+
−package ar.com.hjg.pngj;
+
−
+
−import java.io.File;
+
−import java.io.FileInputStream;
+
−import java.io.IOException;
+
−import java.io.InputStream;
+
−import java.io.OutputStream;
+
−import java.nio.charset.Charset;
+
−import java.util.logging.Logger;
+
−
+
−/**
+
− * Some utility static methods for internal use.
+
− * <p>
+
− * Client code should not normally use this class
+
− * <p>
+
− */
+
−public final class PngHelperInternal {
+
−
+
−  public static final String KEY_LOGGER = "ar.com.pngj";
+
−  public static final Logger LOGGER = Logger.getLogger(KEY_LOGGER);
+
−
+
−  /**
+
−   * Default charset, used internally by PNG for several things
+
−   */
+
−  public static String charsetLatin1name = "ISO-8859-1";
+
−  public static Charset charsetLatin1 = Charset.forName(charsetLatin1name);
+
−  /**
+
−   * UTF-8 is only used for some chunks
+
−   */
+
−  public static String charsetUTF8name = "UTF-8";
+
−  public static Charset charsetUTF8 = Charset.forName(charsetUTF8name);
+
−
+
−  private static ThreadLocal<Boolean> DEBUG = new ThreadLocal<Boolean>() {
+
−    protected Boolean initialValue() {
+
−      return Boolean.FALSE;
+
−    }
+
−  };
+
−
+
−  /**
+
−   * PNG magic bytes
+
−   */
+
−  public static byte[] getPngIdSignature() {
+
−    return new byte[] {-119, 80, 78, 71, 13, 10, 26, 10};
+
−  }
+
−
+
−  public static int doubleToInt100000(double d) {
+
−    return (int) (d * 100000.0 + 0.5);
+
−  }
+
−
+
−  public static double intToDouble100000(int i) {
+
−    return i / 100000.0;
+
−  }
+
−
+
−  public static int readByte(InputStream is) {
+
−    try {
+
−      return is.read();
+
−    } catch (IOException e) {
+
−      throw new PngjInputException("error reading byte", e);
+
−    }
+
−  }
+
−
+
−  /**
+
−   * -1 if eof
+
−   * 
+
−   * PNG uses "network byte order"
+
−   */
+
−  public static int readInt2(InputStream is) {
+
−    try {
+
−      int b1 = is.read();
+
−      int b2 = is.read();
+
−      if (b1 == -1 || b2 == -1)
+
−        return -1;
+
−      return (b1 << 8) | b2;
+
−    } catch (IOException e) {
+
−      throw new PngjInputException("error reading Int2", e);
+
−    }
+
−  }
+
−
+
−  /**
+
−   * -1 if eof
+
−   */
+
−  public static int readInt4(InputStream is) {
+
−    try {
+
−      int b1 = is.read();
+
−      int b2 = is.read();
+
−      int b3 = is.read();
+
−      int b4 = is.read();
+
−      if (b1 == -1 || b2 == -1 || b3 == -1 || b4 == -1)
+
−        return -1;
+
−      return (b1 << 24) | (b2 << 16) | (b3 << 8) + b4;
+
−    } catch (IOException e) {
+
−      throw new PngjInputException("error reading Int4", e);
+
−    }
+
−  }
+
−
+
−  public static int readInt1fromByte(byte[] b, int offset) {
+
−    return (b[offset] & 0xff);
+
−  }
+
−
+
−  public static int readInt2fromBytes(byte[] b, int offset) {
+
−    return ((b[offset] & 0xff) << 8) | ((b[offset + 1] & 0xff));
+
−  }
+
−
+
−  public static final int readInt4fromBytes(byte[] b, int offset) {
+
−    return ((b[offset] & 0xff) << 24) | ((b[offset + 1] & 0xff) << 16)
+
−        | ((b[offset + 2] & 0xff) << 8) | (b[offset + 3] & 0xff);
+
−  }
+
−
+
−  public static void writeByte(OutputStream os, byte b) {
+
−    try {
+
−      os.write(b);
+
−    } catch (IOException e) {
+
−      throw new PngjOutputException(e);
+
−    }
+
−  }
+
−
+
−  public static void writeByte(OutputStream os, byte[] bs) {
+
−    try {
+
−      os.write(bs);
+
−    } catch (IOException e) {
+
−      throw new PngjOutputException(e);
+
−    }
+
−  }
+
−
+
−  public static void writeInt2(OutputStream os, int n) {
+
−    byte[] temp = {(byte) ((n >> 8) & 0xff), (byte) (n & 0xff)};
+
−    writeBytes(os, temp);
+
−  }
+
−
+
−  public static void writeInt4(OutputStream os, int n) {
+
−    byte[] temp = new byte[4];
+
−    writeInt4tobytes(n, temp, 0);
+
−    writeBytes(os, temp);
+
−  }
+
−
+
−  public static void writeInt2tobytes(int n, byte[] b, int offset) {
+
−    b[offset] = (byte) ((n >> 8) & 0xff);
+
−    b[offset + 1] = (byte) (n & 0xff);
+
−  }
+
−
+
−  public static void writeInt4tobytes(int n, byte[] b, int offset) {
+
−    b[offset] = (byte) ((n >> 24) & 0xff);
+
−    b[offset + 1] = (byte) ((n >> 16) & 0xff);
+
−    b[offset + 2] = (byte) ((n >> 8) & 0xff);
+
−    b[offset + 3] = (byte) (n & 0xff);
+
−  }
+
−
+
−
+
−  /**
+
−   * guaranteed to read exactly len bytes. throws error if it can't
+
−   */
+
−  public static void readBytes(InputStream is, byte[] b, int offset, int len) {
+
−    if (len == 0)
+
−      return;
+
−    try {
+
−      int read = 0;
+
−      while (read < len) {
+
−        int n = is.read(b, offset + read, len - read);
+
−        if (n < 1)
+
−          throw new PngjInputException("error reading bytes, " + n + " !=" + len);
+
−        read += n;
+
−      }
+
−    } catch (IOException e) {
+
−      throw new PngjInputException("error reading", e);
+
−    }
+
−  }
+
−
+
−  public static void skipBytes(InputStream is, long len) {
+
−    try {
+
−      while (len > 0) {
+
−        long n1 = is.skip(len);
+
−        if (n1 > 0) {
+
−          len -= n1;
+
−        } else if (n1 == 0) { // should we retry? lets read one byte
+
−          if (is.read() == -1) // EOF
+
−            break;
+
−          else
+
−            len--;
+
−        } else
+
−          // negative? this should never happen but...
+
−          throw new IOException("skip() returned a negative value ???");
+
−      }
+
−    } catch (IOException e) {
+
−      throw new PngjInputException(e);
+
−    }
+
−  }
+
−
+
−  public static void writeBytes(OutputStream os, byte[] b) {
+
−    try {
+
−      os.write(b);
+
−    } catch (IOException e) {
+
−      throw new PngjOutputException(e);
+
−    }
+
−  }
+
−
+
−  public static void writeBytes(OutputStream os, byte[] b, int offset, int n) {
+
−    try {
+
−      os.write(b, offset, n);
+
−    } catch (IOException e) {
+
−      throw new PngjOutputException(e);
+
−    }
+
−  }
+
−
+
−  public static void logdebug(String msg) {
+
−    if (isDebug())
+
−      System.err.println("logdebug: " + msg);
+
−  }
+
−
+
−  // / filters
+
−  public static int filterRowNone(int r) {
+
−    return (int) (r & 0xFF);
+
−  }
+
−
+
−  public static int filterRowSub(int r, int left) {
+
−    return ((int) (r - left) & 0xFF);
+
−  }
+
−
+
−  public static int filterRowUp(int r, int up) {
+
−    return ((int) (r - up) & 0xFF);
+
−  }
+
−
+
−  public static int filterRowAverage(int r, int left, int up) {
+
−    return (r - (left + up) / 2) & 0xFF;
+
−  }
+
−
+
−  public static int filterRowPaeth(int r, int left, int up, int upleft) { // a = left, b = above, c
+
−                                                                          // = upper left
+
−    return (r - filterPaethPredictor(left, up, upleft)) & 0xFF;
+
−  }
+
−
+
−  final static int filterPaethPredictor(final int a, final int b, final int c) { // a = left, b =
+
−                                                                                 // above, c = upper
+
−    // left
+
−    // from http://www.libpng.org/pub/png/spec/1.2/PNG-Filters.html
+
−
+
−    final int p = a + b - c;// ; initial estimate
+
−    final int pa = p >= a ? p - a : a - p;
+
−    final int pb = p >= b ? p - b : b - p;
+
−    final int pc = p >= c ? p - c : c - p;
+
−    // ; return nearest of a,b,c,
+
−    // ; breaking ties in order a,b,c.
+
−    if (pa <= pb && pa <= pc)
+
−      return a;
+
−    else if (pb <= pc)
+
−      return b;
+
−    else
+
−      return c;
+
−  }
+
−
+
−  /**
+
−   * Prits a debug message (prints class name, method and line number)
+
−   * 
+
−   * @param obj : Object to print
+
−   */
+
−  public static void debug(Object obj) {
+
−    debug(obj, 1, true);
+
−  }
+
−
+
−  /**
+
−   * Prits a debug message (prints class name, method and line number)
+
−   * 
+
−   * @param obj : Object to print
+
−   * @param offset : Offset N lines from stacktrace
+
−   */
+
−  static void debug(Object obj, int offset) {
+
−    debug(obj, offset, true);
+
−  }
+
−
+
−  public static InputStream istreamFromFile(File f) {
+
−    FileInputStream is;
+
−    try {
+
−      is = new FileInputStream(f);
+
−    } catch (Exception e) {
+
−      throw new PngjInputException("Could not open " + f, e);
+
−    }
+
−    return is;
+
−  }
+
−
+
−  static OutputStream ostreamFromFile(File f) {
+
−    return ostreamFromFile(f, true);
+
−  }
+
−
+
−  static OutputStream ostreamFromFile(File f, boolean overwrite) {
+
−    return PngHelperInternal2.ostreamFromFile(f, overwrite);
+
−  }
+
−
+
−  /**
+
−   * Prints a debug message (prints class name, method and line number) to stderr and logFile
+
−   * 
+
−   * @param obj : Object to print
+
−   * @param offset : Offset N lines from stacktrace
+
−   * @param newLine : Print a newline char at the end ('\n')
+
−   */
+
−  static void debug(Object obj, int offset, boolean newLine) {
+
−    StackTraceElement ste = new Exception().getStackTrace()[1 + offset];
+
−    String steStr = ste.getClassName();
+
−    int ind = steStr.lastIndexOf('.');
+
−    steStr = steStr.substring(ind + 1);
+
−    steStr +=
+
−        "." + ste.getMethodName() + "(" + ste.getLineNumber() + "): "
+
−            + (obj == null ? null : obj.toString());
+
−    System.err.println(steStr);
+
−  }
+
−
+
−  /**
+
−   * Sets a global debug flag. This is bound to a thread.
+
−   */
+
−  public static void setDebug(boolean b) {
+
−    DEBUG.set(b);
+
−  }
+
−
+
−  public static boolean isDebug() {
+
−    return DEBUG.get().booleanValue();
+
−  }
+
−
+
−  public static long getDigest(PngReader pngr) {
+
−    return pngr.getSimpleDigest();
+
−  }
+
−
+
−  public static void initCrcForTests(PngReader pngr) {
+
−    pngr.prepareSimpleDigestComputation();
+
−  }
+
−
+
−  public static long getRawIdatBytes(PngReader r) { // in case of image with frames, returns the current one
+
−    return r.interlaced ? r.getChunkseq().getDeinterlacer().getTotalRawBytes() : r.getCurImgInfo()
+
−        .getTotalRawBytes();
+
−  }
+
−
+
−}