图片水印的添加

在一些需求中我们需要将一些图片进行认证，如果认证则为其加上水印。具体实现代码如下

$groundImage为添加水印的背景图片路径

$postion 为水印在背景图片上的位置

$waterImage 水印图片的路径

$waterText 添加文字内容

$font 文字大小

$color 文字颜色

note 其中路径为服务器上的绝对路径，不是图片的访问地址

imageWaterMark($groundImage,$positon,$waterImage);
function imageWaterMark($groundImage,$waterPos=0,$waterImage="",$waterText="",$font=5,$color="#FF0000")
{
$isWaterImage = FALSE;//若为TRUE 则添加为文字
$formatMsg = "暂不支持该文件格式，请用图片处理软件将图片转换为GIF、JPG、PNG格式。";
if(! empty($waterImage) && file_exists($waterImage))
{
$isWaterImage = TRUE;
$water_info = getimagesize($waterImage);
$water_w    = $water_info[0];//取得水印图片的宽
$water_h    = $water_info[1];//取得水印图片的高

switch($water_info[2])//取得水印图片的格式
{
case 1:$water_im = imagecreatefromgif($waterImage);break;
case 2:$water_im = imagecreatefromjpeg($waterImage);break;
case 3:$water_im = imagecreatefrompng($waterImage);break;
default:die($formatMsg);
}
}

//读取背景图片
if(!empty($groundImage) && file_exists($groundImage))
{
$ground_info = getimagesize($groundImage);
$ground_w    = $ground_info[0];//取得背景图片的宽
$ground_h    = $ground_info[1];//取得背景图片的高

switch($ground_info[2])//取得背景图片的格式
{
case 1:$ground_im = imagecreatefromgif($groundImage);break;
case 2:$ground_im = imagecreatefromjpeg($groundImage);break;
case 3:$ground_im = imagecreatefrompng($groundImage);break;
default:die($formatMsg);
}
}
else
{
die("需要加水印的图片不存在！");
}

//水印位置
if($isWaterImage)//图片水印
{
$w = $water_w;
$h = $water_h;
$label = "图片的";
}
else//文字水印
{
$temp = imagettfbbox(ceil($textFont*5.5),0,"./cour.ttf",$waterText);//取得使用 TrueType 字体的文本的范围
$w = $temp[2] - $temp[6];
$h = $temp[3] - $temp[7];
unset($temp);
$label = "文字区域";
}
if( ($ground_w<$w) || ($ground_h<$h) )
{
echo "需要加水印的图片的长度或宽度比水印".$label."还小，无法生成水印！";
return;
}
switch($waterPos)
{
case 0://随机
$posX = rand(0,($ground_w - $w));
$posY = rand(0,($ground_h - $h));
break;
case 1://1为顶端居左
$posX = 0;
$posY = 0;
break;
case 2://2为顶端居中
$posX = ($ground_w - $w) / 2;
$posY = 0;
break;
case 3://3为顶端居右
$posX = $ground_w - $w;
$posY = 0;
break;
case 4://4为中部居左
$posX = 0;
$posY = ($ground_h - $h) / 2;
break;
case 5://5为中部居中
$posX = ($ground_w - $w) / 2;
$posY = ($ground_h - $h) / 2;
break;
case 6://6为中部居右
$posX = $ground_w - $w;
$posY = ($ground_h - $h) / 2;
break;
case 7://7为底端居左
$posX = 0;
$posY = $ground_h - $h;
break;
case 8://8为底端居中
$posX = ($ground_w - $w) / 2;
$posY = $ground_h - $h;
break;
case 9://9为底端居右
$posX = $ground_w - $w;
$posY = $ground_h - $h;
break;
default://随机
$posX = rand(0,($ground_w - $w));
$posY = rand(0,($ground_h - $h));
break;
}

//设定图像的混色模式
imagealphablending($ground_im, true);

if($isWaterImage)//图片水印
{
imagecopy($ground_im, $water_im, $posX, $posY, 0, 0, $water_w,$water_h);//拷贝水印到目标文件
}
else//文字水印
{
if( !empty($textColor) && (strlen($textColor)==7) )
{
$R = hexdec(substr($textColor,1,2));
$G = hexdec(substr($textColor,3,2));
$B = hexdec(substr($textColor,5));
}
else
{
die("水印文字颜色格式不正确！");
}
imagestring ( $ground_im, $textFont, $posX, $posY, $waterText, imagecolorallocate($ground_im, $R, $G, $B));
}

//生成水印后的图片
@unlink($groundImage);
switch($ground_info[2])//取得背景图片的格式
{
case 1:imagegif($ground_im,$groundImage);break;
case 2:imagejpeg($ground_im,$groundImage);break;
case 3:imagepng($ground_im,$groundImage);break;
default:die($errorMsg);
}

//释放内存
if(isset($water_info)) unset($water_info);
if(isset($water_im)) imagedestroy($water_im);
unset($ground_info);
imagedestroy($ground_im);
}