php图片增加水印的方法：1、通过“watertext('banner.jpg', 9, '','xx.com');”设置文字水印；2、通过“imagewatermark('404.jpg', 9, 'logo.gif');”设置图片水印。
本文操作环境：windows7系统、php7.1版、dell g3电脑。
php给图片加上图片水印和文字水印实例
下面给大家分享一下php给图片加上图片水印和文字水印实例，这也是网站经常用到的功能，把代码加上去，调用就很简单了。
核心代码：
function imagewatermark($groundimage, $waterpos = 0, $waterimage = "", $watertext = "", $textfont = 5, $textcolor = "#ff0000") { $iswaterimage = false; $formatmsg = "暂不支持该文件格式，请用图片处理软件将图片转换为gif、jpg、png格式。"; //读取水印文件 if (!empty($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), 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 - 10; // -10 是距离右侧10px 可以自己调节 $posy = $ground_h - $h - 10; // -10 是距离底部10px 可以自己调节 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, $water_h); //拷贝水印到目标文件 } else {//文字水印 if (!emptyempty($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);}
文字水印：
watertext('banner.jpg', 9, '','sucaihuo.com'); //背景图片,$waterpos水印位置,水印图片地址
图片水印：
imagewatermark('404.jpg', 9, 'logo.gif'); //背景图片,$waterpos水印位置,水印图片地址
注意：$waterimage 和 $watertext 最好不要同时使用，选其中之一即可，优先使用 $waterimage。
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以上就是php图片增加水印的方法的详细内容。