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(xiàn)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(wǎng)上找了一下，發(fā)現(xiàn)了這篇文章：PHP生成圖片縮略圖
試用了一下后，發(fā)現(xiàn)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(chǔ)上簡單修改優(yōu)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(biāo)圖象地址
private $dstimg;
//臨時創(chuàng)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(biāo)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(yōu)先
imagecopyresampled($newimg, $this->im, 0, 0, 0, 0, $this->resize_width,$this->resize_height, (($this->height)*$resize_ratio), $this->height);
} else {
//寬度優(yōu)先
imagecopyresampled($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(biāo)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(diào)用類的構(gòu)造函數(shù)即可，構(gòu)造函數(shù)如下：
$resizeimage = new resizeimage($imgPath, $width, $height, $isCut, $savePath);
參數(shù)
$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
