Am 27.03.2012 um 13:47 schrieb Marco Tabini: > When you save to a file format that supports metadata, like JPEG, some of the > metadata is stored there, while other is derived from the file name. So, for > example, if you were to save a PNG file to disk with an @2x suffix, upon > loading it with -imageNamed: UIImage would automatically know to set up the > resulting object as a 2x scale image. > > When the filename convention is not available, that metadata needs to be > saved somewhere—in your case, you derive it from the file size, which, as you > mention, is not very portable.
The documentation for UIImage -scale says: "If you load an image from a file whose name includes the @2x modifier, the scale is set to 2.0. If the filename does not include the modifier but is in the PNG or JPEG format and has an associated DPI value, a corresponding scale factor is computed and reflected in this property. " So I would expect PNG images to retain their scale value when saved and loaded. If this does not work, there seems to be a bug somewhere. Ray, did you try to explicitly set the image's scale value before creating the PNG representation? Something like this: UIImage *newImage; NSData *imageData; UIGraphicsBeginImageContext(CGSizeMake(44.0, 44.0)); [selectedImage drawInRect:CGRectMake(0.0, 0.0, 44.0, 44.0)]; newImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); newImage.scale = 2.0; // <--- imageData = UIImagePNGRepresentation(newImage); Andreas _______________________________________________ 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: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
