Faster_Image_B52f1a8_Image_Parser::parseSizeForWebp PHP Метод

    protected function parseSizeForWebp()
    {
        $vp8 = substr($this->stream->read(16), 12, 4);
        $len = unpack("V", $this->stream->read(4));
        switch (trim($vp8)) {
            case 'VP8':
                $this->stream->read(6);
                $width = current(unpack("v", $this->stream->read(2)));
                $height = current(unpack("v", $this->stream->read(2)));
                return [$width & 0x3fff, $height & 0x3fff];
            case 'VP8L':
                $this->stream->read(1);
                $b1 = $this->getByte();
                $b2 = $this->getByte();
                $b3 = $this->getByte();
                $b4 = $this->getByte();
                $width = 1 + (($b2 & 0x3f) << 8 | $b1);
                $height = 1 + (($b4 & 0xf) << 10 | $b3 << 2 | ($b2 & 0xc0) >> 6);
                return [$width, $height];
            case 'VP8X':
                $flags = current(unpack("C", $this->stream->read(4)));
                $b1 = $this->getByte();
                $b2 = $this->getByte();
                $b3 = $this->getByte();
                $b4 = $this->getByte();
                $b5 = $this->getByte();
                $b6 = $this->getByte();
                $width = 1 + $b1 + ($b2 << 8) + ($b3 << 16);
                $height = 1 + $b4 + ($b5 << 8) + ($b6 << 16);
                return [$width, $height];
            default:
                return null;
        }
    }