Re: Question about UIImage, scaling, and UIGraphicsBeginImageContextWithOptions
Re: Question about UIImage, scaling, and UIGraphicsBeginImageContextWithOptions
- Subject: Re: Question about UIImage, scaling, and UIGraphicsBeginImageContextWithOptions
- From: Andreas Mayer <email@hidden>
- Date: Tue, 27 Mar 2012 18:41:33 +0200
Am 27.03.2012 um 17:31 schrieb Ray:
>> 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?
>
> Well, I don't save it to a file, but to a NSData property on a Core Data managed object, and I use UIGraphicsBeginImageContextWithOptions, after which newImage = UIGraphicsGetImageFromCurrentImageContext() will set the scale of "newImage" appropriately (under retina to 2.0, I checked with setting a breakpoint and looking at the scale variable of the image)... It is more that the imageWithData class method on UIImage always will report a scale of 1.0
The scale value is the same as set in UIGraphicsBeginImageContextWithOptions(), as far as I can tell.
But it will be lost when creating PNG data and reading it again. (Since I don't see a way of creating a PNG file without using UIImagePNGRepresentation() it doesn't seem to matter if the data was saved to a file or not.)
So either imageWithData does not restore the scale from PNG data or UIImagePNGRepresentation() does not store it in the first place.
I see that as a bug, since the PNG format is able to hold that information.
Andreas
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