php 圖片縮圖產生程式碼(支援png透明)

效果：

/*
 * desc: Resize Image(png, jpg, gif)
*/
class ResizeImage {
//圖片類型
private $type;
//實際寬度
private $width;
//實際高度
private $height;

 //改變後的寬度
private $resize_width;
//改變後的高度
private $resize_height;
//是否裁圖
private $cut;
//源源圖象
private $srcimg;
//目標圖象位址
private $dstimg;
//暫時建立的圖象
private $im;
function __construct($imgPath, $width, $height, $isCut, $savePath) {
$this->srcimg = $imgPath;
$this->resize_width = $width;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();
//目標圖象位址
$this -> dst_img($savePath);
//--
$this->width = imagesx($this->im);
$this->height = imagesy($this ->im);
//生成圖象
$this->newimg();
ImageDestroy ($this->im);
}
 private function newimg() {
//改變後的圖象的比例
$resize_ratio = ($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,($new-this >resize_width)/$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-1> 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( $this->srcimg);
}
}
//圖像目標位址
private function dst_img($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;
}
}
?> p>

使用時直接呼叫類別的建構子即可，建構子： $resizeimage = new resizeimage($imgPath, $width, $height, $isCut, $savePath);

參數 $imgPath：原圖片地址 $width：縮圖寬 $height：縮圖高 $isCut：是否裁剪，bool值 $savePath：縮圖位址（可以跟原圖片地址相同）

例：

include "ResizeImage.php";
//jpgg
$jpgResize = new ResizeImage("img/test_1920_1200.jpg", 320, 240, false, "img/test_320_240.jpg");
//png = new ResizeImage("img/test_1024_746.png", 320, 240, false, "img/test_320_240.png");
?>