jogamp.opengl.util.pngj.PngReader Maven / Gradle / Ivy
Show all versions of jogl-all Show documentation
package jogamp.opengl.util.pngj;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import java.util.HashSet;
import java.util.zip.CRC32;
import java.util.zip.Inflater;
import java.util.zip.InflaterInputStream;
import jogamp.opengl.util.pngj.ImageLine.SampleType;
import jogamp.opengl.util.pngj.chunks.ChunkHelper;
import jogamp.opengl.util.pngj.chunks.ChunkLoadBehaviour;
import jogamp.opengl.util.pngj.chunks.ChunkRaw;
import jogamp.opengl.util.pngj.chunks.ChunksList;
import jogamp.opengl.util.pngj.chunks.PngChunk;
import jogamp.opengl.util.pngj.chunks.PngChunkIDAT;
import jogamp.opengl.util.pngj.chunks.PngChunkIHDR;
import jogamp.opengl.util.pngj.chunks.PngChunkSkipped;
import jogamp.opengl.util.pngj.chunks.PngMetadata;
/**
* Reads a PNG image, line by line.
*
* The reading sequence is as follows:
* 1. At construction time, the header and IHDR chunk are read (basic image
* info)
* 2. Afterwards you can set some additional global options. Eg.
* {@link #setUnpackedMode(boolean)}, {@link #setCrcCheckDisabled()}.
* 3. Optional: If you call getMetadata() or getChunksLisk() before start
* reading the rows, all the chunks before IDAT are automatically loaded and
* available
* 4a. The rows are read onen by one of the readRowXXX methods:
* {@link #readRowInt(int)}, {@link PngReader#readRowByte(int)}, etc, in order,
* from 0 to nrows-1 (you can skip or repeat rows, but not go backwards)
* 4b. Alternatively, you can read all rows, or a subset, in a single call:
* {@link #readRowsInt()}, {@link #readRowsByte()} ,etc. In general this
* consumes more memory, but for interlaced images this is equally efficient,
* and more so if reading a small subset of rows.
* 5. Read of the last row auyomatically loads the trailing chunks, and ends the
* reader.
* 6. end() forcibly finishes/aborts the reading and closes the stream
*/
public class PngReader {
/**
* Basic image info - final and inmutable.
*/
public final ImageInfo imgInfo;
/**
* not necesarily a filename, can be a description - merely informative
*/
protected final String filename;
private ChunkLoadBehaviour chunkLoadBehaviour = ChunkLoadBehaviour.LOAD_CHUNK_ALWAYS; // see setter/getter
private boolean shouldCloseStream = true; // true: closes stream after ending - see setter/getter
// some performance/defensive limits
private long maxTotalBytesRead = 200 * 1024 * 1024; // 200MB
private int maxBytesMetadata = 5 * 1024 * 1024; // for ancillary chunks - see setter/getter
private int skipChunkMaxSize = 2 * 1024 * 1024; // chunks exceeding this size will be skipped (nor even CRC checked)
private String[] skipChunkIds = { "fdAT" }; // chunks with these ids will be skipped (nor even CRC checked)
private HashSet skipChunkIdsSet; // lazily created from skipChunksById
protected final PngMetadata metadata; // this a wrapper over chunks
protected final ChunksList chunksList;
protected ImageLine imgLine;
// line as bytes, counting from 1 (index 0 is reserved for filter type)
protected final int buffersLen; // nominal length is imgInfo.bytesPerRow + 1 but it can be larger
protected byte[] rowb = null;
protected byte[] rowbprev = null; // rowb previous
protected byte[] rowbfilter = null; // current line 'filtered': exactly as in uncompressed stream
// only set for interlaced PNG
private final boolean interlaced;
private final PngDeinterlacer deinterlacer;
private boolean crcEnabled = true;
// this only influences the 1-2-4 bitdepth format
private boolean unpackedMode = false;
private Inflater inflater = null; // can be reused among several objects. see reuseBuffersFrom()
/**
* Current chunk group, (0-6) already read or reading
*
* see {@link ChunksList}
*/
protected int currentChunkGroup = -1;
protected int rowNum = -1; // last read row number, starting from 0
private long offset = 0; // offset in InputStream = bytes read
private int bytesChunksLoaded; // bytes loaded from anciallary chunks
protected final InputStream inputStream;
protected InflaterInputStream idatIstream;
protected PngIDatChunkInputStream iIdatCstream;
protected CRC32 crctest; // If set to non null, it gets a CRC of the unfiltered bytes, to check for images equality
/**
* Constructs a PngReader from an InputStream.
*
* See also FileHelper.createPngReader(File f) if available.
*
* Reads only the signature and first chunk (IDHR)
*
* @param filenameOrDescription
* : Optional, can be a filename or a description. Just for
* error/debug messages
*
*/
public PngReader(final InputStream inputStream, final String filenameOrDescription) {
this.filename = filenameOrDescription == null ? "" : filenameOrDescription;
this.inputStream = inputStream;
this.chunksList = new ChunksList(null);
this.metadata = new PngMetadata(chunksList);
// starts reading: signature
final byte[] pngid = new byte[8];
PngHelperInternal.readBytes(inputStream, pngid, 0, pngid.length);
offset += pngid.length;
if (!Arrays.equals(pngid, PngHelperInternal.getPngIdSignature()))
throw new PngjInputException("Bad PNG signature");
// reads first chunk
currentChunkGroup = ChunksList.CHUNK_GROUP_0_IDHR;
final int clen = PngHelperInternal.readInt4(inputStream);
offset += 4;
if (clen != 13)
throw new PngjInputException("IDHR chunk len != 13 ?? " + clen);
final byte[] chunkid = new byte[4];
PngHelperInternal.readBytes(inputStream, chunkid, 0, 4);
if (!Arrays.equals(chunkid, ChunkHelper.b_IHDR))
throw new PngjInputException("IHDR not found as first chunk??? [" + ChunkHelper.toString(chunkid) + "]");
offset += 4;
final PngChunkIHDR ihdr = (PngChunkIHDR) readChunk(chunkid, clen, false);
final boolean alpha = (ihdr.getColormodel() & 0x04) != 0;
final boolean palette = (ihdr.getColormodel() & 0x01) != 0;
final boolean grayscale = (ihdr.getColormodel() == 0 || ihdr.getColormodel() == 4);
// creates ImgInfo and imgLine, and allocates buffers
imgInfo = new ImageInfo(ihdr.getCols(), ihdr.getRows(), ihdr.getBitspc(), alpha, grayscale, palette);
interlaced = ihdr.getInterlaced() == 1;
deinterlacer = interlaced ? new PngDeinterlacer(imgInfo) : null;
buffersLen = imgInfo.bytesPerRow + 1;
// some checks
if (ihdr.getFilmeth() != 0 || ihdr.getCompmeth() != 0 || (ihdr.getInterlaced() & 0xFFFE) != 0)
throw new PngjInputException("compression method o filter method or interlaced unrecognized ");
if (ihdr.getColormodel() < 0 || ihdr.getColormodel() > 6 || ihdr.getColormodel() == 1
|| ihdr.getColormodel() == 5)
throw new PngjInputException("Invalid colormodel " + ihdr.getColormodel());
if (ihdr.getBitspc() != 1 && ihdr.getBitspc() != 2 && ihdr.getBitspc() != 4 && ihdr.getBitspc() != 8
&& ihdr.getBitspc() != 16)
throw new PngjInputException("Invalid bit depth " + ihdr.getBitspc());
}
private boolean firstChunksNotYetRead() {
return currentChunkGroup < ChunksList.CHUNK_GROUP_1_AFTERIDHR;
}
private void allocateBuffers() { // only if needed
if (rowbfilter == null || rowbfilter.length < buffersLen) {
rowbfilter = new byte[buffersLen];
rowb = new byte[buffersLen];
rowbprev = new byte[buffersLen];
}
}
/**
* Reads last Internally called after having read the last line. It reads
* extra chunks after IDAT, if present.
*/
private void readLastAndClose() {
// offset = iIdatCstream.getOffset();
if (currentChunkGroup < ChunksList.CHUNK_GROUP_5_AFTERIDAT) {
try {
idatIstream.close();
} catch (final Exception e) {
}
readLastChunks();
}
close();
}
private void close() {
if (currentChunkGroup < ChunksList.CHUNK_GROUP_6_END) { // this could only happen if forced close
try {
idatIstream.close();
} catch (final Exception e) {
}
currentChunkGroup = ChunksList.CHUNK_GROUP_6_END;
}
if (shouldCloseStream) {
try {
inputStream.close();
} catch (final Exception e) {
throw new PngjInputException("error closing input stream!", e);
}
}
}
// nbytes: NOT including the filter byte. leaves result in rowb
private void unfilterRow(final int nbytes) {
final int ftn = rowbfilter[0];
final FilterType ft = FilterType.getByVal(ftn);
if (ft == null)
throw new PngjInputException("Filter type " + ftn + " invalid");
switch (ft) {
case FILTER_NONE:
unfilterRowNone(nbytes);
break;
case FILTER_SUB:
unfilterRowSub(nbytes);
break;
case FILTER_UP:
unfilterRowUp(nbytes);
break;
case FILTER_AVERAGE:
unfilterRowAverage(nbytes);
break;
case FILTER_PAETH:
unfilterRowPaeth(nbytes);
break;
default:
throw new PngjInputException("Filter type " + ftn + " not implemented");
}
if (crctest != null)
crctest.update(rowb, 1, buffersLen - 1);
}
private void unfilterRowAverage(final int nbytes) {
int i, j, x;
for (j = 1 - imgInfo.bytesPixel, i = 1; i <= nbytes; i++, j++) {
x = j > 0 ? (rowb[j] & 0xff) : 0;
rowb[i] = (byte) (rowbfilter[i] + (x + (rowbprev[i] & 0xFF)) / 2);
}
}
private void unfilterRowNone(final int nbytes) {
for (int i = 1; i <= nbytes; i++) {
rowb[i] = (rowbfilter[i]);
}
}
private void unfilterRowPaeth(final int nbytes) {
int i, j, x, y;
for (j = 1 - imgInfo.bytesPixel, i = 1; i <= nbytes; i++, j++) {
x = j > 0 ? (rowb[j] & 0xFF) : 0;
y = j > 0 ? (rowbprev[j] & 0xFF) : 0;
rowb[i] = (byte) (rowbfilter[i] + PngHelperInternal.filterPaethPredictor(x, rowbprev[i] & 0xFF, y));
}
}
private void unfilterRowSub(final int nbytes) {
int i, j;
for (i = 1; i <= imgInfo.bytesPixel; i++) {
rowb[i] = (rowbfilter[i]);
}
for (j = 1, i = imgInfo.bytesPixel + 1; i <= nbytes; i++, j++) {
rowb[i] = (byte) (rowbfilter[i] + rowb[j]);
}
}
private void unfilterRowUp(final int nbytes) {
for (int i = 1; i <= nbytes; i++) {
rowb[i] = (byte) (rowbfilter[i] + rowbprev[i]);
}
}
/**
* Reads chunks before first IDAT. Normally this is called automatically
*
* Position before: after IDHR (crc included) Position after: just after the
* first IDAT chunk id
*
* This can be called several times (tentatively), it does nothing if
* already run
*
* (Note: when should this be called? in the constructor? hardly, because we
* loose the opportunity to call setChunkLoadBehaviour() and perhaps other
* settings before reading the first row? but sometimes we want to access
* some metadata (plte, phys) before. Because of this, this method can be
* called explicitly but is also called implicititly in some methods
* (getMetatada(), getChunksList())
*/
private final void readFirstChunks() {
if (!firstChunksNotYetRead())
return;
int clen = 0;
boolean found = false;
final byte[] chunkid = new byte[4]; // it's important to reallocate in each iteration
currentChunkGroup = ChunksList.CHUNK_GROUP_1_AFTERIDHR;
while (!found) {
clen = PngHelperInternal.readInt4(inputStream);
offset += 4;
if (clen < 0)
break;
PngHelperInternal.readBytes(inputStream, chunkid, 0, 4);
offset += 4;
if (Arrays.equals(chunkid, ChunkHelper.b_IDAT)) {
found = true;
currentChunkGroup = ChunksList.CHUNK_GROUP_4_IDAT;
// add dummy idat chunk to list
chunksList.appendReadChunk(new PngChunkIDAT(imgInfo, clen, offset - 8), currentChunkGroup);
break;
} else if (Arrays.equals(chunkid, ChunkHelper.b_IEND)) {
throw new PngjInputException("END chunk found before image data (IDAT) at offset=" + offset);
}
if (Arrays.equals(chunkid, ChunkHelper.b_PLTE))
currentChunkGroup = ChunksList.CHUNK_GROUP_2_PLTE;
readChunk(chunkid, clen, false);
if (Arrays.equals(chunkid, ChunkHelper.b_PLTE))
currentChunkGroup = ChunksList.CHUNK_GROUP_3_AFTERPLTE;
}
final int idatLen = found ? clen : -1;
if (idatLen < 0)
throw new PngjInputException("first idat chunk not found!");
iIdatCstream = new PngIDatChunkInputStream(inputStream, idatLen, offset);
if(inflater == null) {
inflater = new Inflater();
} else {
inflater.reset();
}
idatIstream = new InflaterInputStream(iIdatCstream, inflater);
if (!crcEnabled)
iIdatCstream.disableCrcCheck();
}
/**
* Reads (and processes) chunks after last IDAT.
**/
void readLastChunks() {
// PngHelper.logdebug("idat ended? " + iIdatCstream.isEnded());
currentChunkGroup = ChunksList.CHUNK_GROUP_5_AFTERIDAT;
if (!iIdatCstream.isEnded())
iIdatCstream.forceChunkEnd();
int clen = iIdatCstream.getLenLastChunk();
final byte[] chunkid = iIdatCstream.getIdLastChunk();
boolean endfound = false;
boolean first = true;
boolean skip = false;
while (!endfound) {
skip = false;
if (!first) {
clen = PngHelperInternal.readInt4(inputStream);
offset += 4;
if (clen < 0)
throw new PngjInputException("bad chuck len " + clen);
PngHelperInternal.readBytes(inputStream, chunkid, 0, 4);
offset += 4;
}
first = false;
if (Arrays.equals(chunkid, ChunkHelper.b_IDAT)) {
skip = true; // extra dummy (empty?) idat chunk, it can happen, ignore it
} else if (Arrays.equals(chunkid, ChunkHelper.b_IEND)) {
currentChunkGroup = ChunksList.CHUNK_GROUP_6_END;
endfound = true;
}
readChunk(chunkid, clen, skip);
}
if (!endfound)
throw new PngjInputException("end chunk not found - offset=" + offset);
// PngHelper.logdebug("end chunk found ok offset=" + offset);
}
/**
* Reads chunkd from input stream, adds to ChunksList, and returns it. If
* it's skipped, a PngChunkSkipped object is created
*/
private PngChunk readChunk(final byte[] chunkid, final int clen, final boolean skipforced) {
if (clen < 0)
throw new PngjInputException("invalid chunk lenght: " + clen);
// skipChunksByIdSet is created lazyly, if fist IHDR has already been read
if (skipChunkIdsSet == null && currentChunkGroup > ChunksList.CHUNK_GROUP_0_IDHR)
skipChunkIdsSet = new HashSet(Arrays.asList(skipChunkIds));
final String chunkidstr = ChunkHelper.toString(chunkid);
final boolean critical = ChunkHelper.isCritical(chunkidstr);
PngChunk pngChunk = null;
boolean skip = skipforced;
if (maxTotalBytesRead > 0 && clen + offset > maxTotalBytesRead)
throw new PngjInputException("Maximum total bytes to read exceeeded: " + maxTotalBytesRead + " offset:"
+ offset + " clen=" + clen);
// an ancillary chunks can be skipped because of several reasons:
if (currentChunkGroup > ChunksList.CHUNK_GROUP_0_IDHR && !critical)
skip = skip || (skipChunkMaxSize > 0 && clen >= skipChunkMaxSize) || skipChunkIdsSet.contains(chunkidstr)
|| (maxBytesMetadata > 0 && clen > maxBytesMetadata - bytesChunksLoaded)
|| !ChunkHelper.shouldLoad(chunkidstr, chunkLoadBehaviour);
if (skip) {
PngHelperInternal.skipBytes(inputStream, clen);
PngHelperInternal.readInt4(inputStream); // skip - we dont call PngHelperInternal.skipBytes(inputStream,
// clen + 4) for risk of overflow
pngChunk = new PngChunkSkipped(chunkidstr, imgInfo, clen);
} else {
final ChunkRaw chunk = new ChunkRaw(clen, chunkid, true);
chunk.readChunkData(inputStream, crcEnabled || critical);
pngChunk = PngChunk.factory(chunk, imgInfo);
if (!pngChunk.crit)
bytesChunksLoaded += chunk.len;
}
pngChunk.setOffset(offset - 8L);
chunksList.appendReadChunk(pngChunk, currentChunkGroup);
offset += clen + 4L;
return pngChunk;
}
/**
* Logs/prints a warning.
*
* The default behaviour is print to stderr, but it can be overriden.
*
* This happens rarely - most errors are fatal.
*/
protected void logWarn(final String warn) {
System.err.println(warn);
}
/**
* @see #setChunkLoadBehaviour(ChunkLoadBehaviour)
*/
public ChunkLoadBehaviour getChunkLoadBehaviour() {
return chunkLoadBehaviour;
}
/**
* Determines which ancillary chunks (metada) are to be loaded
*
* @param chunkLoadBehaviour
* {@link ChunkLoadBehaviour}
*/
public void setChunkLoadBehaviour(final ChunkLoadBehaviour chunkLoadBehaviour) {
this.chunkLoadBehaviour = chunkLoadBehaviour;
}
/**
* All loaded chunks (metada). If we have not yet end reading the image,
* this will include only the chunks before the pixels data (IDAT)
*
* Critical chunks are included, except that all IDAT chunks appearance are
* replaced by a single dummy-marker IDAT chunk. These might be copied to
* the PngWriter
*
*
* @see #getMetadata()
*/
public ChunksList getChunksList() {
if (firstChunksNotYetRead())
readFirstChunks();
return chunksList;
}
int getCurrentChunkGroup() {
return currentChunkGroup;
}
/**
* High level wrapper over chunksList
*
* @see #getChunksList()
*/
public PngMetadata getMetadata() {
if (firstChunksNotYetRead())
readFirstChunks();
return metadata;
}
/**
* If called for first time, calls readRowInt. Elsewhere, it calls the
* appropiate readRowInt/readRowByte
*
* In general, specifying the concrete readRowInt/readRowByte is preferrable
*
* @see #readRowInt(int) {@link #readRowByte(int)}
*/
public ImageLine readRow(final int nrow) {
if (imgLine == null)
imgLine = new ImageLine(imgInfo, SampleType.INT, unpackedMode);
return imgLine.sampleType != SampleType.BYTE ? readRowInt(nrow) : readRowByte(nrow);
}
/**
* Reads the row as INT, storing it in the {@link #imgLine} property and
* returning it.
*
* The row must be greater or equal than the last read row.
*
* @param nrow
* Row number, from 0 to rows-1. Increasing order.
* @return ImageLine object, also available as field. Data is in
* {@link ImageLine#scanline} (int) field.
*/
public ImageLine readRowInt(final int nrow) {
if (imgLine == null)
imgLine = new ImageLine(imgInfo, SampleType.INT, unpackedMode);
if (imgLine.getRown() == nrow) // already read
return imgLine;
readRowInt(imgLine.scanline, nrow);
imgLine.setFilterUsed(FilterType.getByVal(rowbfilter[0]));
imgLine.setRown(nrow);
return imgLine;
}
/**
* Reads the row as BYTES, storing it in the {@link #imgLine} property and
* returning it.
*
* The row must be greater or equal than the last read row. This method
* allows to pass the same row that was last read.
*
* @param nrow
* Row number, from 0 to rows-1. Increasing order.
* @return ImageLine object, also available as field. Data is in
* {@link ImageLine#scanlineb} (byte) field.
*/
public ImageLine readRowByte(final int nrow) {
if (imgLine == null)
imgLine = new ImageLine(imgInfo, SampleType.BYTE, unpackedMode);
if (imgLine.getRown() == nrow) // already read
return imgLine;
readRowByte(imgLine.scanlineb, nrow);
imgLine.setFilterUsed(FilterType.getByVal(rowbfilter[0]));
imgLine.setRown(nrow);
return imgLine;
}
/**
* @see #readRowInt(int[], int)
*/
public final int[] readRow(final int[] buffer, final int nrow) {
return readRowInt(buffer, nrow);
}
/**
* Reads a line and returns it as a int[] array.
*
* You can pass (optionally) a prealocatted buffer.
*
* If the bitdepth is less than 8, the bytes are packed - unless
* {@link #unpackedMode} is true.
*
* @param buffer
* Prealocated buffer, or null.
* @param nrow
* Row number (0 is top). Most be strictly greater than the last
* read row.
*
* @return The scanline in the same passwd buffer if it was allocated, a
* newly allocated one otherwise
*/
public final int[] readRowInt(int[] buffer, final int nrow) {
if (buffer == null)
buffer = new int[unpackedMode ? imgInfo.samplesPerRow : imgInfo.samplesPerRowPacked];
if (!interlaced) {
if (nrow <= rowNum)
throw new PngjInputException("rows must be read in increasing order: " + nrow);
int bytesread = 0;
while (rowNum < nrow)
bytesread = readRowRaw(rowNum + 1); // read rows, perhaps skipping if necessary
decodeLastReadRowToInt(buffer, bytesread);
} else { // interlaced
if (deinterlacer.getImageInt() == null)
deinterlacer.setImageInt(readRowsInt().scanlines); // read all image and store it in deinterlacer
System.arraycopy(deinterlacer.getImageInt()[nrow], 0, buffer, 0, unpackedMode ? imgInfo.samplesPerRow
: imgInfo.samplesPerRowPacked);
}
return buffer;
}
/**
* Reads a line and returns it as a byte[] array.
*
* You can pass (optionally) a prealocatted buffer.
*
* If the bitdepth is less than 8, the bytes are packed - unless
* {@link #unpackedMode} is true.
* If the bitdepth is 16, the least significant byte is lost.
*
*
* @param buffer
* Prealocated buffer, or null.
* @param nrow
* Row number (0 is top). Most be strictly greater than the last
* read row.
*
* @return The scanline in the same passwd buffer if it was allocated, a
* newly allocated one otherwise
*/
public final byte[] readRowByte(byte[] buffer, final int nrow) {
if (buffer == null)
buffer = new byte[unpackedMode ? imgInfo.samplesPerRow : imgInfo.samplesPerRowPacked];
if (!interlaced) {
if (nrow <= rowNum)
throw new PngjInputException("rows must be read in increasing order: " + nrow);
int bytesread = 0;
while (rowNum < nrow)
bytesread = readRowRaw(rowNum + 1); // read rows, perhaps skipping if necessary
decodeLastReadRowToByte(buffer, bytesread);
} else { // interlaced
if (deinterlacer.getImageByte() == null)
deinterlacer.setImageByte(readRowsByte().scanlinesb); // read all image and store it in deinterlacer
System.arraycopy(deinterlacer.getImageByte()[nrow], 0, buffer, 0, unpackedMode ? imgInfo.samplesPerRow
: imgInfo.samplesPerRowPacked);
}
return buffer;
}
/**
* @param nrow
* @deprecated Now {@link #readRow(int)} implements the same funcion. This
* method will be removed in future releases
*/
public ImageLine getRow(final int nrow) {
return readRow(nrow);
}
private void decodeLastReadRowToInt(final int[] buffer, final int bytesRead) {
if (imgInfo.bitDepth <= 8)
for (int i = 0, j = 1; i < bytesRead; i++)
buffer[i] = (rowb[j++] & 0xFF); // http://www.libpng.org/pub/png/spec/1.2/PNG-DataRep.html
else
for (int i = 0, j = 1; j <= bytesRead; i++)
buffer[i] = ((rowb[j++] & 0xFF) << 8) + (rowb[j++] & 0xFF); // 16 bitspc
if (imgInfo.packed && unpackedMode)
ImageLine.unpackInplaceInt(imgInfo, buffer, buffer, false);
}
private void decodeLastReadRowToByte(final byte[] buffer, final int bytesRead) {
if (imgInfo.bitDepth <= 8)
System.arraycopy(rowb, 1, buffer, 0, bytesRead);
else
for (int i = 0, j = 1; j < bytesRead; i++, j += 2)
buffer[i] = rowb[j];// 16 bits in 1 byte: this discards the LSB!!!
if (imgInfo.packed && unpackedMode)
ImageLine.unpackInplaceByte(imgInfo, buffer, buffer, false);
}
/**
* Reads a set of lines and returns it as a ImageLines object, which wraps
* matrix. Internally it reads all lines, but decodes and stores only the
* wanted ones. This starts and ends the reading, and cannot be combined
* with other reading methods.
*
* This it's more efficient (speed an memory) that doing calling
* readRowInt() for each desired line only if the image is interlaced.
*
* Notice that the columns in the matrix is not the pixel width of the
* image, but rather pixels x channels
*
* @see #readRowInt(int) to read about the format of each row
*
* @param rowOffset
* Number of rows to be skipped
* @param nRows
* Total number of rows to be read. -1: read all available
* @param rowStep
* Row increment. If 1, we read consecutive lines; if 2, we read
* even/odd lines, etc
* @return Set of lines as a ImageLines, which wraps a matrix
*/
public ImageLines readRowsInt(final int rowOffset, int nRows, final int rowStep) {
if (nRows < 0)
nRows = (imgInfo.rows - rowOffset) / rowStep;
if (rowStep < 1 || rowOffset < 0 || nRows * rowStep + rowOffset > imgInfo.rows)
throw new PngjInputException("bad args");
final ImageLines imlines = new ImageLines(imgInfo, SampleType.INT, unpackedMode, rowOffset, nRows, rowStep);
if (!interlaced) {
for (int j = 0; j < imgInfo.rows; j++) {
final int bytesread = readRowRaw(j); // read and perhaps discards
final int mrow = imlines.imageRowToMatrixRowStrict(j);
if (mrow >= 0)
decodeLastReadRowToInt(imlines.scanlines[mrow], bytesread);
}
} else { // and now, for something completely different (interlaced)
final int[] buf = new int[unpackedMode ? imgInfo.samplesPerRow : imgInfo.samplesPerRowPacked];
for (int p = 1; p <= 7; p++) {
deinterlacer.setPass(p);
for (int i = 0; i < deinterlacer.getRows(); i++) {
final int bytesread = readRowRaw(i);
final int j = deinterlacer.getCurrRowReal();
final int mrow = imlines.imageRowToMatrixRowStrict(j);
if (mrow >= 0) {
decodeLastReadRowToInt(buf, bytesread);
deinterlacer.deinterlaceInt(buf, imlines.scanlines[mrow], !unpackedMode);
}
}
}
}
end();
return imlines;
}
/**
* Same as readRowsInt(0, imgInfo.rows, 1)
*
* @see #readRowsInt(int, int, int)
*/
public ImageLines readRowsInt() {
return readRowsInt(0, imgInfo.rows, 1);
}
/**
* Reads a set of lines and returns it as a ImageLines object, which wrapas
* a byte[][] matrix. Internally it reads all lines, but decodes and stores
* only the wanted ones. This starts and ends the reading, and cannot be
* combined with other reading methods.
*
* This it's more efficient (speed an memory) that doing calling
* readRowByte() for each desired line only if the image is interlaced.
*
* Notice that the columns in the matrix is not the pixel width of the
* image, but rather pixels x channels
*
* @see #readRowByte(int) to read about the format of each row. Notice that
* if the bitdepth is 16 this will lose information
*
* @param rowOffset
* Number of rows to be skipped
* @param nRows
* Total number of rows to be read. -1: read all available
* @param rowStep
* Row increment. If 1, we read consecutive lines; if 2, we read
* even/odd lines, etc
* @return Set of lines as a matrix
*/
public ImageLines readRowsByte(final int rowOffset, int nRows, final int rowStep) {
if (nRows < 0)
nRows = (imgInfo.rows - rowOffset) / rowStep;
if (rowStep < 1 || rowOffset < 0 || nRows * rowStep + rowOffset > imgInfo.rows)
throw new PngjInputException("bad args");
final ImageLines imlines = new ImageLines(imgInfo, SampleType.BYTE, unpackedMode, rowOffset, nRows, rowStep);
if (!interlaced) {
for (int j = 0; j < imgInfo.rows; j++) {
final int bytesread = readRowRaw(j); // read and perhaps discards
final int mrow = imlines.imageRowToMatrixRowStrict(j);
if (mrow >= 0)
decodeLastReadRowToByte(imlines.scanlinesb[mrow], bytesread);
}
} else { // and now, for something completely different (interlaced)
final byte[] buf = new byte[unpackedMode ? imgInfo.samplesPerRow : imgInfo.samplesPerRowPacked];
for (int p = 1; p <= 7; p++) {
deinterlacer.setPass(p);
for (int i = 0; i < deinterlacer.getRows(); i++) {
final int bytesread = readRowRaw(i);
final int j = deinterlacer.getCurrRowReal();
final int mrow = imlines.imageRowToMatrixRowStrict(j);
if (mrow >= 0) {
decodeLastReadRowToByte(buf, bytesread);
deinterlacer.deinterlaceByte(buf, imlines.scanlinesb[mrow], !unpackedMode);
}
}
}
}
end();
return imlines;
}
/**
* Same as readRowsByte(0, imgInfo.rows, 1)
*
* @see #readRowsByte(int, int, int)
*/
public ImageLines readRowsByte() {
return readRowsByte(0, imgInfo.rows, 1);
}
/*
* For the interlaced case, nrow indicates the subsampled image - the pass must be set already.
*
* This must be called in strict order, both for interlaced or no interlaced.
*
* Updates rowNum.
*
* Leaves raw result in rowb
*
* Returns bytes actually read (not including the filter byte)
*/
private int readRowRaw(final int nrow) {
if (nrow == 0) {
if (firstChunksNotYetRead())
readFirstChunks();
allocateBuffers();
if (interlaced)
Arrays.fill(rowb, (byte) 0); // new subimage: reset filters: this is enough, see the swap that happens lines
}
// below
int bytesRead = imgInfo.bytesPerRow; // NOT including the filter byte
if (interlaced) {
if (nrow < 0 || nrow > deinterlacer.getRows() || (nrow != 0 && nrow != deinterlacer.getCurrRowSubimg() + 1))
throw new PngjInputException("invalid row in interlaced mode: " + nrow);
deinterlacer.setRow(nrow);
bytesRead = (imgInfo.bitspPixel * deinterlacer.getPixelsToRead() + 7) / 8;
if (bytesRead < 1)
throw new PngjExceptionInternal("wtf??");
} else { // check for non interlaced
if (nrow < 0 || nrow >= imgInfo.rows || nrow != rowNum + 1)
throw new PngjInputException("invalid row: " + nrow);
}
rowNum = nrow;
// swap buffers
final byte[] tmp = rowb;
rowb = rowbprev;
rowbprev = tmp;
// loads in rowbfilter "raw" bytes, with filter
PngHelperInternal.readBytes(idatIstream, rowbfilter, 0, bytesRead + 1);
offset = iIdatCstream.getOffset();
if (offset < 0)
throw new PngjExceptionInternal("bad offset ??" + offset);
if (maxTotalBytesRead > 0 && offset >= maxTotalBytesRead)
throw new PngjInputException("Reading IDAT: Maximum total bytes to read exceeeded: " + maxTotalBytesRead
+ " offset:" + offset);
rowb[0] = 0;
unfilterRow(bytesRead);
rowb[0] = rowbfilter[0];
if ((rowNum == imgInfo.rows - 1 && !interlaced) || (interlaced && deinterlacer.isAtLastRow()))
readLastAndClose();
return bytesRead;
}
/**
* Reads all the (remaining) file, skipping the pixels data. This is much
* more efficient that calling readRow(), specially for big files (about 10
* times faster!), because it doesn't even decompress the IDAT stream and
* disables CRC check Use this if you are not interested in reading
* pixels,only metadata.
*/
public void readSkippingAllRows() {
if (firstChunksNotYetRead())
readFirstChunks();
// we read directly from the compressed stream, we dont decompress nor chec CRC
iIdatCstream.disableCrcCheck();
allocateBuffers();
try {
int r;
do {
r = iIdatCstream.read(rowbfilter, 0, buffersLen);
} while (r >= 0);
} catch (final IOException e) {
throw new PngjInputException("error in raw read of IDAT", e);
}
offset = iIdatCstream.getOffset();
if (offset < 0)
throw new PngjExceptionInternal("bad offset ??" + offset);
if (maxTotalBytesRead > 0 && offset >= maxTotalBytesRead)
throw new PngjInputException("Reading IDAT: Maximum total bytes to read exceeeded: " + maxTotalBytesRead
+ " offset:" + offset);
readLastAndClose();
}
/**
* Set total maximum bytes to read (0: unlimited; default: 200MB).
* These are the bytes read (not loaded) in the input stream. If exceeded,
* an exception will be thrown.
*/
public void setMaxTotalBytesRead(final long maxTotalBytesToRead) {
this.maxTotalBytesRead = maxTotalBytesToRead;
}
/**
* @return Total maximum bytes to read.
*/
public long getMaxTotalBytesRead() {
return maxTotalBytesRead;
}
/**
* Set total maximum bytes to load from ancillary chunks (0: unlimited;
* default: 5Mb).
* If exceeded, some chunks will be skipped
*/
public void setMaxBytesMetadata(final int maxBytesChunksToLoad) {
this.maxBytesMetadata = maxBytesChunksToLoad;
}
/**
* @return Total maximum bytes to load from ancillary ckunks.
*/
public int getMaxBytesMetadata() {
return maxBytesMetadata;
}
/**
* Set maximum size in bytes for individual ancillary chunks (0: unlimited;
* default: 2MB).
* Chunks exceeding this length will be skipped (the CRC will not be
* checked) and the chunk will be saved as a PngChunkSkipped object. See
* also setSkipChunkIds
*/
public void setSkipChunkMaxSize(final int skipChunksBySize) {
this.skipChunkMaxSize = skipChunksBySize;
}
/**
* @return maximum size in bytes for individual ancillary chunks.
*/
public int getSkipChunkMaxSize() {
return skipChunkMaxSize;
}
/**
* Chunks ids to be skipped.
* These chunks will be skipped (the CRC will not be checked) and the chunk
* will be saved as a PngChunkSkipped object. See also setSkipChunkMaxSize
*/
public void setSkipChunkIds(final String[] skipChunksById) {
this.skipChunkIds = skipChunksById == null ? new String[] {} : skipChunksById;
}
/**
* @return Chunk-IDs to be skipped.
*/
public String[] getSkipChunkIds() {
return skipChunkIds;
}
/**
* if true, input stream will be closed after ending read
*
* default=true
*/
public void setShouldCloseStream(final boolean shouldCloseStream) {
this.shouldCloseStream = shouldCloseStream;
}
/**
* Normally this does nothing, but it can be used to force a premature
* closing. Its recommended practice to call it after reading the image
* pixels.
*/
public void end() {
if (currentChunkGroup < ChunksList.CHUNK_GROUP_6_END)
close();
}
/**
* Interlaced PNG is accepted -though not welcomed- now...
*/
public boolean isInterlaced() {
return interlaced;
}
/**
* set/unset "unpackedMode"
* If false (default) packed types (bitdepth=1,2 or 4) will keep several
* samples packed in one element (byte or int)
* If true, samples will be unpacked on reading, and each element in the
* scanline will be sample. This implies more processing and memory, but
* it's the most efficient option if you intend to read individual pixels.
* This option should only be set before start reading.
*
* @param unPackedMode
*/
public void setUnpackedMode(final boolean unPackedMode) {
this.unpackedMode = unPackedMode;
}
/**
* @see PngReader#setUnpackedMode(boolean)
*/
public boolean isUnpackedMode() {
return unpackedMode;
}
/**
* Tries to reuse the allocated buffers from other already used PngReader
* object. This will have no effect if the buffers are smaller than necessary.
* It also reuses the inflater.
*
* @param other A PngReader that has already finished reading pixels. Can be null.
*/
public void reuseBuffersFrom(final PngReader other) {
if(other==null) return;
if (other.currentChunkGroup < ChunksList.CHUNK_GROUP_5_AFTERIDAT)
throw new PngjInputException("PngReader to be reused have not yet ended reading pixels");
if (other.rowbfilter != null && other.rowbfilter.length >= buffersLen) {
rowbfilter = other.rowbfilter;
rowb = other.rowb;
rowbprev = other.rowbprev;
}
inflater = other.inflater;
}
/**
* Disables the CRC integrity check in IDAT chunks and ancillary chunks,
* this gives a slight increase in reading speed for big files
*/
public void setCrcCheckDisabled() {
crcEnabled = false;
}
/**
* Just for testing. TO be called after ending reading, only if
* initCrctest() was called before start
*
* @return CRC of the raw pixels values
*/
long getCrctestVal() {
return crctest.getValue();
}
/**
* Inits CRC object and enables CRC calculation
*/
void initCrctest() {
this.crctest = new CRC32();
}
/**
* Basic info, for debugging.
*/
@Override
public String toString() { // basic info
return "filename=" + filename + " " + imgInfo.toString();
}
}