通过“print fread(…)”提供图像速度很慢,怎么办?

我有一个动态缩略图脚本,我发现周围的网络和调整了一点。我添加了一个缓存机制。每当生成新的缩略图时,它都会保存到磁盘,如果再次请求相同的缩略图(具有所有相同的选项),则将使用磁盘副本。

一个片段:

  // name of cached file
  $thumb_file = $_SERVER['DOCUMENT_ROOT'].'/thumbs/cache/'.
                str_replace('/', '_', $_REQUEST['p']).
                ".{$def_width}x{$def_height}".
                ($clamp ? '_'.implode('x',$clamp) : '').
                ($make_png?'.png':'.jpg');

  // get it from cache if it's there
  if ($use_cache && file_exists($thumb_file)) {
    Header("Content-type: image/".($make_png?'png':'jpeg'));

    // this part seems really slow

    $fp=fopen($thumb_file, "rb");
    while (!feof($fp)) print fread($fp, 4096);

    exit();
  }

然而, print fread

弗雷德 还是有别的选择?

为了以防万一,我在下面提供了完整的PHP脚本。

<?php

  $use_cache = $_REQUEST['nc'] ? false : true;
  // $use_cache = false;

  $upfile = $_SERVER['DOCUMENT_ROOT'] .'/'. $_REQUEST['p'];
  $def_width  = $_REQUEST["w"];
  $def_height = $_REQUEST["h"];
  $clamp = $_REQUEST['c'] ? explode("x",$_REQUEST['c']) : null;
  $make_png = $_REQUEST['png'];

  if (!file_exists($upfile)) {
    die();  // $upfile = "nophoto.jpg";
  }

  if (!"{$def_width}{$def_height}") {
    $def_width = $def_height = '100';
  }

  // name of cached file
  $thumb_file = $_SERVER['DOCUMENT_ROOT'].'/thumbs/cache/'.
                str_replace('/', '_', $_REQUEST['p']).
                ".{$def_width}x{$def_height}".
                ($clamp ? '_'.implode('x',$clamp) : '').
                ($make_png?'.png':'.jpg');

  // get it from cache if it's there
  if ($use_cache && file_exists($thumb_file)) {
    Header("Content-type: image/".($make_png?'png':'jpeg'));
    $fp=fopen($thumb_file, "rb");
    while (!feof($fp)) print fread($fp, 4096);
    exit();
  }

  $ext = strtolower(substr($upfile, -3));

  ini_set('memory_limit', '64M');

  if ($ext=="gif") 
    $src = @ImageCreateFromGif ($upfile);
  else if ($ext=="jpg") 
    $src = @ImageCreateFromJpeg($upfile);
  else if ($ext=="png") 
    $src = @ImageCreateFromPng($upfile);

  $size = GetImageSize($upfile); 
  $width = $size[0];
  $height = $size[1];

  $long_side = $def_width;
  if ($def_width < $def_height) $long_side = $def_height;

  if (!$def_width) {
    $factor_h = $height / $def_height;
    $def_width = $width / $factor_h;
  }
  if (!$def_height) {
    $factor_w = $width / $def_width;
    $def_height = $height / $factor_w;
  }
  $factor_w = $width / $def_width;
  $factor_h = $height / $def_height;

  if ($factor_w > $factor_h) {
    $new_height = floor($def_height * $factor_h);
    $new_width = floor($def_width  * $factor_h);
  } else {
    $new_height = floor($def_height * $factor_w);
    $new_width = floor($def_width  * $factor_w);
  }

  if ((!$clamp[0])&&$clamp[0]!=='0') $clamp[0] = 50;
  if ((!$clamp[1])&&$clamp[1]!=='0') $clamp[1] = 50;

  $src_x = ceil(($width  - $new_width)  * ($clamp[0] / 100));
  $src_y = ceil(($height - $new_height) * ($clamp[1] / 100));

  $dst = ImageCreateTrueColor($def_width, $def_height);

  @ImageCopyResampled($dst, $src, 0, 0, $src_x, $src_y, 
                      $def_width, $def_height, $new_width, $new_height);

  Header("Content-type: image/".($make_png?'png':'jpeg'));

  if ($make_png) {
    ImagePng($dst);
    if ($use_cache) { 
      ImagePng($dst, $thumb_file); 
    }
  } else {
    ImageJpeg($dst, null, 95);
    if ($use_cache) { 
      ImageJpeg($dst, $thumb_file, 95); 
    }
  }

  @ImageDestroy($src);
  @ImageDestroy($dst);

?>