PHP 图片处理以转码生成指定分辨率

àì夳堔傛蜴生んèń 2021-08-27 11:01 383阅读 0赞

> 请看实例

/**
        * @todo 图片裁剪
        * @param type $imagepath 初始图片路径
        * @param type $savepath  保存的路径位
        * @param type $newwidth  传入-图像宽
        * @param type $newheight 传入-图像高
        * @return string
        */
        function imageTranscoding($imagepath, $savepath, $newwidth, $newheight) {
            $new_width = intval($newwidth);
            $new_height = intval($newheight);
            if ($new_width < 1 || $new_height < 1) return "参数错误";
            if (!file_exists($imagepath)) return "文件不存在";
    
            $type = exif_imagetype($imagepath);
            $support_type = array(IMAGETYPE_JPEG, IMAGETYPE_PNG, IMAGETYPE_GIF);
            if (!in_array($type, $support_type, true)) return "文件类型不支持";
    
            switch ($type) 
            {
                case IMAGETYPE_JPEG :
                    $src_img = imagecreatefromjpeg($imagepath);
                    break;
                case IMAGETYPE_PNG :
                    $src_img = imagecreatefrompng($imagepath);
                    break;
                case IMAGETYPE_GIF :
                    $src_img = imagecreatefromgif($imagepath);
                    break;
            }
    
            $w = imagesx($src_img);
            $h = imagesy($src_img);
            $ratio_w = 1.0 * $new_width / $w;
            $ratio_h = 1.0 * $new_height / $h;
            $ratio = 1.0;
    
            if (($ratio_w < 1 && $ratio_h < 1) || ($ratio_w > 1 && $ratio_h > 1)) {
                if ($ratio_w < $ratio_h) $ratio = $ratio_h; else  $ratio = $ratio_w;
                $inter_w = (int) ($new_width / $ratio);
                $inter_h = (int) ($new_height / $ratio);
                $inter_img = imagecreatetruecolor($inter_w, $inter_h);
                imagecopy($inter_img, $src_img, 0, 0, 0, 0, $inter_w, $inter_h);
                //更改PHP的内存限制
                ini_set('memory_limit', '18M');
                $new_img = imagecreatetruecolor($new_width, $new_height);
                imagecopyresampled($new_img, $inter_img, 0, 0, 0, 0, $new_width, $new_height, $inter_w, $inter_h);
    
                switch ($type) 
                {
                    case IMAGETYPE_JPEG :
                        imagejpeg($new_img, $savepath, 100);
                        break;
                    case IMAGETYPE_PNG :
                        imagepng($new_img, $savepath, 100);
                        break;
                    case IMAGETYPE_GIF :
                        imagegif($new_img, $savepath, 100);
                        break;
                }
            }
            else {
                $ratio = $ratio_h > $ratio_w ? $ratio_h : $ratio_w;
                $inter_w = (int) ($w * $ratio);
                $inter_h = (int) ($h * $ratio);
                $inter_img = imagecreatetruecolor($inter_w, $inter_h);
                imagecopyresampled($inter_img, $src_img, 0, 0, 0, 0, $inter_w, $inter_h, $w, $h);
                $new_img = imagecreatetruecolor($new_width, $new_height);
                imagecopy($new_img, $inter_img, 0, 0, 0, 0, $new_width, $new_height);
    
                switch ($type) 
                {
                    case IMAGETYPE_JPEG :
                        imagejpeg($new_img, $savepath, 100);
                        break;
                    case IMAGETYPE_PNG :
                        imagepng($new_img, $savepath, 100);
                        break;
                    case IMAGETYPE_GIF :
                        imagegif($new_img, $savepath, 100);
                        break;
                    default :
                        break;
                }
            }
        }

>  
> 
>     $this->imageTranscoding("test2.jpeg", "/test2_300x200.jpeg", 300, 200);
> 
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