On Tue, 31 May 2005 12:38:09, glenn andreas <email@hidden> wrote:
> On May 31, 2005, at 12:26 PM, Santino wrote:
>
>> It seems to me that rowBytes in a QuickDraw PixMap is a short (16
>> bits) and the max value is 0x7FFF but I remember from some the OS8
>> sources that you can not create RGB pixmap with more than 4000 points.
>
> Rowbytes was indeed a short in a PixMap, but the top two bits were
> used as flags, and so as a result, the maximum rowbytes was 0x3fff,
> so 16383/4 gives you a hard limit 4095 for 32 bit pix (and less once
> you took into account padding that was done).
>
> However, "extended" pixmaps (introduced in OS 9?) had a separate
> field for things like this, and it was declared as a long (and "was"
> being the key word here - it was only exposed in one version of the
> headers) so using a gworld as wide as one would reasonably want has
> been doable ever since (there were some minor limitations with
> certain printer drivers in OS 9, but again, that was "back in the day").
I'd add that QTNewGWorldFromPtr does support long rowbytes.
NewGWorldFromPtr doesn't (or didn't, rdar://2935752).
Mike
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