/*

     File: ImageFile.m

 Abstract: ImageFile represents the items displayed in the tableview. ImageFile hangs on to the image name and its original path, and will fetch the actual NSImage from an NSCache. If the NSImage has been evicted, ImageFile will recreate it and put it back in the cache.  It also sends out a ImageFileDidMissCacheNotification at that time.

  Version: 1.0

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 */

#import "ImageFile.h"

#import <Foundation/NSCache.h>

NSString * const ImageFileDidMissCacheNotification = @"ImageFileDidMissCache";

static NSCache *imageCache = nil;

@implementation ImageFile

@synthesize path, name;

/* We use a single NSCache for all instances of ImageFile.  The count limit is set to a value that allows demonstrating the cache evicting objects.

*/

+ (void)initialize {

    if (self == [ImageFile class]) {

        imageCache = [[NSCache alloc] init];

        [imageCache setCountLimit:40];

    }

}

+ (NSCache *)imageCache {

    return imageCache;

}

/* In case we want to have a per-instance cache.

*/

- (NSCache *)imageCache {

    return imageCache;

}

/* We hang on to the path and name of each image.

*/

- (id)initWithPath:(NSString *)location {

    if (self = [super init]) {

    path = [location copy];

        name = [[[NSFileManager defaultManager] displayNameAtPath:location] copy];

    }

    return self;

}

- (void)dealloc {

    [[self imageCache] removeObjectForKey:self.path];

    [path release];

    [name release];

    [super dealloc];

}

/* To return the actual NSImage, we first look in the cache; if that fails, we create a new NSImage and put that in the cache.

*/

- (NSImage *)image {

    NSCache *cache = [self imageCache];

    NSString *imagePath = [self path];

    NSImage *image;

    if (!(image = [cache objectForKey:imagePath])) {

    // Cache miss, recreate image

    image = [[[NSImage alloc] initByReferencingFile:imagePath] autorelease];

    if (image) {    // Insert image in cache

        [cache setObject:image forKey:imagePath];

    }

        [[NSNotificationCenter defaultCenter] postNotificationName:ImageFileDidMissCacheNotification object:self];

    }

    return image;

}

@end