/*

     File: Sobel.m

 Abstract: 

  Version: 1.0

 Disclaimer: IMPORTANT:  This Apple software is supplied to you by Apple

 Inc. ("Apple") in consideration of your agreement to the following

 terms, and your use, installation, modification or redistribution of

 this Apple software constitutes acceptance of these terms.  If you do

 not agree with these terms, please do not use, install, modify or

 redistribute this Apple software.

 In consideration of your agreement to abide by the following terms, and

 subject to these terms, Apple grants you a personal, non-exclusive

 license, under Apple's copyrights in this original Apple software (the

 "Apple Software"), to use, reproduce, modify and redistribute the Apple

 Software, with or without modifications, in source and/or binary forms;

 provided that if you redistribute the Apple Software in its entirety and

 without modifications, you must retain this notice and the following

 text and disclaimers in all such redistributions of the Apple Software.

 Neither the name, trademarks, service marks or logos of Apple Inc. may

 be used to endorse or promote products derived from the Apple Software

 without specific prior written permission from Apple.  Except as

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

 implied, are granted by Apple herein, including but not limited to any

 patent rights that may be infringed by your derivative works or by other

 works in which the Apple Software may be incorporated.

 The Apple Software is provided by Apple on an "AS IS" basis.  APPLE

 MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION

 THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS

 FOR A PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND

 OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS.

 IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL

 OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

 INTERRUPTION) ARISING IN ANY WAY OUT OF THE USE, REPRODUCTION,

 MODIFICATION AND/OR DISTRIBUTION OF THE APPLE SOFTWARE, HOWEVER CAUSED

 AND WHETHER UNDER THEORY OF CONTRACT, TORT (INCLUDING NEGLIGENCE),

 STRICT LIABILITY OR OTHERWISE, EVEN IF APPLE HAS BEEN ADVISED OF THE

 POSSIBILITY OF SUCH DAMAGE.

 Copyright (C) 2013 Apple Inc. All Rights Reserved.

 */

#if TARGET_OS_IPHONE

#import <CoreImage/CoreImage.h>

#else

#import <QuartzCore/QuartzCore.h>

#endif

@interface SobelEdgeH : CIFilter

{

    CIImage *inputImage;

    NSNumber *inputGain;

}

@property (retain, nonatomic) CIImage *inputImage;

@property (copy, nonatomic)   NSNumber *inputGain;

@end

@interface SobelEdgeV : CIFilter

{

    CIImage *inputImage;

    NSNumber *inputGain;

}

@property (retain, nonatomic) CIImage *inputImage;

@property (copy, nonatomic)   NSNumber *inputGain;

@end

@implementation SobelEdgeH

@synthesize inputImage;

@synthesize inputGain;

+ (NSDictionary *)customAttributes

{

    return @{

             kCIAttributeFilterDisplayName : @"Sobel Edge Horizontal",

             kCIAttributeFilterCategories :  @[kCICategoryGradient, kCICategoryVideo, kCICategoryInterlaced, kCICategoryStillImage],

             @"inputGain" :

                 @{

                     kCIAttributeSliderMin : @-1.0,

                     kCIAttributeSliderMax :  @1.0,

                     kCIAttributeDefault   :  @1.0,

                     kCIAttributeType      : kCIAttributeTypeScalar

                     }

             };

}

- (void)setDefaults

{

    self.inputGain = @1.0;

}

- (CIImage *)outputImage

{

    if (inputImage == nil)

        return nil;

    double g = inputGain.doubleValue;

    const CGFloat weights[] = { 1*g, 0, -1*g,

                                2*g, 0, -2*g,

                                1*g, 0, -1*g};

    CIImage* result = nil;

    // The sobel convoloution will produce an image that is 0.5,0.5,0.5,0.5 whereever the image is flat

    // On edges the image will contain values that deviate from that based on the strength and

    // direction of the edge

    result = [CIFilter filterWithName:@"CIConvolution3X3" keysAndValues:

                                    @"inputImage", inputImage,

                                    @"inputWeights", [CIVector vectorWithValues:weights count:9],

                                    @"inputBias", @0.5,

                                    nil].outputImage;

    // Add filters to mage the image look pretty for display purposes.

    // We want the display image to be 0,0,0,1 where the image is flat

    // and closer to 1,1,1,1 based on the strength of the edge

    result = [CIFilter filterWithName:@"CISourceOverCompositing" keysAndValues:

              @"inputImage", result,

              @"inputBackgroundImage", [CIImage imageWithColor:[CIColor colorWithRed:0 green:0 blue:0 alpha:1]],

              nil].outputImage;

    result = [CIFilter filterWithName:@"CIColorPolynomial" keysAndValues:

                                        @"inputImage", result,

                                        @"inputRedCoefficients", [CIVector vectorWithX:1.0 Y:-4.0 Z:4.0 W:0.0],

                                        @"inputGreenCoefficients", [CIVector vectorWithX:1.0 Y:-4.0 Z:4.0 W:0.0],

                                        @"inputBlueCoefficients", [CIVector vectorWithX:1.0 Y:-4.0 Z:4.0 W:0.0],

                                    nil].outputImage;

    return result;

}

@end

@implementation SobelEdgeV

@synthesize inputImage;

@synthesize inputGain;

+ (NSDictionary *)customAttributes

{

    return @{

             kCIAttributeFilterDisplayName : @"Sobel Edge Vertical",

             kCIAttributeFilterCategories :  @[kCICategoryGradient, kCICategoryVideo, kCICategoryInterlaced, kCICategoryStillImage],

             @"inputGain" :

                 @{

                     kCIAttributeSliderMin : @-1.0,

                     kCIAttributeSliderMax :  @1.0,

                     kCIAttributeDefault   :  @1.0,

                     kCIAttributeType      : kCIAttributeTypeScalar

                     }

             };

}

- (void)setDefaults

{

    self.inputGain = @1.0;

}

- (CIImage *)outputImage

{

    if (inputImage == nil)

        return nil;

    double g = inputGain.doubleValue;

    const CGFloat weights[] = {-1*g,-2*g,-1*g,

                                  0,   0,   0,

                                1*g, 2*g, 1*g};

    CIImage* result = nil;

    // The sobel convoloution will produce an image that is 0.5,0.5,0.5,0.5 whereever the image is flat

    // On edges the image will contain values that deviate from that based on the strength and

    // direction of the edge

    result = [CIFilter filterWithName:@"CIConvolution3X3" keysAndValues:

              @"inputImage", inputImage,

              @"inputWeights", [CIVector vectorWithValues:weights count:9],

              @"inputBias", @0.5,

              nil].outputImage;

    // Add filters to mage the image look pretty for display purposes.

    // We want the display image to be 0,0,0,1 where the image is flat

    // and closer to 1,1,1,1 based on the strength of the edge

    result = [CIFilter filterWithName:@"CISourceOverCompositing" keysAndValues:

              @"inputImage", result,

              @"inputBackgroundImage", [CIImage imageWithColor:[CIColor colorWithRed:0 green:0 blue:0 alpha:1]],

              nil].outputImage;

    result = [CIFilter filterWithName:@"CIColorPolynomial" keysAndValues:

              @"inputImage", result,

              @"inputRedCoefficients", [CIVector vectorWithX:1.0 Y:-4.0 Z:4.0 W:0.0],

              @"inputGreenCoefficients", [CIVector vectorWithX:1.0 Y:-4.0 Z:4.0 W:0.0],

              @"inputBlueCoefficients", [CIVector vectorWithX:1.0 Y:-4.0 Z:4.0 W:0.0],

              nil].outputImage;

    return result;

}

@end