php实现给一张图片加上水印效果

function getcolor($i,$c='rand',$a=50){
$cc = '';
switch($c){
case 'white':$cc=imagecolorallocatealpha($i,255,$a);break;
case 'black':$cc=imagecolorallocatealpha($i,$a);break;
case 'red':$cc=imagecolorallocatealpha($i,$a);break;
case 'green':$cc=imagecolorallocatealpha($i,$a);break;
case 'blue':$cc=imagecolorallocatealpha($i,$a);break;
case 'orange':$cc=imagecolorallocatealpha($i,0xff,0x66,0x33,$a);break;
case 'yellow':$cc=imagecolorallocatealpha($i,$a);break;
case 'rand':$cc=imagecolorallocatealpha($i,mt_rand(0,255),$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){
$exts = explode('.',$f);
return end($exts);
}

/**

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

$srcInfo = @getimagesize($imgSrc);
$srcImg_w = $srcInfo[0];
$srcImg_h = $srcInfo[1];

switch ($srcInfo[2])
{
case 1:
$srcim =imagecreatefromgif($imgSrc);
break;
case 2:
$srcim =imagecreatefromjpeg($imgSrc);
break;
case 3:
$srcim =imagecreatefrompng($imgSrc);
break;
default:
die("不支持的图片文件类型");
exit;
}

if(!strcmp($markType,"img"))
{
if(!file_exists($markImg) || empty($markImg))
{
return;
}

$markImgInfo = @getimagesize($markImg);
$markImg_w  = $markImgInfo[0];
$markImg_h  = $markImgInfo[1];

if($srcImg_w < $markImg_w || $srcImg_h < $markImg_h)
{
  return;
}

switch ($markImgInfo[2]) 
{ 
  case 1: 
    $markim =imagecreatefromgif($markImg); 
    break; 
  case 2: 
    $markim =imagecreatefromjpeg($markImg); 
    break; 
  case 3: 
    $markim =imagecreatefrompng($markImg); 
    break; 
  default: 
    die("不支持的水印图片文件类型"); 
    exit; 
}

$logow = $markImg_w;
$logoh = $markImg_h;

}

if(!strcmp($markType,"text"))
{
$fontSize = 16;
if(!empty($markText))
{
if(!file_exists($fontType))
{
return;
}
}
else {
return;
}

$box = @imagettfbbox($fontSize,$markText);
$logow = max($box[2],$box[4]) - min($box[0],$box[6]);
$logoh = max($box[1],$box[3]) - min($box[5],$box[7]);

}

if($markPos == 0)
{
$markPos = rand(1,9);
}

switch($markPos)
{
case 1:
$x = +5;
$y = +5;
break;
case 2:
$x = ($srcImg_w - $logow) / 2;
$y = +5;
break;
case 3:
$x = $srcImg_w - $logow - 5;
$y = +15;
break;
case 4:
$x = +5;
$y = ($srcImg_h - $logoh) / 2;
break;
case 5:
$x = ($srcImg_w - $logow) / 2;
$y = ($srcImg_h - $logoh) / 2;
break;
case 6:
$x = $srcImg_w - $logow - 5;
$y = ($srcImg_h - $logoh) / 2;
break;
case 7:
$x = +5;
$y = $srcImg_h - $logoh - 5;
break;
case 8:
$x = ($srcImg_w - $logow) / 2;
$y = $srcImg_h - $logoh - 5;
break;
case 9:
$x = $srcImg_w - $logow - 5;
$y = $srcImg_h - $logoh -5;
break;
default:
die("此位置不支持");
exit;
}

$dst_img = @imagecreatetruecolor($srcImg_w,$srcImg_h);

imagecopy ( $dst_img,$srcim,$srcImg_w,$srcImg_h);

if(!strcmp($markType,"img"))
{
imagecopy($dst_img,$markim,$logow,$logoh);
imagedestroy($markim);
}

if(!strcmp($markType,"text"))
{
$rgb = explode(',',$TextColor);

$color = imagecolorallocate($dst_img,$rgb[0],$rgb[1],$rgb[2]);
imagettftext($dst_img,$fontSize,$color,$markText);

}

switch ($srcInfo[2])
{
case 1:
imagegif($dst_img,$imgSrc);
break;
case 2:
imagejpeg($dst_img,$imgSrc);
break;
case 3:
imagepng($dst_img,$imgSrc);
break;
default:
die("不支持的水印图片文件类型");
exit;
}

imagedestroy($dst_img);
imagedestroy($srcim);
}