<?php // $Id: imageapi_gd.module,v 1.17 2009-03-11 05:42:47 drewish Exp $

/**
 * @file
 * GD2 toolkit functions
 */

function imageapi_gd_image_sharpen(stdImage $image, $radius, $sigma, $amount, $threshold) {
  $threshold = round($threshold * 255);
  $image->resource = imageapi_gd_unsharp_mask($image->resource, $radius, $sigma, $amount, $threshold);
  return TRUE;
}

// Provide a implementation of imagerotate() and imagefilter() if they
// weren't compiled into PHP.
if (!function_exists('imagerotate')) {
  require_once drupal_get_path('module', 'imageapi') .'/imagerotate.inc';
}
if (!function_exists('imagefilter')) {
  require_once drupal_get_path('module', 'imageapi') .'/imagefilter.inc';
}

/**
 * $sigma is currently unused for _gd_sharp_mask due to 3x3 convolution matrix limit.
 * we should explore properly implementing sigma.
 */
function imageapi_gd_unsharp_mask($img, $radius, $sigma, $amount, $threshold)    {

  ////////////////////////////////////////////////////////////// 
  ////   
  ////                  Unsharp Mask for PHP - version 2.1.1   
  ////   
  ////    Unsharp mask algorithm by Torstein H�nsi 2003-07.   
  ////             thoensi_at_netcom_dot_no.   
  ////               Please leave this notice.   
  ////   
  //////////////////////////////////////////////////////////////
  
  // http://vikjavev.no/computing/ump.php

  // $img is an image that is already created within php using
  // imgcreatetruecolor. No url! $img must be a truecolor image.

  // Attempt to calibrate the parameters to Photoshop:
  if ($amount > 500) $amount = 500;
  $amount = $amount * 0.016;
  if ($radius > 50) $radius = 50;
  $radius = $radius * 2;
  if ($threshold > 255) $threshold = 255;

  $radius = abs(round($radius)); // Only integers make sense.
  if ($radius == 0) {
    return $img; imagedestroy($img);
    break;
  }

  $w = imagesx($img); $h = imagesy($img);
  $img_canvas = imagecreatetruecolor($w, $h);
  $img_blur = imagecreatetruecolor($w, $h);

  // Gaussian blur matrix:
  //                          
  //    1    2    1          
  //    2    4    2          
  //    1    2    1          
  //                          
  //////////////////////////////////////////////////  

  $matrix = array(
    array( 1, 2, 1 ),
    array( 2, 4, 2 ),
    array( 1, 2, 1 ) 
    );

  imagecopy($img_blur, $img, 0, 0, 0, 0, $w, $h);
  imageconvolution($img_blur, $matrix, 16, 0);

  if ($threshold > 0) {
    // Calculate the difference between the blurred pixels and the original
    // and set the pixels
    for ($x = 0; $x < $w-1; $x++)    { // each row
      for ($y = 0; $y < $h; $y++)    { // each pixel

        $rgb_orig = imagecolorat($img, $x, $y);
        $r_orig = (($rgb_orig >> 16) & 0xFF);
        $g_orig = (($rgb_orig >> 8) & 0xFF);
        $b_orig = ($rgb_orig & 0xFF);

        $rgb_blur = imagecolorat($img_blur, $x, $y);

        $r_blur = (($rgb_blur >> 16) & 0xFF);
        $g_blur = (($rgb_blur >> 8) & 0xFF);
        $b_blur = ($rgb_blur & 0xFF);

        // When the masked pixels differ less from the original
        // than the threshold specifies, they are set to their original value.
        $r_new = (abs($r_orig - $r_blur) >= $threshold)
          ? max(0, min(255, ($amount * ($r_orig - $r_blur)) + $r_orig))
          : $r_orig;
        $g_new = (abs($g_orig - $g_blur) >= $threshold)
          ? max(0, min(255, ($amount * ($g_orig - $g_blur)) + $g_orig))
          : $g_orig;
        $b_new = (abs($b_orig - $b_blur) >= $threshold)
          ? max(0, min(255, ($amount * ($b_orig - $b_blur)) + $b_orig))
          : $b_orig;

        if (($r_orig != $r_new) || ($g_orig != $g_new) || ($b_orig != $b_new)) {
          $pix_col = imagecolorallocate($img, $r_new, $g_new, $b_new);
          imagesetpixel($img, $x, $y, $pix_col);
        }
      }
    }
  }
  else{
    for ($x = 0; $x < $w; $x++)    { // each row
      for ($y = 0; $y < $h; $y++)    { // each pixel
        $rgb_orig = imagecolorat($img, $x, $y);
        $r_orig = (($rgb_orig >> 16) & 0xFF);
        $g_orig = (($rgb_orig >> 8) & 0xFF);
        $b_orig = ($rgb_orig & 0xFF);

        $rgb_blur = imagecolorat($img_blur, $x, $y);

        $r_blur = (($rgb_blur >> 16) & 0xFF);
        $g_blur = (($rgb_blur >> 8) & 0xFF);
        $b_blur = ($rgb_blur & 0xFF);

        $r_new = ($amount * ($r_orig - $r_blur)) + $r_orig;
        if ($r_new>255) $r_new=255;
        elseif ($r_new<0) $r_new=0;

        $g_new = ($amount * ($g_orig - $g_blur)) + $g_orig;
        if ($g_new>255) $g_new=255;
        elseif ($g_new<0) $g_new=0;

        $b_new = ($amount * ($b_orig - $b_blur)) + $b_orig;
        if ($b_new>255) $b_new=255;
        elseif ($b_new<0) $b_new=0;

        $rgb_new = ($r_new << 16) + ($g_new <<8) + $b_new;
        imagesetpixel($img, $x, $y, $rgb_new);
      }
    }
  }
  imagedestroy($img_canvas);
  imagedestroy($img_blur);

  return $img;
}