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 木马攻击防御技巧
Jun 13 PHP
用PHP的超级变量$_GET获取HTML表单(Form) 数据
May 07 PHP
PHP daddslashes 使用方法介绍
Oct 26 PHP
PHP+ajaxfileupload+jcrop插件完美实现头像上传剪裁
Jun 09 PHP
php模仿asp Application对象在线人数统计实现方法
Jan 04 PHP
php递归删除目录与文件的方法
Jan 30 PHP
php获取当月最后一天函数分享
Feb 02 PHP
PHP获取photoshop写入图片文字信息的方法
Mar 31 PHP
PHP实现简单的新闻发布系统实例
Jul 28 PHP
Zend Framework分页类用法详解
Mar 22 PHP
thinkPHP中验证码的简单实现方法
Dec 05 PHP
PHP APP微信提现接口代码
Sep 30 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 判断网页是否是utf8编码的方法
2014/06/06 PHP
laravel 模型查询按照whereIn排序的示例
2019/10/16 PHP
JavaScript Event学习补遗 addEventSimple
2010/02/11 Javascript
javascript instanceof,typeof的区别
2010/03/24 Javascript
输入密码检测大写是否锁定js实现代码
2012/12/03 Javascript
jquery win 7透明弹出层效果的简单代码
2013/08/06 Javascript
NodeJS的url截取模块url-extract的使用实例
2013/11/18 NodeJs
js jquery分别实现动态的文件上传操作按钮的添加和删除
2014/01/13 Javascript
JS图像无缝滚动脚本非常好用
2014/02/10 Javascript
使用jquery选择器如何获取父级元素、同级元素、子元素
2014/05/14 Javascript
用js闭包的方法实现多点标注冒泡示例
2014/05/29 Javascript
《JavaScript DOM 编程艺术》读书笔记之JavaScript 简史
2015/01/09 Javascript
在JavaScript中处理数组之reverse()方法的使用
2015/06/09 Javascript
JavaScript实现数组随机排序的方法
2015/06/26 Javascript
js实现兼容性好的微软官网导航下拉菜单效果
2015/09/07 Javascript
Javascript生成全局唯一标识符(GUID,UUID)的方法
2016/02/27 Javascript
jQuery Easy UI中根据第一个下拉框选中的值设置第二个下拉框是否可以编辑
2016/11/29 Javascript
防止重复发送 Ajax 请求
2017/02/15 Javascript
使用 Vue.js 仿百度搜索框的实例代码
2017/05/09 Javascript
JS创建Tag标签的方法详解
2017/06/09 Javascript
javascript按钮禁用和启用的效果实例代码
2017/10/29 Javascript
解决easyui日期时间框ie的兼容的问题
2018/03/01 Javascript
VUE渲染后端返回含有script标签的html字符串示例
2019/10/28 Javascript
NodeJS http模块用法示例【创建web服务器/客户端】
2019/11/05 NodeJs
微信小程序间使用navigator跳转传值问题实例分析
2020/03/27 Javascript
python中的多重继承实例讲解
2014/09/28 Python
使用Python中的线程进行网络编程的入门教程
2015/04/15 Python
Pandas之ReIndex重新索引的实现
2019/06/25 Python
python实现双色球随机选号
2020/01/01 Python
Python datetime 格式化 明天,昨天实例
2020/03/02 Python
基于Python快速处理PDF表格数据
2020/06/03 Python
HTML5 Canvas中使用路径描画二阶、三阶贝塞尔曲线
2015/01/01 HTML / CSS
高校毕业生自我鉴定
2013/10/27 职场文书
同步小康驻村工作简报
2015/07/20 职场文书
Python requests库参数提交的注意事项总结
2021/03/29 Python
windows server2012 R2下安装PaddleOCR服务的的详细步骤
2022/09/23 Servers