《PHP編程：php實現高效獲取圖片尺寸的方法》要點：
本文介紹了PHP編程：php實現高效獲取圖片尺寸的方法，希望對您有用。如果有疑問，可以聯系我們。
PHP實戰本文實例講述了php實現高效獲取圖片尺寸的辦法.分享給大家供大家參考.具體分析如下：
PHP實戰php 獲取圖片尺寸的辦法我們可以使用 getimagesize 獲取圖片尺寸,但是效率是很低的,首先需要獲取整個的圖片信息,然后再進行操作,下面的例子更科學算法更好,我們一起來看看吧.
PHP實戰辦法可以用于快速獲取圖片尺寸信息,獲取JPEG格式圖片的尺寸信息,并且不需要下載讀取整個圖片,經測試這個函數不是對所有JPEG格式的圖片都有效.
PHP實戰1.獲取JPEG格式圖片的尺寸信息,代碼如下:
代碼如下:
<?php
/*
*
*/
?
// Retrieve JPEG width and height without downloading/reading entire image.
function getjpegsize($img_loc) {
??? $handle = fopen($img_loc, "rb") or die("Invalid file stream.");
??? $new_block = NULL;
??? if(!feof($handle)) {
??????? $new_block = fread($handle, 32);
??????? $i = 0;
??????? if($new_block[$i]=="xFF" && $new_block[$i+1]=="xD8" && $new_block[$i+2]=="xFF" && $new_block[$i+3]=="xE0") {
??????????? $i += 4;
??????????? if($new_block[$i+2]=="x4A" && $new_block[$i+3]=="x46" && $new_block[$i+4]=="x49" && $new_block[$i+5]=="x46" && $new_block[$i+6]=="x00") {
????????????????
// Read block size and skip ahead to begin cycling through blocks in search of SOF marker
?
??????????????? $block_size = unpack("H*", $new_block[$i] . $new_block[$i+1]);
??????????????? $block_size = hexdec($block_size[1]);
??????????????? while(!feof($handle)) {
??????????????????? $i += $block_size;
??????????????????? $new_block .= fread($handle, $block_size);
??????????????????? if($new_block[$i]=="xFF") {
????????????????????????
// New block detected, check for SOF marker
?
??????????????????????? $sof_marker = array("xC0", "xC1", "xC2", "xC3", "xC5", "xC6", "xC7", "xC8", "xC9", "xCA", "xCB", "xCD", "xCE", "xCF");
??????????????????????? if(in_array($new_block[$i+1], $sof_marker)) {
????????????????????????????
// SOF marker detected. Width and height information is contained in bytes 4-7 after this byte.
?
??????????????????????????? $size_data = $new_block[$i+2] . $new_block[$i+3] . $new_block[$i+4] . $new_block[$i+5] . $new_block[$i+6] . $new_block[$i+7] . $new_block[$i+8];
??????????????????????????? $unpacked = unpack("H*", $size_data);
??????????????????????????? $unpacked = $unpacked[1];
??????????????????????????? $height = hexdec($unpacked[6] . $unpacked[7] . $unpacked[8] . $unpacked[9]);
??????????????????????????? $width = hexdec($unpacked[10] . $unpacked[11] . $unpacked[12] . $unpacked[13]);
??????????????????????????? return array($width, $height);
??????????????????????? } else {
????????????????????????????
// Skip block marker and read block size
?
??????????????????????????? $i += 2;
??????????????????????????? $block_size = unpack("H*", $new_block[$i] . $new_block[$i+1]);
??????????????????????????? $block_size = hexdec($block_size[1]);
??????????????????????? }
??????????????????? } else {
??????????????????????? return FALSE;
??????????????????? }
??????????????? }
??????????? }
??????? }
??? }
??? return FALSE;
}
?>
2.實例代碼如下:
代碼如下:
$url='http://www.xxxx.com/images/1331189004_28093400.jpg';
$image_content = file_get_contents($url);
$image = imagecreatefromstring($image_content);
$width = imagesx($image);
$height = imagesy($image);
echo $width.'*'.$height."nr";
PHP實戰希望本文所述對大家的PHP程序設計有所贊助.
歡迎參與《PHP編程：php實現高效獲取圖片尺寸的方法》討論，分享您的想法，維易PHP學院為您提供專業教程。
轉載請注明本頁網址：
http://www.snjht.com/jiaocheng/13410.html
