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This Technical Note contains a collection of archived Q&As relating to a specific
topic--questions sent the Developer Support Center (DSC) along with
answers from the DSC engineers. Current Q&A's can be found on the
Macintosh Technical Q&A's web site.
[Oct 01 1990]
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Avoid Macintosh List Manager for manipulating large matrices
Avoid using the Macintosh List Manager for manipulating large matrices like
spreadsheet cells.
The Macintosh List Manager becomes ungainly when handling more than about 500
cells. With several thousand cells, such as a 100x100 matrix, it becomes
downright klunky.
Using standard techniques, the List Manager can store only 32K of data in a
list. For 10,000 cells, this gives you only about 3.2 characters in a cell.
It's possible to switch to a system where each cell contains a pointer to text
to be drawn, but with only 3.2 characters, it's not possible to store a full
pointer (4 bytes). After about 500 cells, the time needed to actually set the
data in the cells becomes noticeable, on the order of 10 to 15 seconds.
Finally, the List Manager has some pretty fundamental restrictions. You cannot,
for instance, create variable-width rows or columns, or hide a single row or
column from a list.
For manipulating large matrices, you're much better off bypassing the List
Manager entirely and writing your own spreadsheet-type mechanism. Consider
caching the cells to a temporary file, depending on your memory requirements.
You'll need to use the Control Manager to set up and process scroll bars, and
you should use QuickDraw to draw the contents of the cells.
Basically, writing a spreadsheet shares many of the same necessary functions
and problems as writing a text editor (replacing TextEdit). Neither one is
simple, but both are possible.
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Creating Macintosh columns with various widths
Date Written: 2/8/91
Last reviewed: 6/14/93
How can I create a Macintosh List Manager list with different size cells for
some columns and different size cells for other columns?
The List Manager doesn't allow variable-sized cells. One cell size fits all, or
not! The List Manager was designed for simple lists (such the standard
get file dialog), but not for spreadsheets. The source of the limitation is
found in the ListRec as documented in Inside Macintosh Volume IV. The
cellSize is a single variable (a Point). If multiple column widths were
allowed, some sort of array would be required to store the width for each
column, and you can see from looking at the ListRec data structure that no
provision was made for this.
You can write your own List definition procedure, which can display alternative
data types (PICTS, ICONS, or perhaps some data type of your own devising), but
these are still limited to one cell size for the entire list. If you wish to
have columns with various widths, you will need to treat each column as a
separate list, or handle the lists entirely yourself as spreadsheet and
database applications do.
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Code for putting a list in a modal dialog box
Date Written: 1/23/92
Last reviewed: 6/14/93
How do I put a list in a Macintosh modal dialog box?
The sample code below puts a list in a modal dialog. There are several points
to note to ensure success: You need to pass a draw procedure to the modal
dialog for your list item. It's important to test for mousedown events in your
modal dialog filter, because the List Manager doesn't check to see if you're
kidding when you tell it you have a mousedown (that's what calling lClick
does...). Also, calling Setport on your dialog in your filter procedure is not
done for you automatically and is important when using GlobalToLocal.
The sample also tests lGetSelect to see that it works OK on these lists (it
does). The dialog in question simply needs two items in its ditl, a button as
item 1 and a user item as item 2. This should work for any sized user item.
pascal listDraw(WindowPtr theWindow, short itemNo)
{
short aItemType;
Handle aControl;
Rect aRect;
Rect dBounds;
Point aPoint;
GetDItem((DialogPtr)theWindow,itemNo,&aItemType,&aControl,&aRect);
PenNormal();
InsetRect(&aRect,-1,-1);
FrameRect(&aRect);
LUpdate(theWindow->visRgn,(ListHandle)GetWRefCon(theWindow));
}
pascal Boolean MyFilter( DialogPtr theDialog, EventRecord *theEvent,
short *itemHit)
{
short aItemType;
Handle aControl;
Rect aRect;
Rect dBounds;
Point aPoint;
SetPort(theDialog);
GetDItem(theDialog,2,&aItemType,&aControl,&aRect);
aPoint = theEvent->where;
GlobalToLocal(&aPoint);
if (PtInRect(aPoint,&aRect))
if (theEvent->what==mouseDown) {
*itemHit = 2;
LClick(aPoint,theEvent->modifiers,
(ListHandle)GetWRefCon((WindowPtr)theDialog));
return true;
};
return false ;
}
void DialogFiddle()
{
DialogPtr aDLog;
short aItemType;
Handle aControl;
Rect aRect;
Rect dBounds;
Point aPoint;
ListHandle myList;
Str255 dummy = ""Unselected Item"";
Str255 wally = ""I am Selected!"";
aDLog = GetNewDialog(987,(Ptr) 0, (WindowPtr) -1);
GetDItem(aDLog,2,&aItemType,&aControl,&aRect);
SetDItem(aDLog,2,aItemType,(Handle)&listDraw,&aRect);
aRect.right -= 16;
dBounds.top = 0;
dBounds.bottom = 0;
dBounds.left = 0;
dBounds.right = 1;
aPoint.h = 0;
aPoint.v = 0;
myList = LNew(&aRect,&dBounds,aPoint,0,(WindowPtr)aDLog,
true,false,false,true);
aItemType = LAddRow(5,0,myList);
LSetCell(&dummy,15,aPoint,myList);
aPoint.v+=1;
LSetCell(&dummy,15,aPoint,myList);
aPoint.v+=1;
LSetCell(&dummy,15,aPoint,myList);
aPoint.v+=1;
LSetCell(&dummy,15,aPoint,myList);
aPoint.v+=1;
LSetCell(&dummy,15,aPoint,myList);
(**myList).selFlags = -128;
SetWRefCon((WindowPtr)aDLog,(long)myList);
do {
aPoint.h = 0;
aPoint.v = 0;
ModalDialog(&MyFilter,&aItemType);
if (aItemType=2)
if (LGetSelect(true,&aPoint,myList))
LSetCell(&wally,14,aPoint,myList);
} while (aItemType==2);
DisposDialog(aDLog);
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