Re: how to cache images
Re: how to cache images
- Subject: Re: how to cache images
- From: Ken Thomases <email@hidden>
- Date: Sat, 08 Jun 2013 21:08:59 -0500
On Jun 8, 2013, at 7:39 PM, Gerriet M. Denkmann wrote:
> 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 isn't the technique I recommended. Don't archive the image object. Create a data representation using +[NSBitmapImageRep representationOfImageRepsInArray:usingType:properties:].
$ python
...
>>> from AppKit import *
>>> u = NSURL.URLWithString_("https://upload.wikimedia.org/wikipedia/commons/e/e2/Sunflower_as_gif_small.gif";)
>>> d1 = NSData.dataWithContentsOfURL_(u)
>>> d1.length()
57270
>>> i = NSImage.alloc().initWithContentsOfURL_(u)
>>> d2 = NSBitmapImageRep.representationOfImageRepsInArray_usingType_properties_(i.representations(), NSGIFFileType, None)
>>> d2.length()
54377
It actually got smaller!
Regards,
Ken
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