Re: Fast image loading + scrolling like iPhoto
Re: Fast image loading + scrolling like iPhoto
- Subject: Re: Fast image loading + scrolling like iPhoto
- From: Ricky Sharp <email@hidden>
- Date: Wed, 5 Jan 2005 11:34:54 -0600
On Jan 5, 2005, at 10:59 AM, Shawn Erickson wrote:
Looking at iPhoto in shark it looks like they are simply drawing the
images using CGContextDrawImage and the trigger for drawing appears to
come out of a call to drawRect:clip: for an NSView (the have some code
in between it looks like). Of course CGContextDrawImage uses vector
operations, etc. to process image data as needed and aspects of video
hardware (likely more and more in the future).
In fact a majority of the time is spent in CGContextDrawImage when
scrolling and viewing a set of images. So it looks like they are just
using standard Quartz2D calls to do this but likely are taking steps
to reuse image references as much as possible because Quartz2D can do
better caching, etc. then.
They obviously adjust down the scaling, etc. when scrolling to reduce
processing over head. The file data appear to be memory mapped.
Didn't even think of looking in Shark to find this out; thanks for this
detailed analysis!
___________________________________________________________
Ricky A. Sharp mailto:email@hidden
Instant Interactive(tm) http://www.instantinteractive.com
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