//

//  Negative.m

//  Image Difference

//

//  Created by jcr on Fri Sep 13 2002.

//  Copyright (c) 2002 Apple Computer, Inc. All rights reserved.

#import "Negative.h"

@interface NSBitmapImageRep (inversion)

- (NSBitmapImageRep *) invertRGBA;  //Various methods for inverting the bitmap data.

- (NSBitmapImageRep *) invertRGB;

- (NSBitmapImageRep *) invertGreyAlpha;

- (NSBitmapImageRep *) invertGrey;

@end

@implementation NSImage (Negative)

- (NSImage *) negativeImage

    {

    NSImage 

        *newImage = [[[self class] alloc] initWithSize:[self size]];

    NSBitmapImageRep 

        *negRep = [[[self representations] objectAtIndex:0] negativeImageRep];

    [newImage addRepresentation:negRep];

    return [newImage autorelease];

    }

@end

@implementation NSBitmapImageRep (Negative)

- (NSBitmapImageRep *) negativeImageRep // Only works for 8bits/sample RGB, RGBA, greyscale or greyScale with Alpha bitmaps

    {

    switch ( [self samplesPerPixel])

        {

        case 4: //RGBA

            return [[[self copy] invertRGBA] autorelease];

        case 3:     // RGB

            return [[[self copy] invertRGB] autorelease];

        case 2: // grey scale with alpha

            return [[[self copy] invertGreyAlpha] autorelease];

        case 1:  // grey scale

          return [[[self copy] invertGrey] autorelease];

        default: 

            return nil;     

        }   

    }

- (NSBitmapImageRep *) invertRGBA

    {

    RGBAPixel

        *pixels = (RGBAPixel *)[self bitmapData];  // -bitmapData returns a void*, not an NSData object ;-)

    int 

        row, 

        column,

        widthInPixels = [self pixelsWide], 

        heightInPixels = [self pixelsHigh];

    for (row = 0; row < heightInPixels; row++)

        for (column = 0; column < widthInPixels; column++)

            {

            RGBAPixel 

                *thisPixel = (RGBAPixel *) &(pixels[((widthInPixels * row) + column)]);

            thisPixel->redByte = (255 - thisPixel->redByte);

            thisPixel->greenByte = (255 - thisPixel->greenByte);

            thisPixel->blueByte = (255 - thisPixel->blueByte);

            // We're not going to invert the alpha...

            }

    return self;        

    }

- (NSBitmapImageRep *) invertRGB

    {

    RGBPixel

        *pixels = (RGBPixel *)[self bitmapData];  // -bitmapData returns a void*, not an NSData object ;-)

    int 

        row, 

        column,

        widthInPixels = [self pixelsWide], 

        heightInPixels = [self pixelsHigh];

    for (row = 0; row < heightInPixels; row++)      

        for (column = 0; column < widthInPixels; column++)

            {

            RGBPixel 

                *thisPixel = &(pixels[((widthInPixels * row) + column)]);

            thisPixel->redByte = (255 - thisPixel->redByte);

            thisPixel->greenByte = (255 - thisPixel->greenByte);

            thisPixel->blueByte = (255 - thisPixel->blueByte);

            }

    return self;        

    }   

- (NSBitmapImageRep *) invertGreyAlpha

    {

    GreyAlphaPixel

        *pixels = (GreyAlphaPixel *)[self bitmapData];  // -bitmapData returns a void*, not an NSData object ;-)

    int 

        row, 

        column,

        widthInPixels = [self pixelsWide], 

        heightInPixels = [self pixelsHigh];

    for (row = 0; row < heightInPixels; row++)      

        for (column = 0; column < widthInPixels; column++)

            {

            GreyAlphaPixel 

                *thisPixel = (GreyAlphaPixel *) &(pixels[((widthInPixels * row) + column)]);

            thisPixel->greyByte = (255 - thisPixel->greyByte);

            }

    return self;        

    }   

- (NSBitmapImageRep *) invertGrey

    {

    GreyPixel

        *pixels = (GreyPixel *)[self bitmapData];  // -bitmapData returns a void*, not an NSData object ;-)

    int 

        row, 

        column,

        widthInPixels = [self pixelsWide], 

        heightInPixels = [self pixelsHigh];

    for (row = 0; row < heightInPixels; row++)      

        for (column = 0; column < widthInPixels; column++)

            {

            GreyPixel 

                *thisPixel = (GreyPixel *) &(pixels[((widthInPixels * row) + column)]);

            *thisPixel = (255 - (*thisPixel));

            }

    return self;        

    }   

@end

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