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<?php
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// $Id: shift.inc,v 1.1.2.1 2008/08/20 16:45:41 skiquel Exp $
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/**
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* @file
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* Shift engine
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* Shifts colors based on 'base' color
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*/
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function _color_engine_shift($style, $info, $palette, $options) {
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$link = (array_search('link', $options) !== FALSE) ? TRUE : FALSE;
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$text = (array_search('text', $options) !== FALSE) ? TRUE : FALSE;
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// Prepare color conversion table
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$conversion = $palette;
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foreach ($conversion as $k => $v) {
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$conversion[$k] = drupal_strtolower($v);
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}
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// Original spot is right here, I'm moving up so i can see it in the debug
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// Bind reference hex to fields
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$reference = array_combine($info['fields'], $info['reference_scheme']);
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// Find all colors in the stylesheet and the chunks in between.
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$style = preg_split('/(#[0-9a-f]{6}|#[0-9a-f]{3})/i', $style, -1, PREG_SPLIT_DELIM_CAPTURE);
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$is_color = FALSE;
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$output = '';
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$base = 'base';
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foreach ($style as $chunk) {
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if ($is_color) {
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$chunk = drupal_strtolower($chunk);
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// Check if this is one of the colors in the default palette.
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if ($key = array_search($chunk, $reference)) {
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$chunk = $conversion[$key];
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}
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// Not a pre-set color. Extrapolate from the base.
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else {
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$chunk = _color_shift($palette[$base], $reference[$base], $chunk, $info['blend_target']);
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}
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}
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else {
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// Determine the most suitable base color for the next color.
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// 'a' declarations. Use link.
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if ($link && preg_match('@[^a-z0-9_-](a)[^a-z0-9_-][^/{]*{[^{]+$@i', $chunk)) {
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$base = 'link';
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}
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// 'color:' styles. Use text.
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else if ($text && preg_match('/(?<!-)color[^{:]*:[^{#]*$/i', $chunk)) {
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$base = 'text';
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}
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// Reset back to base.
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else {
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$base = 'base';
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}
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}
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$output .= $chunk;
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$is_color = !$is_color;
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}
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$style = $output;
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return $style;
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}
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/**
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* Shift a given color, using a reference pair and a target blend color.
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*
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* Note: this function is significantly different from the JS version, as it
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* is written to match the blended images perfectly.
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*
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* Constraint: if (ref2 == target + (ref1 - target) * delta) for some fraction delta
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* then (return == target + (given - target) * delta)
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*
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* Loose constraint: Preserve relative positions in saturation and luminance
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* space.
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*/
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function _color_shift($given, $ref1, $ref2, $target) {
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module_load_include('inc', 'color', 'color.algorithms');
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// We assume that ref2 is a blend of ref1 and target and find
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// delta based on the length of the difference vectors:
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// delta = 1 - |ref2 - ref1| / |white - ref1|
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$target = _color_unpack($target, TRUE);
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$ref1 = _color_unpack($ref1, TRUE);
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$ref2 = _color_unpack($ref2, TRUE);
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$numerator = 0;
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$denominator = 0;
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for ($i = 0; $i < 3; ++$i) {
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$numerator += ($ref2[$i] - $ref1[$i]) * ($ref2[$i] - $ref1[$i]);
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$denominator += ($target[$i] - $ref1[$i]) * ($target[$i] - $ref1[$i]);
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}
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$delta = ($denominator > 0) ? (1 - sqrt($numerator / $denominator)) : 0;
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// Calculate the color that ref2 would be if the assumption was TRUE.
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for ($i = 0; $i < 3; ++$i) {
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$ref3[$i] = $target[$i] + ($ref1[$i] - $target[$i]) * $delta;
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}
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// If the assumption is not TRUE, there is a difference between ref2 and ref3.
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// We measure this in HSL space. Notation: x' = hsl(x).
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$ref2 = _color_rgb2hsl($ref2);
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$ref3 = _color_rgb2hsl($ref3);
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for ($i = 0; $i < 3; ++$i) {
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$shift[$i] = $ref2[$i] - $ref3[$i];
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}
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// Take the given color, and blend it towards the target.
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$given = _color_unpack($given, TRUE);
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for ($i = 0; $i < 3; ++$i) {
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$result[$i] = $target[$i] + ($given[$i] - $target[$i]) * $delta;
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}
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// Finally, we apply the extra shift in HSL space.
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// Note: if ref2 is a pure blend of ref1 and target, then |shift| = 0.
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$result = _color_rgb2hsl($result);
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for ($i = 0; $i < 3; ++$i) {
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$result[$i] = min(1, max(0, $result[$i] + $shift[$i]));
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}
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$result = _color_hsl2rgb($result);
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// Return hex color.
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return _color_pack($result, TRUE);
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}
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