Re: iPhoto-like scroll view
Re: iPhoto-like scroll view
- Subject: Re: iPhoto-like scroll view
- From: Chris Williams <email@hidden>
- Date: Sat, 08 Sep 2007 09:06:31 -0700
- Thread-topic: iPhoto-like scroll view
But those embedded thumbs are almost always terrible quality (using firmware
algorithms), they are tiny, and only exist in some formats from some
sources. My experience is that I never once found one I wanted to use in
my application at least.
However, I'll take your advice and try this (again) and time it.
From: glenn andreas <email@hidden>
Subject: Re: iPhoto-like scroll view
That's one of the advantages of CGImageSourceCreateThumbnailAtIndex,
though, is that in many cases it doesn't have to read the entire file
to generate the thumbnail. For example, many digital cameras embed a
thumbnail in the EXIF data of a JPG file, which
CGImageSourceCreateThumbnailAtIndex can use, allowing for it to only
have to scan in the first couple of K of a file instead of reading
the entire several hundred K. Similar tricks can be done with
progressive jpg files (again just reading the first couple of low
resolution passes, and not the full resolution) and JPEG2000 files.
You might want to check out <http://www.wilshipley.com/blog/2005/09/
jpeg2000-cool-but-slow.html> as well which includes the following quote:
> Followup (9/19): The news gets even better, as it turns out 10.4's
> CGImageSourceCreateThumbnailAtIndex() is 3-7x faster at creating
> JPEG thumbnails than the method I had to use under 10.3: creating a
> CGImageRef using CGImageCreateWithJPEGDataProvider() and then
> drawing it (with antialiasing turned on) into a smaller window.
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