/// <summary>
/// Reads chunks before first IDAT. Position before: after IDHR (crc included)
/// Position after: just after the first IDAT chunk id Returns length of first
/// IDAT chunk , -1 if not found
/// </summary>
///
private void ReadFirstChunks()
{
if (!FirstChunksNotYetRead())
{
return;
}
var clen = 0;
var found = false;
var chunkid = new byte[4]; // it's important to reallocate in each
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 (PngCsUtils.arraysEqual4(chunkid, Hjg.Pngcs.Chunks.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 (PngCsUtils.arraysEqual4(chunkid, Hjg.Pngcs.Chunks.ChunkHelper.b_IEND))
{
throw new PngjInputException("END chunk found before image data (IDAT) at offset=" + offset);
}
var chunkids = ChunkHelper.ToString(chunkid);
if (chunkids.Equals(ChunkHelper.PLTE, System.StringComparison.Ordinal))
{
CurrentChunkGroup = ChunksList.CHUNK_GROUP_2_PLTE;
}
ReadChunk(chunkid, clen, false);
if (chunkids.Equals(ChunkHelper.PLTE, System.StringComparison.Ordinal))
{
CurrentChunkGroup = ChunksList.CHUNK_GROUP_3_AFTERPLTE;
}
}
var idatLen = found ? clen : -1;
if (idatLen < 0)
{
throw new PngjInputException("first idat chunk not found!");
}
iIdatCstream = new PngIDatChunkInputStream(inputStream, idatLen, offset);
idatIstream = new ZlibInputStream(iIdatCstream, true);
}
public void ReadFirstChunks()
{
if (!FirstChunksNotYetRead())
{
return;
}
int num = 0;
bool flag = false;
byte[] array = new byte[4];
CurrentChunkGroup = 1;
while (!flag)
{
num = PngHelperInternal.ReadInt4(inputStream);
offset += 4L;
if (num < 0)
{
break;
}
PngHelperInternal.ReadBytes(inputStream, array, 0, 4);
offset += 4L;
if (PngCsUtils.arraysEqual4(array, ChunkHelper.b_IDAT))
{
flag = true;
CurrentChunkGroup = 4;
chunksList.AppendReadChunk(new PngChunkIDAT(ImgInfo, num, offset - 8), CurrentChunkGroup);
break;
}
if (PngCsUtils.arraysEqual4(array, ChunkHelper.b_IEND))
{
throw new PngjInputException("END chunk found before image data (IDAT) at offset=" + offset.ToString());
}
string text = ChunkHelper.ToString(array);
if (text.Equals("PLTE"))
{
CurrentChunkGroup = 2;
}
ReadChunk(array, num, skipforced: false);
if (text.Equals("PLTE"))
{
CurrentChunkGroup = 3;
}
}
int num2 = flag ? num : (-1);
if (num2 < 0)
{
throw new PngjInputException("first idat chunk not found!");
}
iIdatCstream = new PngIDatChunkInputStream(inputStream, num2, offset);
idatIstream = ZlibStreamFactory.createZlibInputStream(iIdatCstream, leaveOpen: true);
if (!crcEnabled)
{
iIdatCstream.DisableCrcCheck();
}
}
/// <summary>
/// Reads (and processes ... up to a point) chunks after last IDAT.
/// </summary>
///
private void ReadLastChunks()
{
CurrentChunkGroup = ChunksList.CHUNK_GROUP_5_AFTERIDAT;
// PngHelper.logdebug("idat ended? " + iIdatCstream.isEnded());
if (!iIdatCstream.IsEnded())
{
iIdatCstream.ForceChunkEnd();
}
var clen = iIdatCstream.GetLenLastChunk();
var chunkid = iIdatCstream.GetIdLastChunk();
var endfound = false;
var first = true;
while (!endfound)
{
var skip = false;
if (!first)
{
clen = PngHelperInternal.ReadInt4(inputStream);
offset += 4;
if (clen < 0)
{
throw new PngjInputException("bad len " + clen);
}
PngHelperInternal.ReadBytes(inputStream, chunkid, 0, 4);
offset += 4;
}
first = false;
if (PngCsUtils.arraysEqual4(chunkid, ChunkHelper.b_IDAT))
{
skip = true; // extra dummy (empty?) idat chunk, it can happen, ignore it
}
else if (PngCsUtils.arraysEqual4(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);
}
public void ReadLastChunks()
{
CurrentChunkGroup = 5;
if (!iIdatCstream.IsEnded())
{
iIdatCstream.ForceChunkEnd();
}
int num = iIdatCstream.GetLenLastChunk();
byte[] idLastChunk = iIdatCstream.GetIdLastChunk();
bool flag = false;
bool flag2 = true;
bool flag3 = false;
while (!flag)
{
flag3 = false;
if (!flag2)
{
num = PngHelperInternal.ReadInt4(inputStream);
offset += 4L;
if (num < 0)
{
throw new PngjInputException("bad len " + num.ToString());
}
PngHelperInternal.ReadBytes(inputStream, idLastChunk, 0, 4);
offset += 4L;
}
flag2 = false;
if (PngCsUtils.arraysEqual4(idLastChunk, ChunkHelper.b_IDAT))
{
flag3 = true;
}
else if (PngCsUtils.arraysEqual4(idLastChunk, ChunkHelper.b_IEND))
{
CurrentChunkGroup = 6;
flag = true;
}
ReadChunk(idLastChunk, num, flag3);
}
if (!flag)
{
throw new PngjInputException("end chunk not found - offset=" + offset.ToString());
}
}
private void EndChunkGoForNext()
{
// Called after readging the last byte of chunk
// Checks CRC, and read ID from next CHUNK
// Those values are left in idLastChunk / lenLastChunk
// Skips empty IDATS
do
{
var crc = PngHelperInternal.ReadInt4(inputStream);
offset += 4;
if (checkCrc)
{
var crccalc = (int)crcEngine.GetValue();
if (lenLastChunk > 0 && crc != crccalc)
{
throw new PngjBadCrcException("error reading idat; offset: " + offset.ToString(CultureInfo.CurrentCulture));
}
crcEngine.Reset();
}
lenLastChunk = PngHelperInternal.ReadInt4(inputStream);
if (lenLastChunk < 0)
{
throw new PngjInputException("invalid len for chunk: " + lenLastChunk.ToString(CultureInfo.CurrentCulture));
}
toReadThisChunk = lenLastChunk;
PngHelperInternal.ReadBytes(inputStream, idLastChunk, 0, 4);
offset += 8;
ended = !PngCsUtils.arraysEqual4(idLastChunk, Chunks.ChunkHelper.b_IDAT);
if (!ended)
{
foundChunksInfo.Add(new IdatChunkInfo(lenLastChunk, offset - 8));
if (checkCrc)
{
crcEngine.Update(idLastChunk, 0, 4);
}
}
} while (lenLastChunk == 0 && !ended);
// rarely condition is true (empty IDAT ??)
}
private void EndChunkGoForNext()
{
// Called after readging the last byte of chunk
// Checks CRC, and read ID from next CHUNK
// Those values are left in idLastChunk / lenLastChunk
// Skips empty IDATS
do
{
int crc = Hjg.Pngcs.PngHelperInternal.ReadInt4(inputStream); //
offset += 4;
if (checkCrc)
{
int crccalc = (int)crcEngine.GetValue();
if (lenLastChunk > 0 && crc != crccalc)
{
throw new PngjBadCrcException("error reading idat; offset: " + offset);
}
crcEngine.Reset();
}
lenLastChunk = Hjg.Pngcs.PngHelperInternal.ReadInt4(inputStream);
if (lenLastChunk < 0)
{
throw new PngjInputException("invalid len for chunk: " + lenLastChunk);
}
toReadThisChunk = lenLastChunk;
Hjg.Pngcs.PngHelperInternal.ReadBytes(inputStream, idLastChunk, 0, 4);
offset += 8;
ended = !PngCsUtils.arraysEqual4(idLastChunk, Hjg.Pngcs.Chunks.ChunkHelper.b_IDAT);
if (!ended)
{
foundChunksInfo.Add(new PngIDatChunkInputStream.IdatChunkInfo(lenLastChunk, (offset - 8)));
if (checkCrc)
{
crcEngine.Update(idLastChunk, 0, 4);
}
}
// PngHelper.logdebug("IDAT ended. next len= " + lenLastChunk + " idat?" +
// (!ended));
} while (lenLastChunk == 0 && !ended);
// rarely condition is true (empty IDAT ??)
}
public void EndChunkGoForNext()
{
while (true)
{
int num = PngHelperInternal.ReadInt4(inputStream);
offset += 4L;
if (checkCrc)
{
int value = (int)crcEngine.GetValue();
if (lenLastChunk > 0 && num != value)
{
throw new PngjBadCrcException("error reading idat; offset: " + offset.ToString());
}
crcEngine.Reset();
}
lenLastChunk = PngHelperInternal.ReadInt4(inputStream);
if (lenLastChunk < 0)
{
break;
}
toReadThisChunk = lenLastChunk;
PngHelperInternal.ReadBytes(inputStream, idLastChunk, 0, 4);
offset += 8L;
ended = !PngCsUtils.arraysEqual4(idLastChunk, ChunkHelper.b_IDAT);
if (!ended)
{
foundChunksInfo.Add(new IdatChunkInfo(lenLastChunk, offset - 8));
if (checkCrc)
{
crcEngine.Update(idLastChunk, 0, 4);
}
}
if (lenLastChunk != 0 || ended)
{
return;
}
}
throw new PngjInputException("invalid len for chunk: " + lenLastChunk.ToString());
}
/// <summary>
/// Constructs a PNGReader objet from a opened Stream
/// </summary>
/// <remarks>The constructor reads the signature and first chunk (IDHR)<seealso cref="FileHelper.CreatePngReader(string)"/>
/// </remarks>
///
/// <param name="inputStream"></param>
/// <param name="filename">Optional, can be the filename or a description.</param>
public PngReader(Stream inputStream, String filename)
{
this.filename = (filename == null) ? "" : filename;
this.inputStream = inputStream;
this.chunksList = new ChunksList(null);
this.metadata = new PngMetadata(chunksList);
this.offset = 0;
// set default options
this.CurrentChunkGroup = -1;
this.ShouldCloseStream = true;
this.MaxBytesMetadata = 5 * 1024 * 1024;
this.MaxTotalBytesRead = 200 * 1024 * 1024; // 200MB
this.SkipChunkMaxSize = 2 * 1024 * 1024;
this.SkipChunkIds = new string[] { "fdAT" };
this.ChunkLoadBehaviour = Hjg.Pngcs.Chunks.ChunkLoadBehaviour.LOAD_CHUNK_ALWAYS;
// starts reading: signature
byte[] pngid = new byte[8];
PngHelperInternal.ReadBytes(inputStream, pngid, 0, pngid.Length);
offset += pngid.Length;
if (!PngCsUtils.arraysEqual(pngid, PngHelperInternal.PNG_ID_SIGNATURE))
{
throw new PngjInputException("Bad PNG signature");
}
CurrentChunkGroup = ChunksList.CHUNK_GROUP_0_IDHR;
// reads first chunk IDHR
int clen = PngHelperInternal.ReadInt4(inputStream);
offset += 4;
if (clen != 13)
{
throw new Exception("IDHR chunk len != 13 ?? " + clen);
}
byte[] chunkid = new byte[4];
PngHelperInternal.ReadBytes(inputStream, chunkid, 0, 4);
if (!PngCsUtils.arraysEqual4(chunkid, ChunkHelper.b_IHDR))
{
throw new PngjInputException("IHDR not found as first chunk??? ["
+ ChunkHelper.ToString(chunkid) + "]");
}
offset += 4;
PngChunkIHDR ihdr = (PngChunkIHDR)ReadChunk(chunkid, clen, false);
bool alpha = (ihdr.Colormodel & 0x04) != 0;
bool palette = (ihdr.Colormodel & 0x01) != 0;
bool grayscale = (ihdr.Colormodel == 0 || ihdr.Colormodel == 4);
// creates ImgInfo and imgLine, and allocates buffers
ImgInfo = new ImageInfo(ihdr.Cols, ihdr.Rows, ihdr.Bitspc, alpha, grayscale, palette);
rowb = new byte[ImgInfo.BytesPerRow + 1];
rowbprev = new byte[rowb.Length];
rowbfilter = new byte[rowb.Length];
interlaced = ihdr.Interlaced == 1;
deinterlacer = interlaced ? new PngDeinterlacer(ImgInfo) : null;
// some checks
if (ihdr.Filmeth != 0 || ihdr.Compmeth != 0 || (ihdr.Interlaced & 0xFFFE) != 0)
{
throw new PngjInputException("compmethod or filtermethod or interlaced unrecognized");
}
if (ihdr.Colormodel < 0 || ihdr.Colormodel > 6 || ihdr.Colormodel == 1 ||
ihdr.Colormodel == 5)
{
throw new PngjInputException("Invalid colormodel " + ihdr.Colormodel);
}
if (ihdr.Bitspc != 1 && ihdr.Bitspc != 2 && ihdr.Bitspc != 4 && ihdr.Bitspc != 8 &&
ihdr.Bitspc != 16)
{
throw new PngjInputException("Invalid bit depth " + ihdr.Bitspc);
}
}
public PngReader(Stream inputStream, string filename)
{
this.filename = ((filename == null) ? "" : filename);
this.inputStream = inputStream;
chunksList = new ChunksList(null);
metadata = new PngMetadata(chunksList);
offset = 0L;
CurrentChunkGroup = -1;
ShouldCloseStream = true;
MaxBytesMetadata = 5242880L;
MaxTotalBytesRead = 209715200L;
SkipChunkMaxSize = 2097152;
SkipChunkIds = new string[1]
{
"fdAT"
};
ChunkLoadBehaviour = ChunkLoadBehaviour.LOAD_CHUNK_ALWAYS;
byte[] array = new byte[8];
PngHelperInternal.ReadBytes(inputStream, array, 0, array.Length);
offset += array.Length;
if (!PngCsUtils.arraysEqual(array, PngHelperInternal.PNG_ID_SIGNATURE))
{
throw new PngjInputException("Bad PNG signature");
}
CurrentChunkGroup = 0;
int num = PngHelperInternal.ReadInt4(inputStream);
offset += 4L;
if (num != 13)
{
throw new Exception("IDHR chunk len != 13 ?? " + num.ToString());
}
byte[] array2 = new byte[4];
PngHelperInternal.ReadBytes(inputStream, array2, 0, 4);
if (!PngCsUtils.arraysEqual4(array2, ChunkHelper.b_IHDR))
{
throw new PngjInputException("IHDR not found as first chunk??? [" + ChunkHelper.ToString(array2) + "]");
}
offset += 4L;
PngChunkIHDR pngChunkIHDR = (PngChunkIHDR)ReadChunk(array2, num, skipforced: false);
bool alpha = (pngChunkIHDR.Colormodel & 4) != 0;
bool palette = (pngChunkIHDR.Colormodel & 1) != 0;
bool grayscale = pngChunkIHDR.Colormodel == 0 || pngChunkIHDR.Colormodel == 4;
ImgInfo = new ImageInfo(pngChunkIHDR.Cols, pngChunkIHDR.Rows, pngChunkIHDR.Bitspc, alpha, grayscale, palette);
rowb = new byte[ImgInfo.BytesPerRow + 1];
rowbprev = new byte[rowb.Length];
rowbfilter = new byte[rowb.Length];
interlaced = (pngChunkIHDR.Interlaced == 1);
deinterlacer = (interlaced ? new PngDeinterlacer(ImgInfo) : null);
if (pngChunkIHDR.Filmeth != 0 || pngChunkIHDR.Compmeth != 0 || (pngChunkIHDR.Interlaced & 0xFFFE) != 0)
{
throw new PngjInputException("compmethod or filtermethod or interlaced unrecognized");
}
if (pngChunkIHDR.Colormodel < 0 || pngChunkIHDR.Colormodel > 6 || pngChunkIHDR.Colormodel == 1 || pngChunkIHDR.Colormodel == 5)
{
throw new PngjInputException("Invalid colormodel " + pngChunkIHDR.Colormodel.ToString());
}
if (pngChunkIHDR.Bitspc != 1 && pngChunkIHDR.Bitspc != 2 && pngChunkIHDR.Bitspc != 4 && pngChunkIHDR.Bitspc != 8 && pngChunkIHDR.Bitspc != 16)
{
throw new PngjInputException("Invalid bit depth " + pngChunkIHDR.Bitspc.ToString());
}
}