How to crop and zoom images in PHP

This article mainly introduces the methods of cropping and scaling PHP images. The editor thinks it is quite good, so I will share it with you now and give it as a reference. Let’s follow the editor and take a look.

This article introduces examples of PHP image cropping and scaling. There is not much nonsense. The specific code is as follows:

/*

 *exif_imagetype -- 判断一个图像的类型

 *功能说明：函数功能是把一个图像裁剪为任意大小的图像，并保持图像不变形

 *参数说明：输入 需要处理图片的 文件名，生成新图片的保存文件名，生成新图片的宽，生成新图片的高

 */

 

// 获得任意大小图像，不足地方拉伸，不产生变形，不留下空白

function image_resize($src_file, $dst_file, $new_width, $new_height)

{

  $new_width = intval($new_width);

   

  $new_height = intval($new_width);

   

  if ($new_width < 1 || $new_height < 1)

  {

    echo "params width or height error !";

    exit();

  }

   

  if (!file_exists($src_file))

  {

    echo $src_file . " is not exists !";

    exit();

  }

   

  // 图像类型

  $type = exif_imagetype($src_file);

   

  $support_type = array(IMAGETYPE_JPEG, IMAGETYPE_PNG, IMAGETYPE_GIF);

   

  if (!in_array($type, $support_type, true))

  {

     

    echo "this type of image does not support! only support jpg , gif or png";

    exit();

  }

   

  //Load image

   

  switch($type)

  {

    case IMAGETYPE_JPEG :

       

      $src_img = imagecreatefromjpeg($src_file);

       

      break;

       

    case IMAGETYPE_PNG :

       

      $src_img = imagecreatefrompng($src_file);

       

      break;

       

    case IMAGETYPE_GIF :

       

      $src_img = imagecreatefromgif($src_file);

       

      break;

       

    default :

      echo "Load image error!";

       

      exit();

  }

   

  $w = imagesx($src_img);

   

  $h = imagesy($src_img);

   

  $ratio_w = 1.0 * $new_width / $w;

   

  $ratio_h = 1.0 * $new_height / $h;

   

  $ratio = 1.0;

   

  // 生成的图像的高宽比原来的都小，或都大 ，原则是 取大比例放大，取大比例缩小（缩小的比例就比较小了）

   

  if (($ratio_w < 1 && $ratio_h < 1) || ($ratio_w > 1 && $ratio_h > 1))

  {

     

    if ($ratio_w < $ratio_h) {

       

      $ratio = $ratio_h;

       

      // 情况一，宽度的比例比高度方向的小，按照高度的比例标准来裁剪或放大

       

    } else {

       

      $ratio = $ratio_w;

       

    }

     

    // 定义一个中间的临时图像，该图像的宽高比 正好满足目标要求

     

    $inter_w = (int)($new_width / $ratio);

     

    $inter_h = (int)($new_height / $ratio);

     

    $inter_img = imagecreatetruecolor($inter_w, $inter_h);

     

    //var_dump($inter_img);

     

    imagecopy($inter_img, $src_img, 0, 0, 0, 0, $inter_w, $inter_h);

     

    // 生成一个以最大边长度为大小的是目标图像$ratio比例的临时图像

    // 定义一个新的图像

     

    $new_img = imagecreatetruecolor($new_width, $new_height);

     

    //var_dump($new_img);exit();

    imagecopyresampled($new_img, $inter_img, 0, 0, 0, 0, $new_width, $new_height, $inter_w, $inter_h);

     

    switch($type)

    {

      case IMAGETYPE_JPEG :

         

        // 存储图像

        imagejpeg($new_img, $dst_file, 100);

         

        break;

         

      case IMAGETYPE_PNG :

         

        imagepng($new_img, $dst_file, 100);

         

        break;

         

      case IMAGETYPE_GIF :

         

        imagegif($new_img, $dst_file, 100);

         

        break;

         

      default :

         

        break;

    }

     

  }// end if 1

   

  // 2 目标图像 的一个边大于原图，一个边小于原图 ，先放大平普图像，然后裁剪

   

  // =if( ($ratio_w < 1 && $ratio_h > 1) || ($ratio_w >1 && $ratio_h <1) )

   

  else {

     

    $ratio = $ratio_h > $ratio_w ? $ratio_h : $ratio_w;

     

    //取比例大的那个值

     

    // 定义一个中间的大图像，该图像的高或宽和目标图像相等，然后对原图放大

     

    $inter_w = (int)($w * $ratio);

     

    $inter_h = (int)($h * $ratio);

     

    $inter_img = imagecreatetruecolor($inter_w, $inter_h);

     

    //将原图缩放比例后裁剪

     

    imagecopyresampled($inter_img, $src_img, 0, 0, 0, 0, $inter_w, $inter_h, $w, $h);

     

    // 定义一个新的图像

     

    $new_img = imagecreatetruecolor($new_width, $new_height);

     

    imagecopy($new_img, $inter_img, 0, 0, 0, 0, $new_width, $new_height);

     

    switch($type)

    {

      case IMAGETYPE_JPEG :

         

        // 存储图像

        imagejpeg($new_img, $dst_file, 100);

         

        break;

         

      case IMAGETYPE_PNG :

         

        imagepng($new_img, $dst_file, 100);

        break;

         

      case IMAGETYPE_GIF :

         

        imagegif($new_img, $dst_file, 100);

         

        break;

         

      default :

         

        break;

    }

     

  }// if3

   

}// end function

//输出新图片

image_resize(&#39;test.jpg&#39;, &#39;demo.jpg&#39;, &#39;1200px&#39;, &#39;1200px&#39;);

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

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