com.packenius.datadivider.jpeg.APPxSegment Maven / Gradle / Ivy

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package com.packenius.datadivider.jpeg;

import com.packenius.datadivider.SubContentCrossPointer;
import com.packenius.dumpapi.CrossPointer;
import com.packenius.dumpapi.DumpReader;

public class APPxSegment extends VariableLengthMarker {
    public APPxSegment(DumpReader reader, int marker) {
        super(reader, "APP" + (marker - 0xe0), "Application marker segment", false);
        if (isJFIF(reader, marker)) {
            readApp0JfifContent(reader);
        } else if (isExif(reader, marker)) {
            readApp1ExifContent(reader);
        } else {
            readContentBytes("APP" + (marker - 0xe0) + "Application marker segment content.");
        }
        setEndAddress(reader);
    }

    private boolean isJFIF(DumpReader reader, int marker) {
        return length > 8 //
                && reader.getDeltaByte(0) == 'J' //
                && reader.getDeltaByte(1) == 'F' //
                && reader.getDeltaByte(2) == 'I' //
                && reader.getDeltaByte(3) == 'F' //
                && reader.getDeltaByte(4) == 0 //
        ;
    }

    private void readApp0JfifContent(DumpReader reader) {
        reader.readBytes(5, "JFIF APP0 block");
        reader.readU1("Major version byte");
        reader.readU1("Minor version byte");
        reader.readU1("Units for X and Y density (0:pixel, 1:inch, 2:cm");
        reader.readBigEndianS2("Horizontal pixel density");
        reader.readBigEndianS2("Vertical pixel density");
        int tpx = reader.readU1("Thumbnail horizontal pixel count").value;
        int tpy = reader.readU1("Thumbnail vertical pixel count").value;
        int remLength = length - 16;

        // There must be 3*x*y thumbnail pixels (3: RGB).
        if (3 * tpx * tpy != remLength) {
            throw new RuntimeException(
                    "Wrong number of bytes for thumbnail pixels! Not " + remLength + ", but " + 3 * tpx * tpy);
        }
        reader.readBytes(remLength, "Thumbnail RGB bytes");
    }

    private boolean isExif(DumpReader reader, int marker) {
        return length > 9 //
                && reader.getDeltaByte(0) == 'E' //
                && reader.getDeltaByte(1) == 'x' //
                && reader.getDeltaByte(2) == 'i' //
                && reader.getDeltaByte(3) == 'f' //
                && reader.getDeltaByte(4) == 0 //
                && reader.getDeltaByte(5) == 0 //
        ;
    }

    private void readApp1ExifContent(DumpReader reader) {
        reader.readBytes(6, "Exif APP1 block");
        int remLength = length - 8;
        byte[] tiffBytes = reader.readBytes(remLength, "TIFF thumbnail content");
        CrossPointer tiffCP = new SubContentCrossPointer(tiffBytes);
        setCrossPointer(tiffCP);
    }
}