/// <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();
}
}
private void ReadFirstChunks()
{
if ( !FirstChunksNotYetRead () )
return;
int clen = 0;
bool found = false;
byte [] chunkid = new byte [ 4 ];
this.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;
this.CurrentChunkGroup = ChunksList.CHUNK_GROUP_4_IDAT;
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 );
}
String chunkids = ChunkHelper.ToString ( chunkid );
if ( chunkids.Equals ( ChunkHelper.PLTE ) )
this.CurrentChunkGroup = ChunksList.CHUNK_GROUP_2_PLTE;
ReadChunk ( chunkid, clen, false );
if ( chunkids.Equals ( ChunkHelper.PLTE ) )
this.CurrentChunkGroup = ChunksList.CHUNK_GROUP_3_AFTERPLTE;
}
int idatLen = found ? clen : -1;
if ( idatLen < 0 )
throw new PngjInputException ( "first idat chunk not found!" );
iIdatCstream = new PngIDatChunkInputStream ( inputStream, idatLen, offset );
idatIstream = ZlibStreamFactory.createZlibInputStream ( iIdatCstream, true );
if ( !crcEnabled )
iIdatCstream.DisableCrcCheck ();
}