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,本文代碼基於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
試用了一下後，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
? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 <?php /* * desc: Resize Image(png, jpg, gif) * author: 十年後的盧哥哥 * 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; //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
? 1 2 3 4 5 6 7 8 9 10 <?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
