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這篇文章主要介紹了支持png透明圖片的php生成縮略圖類分享,本文代碼基于GD2圖形庫,實現支持png透明圖片生成縮略圖,需要的朋友可以參考下

注：此功能依賴GD2圖形庫

最近要用php生成縮略圖，在網上找了一下，發現了這篇文章：PHP生成圖片縮略圖

試用了一下后，發現有這樣幾個問題：

1、png圖片生成的縮略圖是jpg格式的

2、png圖片生成的縮略圖沒有了透明（半透明）效果（填充了黑色背景）

3、代碼語法比較老

因此，在這個版本的基礎上簡單修改優化了一下。

PHP生成縮略圖類

<?php

/*

* desc: Resize Image(png, jpg, gif)

* author: 十年后的盧哥哥

* date: 2014.11.13

*/

class ResizeImage {

//圖片類型

private $type;

//實際寬度

private $width;

//實際高度

private $height;

//改變后的寬度

private $resize_width;

//改變后的高度

private $resize_height;

//是否裁圖

private $cut;

//源圖象

private $srcimg;

//目標圖象地址

private $dstimg;

//臨時創建的圖象

private $im;

function __construct($imgPath, $width, $height, $isCut, $savePath) {

$this->srcimg = $imgPath;

$this->resize_width = $width;

$this->resize_height = $height;

$this->cut = $isCut;

//圖片的類型

$this->type = strtolower(substr(strrchr($this->srcimg,"."),1));

//初始化圖象

$this->initi_img();

//目標圖象地址

$this -> dst_img($savePath);

//--

$this->width = imagesx($this->im);

$this->height = imagesy($this->im);

//生成圖象

$this->newimg();

ImageDestroy ($this->im);

}

private function newimg() {

//改變后的圖象的比例

$resize_ratio = ($this->resize_width)/($this->resize_height);

//實際圖象的比例

$ratio = ($this->width)/($this->height);

if($this->cut) {

//裁圖

$newimg = imagecreatetruecolor($this->resize_width,$this->resize_height);

if($this->type=="png") {

imagefill($newimg, 0, 0, imagecolorallocatealpha($newimg, 0, 0, 0, 127));

}

if($ratio>=$resize_ratio) {

//高度優先

imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width,$this->resize_height, (($this->height)*$resize_ratio), $this->height);

} else {

//寬度優先

imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, $this->resize_height, $this->width, (($this->width)/$resize_ratio));

}

} else {

//不裁圖

if($ratio>=$resize_ratio) {

$newimg = imagecreatetruecolor($this->resize_width,($this->resize_width)/$ratio);

if($this->type=="png") {

imagefill($newimg, 0, 0, imagecolorallocatealpha($newimg, 0, 0, 0, 127));

}

imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width, ($this->resize_width)/$ratio, $this->width, $this->height);

} else {

$newimg = imagecreatetruecolor(($this->resize_height)*$ratio,$this->resize_height);

if($this->type=="png") {

imagefill($newimg, 0, 0, imagecolorallocatealpha($newimg, 0, 0, 0, 127));

}

imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, ($this->resize_height)*$ratio, $this->resize_height, $this->width, $this->height);

}

}

if($this->type=="png") {

imagesavealpha($newimg, true);

imagepng ($newimg,$this->dstimg);

} else {

imagejpeg ($newimg,$this->dstimg);

}

}

//初始化圖象

private function initi_img() {

if($this->type=="jpg") {

$this->im = imagecreatefromjpeg($this->srcimg);

}

if($this->type=="gif") {

$this->im = imagecreatefromgif($this->srcimg);

}

if($this->type=="png") {

$this->im = imagecreatefrompng($this->srcimg);

}

}

//圖象目標地址

private function dst_img($dstpath) {

$full_length = strlen($this->srcimg);

$type_length = strlen($this->type);

$name_length = $full_length-$type_length;

$name = substr($this->srcimg,0,$name_length-1);

$this->dstimg = $dstpath;

}

}

?>

使用

使用時，直接調用類的構造函數即可，構造函數如下：

$resizeimage = new resizeimage($imgPath, $width, $height, $isCut, $savePath);

參數

$imgPath：原圖片地址

$width：縮略圖寬

$height：縮略圖高

$isCut：是否裁剪，bool值

$savePath：縮略圖地址（可以跟原圖片地址相同）

示例

<?php

include "ResizeImage.php";

//jpg

$jpgResize = new ResizeImage("img/test_1920_1200.jpg", 320, 240, false, "img/test_320_240.jpg");

//png

$pngResize = new ResizeImage("img/test_1024_746.png", 320, 240, false, "img/test_320_240.png");

?>

效果

更多信息請查看IT技術專欄