Re: 1-bit NSBitmapImageRep?
Re: 1-bit NSBitmapImageRep?
- Subject: Re: 1-bit NSBitmapImageRep?
- From: Graham Cox <email@hidden>
- Date: Fri, 18 Apr 2008 14:17:14 +1000
- Resent-date: Fri, 18 Apr 2008 14:17:42 +1000
- Resent-from: Graham Cox <email@hidden>
- Resent-message-id: <email@hidden>
- Resent-to: Cocoa-Dev List <email@hidden>
Thanks for this, and to others who suggested the same thing - it works
GREAT, and was a trivial change to make in my app. It also allowed me
to cut out a whole bunch of stuff having to do with maintaining the
bitmap cache - I do love it when I can chop lots of code out and
things work better ;-)
Thanks again,
G.
On 18 Apr 2008, at 12:07 pm, Michael Ash wrote:
There is an easy, although deeply non-obvious, way to do 100% correct
hit testing with any stylistic variations, and even to hit test with
fill versus stroke. In fact, you're almost there, and just need to
take it a little bit further.
The answer is, instead of drawing into a big context and then checking
the pixel value of the location in question, you draw into a very
teeny context with a proper transform set up. Create a 1x1 context,
set up the proper affine transform to make that pixel be the one
you're hit testing, then draw whatever it is you're drawing.
Afterwards, check your one pixel: if it's dark, you hit, if it's
light, you missed.
You're still wasting the memory for an 8-bit context, but at least
it's only 7 bits wasted. :)
Mike
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