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From: engber@gumball.ils.nwu.edu (Mike Engber)
Newsgroups: comp.sys.mac.programmer
Subject: Follow Up On Centering DLOGs & ALRTs
Summary: a modest solution
Message-ID: <6178@accuvax.nwu.edu>
Date: 9 Apr 90 14:38:30 GMT
References: <1990Apr9.125651.23391@ncsuvx.ncsu.edu>
Sender: news@accuvax.nwu.edu
Reply-To: engber@gumball (Mike Engber)
Distribution: comp
Organization: The Institute for the Learning Sciences
Lines: 103


Thanks for all the replys to my centering DLOG/ALRT question. I used the
best ideas to synthesize my solution which I think elegant enough to be
worth sharing. Attached are the relevant portions of my .h & .c files.

A couple of notes:

Several people`s solutions burned in the rsrc ids of the standard
file dialogs. You may want to note that there are named constants for
these values: putDlgID  & getDlgID.

All the solutions I was sent used screenBits.bounds. Is this what you
want in a multi-monitor situation? If not, what should you do?

Feel free to use/modify/comment-on this code, especially if you notice
any bugs or questionable practices.

-ME

---

/* DialogUtils.h */

/* Return topLeft point to center standard file dialogs. */
extern Point DU_StdPutWhere(void);
extern Point DU_StdGetWhere(void);

/*
 * Pre-load and center ALRT/DLOG template resources. Changes do not affect
 *  the resource file, but if the ALRT/DLOG is created soon after the call
 *  it will use the modified (centered) template in memory. Both routines
 *  return the passed rsrc id to allow calls like:
 *      Alert(DU_CenterALRT(alertID),filter);
 *      GetNewDialog(DU_CenterDLOG(dlogID),dStorage,behindWindow);
 */
extern short DU_CenterALRT(short rsrcId);
extern short DU_CenterDLOG(short rsrcId);


/* ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- ----- */


/* DialogUtils.c */
 
#include "DialogUtils.h"

static void DU_CenterRect(Rect* rect_p){
/*
 * Alligns *rect_p wrt screenBits.bounds - LR centered & in upper 1/3
 */

    /* exactly centered */
    OffsetRect(rect_p,
            (screenBits.bounds.right + screenBits.bounds.left)/2 -
                (rect_p->right + rect_p->left)/2
        ,
            (screenBits.bounds.top + screenBits.bounds.bottom)/2 -
                (rect_p->top + rect_p->bottom)/2
        );
    
    /* up a bit */
    OffsetRect(rect_p,0, 
        GetMBarHeight() - 2*(rect_p->top - screenBits.bounds.top)/3);
}

static Point DU_Where(short rsrcId){
/*
 * Returns centering point for the topLeft corner of a dialog.
 */
    Handle  h = GetResource('DLOG',rsrcId);
    Rect    r = {0,0,0,0};
    if(h){
        r = *((Rect*)(*h));
        DU_CenterRect(&r);
        ReleaseResource(h);
    }
    return topLeft(r);
}

Point DU_StdPutWhere(void){
    return DU_Where(putDlgID);
}

Point DU_StdGetWhere(void){
    return DU_Where(getDlgID);
}

static short DU_Center(ResType type, short rsrcId){
/*
 * Reads in an 'ALRT' or 'DLOG' rsrc template & centers it's display Rect.
 */
    Handle  h = GetResource(type,rsrcId);
    if(h) DU_CenterRect((Rect*)(*h));
    return rsrcId;
}

short DU_CenterALRT(short rsrcId){
    return DU_Center('ALRT',rsrcId);
}

short DU_CenterDLOG(short rsrcId){
    return DU_Center('DLOG',rsrcId);
}