/*

     File: MyHazeFilter.m

 Abstract: Custom CIFilter.

  Version: 1.1

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 */

#import "MyHazeFilter.h"

@implementation MyHazeFilter

{

    CIImage   *inputImage;

    CIColor   *inputColor;

    NSNumber  *inputDistance;

    NSNumber  *inputSlope;

}

static CIKernel *hazeRemovalKernel = nil;

+ (void)registerFilter

{

    NSArray *filterCategories = @[kCICategoryColorAdjustment, kCICategoryVideo, kCICategoryStillImage,

    kCICategoryInterlaced, kCICategoryNonSquarePixels];

    NSDictionary *attributes = @{

        kCIAttributeFilterDisplayName : @"Haze Remover",

        kCIAttributeFilterCategories : filterCategories };

    [CIFilter registerFilterName:@"MyHazeRemover" constructor:(id <CIFilterConstructor>)self classAttributes:attributes];

}

+ (CIFilter *)filterWithName:(NSString *)name

{

    return [[self alloc] init];

}

- (id)init

{

    self = [super init];

    if (self) {

        if (hazeRemovalKernel == nil)

        {

            // Load the haze removal kernel.

            NSBundle *bundle = [NSBundle bundleForClass: [self class]];

            NSURL *kernelURL = [bundle URLForResource:@"MyHazeRemoval" withExtension:@"cikernel"];

            NSError *error;

            NSString *kernelCode = [NSString stringWithContentsOfURL:kernelURL encoding:NSUTF8StringEncoding error:&error];

            if (kernelCode == nil) {

                NSLog(@"Error loading kernel code string in %@\n%@", NSStringFromSelector(_cmd), [error localizedDescription]);

                abort();

            }

            NSArray *kernels = [CIKernel kernelsWithString:kernelCode];

            hazeRemovalKernel = [kernels objectAtIndex:0];

        }

    }

    return self;

}

- (CIImage *)outputImage

{

    CISampler *src = [CISampler samplerWithImage: inputImage];

    return [self apply: hazeRemovalKernel, src, inputColor, inputDistance,

        inputSlope, kCIApplyOptionDefinition, [src definition], nil];

}

- (NSDictionary *)customAttributes

{

    NSDictionary *distanceDictionary = @{

        kCIAttributeMin : @0.0,

        kCIAttributeMax : @1.0,

        kCIAttributeSliderMin : @0.0,

        kCIAttributeSliderMax : @0.7,

        kCIAttributeDefault : @0.2,

        kCIAttributeIdentity : @0.0,

        kCIAttributeType : kCIAttributeTypeScalar };

    NSDictionary *slopeDictionary = @{

        kCIAttributeSliderMin : @-0.01,

        kCIAttributeSliderMax : @0.01,

        kCIAttributeDefault : @0.00,

        kCIAttributeIdentity : @0.00,

        kCIAttributeType : kCIAttributeTypeScalar

    };

    NSDictionary *colorDictionary = @{

        kCIAttributeDefault : [CIColor colorWithRed:1.0 green:1.0 blue:1.0 alpha:1.0]

    };

    return @{

        @"inputDistance" : distanceDictionary,

        @"inputSlope" : slopeDictionary,

        @"inputColor": colorDictionary,

        // This is needed because the filter is registered under a different name than the class.

        kCIAttributeFilterName : @"MyHazeRemover"

    };

}

@end