How exactly to make a CGImageRef from an image on disk

问题

I've looked around everywhere to no avail. I'm doing some image loading in a thread and since UIKit is not thread safe I'm going to have to store the images as CGImageRefs but I can't figure out how to do this. I haven't played with any of the Quartz stuff before so it's confusing me. Basically I just need to load a JPG from the disk into a CGImageRef. Also for bonus points, is there anyway to load a GIF into a CGImageRef?

回答1:

gcamp is more or less correct, you are pretty safe to use this on a background thread, but to answer your question, I believe the following would work.

CGDataProviderRef dataProvider = CGDataProviderCreateWithFilename("file");
CGImageRef image = CGImageCreateWithPNGDataProvider(dataProvider, NULL, NO, kCGRenderingIntentDefault);

There is also a function for jpg images, CGImageCreateWithJPEGDataProvider.

(be sure to release the data provider and image when done)

回答2:

I think the simplest way is to use UIKit and use the CGImage propriety of UIImage.

Something like that :

UIImage* image = [UIImage imageNamed:@"Your Image.png"];
CGImageRef imageRef = image.CGImage;

来源：https://stackoverflow.com/questions/3550201/how-exactly-to-make-a-cgimageref-from-an-image-on-disk