On 9 Jun 2013, at 08:57, Kyle Sluder <[email protected]> wrote:
> On Jun 8, 2013, at 5:39 PM, "Gerriet M. Denkmann" <[email protected]>
> wrote:
>
>>
>> On 9 Jun 2013, at 06:23, Jens Alfke <[email protected]> wrote:
>>
>>>
>>> On Jun 8, 2013, at 12:24 PM, Ken Thomases <[email protected]> wrote:
>>>
>>>> I haven't done the experiment, but I don't believe this is necessarily
>>>> true. NSBitmapImageRep is documented (in the Snow Leopard release notes)
>>>> as keeping the original image data and not re-encoding or exploding file
>>>> sizes on being saved.
>>>
>>> I did not know this — guess I haven’t been reading the release notes
>>> closely enough.
>>
>> url = some/picture.gif
>> NSDataReadingOptions mask = 0; // NSDataReadingUncached
>> NSData *data = [ NSData dataWithContentsOfURL: url options: mask error:
>> &outError ];
>> got 19420 bytes
>>
>> NSImage *image = [ [ NSImage alloc ] initWithContentsOfURL: url ];
>> BOOL ok = [ NSArchiver archiveRootObject: image toFile: @"/tmp/anImage" ];
>> got 307559 bytes (NSKeyedArchiver adds another half kB)
>>
>> This 16-fold increase of data is - regardless of image quality - not
>> acceptable for my purposes.
>
> This is why you don't use NSArchiver for data blobs: it writes them out as
> Base64-encoded plist strings.
My gif-image has only one representation:
"NSBitmapImageRep 0x109cdf610 Size={320, 320} ColorSpace=Device RGB colorspace
BPS=8 BPP=32 Pixels=320x320 Alpha=NO Planar=NO Format=0
CurrentBacking=<CGImageRef: 0x10c878eb0> CGImageSource=0x116e02580"
And the archive contains (among a few other things, like an NSColor) an
NSBitmapImageRep, which contains a characterArray of 307394 chars = 3 * 320 *
320 + 194.
This is the archiver format, not the property list format.
So it seems that in initialising my image with gif-data, the original data was
somehow lost.
And when I do:
NSArray *imageReps = [ self.imageView.image representations];
NSData *gifData = [ NSBitmapImageRep representationOfImageRepsInArray:
imageReps usingType: NSGIFFileType properties: nil ];
it gets smaller indeed. From 19k to about 3k -- But: while the original was an
animated gif,
the new gifData is no longer animated. Not very useful to me.
I looked at the properties parameter, but did not see anything relating to
animation.
Kind regards,
Gerriet.
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