<?php/** * Watermarking API * @author $Author: Brian Vaughn $ http://boynamedbri.com/  -  http://portfolio.boynamedbri.com/ -  @ devshed http://www.devshed.com/c/a/PHP/Dynamic-Watermarking-with-PHP/ * @author $Author: Paul Moers <mail@saulmade.nl> $ - small changes to place the watermark on a given coordinate and to only handle watermark area * @package ImageManager */class watermark{	# given two images, return a blended watermarked image	function create_watermark( $main_img_obj, $watermark_img_obj, $alpha_level = 100, $watermarkX = -1, $watermarkY = -1 ) {		$alpha_level	/= 100;	# convert 0-100 (%) alpha to decimal			# calculate our images dimensions		$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( $watermark_img_obj );				# determine watermark area for given coordinates		if ($watermarkX > - 1 && $watermarkY > -1)		{			$main_img_obj_min_x	= $watermarkX;			$main_img_obj_max_x	= $watermarkX + $watermark_img_obj_w;			$main_img_obj_min_y	= $watermarkY;			$main_img_obj_max_y	= $watermarkY + $watermark_img_obj_h;		}		# determine watermark area when centered		else		{			$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 ) );		}		# create image copy to hold merged changes		$return_img	= $main_img_obj;		# walk through the watermark area		for( $y = $main_img_obj_min_y; $y < $main_img_obj_max_y; $y++ ) {			for( $x = $main_img_obj_min_x; $x < $main_img_obj_max_x; $x++ ) {				$return_color	= NULL;								# determine the correct pixel location within our watermark				$watermark_x	= $x - $main_img_obj_min_x;				$watermark_y	= $y - $main_img_obj_min_y;								# fetch color information for both of our images				$main_rgb = imagecolorsforindex( $main_img_obj, imagecolorat( $main_img_obj, $x, $y ) );								# if our watermark has a non-transparent value at this pixel intersection				# and we're still within the bounds of the watermark image				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 ) );										# using image alpha, and user specified alpha, calculate average					$watermark_alpha	= round( ( ( 127 - $watermark_rbg['alpha'] ) / 127 ), 2 );					$watermark_alpha	= $watermark_alpha * $alpha_level;									# calculate the color 'average' between the two - taking into account the specified 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 );					# calculate a color index value using the average RGB values we've determined					$return_color	= $this->_get_image_color( $return_img, $avg_red, $avg_green, $avg_blue );									# if we're not dealing with an average color here, then let's just copy over the main color				} else {					$return_color	= imagecolorat( $main_img_obj, $x, $y );									} # END if watermark						# draw the appropriate color onto the return image				imagesetpixel( $return_img, $x, $y, $return_color );					} # END for each X pixel		} # END for each Y pixel					# return the resulting, watermarked image for display		return $return_img;		} # END create_watermark()		# average two colors given an alpha	function _get_ave_color( $color_a, $color_b, $alpha_level ) {		return round( ( ( $color_a * ( 1 - $alpha_level ) ) + ( $color_b	* $alpha_level ) ) );	} # END _get_ave_color()			# return closest pallette-color match for RGB values	function _get_image_color($im, $r, $g, $b) {		$c=imagecolorexact($im, $r, $g, $b);		if ($c>0) return $c;		$c=imagecolorallocate($im, $r, $g, $b);		if ($c>0) return $c;		return imagecolorclosest($im, $r, $g, $b);	} # EBD _get_image_color()} # END watermark API?>