php 裁剪图片

/**
     * 裁剪图片
     * imageCropper
     * @param string $source_path 图片地址
     * @param string $w_file_path 要保存的地址
     */
    public  function imageCropper($source_path, $w_file_path)
    {
        list($target_width, $height, $type, $attr) = getimagesize($source_path);
        $target_height = $height - ceil($height/6) - 10;
        $source_info = getimagesize($source_path);
        $source_width = $source_info[0];
        $source_height = $source_info[1];
        $source_mime = $source_info['mime'];
        $source_ratio = $source_height / $source_width;
        $target_ratio = $target_height / $target_width;
        if ($source_ratio > $target_ratio) {
            // image-to-height
            $cropped_width = $source_width;
            $cropped_height = $source_width * $target_ratio;
            $source_x = 0;
            $source_y = ($source_height - $cropped_height) / 2;
        } elseif ($source_ratio < $target_ratio) {
            //image-to-widht
            $cropped_width = $source_height / $target_ratio;
            $cropped_height = $source_height;
            $source_x = ($source_width - $cropped_width) / 2;
            $source_y = 0;
        } else {
            //image-size-ok
            $cropped_width = $source_width;
            $cropped_height = $source_height;
            $source_x = 0;
            $source_y = 0;
        }
        switch ($source_mime) {
            case 'image/gif':
                $source_image = imagecreatefromgif($source_path);
                break;
            case 'image/jpeg':
                $source_image = imagecreatefromjpeg($source_path);
                break;
            case 'image/png':
                $source_image = imagecreatefrompng($source_path);
                break;
            default:
                return;
                break;
        }
        $target_image = imagecreatetruecolor($target_width, $target_height);
        $cropped_image = imagecreatetruecolor($cropped_width, $cropped_height);
        // copy
        imagecopy($cropped_image, $source_image, 0, 0, $source_x, $source_y, $cropped_width, $cropped_height);
        // zoom
        imagecopyresampled($target_image, $cropped_image, 0, 0, 0, 0, $target_width, $target_height, $cropped_width, $cropped_height);
//        header('Content-Type: image/jpeg');
        $res = imagepng($target_image,$w_file_path);
        return $res;
//        imagedestroy($source_image);
//        imagedestroy($target_image);
//        imagedestroy($cropped_image);
    }