private ImageDescriptor readImageDescriptor()

in src/main/java/org/apache/commons/imaging/formats/gif/GifImageParser.java [826:895]
60 lines of code
10 McCabe index (conditional complexity)

    private ImageDescriptor readImageDescriptor(final GifHeaderInfo ghi,
            final int blockCode, final InputStream is, final boolean stopBeforeImageData,
            final FormatCompliance formatCompliance) throws ImagingException,
            IOException {
        final int imageLeftPosition = read2Bytes("Image Left Position", is, "Not a Valid GIF File", getByteOrder());
        final int imageTopPosition = read2Bytes("Image Top Position", is, "Not a Valid GIF File", getByteOrder());
        final int imageWidth = read2Bytes("Image Width", is, "Not a Valid GIF File", getByteOrder());
        final int imageHeight = read2Bytes("Image Height", is, "Not a Valid GIF File", getByteOrder());
        final byte packedFields = readByte("Packed Fields", is, "Not a Valid GIF File");

        if (formatCompliance != null) {
            formatCompliance.checkBounds("Width", 1, ghi.logicalScreenWidth, imageWidth);
            formatCompliance.checkBounds("Height", 1, ghi.logicalScreenHeight, imageHeight);
            formatCompliance.checkBounds("Left Position", 0, ghi.logicalScreenWidth - imageWidth, imageLeftPosition);
            formatCompliance.checkBounds("Top Position", 0, ghi.logicalScreenHeight - imageHeight, imageTopPosition);
        }

        if (LOGGER.isLoggable(Level.FINEST)) {
            logByteBits("PackedFields bits", packedFields);
        }

        final boolean localColorTableFlag = (((packedFields >> 7) & 1) > 0);
        if (LOGGER.isLoggable(Level.FINEST)) {
            LOGGER.finest("LocalColorTableFlag: " + localColorTableFlag);
        }
        final boolean interlaceFlag = (((packedFields >> 6) & 1) > 0);
        if (LOGGER.isLoggable(Level.FINEST)) {
            LOGGER.finest("Interlace Flag: " + interlaceFlag);
        }
        final boolean sortFlag = (((packedFields >> 5) & 1) > 0);
        if (LOGGER.isLoggable(Level.FINEST)) {
            LOGGER.finest("Sort Flag: " + sortFlag);
        }

        final byte sizeOfLocalColorTable = (byte) (packedFields & 7);
        if (LOGGER.isLoggable(Level.FINEST)) {
            LOGGER.finest("SizeofLocalColorTable: " + sizeOfLocalColorTable);
        }

        byte[] localColorTable = null;
        if (localColorTableFlag) {
            localColorTable = readColorTable(is, sizeOfLocalColorTable);
        }

        byte[] imageData = null;
        if (!stopBeforeImageData) {
            final int lzwMinimumCodeSize = is.read();

            final GenericGifBlock block = readGenericGifBlock(is, -1);
            final byte[] bytes = block.appendSubBlocks();
            final InputStream bais = new ByteArrayInputStream(bytes);

            final int size = imageWidth * imageHeight;
            final MyLzwDecompressor myLzwDecompressor = new MyLzwDecompressor(
                    lzwMinimumCodeSize, ByteOrder.LITTLE_ENDIAN, false);
            imageData = myLzwDecompressor.decompress(bais, size);
        } else {
            final int LZWMinimumCodeSize = is.read();
            if (LOGGER.isLoggable(Level.FINEST)) {
                LOGGER.finest("LZWMinimumCodeSize: " + LZWMinimumCodeSize);
            }

            readGenericGifBlock(is, -1);
        }

        return new ImageDescriptor(blockCode,
                imageLeftPosition, imageTopPosition, imageWidth, imageHeight,
                packedFields, localColorTableFlag, interlaceFlag, sortFlag,
                sizeOfLocalColorTable, localColorTable, imageData);
    }