php產生圖片縮圖，支援png透明

標籤：des   style   blog   http   io   color   os   使用   sp   

註：此功能依賴GD2圖形庫

最近要用php產生縮圖，在網上找了一下，發現了這篇文章：PHP產生圖片縮圖

試用了一下後，發現有這樣幾個問題：

1、png圖片產生的縮圖是jpg格式的

2、png圖片產生的縮圖沒有了透明（半透明）效果（填充了黑色背景）

3、代碼文法比較老

因此，在這個版本的基礎上簡單修改最佳化了一下。

PHP產生縮圖類

<?php    /*     * desc: Resize Image(png, jpg, gif)     * author: 十年後的盧哥哥(http://www.cnblogs.com/lurenjiashuo/)     * date: 2014.11.13     * base from: http://www.oschina.net/code/snippet_5189_2491     */    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;        //源圖象        private $srcimg;        //靶心圖表象地址        private $dstimg;        //臨時建立的圖象        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();            //靶心圖表象地址            $this -> dst_img($savePath);            //--            $this->width = imagesx($this->im);            $this->height = imagesy($this->im);            //產生圖象            $this->newimg();            ImageDestroy ($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,($this->resize_width)/$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，直接調用類的建構函式即可，建構函式如下：

$resizeimage = new resizeimage($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：縮圖地址（可以跟原圖片地址相同）

樣本

<?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

  

php產生圖片縮圖，支援png透明