Generates a tile image from an input image.

gistfile1.m

- (UIImage *) tileImageFromImage:(UIImage *)image
{
   CGImageRef        imageRef;
   CGContextRef      context;
   CGColorSpaceRef   color;
   CGFloat           w;
   CGFloat           h;
   CGFloat           r;
   CGFloat           m;
   NSInteger         pos;
   CGFloat           components[8];
   CGGradientRef     gradLight;
   CGGradientRef     gradDark;

   // image information
   w = image.size.width;
   h = image.size.height;
   r = w * 0.1;
   r = (r < 10) ? 10 : r;
   m = 0;

   NSLog(@"Image dimensions: %fx%f", w, h);

   // create drawing context using UIImage parameters
   color   = CGColorSpaceCreateDeviceRGB();
   context = CGBitmapContextCreate(
      NULL,                                      // pointer where drawing is rendered
      CGImageGetWidth(image.CGImage),            // The width, in pixels, of the bitmap
      CGImageGetHeight(image.CGImage),           // The height, in pixels, of the bitmap
      CGImageGetBitsPerComponent(image.CGImage), // bits to use for each component of a pixel
      CGImageGetBytesPerRow(image.CGImage),      // bytes of memory to use per row of the bitmap
      CGImageGetColorSpace(image.CGImage),       // The color space to use for the bitmap context
      kCGImageAlphaPremultipliedLast             // Specify whether the bitmap contains alpha
   );

   // First Pass:  Round corners of context and import image
   // Second Pass: trace outside border of bevel
   //
   //    A   B           C  D
   //      *-*-----------*-*        A = (m, m)          G = (w-m, h-m)
   //    L *               * E      B = (r+m, m)        H = (w-r-m, h-m)
   //      |               |        C = (w-r-m, m)      I = (r+m, h-m)
   //      |               |        D = (w-m, m)        J = (m, h-m)
   //      |               |        E = (w-m, h-r-m)    K = (m, h-r-m)
   //      |               |        F = (w-m, h-r-m)    L = (m, r+m)
   //    K *               * F
   //      *-*-----------*-*        w = width           r = bend radius
   //    J   I           H   G      h = height          m = margin
   //
   for(pos = 0; pos < 2; pos++)
   {
      CGContextMoveToPoint(context,    r+m, m);                  // start: B
      CGContextAddLineToPoint(context, r+m, m);                  // line:  C
      CGContextAddArcToPoint(context,  w-m, m, w-m, h-r-m, r);   // arc:   D,E
      CGContextAddLineToPoint(context, w-m, h-r-m);              // line:  F
      CGContextAddArcToPoint(context,  w-m, h-m, w-r-m, h-m, r); // arc:   G,H
      CGContextAddLineToPoint(context, r+m, h-m);                // line:  I
      CGContextAddArcToPoint(context,  m, h-m, m, h-r-m, r);     // arc:   J,K
      CGContextAddLineToPoint(context, m,   r+m);                // line:  L
      CGContextAddArcToPoint(context,  m, m, r+m, m, r);         // arc:   A,B
      CGContextClosePath(context);
      if (pos == 0)
      {
         // clip of context
         CGContextClip(context);

         // copy image into context
         CGContextDrawImage(context, CGRectMake(0, 0, w, h), image.CGImage);
      };
   };

   // trace inside border of bevel
   m = (r/2);
   r /= 2;
   CGContextMoveToPoint(context,    r+m, m);                  // start: B
   CGContextAddArcToPoint(context,  m, m, m, r+m, r);         // arc:   A,L
   CGContextAddLineToPoint(context, m, h-r-m);                // line:  K
   CGContextAddArcToPoint(context,  m, h-m, r+m, h-m, r);     // arc:   J, I
   CGContextAddLineToPoint(context, w-r-m, h-m);              // line:  H
   CGContextAddArcToPoint(context,  w-m, h-m, w-m, h-r-m, r); // arc:   G, F
   CGContextAddLineToPoint(context, w-m, h-r-m);              // line:  E
   CGContextAddArcToPoint(context,  w-m, m, w-r-m, m, r);     // arc:   D, C
   CGContextAddLineToPoint(context, r+m, m);                  // line:  B
   CGContextClosePath(context);
   CGContextClip(context);

   // creates dark gradient
   components[0] = 0.0; // first color (red)
   components[1] = 0.0; // first color (green)
   components[2] = 0.0; // first color (blue)
   components[3] = 0.4; // first color (alpha)
   components[4] = 0.0; // second color (red)
   components[5] = 0.0; // second color (green)
   components[6] = 0.0; // second color (blue)
   components[7] = 0.0; // second color (alpha)
   gradDark = CGGradientCreateWithColorComponents(color, components, NULL, 2);

   // creates light gradient
   components[0] = 1.0; // first color (red)
   components[1] = 1.0; // first color (green)
   components[2] = 1.0; // first color (blue)
   components[3] = 0.4; // first color (alpha)
   components[4] = 1.0; // second color (red)
   components[5] = 1.0; // second color (green)
   components[6] = 1.0; // second color (blue)
   components[7] = 0.0; // second color (alpha)
   gradLight = CGGradientCreateWithColorComponents(color, components, NULL, 2);

   // applies gradient to bottom side
   CGContextDrawLinearGradient
   (
      context,                 // A Quartz graphics context.
      gradDark,                // A CGGradient object.
      CGPointMake(0, 0),       // Starting point of the gradient.
      CGPointMake(0, (m*2)),   // Ending point of the gradient.
      kCGGradientDrawsBeforeStartLocation
   );
   
   // applies gradient to right side
   CGContextDrawLinearGradient
   (
      context,                 // A Quartz graphics context.
      gradDark,                // A CGGradient object.
      CGPointMake(w,       0), // Starting point of the gradient.
      CGPointMake(w-(m*2), 0), // Ending point of the gradient.
      kCGGradientDrawsBeforeStartLocation
   );

   // applies gradient to left side
   CGContextDrawLinearGradient
   (
      context,                 // A Quartz graphics context.
      gradLight,               // A CGGradient object.
      CGPointMake(0, 0),       // Starting point of the gradient.
      CGPointMake((m*2), 0),   // Ending point of the gradient.
      kCGGradientDrawsBeforeStartLocation
   );
   
   // applies gradient to top side
   CGContextDrawLinearGradient
   (
      context,                 // A Quartz graphics context.
      gradLight,               // A CGGradient object.
      CGPointMake(0, h),       // Starting point of the gradient.
      CGPointMake(0, h-(m*2)), // Ending point of the gradient.
      kCGGradientDrawsBeforeStartLocation
   );

   // convert context back to UIImage
   imageRef = CGBitmapContextCreateImage(context);
   image    = [UIImage imageWithCGImage:imageRef];
   CGImageRelease(imageRef);

   // frees resources
   CGGradientRelease(gradDark);
   CGGradientRelease(gradLight);
   CGContextRelease(context);
   CGColorSpaceRelease(color);

   return(image);
}