/*

     File: ATDesktopEntity.h 

 Abstract: A sample model object. A base abstract class (ATDesktopEntity) implements caching of a file URL. One concrete subclass implements the ability to have an array of children (ATDesktopFolderEntity). Another (ATDesktopImageEntity) represents an image suitable for the desktop wallpaper.

  Version: 1.1 

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*/

#import <Cocoa/Cocoa.h>

// Base abstract class that wraps a file system URL 

@interface ATDesktopEntity : NSObject {

@private

    NSURL *_fileURL;

}

- (id)initWithFileURL:(NSURL *)fileURL;

@property (retain, readonly) NSString *title;

@property (retain) NSURL *fileURL;

@end

// Concrete subclass of ATDesktopEntity that loads children from a folder

@interface ATDesktopFolderEntity : ATDesktopEntity {

@private

    NSArray *_children;

}

@property(retain, readonly) NSArray *children;

@end

// Concrete subclass of ATDesktopEntity that adds support for loading an image at the given URL and stores a fillColor property

@interface ATDesktopImageEntity : ATDesktopEntity {

@private

    BOOL _imageLoading;

    NSImage *_image;

    NSImage *_thumbnailImage;

    NSColor *_fillColor;

    NSString *_fillColorName;

}

@property (retain) NSColor *fillColor;

@property (copy) NSString *fillColorName;

// Access to the image. This property can be observed to find out when it changes and is fully loaded.

@property (retain) NSImage *image;

@property (readonly, retain) NSImage *thumbnailImage;

// Asynchronously loads the image (if not already loaded). A KVO notification is sent out when the image is loaded.

- (void)loadImage;

// A nil image isn't loaded (or couldn't be loaded). An image that is in the process of loading has imageLoading set to YES

@property (readonly) BOOL imageLoading;

@end

// Declared constants to avoid typos in KVO. Common prefixes are used for easy code completion.

extern NSString *const ATEntityPropertyNamedFillColor;

extern NSString *const ATEntityPropertyNamedFillColorName;

extern NSString *const ATEntityPropertyNamedImage;

extern NSString *const ATEntityPropertyNamedThumbnailImage;