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;
this.CurrentChunkGroup = -1;
this.ShouldCloseStream = true;
this.MaxBytesMetadata = 5 * 1024 * 1024;
this.MaxTotalBytesRead = 200 * 1024 * 1024;
this.SkipChunkMaxSize = 2 * 1024 * 1024;
this.SkipChunkIds = new string [] { "fdAT" };
this.ChunkLoadBehaviour = Hjg.Pngcs.Chunks.ChunkLoadBehaviour.LOAD_CHUNK_ALWAYS;
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;
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 );
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;
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 );
}
/// <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);
}
}