How to implement image scaling and logo watermark functions in PHP

This article mainly introduces the functions of proportional scaling and logo watermarking of images in PHP, and analyzes the operating techniques of proportional scaling and logo watermarking of PHP images in the form of examples. Friends in need can refer to the following

The details are as follows:

/**
 * 等比缩放函数（以保存的方式实现）
 * @param string $picname 被缩放的处理图片源
 * @param int $maxx 缩放后图片的最大宽度
 * @param int $maxy 缩放后图片的最大高度
 * @param string $pre 缩放后图片名的前缀名
 * @return String 返回后的图片名称(带路径)，如a.jpg=>s_a.jpg
 */
function imageUpdateSize($picname,$maxx=100,$maxy=100,$pre="s_"){
  $info = getimageSize($picname); //获取图片的基本信息
  $w = $info[0];//获取宽度
  $h = $info[1];//获取高度
  //获取图片的类型并为此创建对应图片资源
  switch($info[2]){
    case 1: //gif
      $im = imagecreatefromgif($picname);
      break;
    case 2: //jpg
      $im = imagecreatefromjpeg($picname);
      break;
    case 3: //png
      $im = imagecreatefrompng($picname);
      break;
    default:
      die("图片类型错误！");
  }
  //计算缩放比例
  if(($maxx/$w)>($maxy/$h)){
    $b = $maxy/$h;
  }else{
    $b = $maxx/$w;
  }
  //计算出缩放后的尺寸
  $nw = floor($w*$b);
  $nh = floor($h*$b);
  //创建一个新的图像源(目标图像)
  $nim = imagecreatetruecolor($nw,$nh);
  //执行等比缩放
  imagecopyresampled($nim,$im,0,0,0,0,$nw,$nh,$w,$h);
  //输出图像（根据源图像的类型，输出为对应的类型）
  $picinfo = pathinfo($picname);//解析源图像的名字和路径信息
  $newpicname= $picinfo["dirname"]."/".$pre.$picinfo["basename"];
  switch($info[2]){
    case 1:
      imagegif($nim,$newpicname);
      break;
    case 2:
      imagejpeg($nim,$newpicname);
      break;
    case 3:
      imagepng($nim,$newpicname);
      break;
  }
  //释放图片资源
  imagedestroy($im);
  imagedestroy($nim);
  //返回结果
  return $newpicname;
}
//测试：
//echo imageUpdateSize("./images/bg.jpg",200,200,"ss_"); // ./images/s_bg.jpg

/**
 * 为一张图片添加上一个logo图片水印（以保存的方式实现）
 * @param string $picname 被处理图片源
 * @param string $logo 水印图片
 * @param string $pre 处理后图片名的前缀名
 * @return String 返回后的图片名称(带路径)，如a.jpg=>n_a.jpg
 */
function imageUpdateLogo($picname,$logo,$pre="n_"){
  $picnameinfo = getimageSize($picname); //获取图片源的基本信息
  $logoinfo = getimageSize($logo); //获取logo图片的基本信息
  //var_dump($logoinfo);
  //根据图片类型创建出对应的图片源
  switch($picnameinfo[2]){
    case 1: //gif
      $im = imagecreatefromgif($picname);
      break;
    case 2: //jpg
      $im = imagecreatefromjpeg($picname);
      break;
    case 3: //png
      $im = imagecreatefrompng($picname);
      break;
    default:
      die("图片类型错误！");
  }
  //根据logo图片类型创建出对应的图片源
  switch($logoinfo[2]){
    case 1: //gif
      $logoim = imagecreatefromgif($logo);
      break;
    case 2: //jpg
      $logoim = imagecreatefromjpeg($logo);
      break;
    case 3: //png
      $logoim = imagecreatefrompng($logo);
      break;
    default:
      die("logo图片类型错误！");
  }
  //执行图片水印处理
  imagecopyresampled($im,$logoim,$picnameinfo[0]-$logoinfo[0],$picnameinfo[1]-$logoinfo[1],0,0,$logoinfo[0],$logoinfo[1],$logoinfo[0],$logoinfo[1]);
  //输出图像（根据源图像的类型，输出为对应的类型）
  $picinfo = pathinfo($picname);//解析源图像的名字和路径信息
  $newpicname= $picinfo["dirname"]."/".$pre.$picinfo["basename"];
  switch($picnameinfo[2]){
    case 1:
      imagegif($im,$newpicname);
      break;
    case 2:
      imagejpeg($im,$newpicname);
      break;
    case 3:
      imagepng($im,$newpicname);
      break;
  }
  //释放图片资源
  imagedestroy($im);
  imagedestroy($logoim);
  //返回结果
  return $newpicname;
}
//测试
echo imageUpdateLogo("./images/bg2.jpg","./images/s_1.png");

The above is the entire content of this article, I hope it will be helpful to everyone’s study .

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