//

//  NSImageGradients.m

//  Transformed Image

//

//  Created by John C. Randolph on Thu May 09 2002.

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

//

#import "NSImageGradients.h"

  // Just one function to declare...

float distance(NSPoint aPoint);

enum pixelComponents { red, green, blue, alpha };

NSSize gradientSize = {256.0, 256.0};

@implementation NSImage (Gradients)

+ (NSImage *) prettyGradientImageForWWDCDemo

  {

  NSImage 

    *newImage = [[self alloc] initWithSize:gradientSize];  // In this case, the pixel dimensions match the image size.

  int

    pixelsWide = gradientSize.width,

    pixelsHigh = gradientSize.height;    

  NSBitmapImageRep *bitmapRep = 

    [[NSBitmapImageRep alloc] 

      initWithBitmapDataPlanes: nil  // Nil pointer makes the kit allocate the pixel buffer for us.

      pixelsWide: pixelsWide  // The compiler will convert these to integers, but I just wanted to  make it quite explicit

      pixelsHigh: pixelsHigh //

      bitsPerSample: 8

      samplesPerPixel: 4  // Four samples, that is: RGBA

      hasAlpha: YES

      isPlanar: NO  // The math can be simpler with planar images, but performance suffers..

      colorSpaceName: NSCalibratedRGBColorSpace  // A calibrated color space gets us ColorSync for free.

      bytesPerRow: 0     // Passing zero means "you figure it out."

      bitsPerPixel: 32];  // This must agree with bitsPerSample and samplesPerPixel.

  unsigned char 

    *imageBytes = [bitmapRep bitmapData];  // -bitmapData returns a void*, not an NSData object ;-)

  int row = pixelsHigh;

  while(row--)

    {

    int col = pixelsWide;

    while(col--) 

      {

      int 

        pixelIndex = 4 * (row * pixelsWide + col);

      imageBytes[pixelIndex + red] = rint(fmod(distance(NSMakePoint(col/1.5,(255-row)/1.5)),255.0));  //red

      imageBytes[pixelIndex + green] = rint(fmod(distance(NSMakePoint(col/1.5, row/1.5)),255.0));  // green

      imageBytes[pixelIndex + blue] = rint(fmod(distance(NSMakePoint((255-col)/1.5,(255-row)/1.5)),255.0));  // blue

      imageBytes[pixelIndex + alpha] = 255;  // Not doing anything tricky with the Alpha value here...

      }

    }

  [newImage addRepresentation:bitmapRep];

  return [newImage autorelease];

  }

@end

float distance(NSPoint aPoint)  // Stole this from some guy named Pythagoras..  Returns the distance of aPoint from the origin.

  {

  return sqrt(aPoint.x * aPoint.x + aPoint.y *aPoint.y);

  }

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