PHP生成自适应大小的缩略图类及使用方法分享


Posted in PHP onMay 06, 2014

把下面的代码直接复制,新建一个文件叫做 thumbnailimage.php  ,文件名最好不要用大写,把以下代码复制进去:

<?php
define ( 'MAX_IMG_SIZE', 100000 );
// Supported image types
define ( 'THUMB_JPEG', 'image/jpeg' );
define ( 'THUMB_PNG', 'image/png' );
define ( 'THUMB_GIF', 'image/gif' );
// Interlacing modes
define ( 'INTERLACE_OFF', 0 );
define ( 'INTERLACE_ON', 1 );
// Output modes
define ( 'STDOUT', '' );
// Empty constants
define ( 'NO_LOGO', '' );
define ( 'NO_LABEL', '' );
// Logo and label positioning
define ( 'POS_LEFT', 0 );
define ( 'POS_RIGHT', 1 );
define ( 'POS_CENTER', 2 );
define ( 'POS_TOP', 3 );
define ( 'POS_BOTTOM', 4 );
// Error messages
define ( 'E_001', 'File <b>%s</b> do not exist' );
define ( 'E_002', 'Failed reading image data from <b>%s</b>' );
define ( 'E_003', 'Cannot create the copy of <b>%s</b>' );
define ( 'E_004', 'Cannot copy the logo image' );
define ( 'E_005', 'Cannot create final image' );
// ****************************************************************************
// CLASS DEFINITION
// ****************************************************************************
class ThumbnailImage
{
// ****************************************************************************
// PUBLIC PROPERTIES
// ****************************************************************************
  var $src_file;  // source image file
  var $dest_file; // destination image file
  var $dest_type;  // destination image type
  var $interlace; // destination image interlacing mode
  var $jpeg_quality; // quality of resulting JPEG
  var $max_width; // maximal thumbnail width
  var $max_height; // maximal thumbnail height
  var $fit_to_max; // enlarge small images?
  var $logo; // array of logo parameters
  var $label; // array of label parameters
// ****************************************************************************
// CLASS CONSTRUCTOR
// ****************************************************************************
  /*
    Description:
      Defines default values for properties.
    Prototype:
      void ThumbImg ( string src_file = '' )
    Parameters:
      src_file - source image filename
  */
  function ThumbnailImage ( $src_file = '' )
  {
    $this->src_file = $src_file;
    $this->dest_file = STDOUT;
    $this->dest_type = THUMB_JPEG;
    $this->interlace = INTERLACE_OFF;
    $this->jpeg_quality = -1;
    $this->max_width = 100;
    $this->max_height = 90;
    $this->fit_to_max = FALSE;
    $this->logo['file'] = NO_LOGO;
    $this->logo['vert_pos'] = POS_TOP;
    $this->logo['horz_pos'] = POS_LEFT;
    $this->label['text'] = NO_LABEL;
    $this->label['vert_pos'] = POS_BOTTOM;
    $this->label['horz_pos'] = POS_RIGHT;
    $this->label['font'] = '';
    $this->label['size'] = 20;
    $this->label['color'] = '#000000';
    $this->label['angle'] = 0;
  }
// ****************************************************************************
// PRIVATE METHODS
// ****************************************************************************
  /*
    Description:
      Extracts decimal color components from hex color string.
    Prototype:
      array ParseColor ( string hex_color )
    Parameters:
      hex_color - color in '#rrggbb' format
    Return:
      Decimal values for red, green and blue color components.
  */
  function ParseColor ( $hex_color )
  {
    if ( strpos ( $hex_color, '#' ) === 0 )
      $hex_color = substr ( $hex_color, 1 );
    $r = hexdec ( substr ( $hex_color, 0, 2 ) );
    $g = hexdec ( substr ( $hex_color, 2, 2 ) );
    $b = hexdec ( substr ( $hex_color, 4, 2 ) );
    return array ( $r, $g, $b );
  }
  /*
    Description:
      Retrives image data as a string.
      Thanks to Luis Larrateguy for the idea of this function.
    Prototype:
      string GetImageStr ( string image_file )
    Parameters:
      image_file - filename of image
    Return:
      Image file contents string.
  */
  function GetImageStr ( $image_file )
  {
    if ( function_exists ( 'file_get_contents' ) )
    {
      $str = @file_get_contents ( $image_file );
      if ( ! $str )
      {
        $err = sprintf( E_002, $image_file );
        trigger_error( $err, E_USER_ERROR );
      }
      return $str;
    }
    $f = fopen ( $image_file, 'rb' );
    if ( ! $f )
    {
      $err = sprintf( E_002, $image_file );
      trigger_error( $err, E_USER_ERROR );
    }
    $fsz = @filesize ( $image_file );
    if ( ! $fsz )
      $fsz = MAX_IMG_SIZE;
    $str = fread ( $f, $fsz );
    fclose ( $f );
    return $str;
  }
  /*
    Description:
      Loads image from file.
    Prototype:
      resource LoadImage ( string image_file, int &image_width, int &image_height )
    Parameters:
      image_file - filename of image
      image_width - width of loaded image
      image_height - height of loaded image
    Return:
      Image identifier representing the image obtained from the given file.
  */
  function LoadImage ( $image_file, &$image_width, &$image_height )
  {
    $image_width = 0;
    $image_height = 0;
    $image_data = $this->GetImageStr( $image_file );
    $image = imagecreatefromstring ( $image_data );
    if ( ! $image )
    {
      $err = sprintf( E_003, $image_file );
      trigger_error( $err, E_USER_ERROR );
    }
    $image_width = imagesx ( $image );
    $image_height = imagesy ( $image );
    return $image;
  }
  /*
    Description:
      Calculates thumbnail image sizes from source image width and height.
    Prototype:
      array GetThumbSize ( int src_width, int src_height )
    Parameters:
      src_width - width of source image
      src_height - height of source image
    Return:
      An array with 2 elements. Index 0 contains the width of thumbnail image
      and index 1 contains the height.
  */
  function GetThumbSize ( $src_width, $src_height )
  {
    $max_width = $this->max_width;
    $max_height = $this->max_height;
    $x_ratio = $max_width / $src_width;
    $y_ratio = $max_height / $src_height;
    $is_small = ( $src_width <= $max_width && $src_height <= $max_height );
    if ( ! $this->fit_to_max && $is_small )
    {
      $dest_width = $src_width;
      $dest_height = $src_height;
    }
    elseif ( $x_ratio * $src_height < $max_height )
    {
      $dest_width = $max_width;
      $dest_height = ceil ( $x_ratio * $src_height );
    }
    else
    {
      $dest_width = ceil ( $y_ratio * $src_width );
      $dest_height = $max_height;
    }
    return array ( $dest_width, $dest_height );
  }
  /*
    Description:
      Adds logo image to thumbnail.
    Prototype:
      void AddLogo ( int thumb_width, int thumb_height, resource &thumb_img )
    Parameters:
      thumb_width - width of thumbnail image
      thumb_height - height of thumbnail image
      thumb_img - thumbnail image identifier
  */
  function AddLogo ( $thumb_width, $thumb_height, &$thumb_img )
  {
    extract ( $this->logo );
    $logo_image = $this->LoadImage ( $file, $logo_width, $logo_height );
    if ( $vert_pos == POS_CENTER )
      $y_pos = ceil ( $thumb_height / 2 - $logo_height / 2 );
    elseif ($vert_pos == POS_BOTTOM)
      $y_pos = $thumb_height - $logo_height;
    else
      $y_pos = 0;
    if ( $horz_pos == POS_CENTER )
      $x_pos = ceil ( $thumb_width / 2 - $logo_width / 2 );
    elseif ( $horz_pos == POS_RIGHT )
      $x_pos = $thumb_width - $logo_width;
    else
      $x_pos = 0;
    if ( ! imagecopy ( $thumb_img, $logo_image, $x_pos, $y_pos, 0, 0,
      $logo_width, $logo_height ) )
      trigger_error( E_004, E_USER_ERROR );
  }
  /*
    Description:
      Adds label text to thumbnail.
    Prototype:
      void AddLabel ( int thumb_width, int thumb_height, resource &thumb_img )
    Parameters:
      thumb_width - width of thumbnail image
      thumb_height - height of thumbnail image
      thumb_img - thumbnail image identifier
  */
  function AddLabel ( $thumb_width, $thumb_height, &$thumb_img )
  {
    extract ( $this->label );
    list( $r, $g, $b ) = $this->ParseColor ( $color );
    $color_id = imagecolorallocate ( $thumb_img, $r, $g, $b );
    $text_box = imagettfbbox ( $size, $angle, $font, $text );
    $text_width = $text_box [ 2 ] - $text_box [ 0 ];
    $text_height = abs ( $text_box [ 1 ] - $text_box [ 7 ] );
    if ( $vert_pos == POS_TOP )
      $y_pos = 5 + $text_height;
    elseif ( $vert_pos == POS_CENTER )
      $y_pos = ceil( $thumb_height / 2 - $text_height / 2 );
    elseif ( $vert_pos == POS_BOTTOM )
      $y_pos = $thumb_height - $text_height;
    if ( $horz_pos == POS_LEFT )
      $x_pos = 5;
    elseif ( $horz_pos == POS_CENTER )
      $x_pos = ceil( $thumb_width / 2 - $text_width / 2 );
    elseif ( $horz_pos == POS_RIGHT )
      $x_pos = $thumb_width - $text_width -5;
    imagettftext ( $thumb_img, $size, $angle, $x_pos, $y_pos,
      $color_id, $font, $text );
  }
  /*
    Description:
      Output thumbnail image into the browser.
    Prototype:
      void OutputThumbImage ( resource dest_image )
    Parameters:
      dest_img - thumbnail image identifier
  */
  function OutputThumbImage ( $dest_image )
  {
    imageinterlace ( $dest_image, $this->interlace );
    header ( 'Content-type: ' . $this->dest_type );
    if ( $this->dest_type == THUMB_JPEG )
      imagejpeg ( $dest_image, '', $this->jpeg_quality );
    elseif ( $this->dest_type == THUMB_GIF )
      imagegif($dest_image);
    elseif ( $this->dest_type == THUMB_PNG )
      imagepng ( $dest_image );
  }
  /*
    Description:
      Save thumbnail image into the disc file.
    Prototype:
      void SaveThumbImage ( string image_file, resource dest_image )
    Parameters:
      image_file - destination file name
      dest_img - thumbnail image identifier
  */
  function SaveThumbImage ( $image_file, $dest_image )
  {
    imageinterlace ( $dest_image, $this->interlace );
    if ( $this->dest_type == THUMB_JPEG )
      imagejpeg ( $dest_image, $this->dest_file, $this->jpeg_quality );
    elseif ( $this->dest_type == THUMB_GIF )
      imagegif ( $dest_image, $this->dest_file );
    elseif ( $this->dest_type == THUMB_PNG )
      imagepng ( $dest_image, $this->dest_file );
  }
// ****************************************************************************
// PUBLIC METHODS
// ****************************************************************************
  /*
    Description:
      Output thumbnail image into the browser or disc file according to the
      values of parameters.
    Prototype:
      void Output ( )
  */
  function Output()
  {
    $src_image = $this->LoadImage($this->src_file, $src_width, $src_height);
    $dest_size = $this->GetThumbSize($src_width, $src_height);
    $dest_width=$dest_size[0];
    $dest_height=$dest_size[1];
    $dest_image=imagecreatetruecolor($dest_width, $dest_height);
    if (!$dest_image)
      trigger_error(E_005, E_USER_ERROR);
    imagecopyresampled( $dest_image, $src_image, 0, 0, 0, 0,
      $dest_width, $dest_height, $src_width, $src_height );
    if ($this->logo['file'] != NO_LOGO)
      $this->AddLogo($dest_width, $dest_height, $dest_image);
    if ($this->label['text'] != NO_LABEL)
      $this->AddLabel($dest_width, $dest_height, $dest_image);
    if ($this->dest_file == STDOUT)
      $this->OutputThumbImage ( $dest_image );
    else
      $this->SaveThumbImage ( $this->dest_file, $dest_image );
    imagedestroy ( $src_image );
    imagedestroy ( $dest_image );
  }
} // End of class definition
?>

使用方法:
1、首先引用该php文件(不要告诉我不会)
2、调用代码
 $tis = new ThumbnailImage();
     $tis->src_file  = "这里写源文件的路径"
     $tis->dest_type = THUMB_JPEG;//生成图片的类型是 jpg
      $tis->dest_file = '这里写目标文件的路径';
     $tis->max_width = 120;//自适应大小,但是最大宽度为120
     $tis->max_height = 4000; //自适应大小,但是最大高度为4000
     $tis->Output();

代码关键在于 max_width 和max_height,填多少,就会帮你生成一个 差不多大小的文件,一般来说除非你的图片很有个性,譬如很长,否则缩略图生成的还是很体贴的。

PHP 相关文章推荐
php中DOMDocument简单用法示例代码(XML创建、添加、删除、修改)
Dec 19 PHP
第四章 php数学运算
Dec 30 PHP
PHP filter_var() 函数 Filter 函数
Apr 25 PHP
ThinkPHP应用模式扩展详解
Jul 16 PHP
CodeIgniter中使用cookie的三种方式详解
Jul 18 PHP
PHP基于yii框架实现生成ICO图标
Nov 13 PHP
php生成4位数字验证码的实现代码
Nov 23 PHP
ThinkPHP项目分组配置方法分析
Mar 23 PHP
PHP大神的十大优良习惯
Sep 14 PHP
如何使用php等比例缩放图片
Oct 12 PHP
php面试中关于面向对象的相关问题
Feb 13 PHP
PHP 图片合成、仿微信群头像的方法示例
Oct 25 PHP
php 解压rar文件及zip文件的方法
May 05 #PHP
php中session过期时间设置及session回收机制介绍
May 05 #PHP
使用php语句将数据库*.sql文件导入数据库
May 05 #PHP
PHP判断是否有Get参数的方法
May 05 #PHP
php快递单号查询接口使用示例
May 05 #PHP
JS异常处理try..catch语句的作用和实例
May 05 #PHP
php生成短网址示例
May 05 #PHP
You might like
php 执行系统命令的方法
2009/07/07 PHP
编译php 5.2.14+fpm+memcached(具体操作详解)
2013/06/18 PHP
PHP批量删除、清除UTF-8文件BOM头的代码实例
2014/04/14 PHP
php实现递归抓取网页类实例
2015/04/03 PHP
Nigma vs Alliance BO5 第五场2.14
2021/03/10 DOTA
javascript开发技术大全-第3章 js数据类型
2011/07/03 Javascript
JS跨域代码片段
2012/08/30 Javascript
JS简单实现登陆验证附效果图
2013/11/19 Javascript
JavaScript函数内部属性和函数方法实例详解
2016/03/17 Javascript
Nodejs Stream 数据流使用手册
2016/04/17 NodeJs
JS只能输入正整数的简单实例
2016/10/07 Javascript
深入理解JS实现快速排序和去重
2016/10/17 Javascript
微信小程序中上传图片并进行压缩的实现代码
2018/08/28 Javascript
微信小程序实现日历功能
2018/11/27 Javascript
js实现通过开始结束控制的计时器
2019/02/25 Javascript
优化Vue项目编译文件大小的方法步骤
2019/05/27 Javascript
[04:46]2018年度玩家喜爱的电竞媒体-完美盛典
2018/12/16 DOTA
python实现备份目录的方法
2015/08/03 Python
解决python中无法自动补全代码的问题
2018/12/04 Python
python django生成迁移文件的实例
2019/08/31 Python
python 调试冷知识(小结)
2019/11/11 Python
基于Python实现ComicReaper漫画自动爬取脚本过程解析
2019/11/11 Python
移动端Html5页面生成图片解决方案
2018/08/07 HTML / CSS
Lyle & Scott苏格兰金鹰官网:英国皇室御用品牌
2018/05/09 全球购物
美国战术品牌:5.11 Tactical
2019/05/01 全球购物
销售高级职员求职信
2013/10/29 职场文书
青年创业培训欢迎词
2014/01/10 职场文书
写好自荐信需做到的5要点
2014/03/07 职场文书
学生会竞聘书范文
2014/03/31 职场文书
《中国梦我的梦》小学生演讲稿
2014/08/20 职场文书
酒店工程部经理岗位职责
2015/04/09 职场文书
2015年保管员工作总结
2015/04/30 职场文书
2019森林防火宣传标语大全!
2019/07/03 职场文书
JavaScript 防篡改对象的用法示例
2021/04/24 Javascript
浅谈redis整数集为什么不能降级
2021/07/25 Redis
vue 自定义组件添加原生事件
2022/04/21 Vue.js