PHP implements function to generate image thumbnails

This article mainly introduces to you the function of generating image thumbnails implemented by PHP based on the GD library, which involves PHP's operation skills related to image attributes. Friends in need can refer to it. I hope it can help you.

<?php
/**
 * 生成缩略图函数（支持图片格式：gif、jpeg、png和bmp）
 * @author ruxing.li
 * @param string $src   源图片路径
 * @param int  $width  缩略图宽度（只指定高度时进行等比缩放）
 * @param int  $width  缩略图高度（只指定宽度时进行等比缩放）
 * @param string $filename 保存路径（不指定时直接输出到浏览器）
 * @return bool
 */
function mkThumbnail($src, $width = null, $height = null, $filename = null) {
  if (!isset($width) && !isset($height))
    return false;
  if (isset($width) && $width <= 0)
    return false;
  if (isset($height) && $height <= 0)
    return false;
  $size = getimagesize($src);
  if (!$size)
    return false;
  list($src_w, $src_h, $src_type) = $size;
  $src_mime = $size[&#39;mime&#39;];
  switch($src_type) {
    case 1 :
      $img_type = &#39;gif&#39;;
      break;
    case 2 :
      $img_type = &#39;jpeg&#39;;
      break;
    case 3 :
      $img_type = &#39;png&#39;;
      break;
    case 15 :
      $img_type = &#39;wbmp&#39;;
      break;
    default :
      return false;
  }
  if (!isset($width))
    $width = $src_w * ($height / $src_h);
  if (!isset($height))
    $height = $src_h * ($width / $src_w);
  $imagecreatefunc = &#39;imagecreatefrom&#39; . $img_type;
  $src_img = $imagecreatefunc($src);
  $dest_img = imagecreatetruecolor($width, $height);
  imagecopyresampled($dest_img, $src_img, 0, 0, 0, 0, $width, $height, $src_w, $src_h);
  $imagefunc = &#39;image&#39; . $img_type;
  if ($filename) {
    $imagefunc($dest_img, $filename);
  } else {
    header(&#39;Content-Type: &#39; . $src_mime);
    $imagefunc($dest_img);
  }
  imagedestroy($src_img);
  imagedestroy($dest_img);
  return true;
}
$result = mkThumbnail(&#39;./IMG_3324.JPG&#39;, 147, 147);

Note: Remember to turn on the GD library support first

Related recommendations:

PHP implementation can add watermarks and generate Thumbnail processing tool

thinkphp5 method of uploading images and generating thumbnails

AJAX method of previewing and uploading images and generating thumbnails

The above is the detailed content of PHP implements function to generate image thumbnails. For more information, please follow other related articles on the PHP Chinese website!