/*

     File: ImageAsset.m

 Abstract: ImageAsset Model Class for CocoaSlides

  Version: 1.5

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 expressly stated in this notice, no other rights or licenses, express or

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 */

#import "ImageAsset.h"

#import "NSImage+Conversion.h"

@implementation ImageAsset

+ (NSArray *)fileTypes {

    return [NSImage imageFileTypes];

}

- (void)dealloc {

    if (imageProperties) {

        CFRelease(imageProperties);

    }

    if (imageSource) {

        CFRelease(imageSource);

    }

    [super dealloc];

}

- (NSInteger)pixelsWide {

    if (!imageProperties)

        [self loadMetadata];

    return [[(NSDictionary *)imageProperties valueForKey:(NSString *)kCGImagePropertyPixelWidth] intValue];

}

- (NSInteger)pixelsHigh {

    if (!imageProperties)

        [self loadMetadata];

    return [[(NSDictionary *)imageProperties valueForKey:(NSString *)kCGImagePropertyPixelHeight] intValue];

}

/*

    Many kinds of image files contain prerendered thumbnail images that can be quickly loaded without having to decode the entire contents of the image file and reconstruct the full-size image.  The ImageIO framework's CGImageSource API provides a means to do this, using the CGImageSourceCreateThumbnailAtIndex() function.  For more information on CGImageSource objects and their capabilities, see the CGImageSource reference on the Apple Developer Connection website, at http://developer.apple.com/documentation/GraphicsImaging/Reference/CGImageSource/Reference/reference.html

*/

- (BOOL)createImageSource {

    if (imageSource == NULL) {

        // Compose absolute URL to file.

        NSURL *sourceURL = [[self url] absoluteURL];

        if (sourceURL == nil) {

            return NO;

        }

        // Create a CGImageSource from the URL.

        imageSource = CGImageSourceCreateWithURL((CFURLRef)sourceURL, NULL);

        if (imageSource == NULL) {

            return NO;

        }

        CFStringRef imageSourceType = CGImageSourceGetType(imageSource);

        if (imageSourceType == NULL) {

            CFRelease(imageSource);

            return NO;

        }

    }

    return imageSource ? YES : NO;

}

- (BOOL)loadMetadata {

    if (imageProperties == NULL) {

        if (![self createImageSource]) {

            return NO;

        }

        // This code looks at the first image only.

        // To be truly general, we'd need to handle the possibility of an image source

        // having more than one image to offer us.

        //

        NSInteger index = 0;

        imageProperties = CGImageSourceCopyPropertiesAtIndex(imageSource, index, NULL);

    }

    // Return indicating success!

    return imageProperties ? YES : NO;

}

- (BOOL)loadPreviewImage {

    BOOL success;

    if (![self createImageSource]) return NO;

    NSDictionary *options = [[NSDictionary alloc] initWithObjectsAndKeys:

        // Ask ImageIO to create a thumbnail from the file's image data, if it can't find

        // a suitable existing thumbnail image in the file.  We could comment out the following

        // line if only existing thumbnails were desired for some reason (maybe to favor

        // performance over being guaranteed a complete set of thumbnails).

        [NSNumber numberWithBool:YES], (NSString *)kCGImageSourceCreateThumbnailFromImageIfAbsent,

        [NSNumber numberWithInt:160], (NSString *)kCGImageSourceThumbnailMaxPixelSize,

        nil];

    CGImageRef thumbnail = CGImageSourceCreateThumbnailAtIndex(imageSource, 0, (CFDictionaryRef)options);

    NSImage *image = [[NSImage alloc] initWithCGImage:thumbnail];

    [self performSelectorOnMainThread:@selector(setPreviewImage:) withObject:image waitUntilDone:NO];

    success = image ? YES : NO;

    [image release];

    CGImageRelease(thumbnail);

    [options release];

    return success;

}

@end