/// <summary>
/// Reads the raw image information from the specified stream.
/// </summary>
/// <param name="stream">The <see cref="Stream"/> containing image data.</param>
public IImageInfo Identify(Stream stream)
{
var metadata = new ImageMetadata();
PngMetadata pngMetadata = metadata.GetFormatMetadata(PngFormat.Instance);
this.currentStream = stream;
this.currentStream.Skip(8);
try
{
while (!this.isEndChunkReached && this.TryReadChunk(out PngChunk chunk))
{
try
{
switch (chunk.Type)
{
case PngChunkType.Header:
this.ReadHeaderChunk(pngMetadata, chunk.Data.Array);
break;
case PngChunkType.Physical:
this.ReadPhysicalChunk(metadata, chunk.Data.GetSpan());
break;
case PngChunkType.Gamma:
this.ReadGammaChunk(pngMetadata, chunk.Data.GetSpan());
break;
case PngChunkType.Data:
this.SkipChunkDataAndCrc(chunk);
break;
case PngChunkType.Text:
this.ReadTextChunk(pngMetadata, chunk.Data.Array.AsSpan(0, chunk.Length));
break;
case PngChunkType.End:
this.isEndChunkReached = true;
break;
}
}
finally
{
chunk.Data?.Dispose(); // Data is rented in ReadChunkData()
}
}
}
finally
{
this.scanline?.Dispose();
this.previousScanline?.Dispose();
}
if (this.header.Width == 0 && this.header.Height == 0)
{
PngThrowHelper.ThrowNoHeader();
}
return(new ImageInfo(new PixelTypeInfo(this.CalculateBitsPerPixel()), this.header.Width, this.header.Height, metadata));
}
/// <inheritdoc/>
public IImageInfo Identify(BufferedReadStream stream)
{
var metadata = new ImageMetadata();
PngMetadata pngMetadata = metadata.GetPngMetadata();
this.currentStream = stream;
this.currentStream.Skip(8);
try
{
while (!this.isEndChunkReached && this.TryReadChunk(out PngChunk chunk))
{
try
{
switch (chunk.Type)
{
case PngChunkType.Header:
this.ReadHeaderChunk(pngMetadata, chunk.Data.Array);
break;
case PngChunkType.Physical:
this.ReadPhysicalChunk(metadata, chunk.Data.GetSpan());
break;
case PngChunkType.Gamma:
this.ReadGammaChunk(pngMetadata, chunk.Data.GetSpan());
break;
case PngChunkType.Data:
this.SkipChunkDataAndCrc(chunk);
break;
case PngChunkType.Text:
this.ReadTextChunk(pngMetadata, chunk.Data.Array.AsSpan(0, chunk.Length));
break;
case PngChunkType.CompressedText:
this.ReadCompressedTextChunk(pngMetadata, chunk.Data.Array.AsSpan(0, chunk.Length));
break;
case PngChunkType.InternationalText:
this.ReadInternationalTextChunk(pngMetadata, chunk.Data.Array.AsSpan(0, chunk.Length));
break;
case PngChunkType.Exif:
if (!this.ignoreMetadata)
{
var exifData = new byte[chunk.Length];
Buffer.BlockCopy(chunk.Data.Array, 0, exifData, 0, chunk.Length);
metadata.ExifProfile = new ExifProfile(exifData);
}
break;
case PngChunkType.End:
this.isEndChunkReached = true;
break;
}
}
finally
{
chunk.Data?.Dispose(); // Data is rented in ReadChunkData()
}
}
}
finally
{
this.scanline?.Dispose();
this.previousScanline?.Dispose();
}
if (this.header.Width == 0 && this.header.Height == 0)
{
PngThrowHelper.ThrowNoHeader();
}
return(new ImageInfo(new PixelTypeInfo(this.CalculateBitsPerPixel()), this.header.Width, this.header.Height, metadata));
}
