On Tue, Sep 8, 2009 at 10:30 AM, Benjamin Rister <bdris...@gmail.com> wrote:
> Hi Ken, > > Thanks for your response. > > The "size" of an image is the default size of the rect in which it's drawn >> when the person drawing it doesn't have any more specific information. >> That's a concept that there can only be one of for the entire image, so >> it's confusing if the -size for contained reps doesn't match that of the >> image itself. >> > > > I'm not concerned/confused about the results of -[NSImage size], I know > it'll draw wherever I ask it to in whatever space that is. > > The -size is unrelated to the number of pixels in a rep. The ratio >> determines resolution. Reps can definitely have different numbers of >> pixels. >> > > > The issue/question comes from tiffutil's explicit warning that NSImage > doesn't like it or may be confused if the net sizes of the different > representations in the tiff are different. So the reps can have different > numbers of pixels, but if the dpi is the same across the different reps, > they have different "real sizes," and man tiffutil says that that is a > problem. > > So it's perfectly fine to pack in different representations with different >> numbers of pixels. What the docs encourage is setting the metadata so that >> the -size of each representation is the same. >> > > man tiffutil says that NSImage may not be able to "successfully choose the > right size image out of the generated TIFF file." That sounds much stronger > to me than encouraging it so that -size isn't potentially confusing to a > programmer calling it. > > I'm not questioning whether what you say about the frameworks is true, just > making sure we're on the same page, because you said the doc says one thing > and that's not what I read in it. =) > > So to be clear: if I create a TIFF image, with tiffutil -cat, that has > 9x...@72dpi, 16x1...@72dpi, 32x3...@72dpi: > - This is an entirely supported configuration, despite what man tiffutil > says and the warning it generates. > No, these reps would not have the same -size. If you set the DPI metadata for the reps to 72, 128, and 256 respectively, then each rep would have -size 9x9. This is what I meant above. It's fine to have different pixel sizes, but it's best to set the metadata so that the -size is consistent. > - NSImage will correctly choose and draw representations now and in the > future when drawn at different sizes, and both at 1.0 and non-1.0 scale > factors. For instance, it will use the 32x3...@72dpi rep to fill a > 16x16pt space at scale 2.0, even though the 16x1...@72dpi is the one that > matches the physical size, despite the NSImage docs only giving rules based > on color space, dpi, and bit depth for choosing representations. > > Is this correct, and something I can safely rely upon? > > Thanks, > Benjamin Rister > _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
