php 图片缩放

源代码

/**
     * 缩放图片
     * @param $filename 图片地址
     * @param $per 缩放倍数 1.2   0.3
     * @return string
     */
    private function scaleImg($filename,$per){
        $per_str=implode('_', explode('.', $per));
        $new_file_name=__DIR__.'/xxx_scale_'.$per_str.'.png';
        //如果图片大小大于1
        if (getimagesize($filename) > 1) {
            list($width, $height) = getimagesize($filename);
            $n_w = $width * $per;
            $n_h = $height * $per;
            $new = imagecreatetruecolor($n_w, $n_h);
            $img = imagecreatefromstring(file_get_contents($filename));
            //copy部分图像并调整
            imagecopyresized($new, $img, 0, 0, 0, 0, $n_w, $n_h, $width, $height);
            //图像输出新图片、另存为
            imagepng($new, $new_file_name);
            imagedestroy($new);
            imagedestroy($img);
        }
        return $new_file_name;