支持png透明图片的php生成缩略图类分享

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注:此功能依赖GD2图形库

最近要用PHP生成缩略图,在网上找了一下,发现了这篇文章PHP生成图片缩略图

试用了一下后,发现有这样几个问题:

1、png图片生成缩略图是jpg格式的

2、png图片生成缩略图没有了透明(半透明)效果(填充了黑色背景)

3、代码语法比较老

因此,在这个版本的基础上简单修改优化了一下。

PHP生成缩略图

PHP;"> function __construct($imgPath,$width,$height,$isCut,$savePath) { $this->srcimg = $imgPath; $this->resize_width = $width; $this->resize_height = $height; $this->cut = $isCut; //<a href="/tag/tupian/" target="_blank" class="keywords">图片</a>的类型 $this->type = strtolower(substr(strrchr($this->srcimg,"."),1)); //初始化图象 $this->initi_img(); //目标图象地址 $this -> dst_img($savePath); //-- $this->width = imagesx($this->im); $this->height = imagesy($this->im); //<a href="/tag/shengcheng/" target="_blank" class="keywords">生成</a>图象 $this->newimg(); ImageDestroy ($this->im); } private function newimg() { //改变后的图象的比例 $resize_ratio = ($this->resize_width)/($this->resize_height); //实际图象的比例 $ratio = ($this->width)/($this->height); if($this->cut) { //裁图 $newimg = imagecreatetruecolor($this->resize_width,$this->resize_height); if($this->type=="png") { imagefill($newimg,imagecolorallocatealpha($newimg,127)); } if($ratio>=$resize_ratio) { //高度优先 imagecopyresampled($newimg,$this->im,$this->resize_width,$this->resize_height,(($this->height)*$resize_ratio),$this->height); } else { //宽度优先 imagecopyresampled($newimg,$this->width,(($this->width)/$resize_ratio)); } } else { //不裁图 if($ratio>=$resize_ratio) { $newimg = imagecreatetruecolor($this->resize_width,($this->resize_width)/$ratio); if($this->type=="png") { imagefill($newimg,127)); } imagecopyresampled($newimg,($this->resize_width)/$ratio,$this->height); } else { $newimg = imagecreatetruecolor(($this->resize_height)*$ratio,$this->resize_height); if($this->type=="png") { imagefill($newimg,($this->resize_height)*$ratio,$this->height); } } if($this->type=="png") { imagesavealpha($newimg,true); imagepng ($newimg,$this->dstimg); } else { imagejpeg ($newimg,$this->dstimg); } } //初始化图象 private function initi_img() { if($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); } } //图象目标地址 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,$name_length-1); $this->dstimg = $dstpath; }

}
?>

使用

使用时,直接调用类的构造函数即可,构造函数如下:

$resizeimage = new resizeimage($imgPath,$savePath);

参数

$imgPath:原图片地址

$width:缩略图

$height:缩略图

$isCut:是否裁剪,bool值

$savePath:缩略图地址(可以跟原图片地址相同)

示例

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","img/test_320_240.png");

?>

效果

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