php解析ipa应用图标只能解析出一半的问题

Question

问题

工作中碰到一个问题，需要使用php来解析上传的ipa应用图标，经过多方搜索，找到一短php程序可行进行此操作，但是出现一个致命问题：解析出来的的应用图标只有一半，因此特来请教各位大侠指点一二。

资源

核心文件unCrush.php

<?php

class unCrush
{

    private $pngFilePath;

    public function __construct($path = null)
    {
        if ($path !== null) {
            $this->pngFilePath = $path;
        }
    }

    /**
     * Decodes optimized pngs
     * @param string $path
     * @return string $img or an epmty string if path was specified
     */
    public function decode($path = null)
    {
        $img = $this->pdecode();

        if (!$img) {
            return false;
        }

        if ($path !== null) {

            file_put_contents($path, $img);

            return true;

        } else {

            return $img;

        }

    }

    /**
     * Decodes Apple optimized png
     * @return string $imageData
     */
    private function pdecode()
    {

        $fh = fopen($this->pngFilePath, 'r');

        $headerData = fread($fh, 8);

        $header = unpack("C1highbit/A3signature/C2lineendings/C1eof/C1eol", $headerData);
        // check if it's a PNG image
        if (!is_array($header) && !$header['highbit'] == 0x89 && !$header['signature'] == "PNG") {
            return false;
        }

        $chunks = array();
        $isIphoneCompressed = false;
        $cnt = 0;
        $uncompressed = '';
        while (!feof($fh)) {
            $data = fread($fh, 8);
            if (strlen($data) > 0) { // Fix for empty parts
                // Unpack the chunk
                $chunk = unpack("N1length/A4type", $data); // get the type and length of the chunk
                $data = @fread($fh, $chunk['length']); // can be 0...
                $dataCrc = fread($fh, 4); // get the crc
                $crc = unpack("N1crc", $dataCrc);
                $chunk['crc'] = $crc['crc'];

                // This chunk is first when it's a iPhone compressed image
                if ($chunk['type'] == 'CgBI') {
                    $isIphoneCompressed = true;
                }
                // Extract the header if needed
                if ($chunk['type'] == 'IHDR' && $isIphoneCompressed) {
                    $width = unpack('N*', substr($data, 0, 4));
                    $height = unpack('N*', substr($data, 4, 4));
                    $width = $width[1]; //180
                    $height = $height[1]; //180

                    $depth = unpack('C1', substr($data, 8, 1));
                    $depth = $depth[1]; // 8

                    $ctype = unpack('C1', substr($data, 9, 1));
                    $ctype = $ctype[1]; // 6

                    $compression = unpack('C1', substr($data, 10, 1));
                    $compression = $compression[1]; //0

                    $filter = unpack('C1', substr($data, 11, 1));
                    $filter = $filter[1]; // 0

                    $interlace = unpack('C1', substr($data, 11, 1));
                    $interlace = $interlace[1]; // 0

                }

                // Extract and mutate the data chunk if needed (can be multiple)
                if ($chunk['type'] == 'IDAT' && $isIphoneCompressed) {
                    set_error_handler(function ($errno, $errstr, $errfile, $errline, array $errcontext) {

                        return false;

                        // error was suppressed with the @-operator
                        if (0 === error_reporting())
                            return false;

                        //throw new ErrorException($errstr, 0, $errno, $errfile, $errline);
                    });

                    try {
                        $uncompressed .= gzinflate($data);
                    } catch (Exception $e) {
                        var_dump($e->getMessage());
                        restore_error_handler();
                        return false;
                    }


                }


                $chunk['data'] = $data;

                // Add the chunk to the chunks array so we can rebuild the thing
                $chunks[] = $chunk;

            }
        }
        // IHDR
        $out = $headerData;
        $out .= pack('N', $chunks[1]['length']);
        $out .= $chunks[1]['type'];
        $out .= $chunks[1]['data'];
        $out .= pack('N', $chunks[1]['crc']);
        // data stream
        $newData = '';
        for ($y = 0; $y < $height; $y++) {
            $i = strlen($newData); // setting the offset
            $newData .= $uncompressed[$i]; // inject the first pixel, don't know why...
            for ($x = 0; $x < $width; $x++) {
                $i = strlen($newData); // setting the offset
                // Now we need to swap the BGRA to RGBA
                $newData .= $uncompressed[$i + 2]; // Place the Red pixel
                $newData .= $uncompressed[$i + 1]; // Place the Green pixel
                $newData .= $uncompressed[$i + 0]; // Place the Blue pixel
                $newData .= $uncompressed[$i + 3]; // Place the Aplha byte
            }

        }
        $compressed = gzcompress($newData);
        $out .= pack('N', strlen($compressed));
        $out .= 'IDAT';
        $out .= $compressed;
        $out .= pack('N', crc32('IDAT' . $compressed));

        // IEND
        $out .= pack('N', 0);
        $out .= 'IEND';
        $out .= pack('N', crc32('IEND' . null));

        return $out;

    }

    public function setPath($path)
    {
        if ($path !== null) {
            $this->pngFilePath = $path;
        }
    }
}

需要解析的图片

SF无法解析该图片，故改为百度网盘链接

测试代码index.php

ini_set('error_reporting', 'E_ALL & ~E_NOTICE');
header('Content-type: image/png');
require_once './unCrush.php';
$file = './test.png';

$png = new unCrush($file);
echo $png->decode();

Answer 1

还是自己解决了，顺手造了个轮子，Github地址在这里

Answer 2

解析IDAT数据块，不能分开解码。