<?php
class watermark { public function create_watermark( $main_img_obj, $watermark_img_obj, $alpha_level = 100 ) { $alpha_level /= 100;
$main_img_obj_w = imagesx( $main_img_obj ); $main_img_obj_h = imagesy( $main_img_obj ); $watermark_img_obj_w = imagesx( $watermark_img_obj ); $watermark_img_obj_h = imagesy( $watermark_img_obj );
$main_img_obj_min_x = floor( ( $main_img_obj_w / 2 ) - ( $watermark_img_obj_w / 2 ) ); $main_img_obj_max_x = ceil( ( $main_img_obj_w / 2 ) + ( $watermark_img_obj_w / 2 ) ); $main_img_obj_min_y = floor( ( $main_img_obj_h / 2 ) - ( $watermark_img_obj_h / 2 ) ); $main_img_obj_max_y = ceil( ( $main_img_obj_h / 2 ) + ( $watermark_img_obj_h / 2 ) );
$return_img = imagecreatetruecolor( $main_img_obj_w, $main_img_obj_h );
for( $y = 0; $y < $main_img_obj_h; $y++ ) { for( $x = 0; $x < $main_img_obj_w; $x++ ) { $return_color = NULL;
$watermark_x = $x - $main_img_obj_min_x; $watermark_y = $y - $main_img_obj_min_y;
$main_rgb = imagecolorsforindex( $main_img_obj, imagecolorat( $main_img_obj, $x, $y ) );
if ( $watermark_x >= 0 && $watermark_x < $watermark_img_obj_w && $watermark_y >= 0 && $watermark_y < $watermark_img_obj_h ) { $watermark_rbg = imagecolorsforindex( $watermark_img_obj, imagecolorat( $watermark_img_obj, $watermark_x, $watermark_y ) );
$watermark_alpha = round( ( ( 127 - $watermark_rbg['alpha'] ) / 127 ), 2 ); $watermark_alpha = $watermark_alpha * $alpha_level;
$avg_red= $this->_get_ave_color( $main_rgb['red'],$watermark_rbg['red'],$watermark_alpha ); $avg_green = $this->_get_ave_color( $main_rgb['green'], $watermark_rbg['green'], $watermark_alpha ); $avg_blue= $this->_get_ave_color( $main_rgb['blue'], $watermark_rbg['blue'],$watermark_alpha );
$return_color = $this->_get_image_color( $return_img, $avg_red, $avg_green, $avg_blue );
} else { $return_color = imagecolorat( $main_img_obj, $x, $y );
}
imagesetpixel( $return_img, $x, $y, $return_color );
} }
return $return_img; }
public function _get_ave_color( $color_a, $color_b, $alpha_level ) { return round( ( ( $color_a * ( 1 - $alpha_level ) ) + ( $color_b * $alpha_level ) ) ); }
public function _get_image_color($im, $r, $g, $b) { $c=imagecolorexact($im, $r, $g, $b); if ($c!=-1) return $c; $c=imagecolorallocate($im, $r, $g, $b); if ($c!=-1) return $c; return imagecolorclosest($im, $r, $g, $b); } }
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