这篇文章主要介绍“如何使用PHP图片等比缩放类SimpleImage”，在日常操作中，相信很多人在如何使用PHP图片等比缩放类SimpleImage问题上存在疑惑，小编查阅了各式资料，整理出简单好用的操作方法，希望对大家解答”如何使用PHP图片等比缩放类SimpleImage”的疑惑有所帮助！接下来，请跟着小编一起来学习吧！
使用方法示例：
设定宽度，等比例缩放
复制代码 代码如下:
<?php
include('SimpleImage.php');
$image = new SimpleImage();
$image->load('picture.jpg');
$image->resizeToWidth(250);
$image->save('picture2.jpg');?>
设定高度，等比例缩放
复制代码 代码如下:
<?php
include('SimpleImage.php');
$image = new SimpleImage();
$image->load('picture.jpg');
$image->resizeToHeight(500);
$image->save('picture2.jpg');
$image->resizeToHeight(200);
$image->save('picture3.jpg');?>
按比例，缩放至50%
复制代码 代码如下:
<?php
include('SimpleImage.php');
$image = new SimpleImage();
$image->load('picture.jpg');
$image->scale(50);
$image->save('picture2.jpg');?>
缩放后直接输出到屏幕
复制代码 代码如下:
<?php
header('Content-Type: image/jpeg');
include('SimpleImage.php');
$image = new SimpleImage();
$image->load('picture.jpg');
$image->resizeToWidth(150);
$image->output();?>
使用例子：
复制代码 代码如下:
<?php
include("SimpleImage.php");//图片处理类在下面
$url="https://cache.yisu.com/upload/information/20201209/266/42940.jpg";
$picfile = down($url);//下载图片（下载图片的路径可以处理完成后清空，这里未进行处理）
$res = new SimpleImage();//图片处理实例
$res = $res->load($picfile);
$tmpfile = tempfile().'.jpg';//创建一个路径文件用来保存图片
$width = '30';//设定图片的宽度
$res->resizeToWidth($width);
$res->save($tmpfile);//把处理后的图片保存（无.jpg后缀）
//这里总共产生了3个文件，一个是下载的图片文件，一个是临时文件，最后一个是处理的图片文件。需要优化清理掉前两个文件。
function down($url)
{
$http = array();
$header = "http://f3.v.veimg.cn";
if ($header) {
$http['header'] = $header;
}
$http['timeout'] = 50;
$ctx = stream_context_create(array(
'http' => $http,
));
$content = @file_get_contents($url, 0, $ctx);
sleep(1);
if (!$content) {
return false;
}
$tmpfile = tempfile();
file_put_contents($tmpfile, $content);
return $tmpfile;
}
function tempfile()
{
$path = dirname(__FILE__);
$path .= '/spider/' . date('Ymd') . '/'.date('His').'-' . (int)(time() / 300);
if (!file_exists($path)) {
mkdir($path, 0777, true);
}
do {
$file = $path . '/' . dechex(mt_rand());
}
while (file_exists($file));
touch($file);
return $file;
}
图片处理类源码（官网地址：http://www.white-hat-web-design.co.uk/blog/resizing-images-with-php/）：
复制代码 代码如下:
<?php
/*
* File: SimpleImage.php
* Author: Simon Jarvis
* Copyright: 2006 Simon Jarvis
* Date: 08/11/06
* Link: http://www.white-hat-web-design.co.uk/articles/php-image-resizing.php
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details:
* http://www.gnu.org/licenses/gpl.html
*
*/
class SimpleImage {
var $image;
var $image_type;
function load($filename) {
$image_info = getimagesize($filename);
$this->image_type = $image_info[2];
if( $this->image_type == IMAGETYPE_JPEG ) {
$this->image = @imagecreatefromjpeg($filename);
} elseif( $this->image_type == IMAGETYPE_GIF ) {
$this->image = @imagecreatefromgif($filename);
} elseif( $this->image_type == IMAGETYPE_PNG ) {
$this->image = @imagecreatefrompng($filename);
}
if (!$this->image) {
return false;
}
return $this;
}
function save($filename, $image_type=IMAGETYPE_JPEG, $compression=75, $permissions=null) {
if( $image_type == IMAGETYPE_JPEG ) {
imagejpeg($this->image,$filename,$compression);
} elseif( $image_type == IMAGETYPE_GIF ) {
imagegif($this->image,$filename);
} elseif( $image_type == IMAGETYPE_PNG ) {
imagepng($this->image,$filename);
}
if( $permissions != null) {
chmod($filename,$permissions);
}
}
function output($image_type=IMAGETYPE_JPEG) {
if( $image_type == IMAGETYPE_JPEG ) {
imagejpeg($this->image);
} elseif( $image_type == IMAGETYPE_GIF ) {
imagegif($this->image);
} elseif( $image_type == IMAGETYPE_PNG ) {
imagepng($this->image);
}
}
function getWidth() {
return imagesx($this->image);
}
function getHeight() {
return imagesy($this->image);
}
function resizeToHeight($height) {
$ratio = $height / $this->getHeight();
$width = $this->getWidth() * $ratio;
$this->resize($width,$height);
}
function resizeToWidth($width) {
if ($this->getWidth() < $width) {
$width = $this->getWidth();
}
$ratio = $width / $this->getWidth();
$height = $this->getheight() * $ratio;
$this->resize($width,$height);
}
function scale($scale) {
$width = $this->getWidth() * $scale/100;
$height = $this->getheight() * $scale/100;
$this->resize($width,$height);
}
function resize($width,$height) {
$new_image = imagecreatetruecolor($width, $height);
imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight());
$this->image = $new_image;
}
function resize2($width,$height) {
$new_image = imagecreatetruecolor($width, $height);
if( $this->image_type == IMAGETYPE_GIF || $this->image_type == IMAGETYPE_PNG ) {
$current_transparent = imagecolortransparent($this->image);
if($current_transparent != -1) {
$transparent_color = imagecolorsforindex($this->image, $current_transparent);
$current_transparent = imagecolorallocate($new_image, $transparent_color['red'], $transparent_color['green'], $transparent_color['blue']);
imagefill($new_image, 0, 0, $current_transparent);
imagecolortransparent($new_image, $current_transparent);
} elseif( $this->image_type == IMAGETYPE_PNG) {
imagealphablending($new_image, false);
$color = imagecolorallocatealpha($new_image, 0, 0, 0, 127);
imagefill($new_image, 0, 0, $color);
imagesavealpha($new_image, true);
}
}
imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight());
$this->image = $new_image;
}
}
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