date: 21 Jun 88 01:34:13 GMT
References: <CMM.0.86.582748031.lipa@polya.stanford.edu>
Sender: news@husc6.harvard.edu
Reply-To: fry@huma1.UUCP (David Fry)
Organization: Harvard Math Department
Lines: 66

In article <CMM.0.86.582748031.lipa@polya.stanford.edu> lipa@POLYA.STANFORD.EDU (William Lipa) writes:
>As far as I can tell, centering alerts is much harder than centering dialogs.
>Try it sometime, you'll like it!

Centering alerts is very simple.  You simply read in the
Handle of the ALRT resource, center it and immediately call
Alert().  Here's an example in C.  A similar technique can be
used to center StdFile dialogs.  


/* 
   The variables ScreenHeight and ScreenWidth are calculated at
   runtime and mean what you think they mean.  They should take into
   account variable menuBar heights and multiple screens on Mac IIs.
*/

CenterAlert(ID)
short	ID;
{
	AlertTHndl 		aboutALRT;
	    
    aboutALRT = GetResource('ALRT',ID);
    CenterRBox(aboutALRT);
	Alert(ID, 0L);
	ReleaseResource(aboutALRT);  
}

CenterRBox(boxHandle)
Handle boxHandle;
{
/* 
	given a Handle to a block (usually a resource) whose first 8 
	bytes represent a box on the screen, this function changes 
	that rectangle to be positioned nicely on the screen
*/
	int		w,h;
	Rect	temp;

    temp =  *(Rect *)*boxHandle;
    h = temp.bottom - temp.top;
    CenterRect(&temp);
    temp.top = menuH + (ScreenHeight - h)/3;
    temp.bottom = temp.top + h;
    *(Rect *)*boxHandle = temp;
}	

CenterRect(r)
Rect	*r;
{
/* "centers" a rectangle on the screen */
	int	w,h;
	
	w = r->right - r->left;
	h = r->bottom - r->top;
	r->left = (ScreenWidth - w)/2;
	r->right = r->left + w;
	r->top = (ScreenHeight - h - menuH)/2
		+ menuH;
	r->bottom = r->top + h;
}


David Fry				fry@huma1.harvard.EDU
Department of Mathematics		fry@huma1.bitnet
Harvard University			...!harvard!huma1!fry
Cambridge, MA  02138