/*

     File: APLAsyncImageActivityItemProvider.m

 Abstract: Subclass of UIActivityItemProvider that downloads a file asynchronously after the user has chosen their sharing option.

  Version: 1.0

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 */

#import "APLAsyncImageActivityItemProvider.h"

#import "UIImage+Resize.h"

@interface APLAsyncImageActivityItemProvider()

@property (strong, atomic) UIImage *image; //Use atomic to make sure access is synchronized.

@end

@implementation APLAsyncImageActivityItemProvider

- (id)activityViewControllerPlaceholderItem:(UIActivityViewController *)activityViewController

{

    return [[UIImage alloc] init];

}

/****************************************************

 item

 The item method runs on a secondary thread using an NSOperationQueue (UIActivityItemProvider subclasses NSOperation).

 The implementation of this method loads an image from the app's bundle and applies two filters to it.

 ******************************************************/

- (id)item

{

    //Notify the delegate on the main thread that the processing is beginning.

    dispatch_async(dispatch_get_main_queue(), ^{

        [self.delegate imageActivityItemProviderPreprocessingDidBegin:self];

    });

    //Load image.

    UIImage *image = [UIImage imageNamed:@"Flower.png"];

    //Start progress.

    dispatch_async(dispatch_get_main_queue(), ^{

        [self.delegate imageActivityItemProvider:self preprocessingProgressDidUpdate:0.2];

    });

    //Create Core Image context.

    CIContext *context = [CIContext contextWithOptions:nil];

    //Scale image for context.

    CGFloat scale = [[UIScreen mainScreen] scale];

    CGSize imageSize = CGSizeMake([context inputImageMaximumSize].width/scale/1.5, [context inputImageMaximumSize].height/scale/1.5);

    image = [UIImage imageWithImage:image scaledToFitToSize:imageSize];

    //Update progress after scaling.

    dispatch_async(dispatch_get_main_queue(), ^{

        [self.delegate imageActivityItemProvider:self preprocessingProgressDidUpdate:0.5];

    });

    //Add sepia filter.

    CIImage *sepiaImage = [CIImage imageWithCGImage:[image CGImage]];

    CIFilter *filter = [CIFilter filterWithName:@"CISepiaTone"];

    [filter setValue:sepiaImage forKey:kCIInputImageKey];

    CIImage *sepiaResult = [filter valueForKey:kCIOutputImageKey];

    //First filter complete.

    dispatch_async(dispatch_get_main_queue(), ^{

        [self.delegate imageActivityItemProvider:self preprocessingProgressDidUpdate:0.7];

    });

    //Add gloom filter.

    CIFilter *gloom = [CIFilter filterWithName:@"CIGloom"];

    [gloom setValue:sepiaResult forKey:kCIInputImageKey];

    [gloom setValue: [NSNumber numberWithFloat: 1.75] forKey: @"inputIntensity"];

    CIImage *gloomResult = [gloom valueForKey:kCIOutputImageKey];

    //Second filter complete.

    dispatch_async(dispatch_get_main_queue(), ^{

        [self.delegate imageActivityItemProvider:self preprocessingProgressDidUpdate:0.9];

    });

    //Create CGImage with filters applied.

    CGImageRef cgImage = [context createCGImage:gloomResult fromRect:[gloomResult extent]];

    //Progress completed.

    dispatch_async(dispatch_get_main_queue(), ^{

        [self.delegate imageActivityItemProvider:self preprocessingProgressDidUpdate:1.0];

    });

    //Notify the delegate on the main thread that the processing has finished.

    dispatch_async(dispatch_get_main_queue(), ^{

        [self.delegate imageActivityItemProviderPreprocessingDidEnd:self];

    });

    UIImage *newImage = [UIImage imageWithCGImage:cgImage];

    CFRelease(cgImage);

    self.image = newImage;

    return newImage;

}

- (UIImage *)activityViewController:(UIActivityViewController *)activityViewController thumbnailImageForActivityType:(NSString *)activityType suggestedSize:(CGSize)size

{

    //The filtered image is the image to display on the other side.

    return [UIImage imageWithImage:self.image scaledToFillToSize:size];

}

@end