// tokenizes a string for PBM and PGM headers and plain PBM and PGM data. If oneChar is true,
// then
// rather than parsing a whole string, a single character is read (not including whitespace or
// comments)
static String tokenizeString(InputStream stream, boolean oneChar) throws IOException {
final int EOF = -1;
StringBuilder b = new StringBuilder();
int c;
boolean inComment = false;
while (true) {
c = stream.read();
if (c == EOF)
throw new IOException(
"Stream ended prematurely, before table reading was completed."); // no more tokens
else if (inComment) {
if (c == '\r' || c == '\n') // escape the comment
inComment = false;
else {
} // do nothing
} else if (Character.isWhitespace((char) c)) {
} // do nothing
else if (c == '#') // start of a comment
{
inComment = true;
} else // start of a string
{
b.append((char) c);
break;
}
}
if (oneChar) return b.toString();
// at this point we have a valid string. We read until whitespace or a #
while (true) {
c = stream.read();
if (c == EOF) break;
else if (c == '#') // start of comment, read until a '\n'
{
while (true) {
c = stream.read(); // could hit EOF, which is fine
if (c == EOF) break;
else if (c == '\r' || c == '\n') break;
}
// break; // comments are not delimiters
} else if (Character.isWhitespace((char) c)) break;
else b.append((char) c);
}
return b.toString();
}
// Loads raw PGM files after the first-line header is stripped
static int[][] loadRawPGM(InputStream stream) throws IOException {
int width = tokenizeInt(stream);
int height = tokenizeInt(stream);
int maxVal = tokenizeInt(stream);
if (width < 0) throw new IOException("Invalid width: " + width);
if (height < 0) throw new IOException("Invalid height: " + height);
if (maxVal <= 0) throw new IOException("Invalid maximum value: " + maxVal);
// this single whitespace character will have likely already been consumed by reading maxVal
// stream.read(); // must be a whitespace
int[][] field = new int[width][height];
for (int i = 0; i < height; i++)
for (int j = 0; j < width; j++) {
if (maxVal < 256) // one byte
field[j][i] = stream.read();
else if (maxVal < 65536) // two bytes
field[j][i] =
(stream.read() << 8) & stream.read(); // two bytes, most significant byte first
else if (maxVal < 16777216) // three bytes -- this is nonstandard
field[j][i] =
(stream.read() << 16)
& (stream.read() << 8)
& stream.read(); // three bytes, most significant byte first
else // four bytes -- this is nonstandard
field[j][i] =
(stream.read() << 24)
& (stream.read() << 16)
& (stream.read() << 8)
& stream.read(); // three bytes, most significant byte first
}
return field;
}
// Loads raw PBM files after the first-line header is stripped
static int[][] loadRawPBM(InputStream stream) throws IOException {
int width = tokenizeInt(stream);
int height = tokenizeInt(stream);
if (width < 0) throw new IOException("Invalid width in PBM: " + width);
if (height < 0) throw new IOException("Invalid height in PBM: " + height);
// this single whitespace character will have likely already been consumed by reading height
// stream.read(); // must be a whitespace
int[][] field = new int[width][height];
for (int i = 0; i < height; i++) {
int data = 0;
int count = 0;
for (int j = 0; j < width; j++) {
if (count == 0) {
data = stream.read();
count = 8;
}
count--;
field[j][i] = (data >> count) & 0x1;
}
}
return field;
}