php函数缩放图片大小,PHP图片重新采样及大小缩放函数imagecopyresampled用法实例

淩亂°似流年 2023-01-15 08:21 160阅读 0赞

(PHP 4 >= 4.0.6, PHP 5)

imagecopyresampled — 重采样拷贝部分图像并调整大小

imagecopyresampled() 将一幅图像中的一块正方形区域拷贝到另一个图像中，平滑地插入像素值，减小了图像的大小而仍然保持了极大的清晰度。如果源和目标的宽度和高度不同，则会进行相应的图像收缩和拉伸。坐标指的是左上角。本函数可用来在同一幅图内部拷贝(如果 dst\_image 和src\_image 相同的话)区域，但如果区域交迭的话则结果不可预知。

函数参数如下：

bool imagecopyresampled ( resource $dst\_image , resource $src\_image , int $dst\_x , int $dst\_y , int $src\_x , int $src\_y , int $dst\_w , int $dst\_h , int $src\_w , int $src\_h )

今天根据这个函数写了个方法，能够等比缩放图片的大小，并且可以设置宽度固定高度等比缩放，或者高度固定宽度等比缩放，或者设置最大宽和最大高。具体代码如下：

/\*\*

\* 图片缩放函数(可设置高度固定，宽度固定或者最大宽高，支持gif/jpg/png三种类型)

\* Author : Specs

\* Homepage: https://9iphp.com

\* @param string $source\_path 源图片

\* @param int $target\_width 目标宽度

\* @param int $target\_height 目标高度

\* @param string $fixed\_orig 锁定宽高(可选参数 width、height或者空值)

\* @return string

\*/

function myImageResize($source\_path, $target\_width = 200, $target\_height = 200, $fixed\_orig = '')\{

$source\_info = getimagesize($source\_path);

$source\_width = $source\_info\[0\];

$source\_height = $source\_info\[1\];

$source\_mime = $source\_info\['mime'\];

$ratio\_orig = $source\_width / $source\_height;

if ($fixed\_orig == 'width')\{

//宽度固定

$target\_height = $target\_width / $ratio\_orig;

\}elseif ($fixed\_orig == 'height')\{

//高度固定

$target\_width = $target\_height \* $ratio\_orig;

\}else\{

//最大宽或最大高

if ($target\_width / $target\_height > $ratio\_orig)\{

$target\_width = $target\_height \* $ratio\_orig;

\}else\{

$target\_height = $target\_width / $ratio\_orig;

switch ($source\_mime)\{

case 'image/gif':

$source\_image = imagecreatefromgif($source\_path);

break;

case 'image/jpeg':

$source\_image = imagecreatefromjpeg($source\_path);

break;

case 'image/png':

$source\_image = imagecreatefrompng($source\_path);

break;

default:

return false;

break;

$target\_image = imagecreatetruecolor($target\_width, $target\_height);

imagecopyresampled($target\_image, $source\_image, 0, 0, 0, 0, $target\_width, $target\_height, $source\_width, $source\_height);

//header('Content-type: image/jpeg');

$imgArr = explode('.', $source\_path);

$target\_path = $imgArr\[0\] . '\_new.' . $imgArr\[1\];

imagejpeg($target\_image, $target\_path, 100);

用法如下：

myImageResize($filename, 200, 200); //最大宽高

myImageResize($filename, 200, 200, 'width'); //宽度固定

myImageResize($filename, 200, 200, 'height'); //高度固定

宽图结果如下：

![7ca939922c78bec830cb34afc6dbff4b.png][](原图)

![242ec73034f6f2ca1687de19e0f14fc7.png][]

最大宽高

![6113a4389f2ad19ba6ea372cc9ed7f5f.png][] 固定高

![d806282cd16589d88fc7453ecf705d32.png][]

固定宽

高图结果如下：

![8c9b32919c575f9dc26c9288c97d9b28.png][]

原图

![f03ff05ace6c9a673356a5cefaa34bc7.png][]

最大宽高

![038a201d9a501c5488a805374420c233.png][]

固定高

![b14045d2c7b15622cb2cf666b900e077.png][]

固定宽

附：把图片剪切为固定大小的函数：

function imagecropper($source\_path, $target\_width, $target\_height)\{

$source\_info = getimagesize($source\_path);

$source\_width = $source\_info\[0\];

$source\_height = $source\_info\[1\];

$source\_mime = $source\_info\['mime'\];

$source\_ratio = $source\_height / $source\_width;

$target\_ratio = $target\_height / $target\_width;

// 源图过高

if ($source\_ratio > $target\_ratio)\{

$cropped\_width = $source\_width;

$cropped\_height = $source\_width \* $target\_ratio;

$source\_x = 0;

$source\_y = ($source\_height - $cropped\_height) / 2;

\}elseif ($source\_ratio < $target\_ratio)\{ // 源图过宽

$cropped\_width = $source\_height / $target\_ratio;

$cropped\_height = $source\_height;

$source\_x = ($source\_width - $cropped\_width) / 2;

$source\_y = 0;

\}else\{ // 源图适中

$cropped\_width = $source\_width;

$cropped\_height = $source\_height;

$source\_x = 0;

$source\_y = 0;

switch ($source\_mime)\{

case 'image/gif':

$source\_image = imagecreatefromgif($source\_path);

break;

case 'image/jpeg':

$source\_image = imagecreatefromjpeg($source\_path);

break;

case 'image/png':

$source\_image = imagecreatefrompng($source\_path);

break;

default:

return false;

break;

$target\_image = imagecreatetruecolor($target\_width, $target\_height);

$cropped\_image = imagecreatetruecolor($cropped\_width, $cropped\_height);

// 裁剪

imagecopy($cropped\_image, $source\_image, 0, 0, $source\_x, $source\_y, $cropped\_width, $cropped\_height);

// 缩放

imagecopyresampled($target\_image, $cropped\_image, 0, 0, 0, 0, $target\_width, $target\_height, $cropped\_width, $cropped\_height);

$dotpos = strrpos($source\_path, '.');

$imgName = substr($source\_path, 0, $dotpos);

$suffix = substr($source\_path, $dotpos);

$imgNew = $imgName . '\_small' . $suffix;

imagejpeg($target\_image, $imgNew, 100);

imagedestroy($source\_image);

imagedestroy($target\_image);

imagedestroy($cropped\_image);

[7ca939922c78bec830cb34afc6dbff4b.png]: /images/20221022/15be6da8879b449bae799cdd6de2e4cb.png
[242ec73034f6f2ca1687de19e0f14fc7.png]: /images/20221022/22c8912266d14d59811245a8574220bf.png
[6113a4389f2ad19ba6ea372cc9ed7f5f.png]: /images/20221022/1fa1ac33efe04659b8f017bcdf905f3f.png
[d806282cd16589d88fc7453ecf705d32.png]: /images/20221022/bd8c4182f4ed47cd9f6059fc7944b3d1.png
[8c9b32919c575f9dc26c9288c97d9b28.png]: /images/20221022/4ff65ce4964548fea1a47a48cded1118.png
[f03ff05ace6c9a673356a5cefaa34bc7.png]: /images/20221022/85fff7c3726f4c4aa760f5ae128bfaf1.png
[038a201d9a501c5488a805374420c233.png]: /images/20221022/682d30df88f24b8c835c47e48a7bb2f2.png
[b14045d2c7b15622cb2cf666b900e077.png]: /images/20221022/0b32133309d44820b20a9a8ea0b2af70.png