87 lines
3.4 KiB
PHP
87 lines
3.4 KiB
PHP
<?php
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// $ID $
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/**
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* @file routine for image layering
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*
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*/
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/****************************************************************************************************************************************/
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/**
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* Note that the below code is laboriously slow - it takes and compares every pixel of the two inputs
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* and calculates a new valus for each of them. this is only a fallback because reliable image toolkit
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* transparencies was buggy on certain platforms :(
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*/
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//Niko (http://www.codeguru.com.ua)
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class watermark {
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function create_watermark($main_img_obj, $watermark_img_obj, $x_ins, $y_ins, $alpha_level = 100) {
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$alpha_level /= 100;
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# Should this change to match both images?
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#$main_img_obj_w = max(imagesx($main_img_obj), imagesx($watermark_img_obj));
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#$main_img_obj_h = max(imagesy($main_img_obj), imagesy($watermark_img_obj));
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$main_img_obj_w = imagesx($main_img_obj);
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$main_img_obj_h = imagesy($main_img_obj);
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$watermark_img_obj_w = imagesx($watermark_img_obj);
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$watermark_img_obj_h = imagesy($watermark_img_obj);
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$main_img_obj_min_x = $x_ins;
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$main_img_obj_min_y = $y_ins;
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$return_img = imagecreatetruecolor($main_img_obj_w, $main_img_obj_h);
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imagesavealpha($return_img, true);
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imagealphablending($return_img, false);
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for ($y = 0; $y < $main_img_obj_h; $y++) {
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for ($x = 0; $x < $main_img_obj_w; $x++) {
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$return_color = NULL;
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$watermark_x = $x - $main_img_obj_min_x;
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$watermark_y = $y - $main_img_obj_min_y;
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$main_rgb = imagecolorsforindex($main_img_obj, imagecolorat($main_img_obj, $x, $y));
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if ($watermark_x >= 0 && $watermark_x < $watermark_img_obj_w && $watermark_y >= 0 && $watermark_y < $watermark_img_obj_h) {
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$watermark_rbg = imagecolorsforindex($watermark_img_obj, imagecolorat($watermark_img_obj, $watermark_x, $watermark_y));
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$watermark_alpha = round(((127 - $watermark_rbg['alpha']) / 127), 2);
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$watermark_alpha = $watermark_alpha * $alpha_level;
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$avg_red = $this->_get_ave_color($main_rgb['red'], $watermark_rbg['red'], $watermark_alpha);
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$avg_green = $this->_get_ave_color($main_rgb['green'], $watermark_rbg['green'], $watermark_alpha);
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$avg_blue = $this->_get_ave_color($main_rgb['blue'], $watermark_rbg['blue'], $watermark_alpha);
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// TODO figure out the maths for merging two transparent images
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$new_alpha = min($watermark_rbg['alpha'], $main_rgb['alpha']);
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#$new_alpha = $main_rgb['alpha'];
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#$new_alpha = 0;
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$return_color = $this->_get_image_color($return_img, $avg_red, $avg_green, $avg_blue, $new_alpha);
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}
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else {
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$return_color = imagecolorat($main_img_obj, $x, $y);
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}
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imagesetpixel($return_img, $x, $y, $return_color);
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}
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}
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return $return_img;
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}
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function _get_ave_color($color_a, $color_b, $alpha_level) {
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return round((($color_a * (1 - $alpha_level)) + ($color_b * $alpha_level)));
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}
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function _get_image_color($im, $r, $g, $b, $alpha) {
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$c = imagecolorexactalpha($im, $r, $g, $b, $alpha);
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if ($c != -1)
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return $c;
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$c = imagecolorallocate($im, $r, $g, $b, $alpha);
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if ($c != -1)
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return $c;
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return imagecolorclosest($im, $r, $g, $b, $alpha);
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}
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}
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/****************************************************************************************************************************************/
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