给图片加水印

<?php
/**
  * 功能：给一张图片加上水印效果
  *           $i  要加水印效果的图片
  *           $t  水印文字
  *           $size 文字大小
  *           $pos 水印的位置
  *   		   $color 文字的颜色
  *           $flag 是布尔值，主要用来区分是不是原图上加水印
  *           $type 如果$flag等于false 则新图上加上水印 新文件名为 原名_txt.jpg
  */
function txt($i,$t=&#39;版权所有&#39;,$size=25,$pos=5,$color=&#39;rand&#39;,$flag=true,$type=&#39;_txt&#39;){
	$img = imagecreatefromjpeg($i);
	$w = imagesx($img);
	$h = imagesy($img);
	$font = dirname(__FILE__).&#39;/font/ls.ttf&#39;;
	$ps = imagettfbbox($size,0,$font,$t);
	$tw = $ps[4];
	$th = abs($ps[5]);
	switch($pos){
		case 1:break;	
		case 2:break;	
		case 3:break;	
		case 4:break;	
		case 5:$x=($w-$tw)/2;$y=($h-$th)/2+$th;break;	
		case 6:break;	
		case 7:break;	
		case 8:break;	
		case 9:break;	
		default:break;
	}
	$c = getcolor($img,$color);
	imagettftext($img,$size,0,$x,$y,$c,$font,$t);
	if($flag){
		imagejpeg($img,$i);	
	}else{
		$ext = ext($i);
		$ppp = rtrim($i,&#39;.&#39;.$ext);
		$ppp = $ppp.$type.&#39;.&#39;.$ext;
		imagejpeg($img,$ppp);
	}
}

function getcolor($i,$c=&#39;rand&#39;,$a=50){
	$cc = &#39;&#39;;
	switch($c){
		case &#39;white&#39;:$cc=imagecolorallocatealpha($i,255,255,255,$a);break;
		case &#39;black&#39;:$cc=imagecolorallocatealpha($i,0,0,0,$a);break;
		case &#39;red&#39;:$cc=imagecolorallocatealpha($i,255,0,0,$a);break;
		case &#39;green&#39;:$cc=imagecolorallocatealpha($i,0,255,0,$a);break;
		case &#39;blue&#39;:$cc=imagecolorallocatealpha($i,0,0,255,$a);break;
		case &#39;orange&#39;:$cc=imagecolorallocatealpha($i,0xff,0x66,0x33,$a);break;
		case &#39;yellow&#39;:$cc=imagecolorallocatealpha($i,255,255,0,$a);break;
		case &#39;rand&#39;:$cc=imagecolorallocatealpha($i,mt_rand(0,255),mt_rand(0,255),mt_rand(0,255),$a);break;
		default:
			$cs = substr($c,1);
			$ok = str_split($cs,2);
			$cc = imagecolorallocatealpha($i,hexdec($ok[0]),hexdec($ok[1]),hexdec($ok[2]),$a);
		break;		
	}
	return $cc;
}


/**
 * 功能是：返回扩展名
 */
 
function ext($f){
	$exts = explode(&#39;.&#39;,$f);
	return end($exts);
}

/**
  *  功能是：返回文件名，不含扩展名
  */
function name($f){
	$s = explode(&#39;/&#39;,$f);
	$fn = end($s);
	return rtrim($fn,&#39;.&#39;.ext($f));
}