/// <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));
}
/// <summary>
/// Decodes the image from the specified stream to the <see cref="ImageFrame{TPixel}"/>.
/// </summary>
/// <typeparam name="TPixel">The pixel format.</typeparam>
/// <param name="configuration">The configuration for the image.</param>
/// <param name="stream">The <see cref="Stream"/> containing image data.</param>
/// <returns>The decoded image.</returns>
public Image <TPixel> Decode <TPixel>(Configuration configuration, Stream stream)
where TPixel : unmanaged, IPixel <TPixel>
{
var decoder = new PngDecoderCore(configuration, this);
try
{
return(decoder.Decode <TPixel>(stream));
}
catch (InvalidMemoryOperationException ex)
{
Size dims = decoder.Dimensions;
PngThrowHelper.ThrowInvalidImageContentException($"Can not decode image. Failed to allocate buffers for possibly degenerate dimensions: {dims.Width}x{dims.Height}.", ex);
// Not reachable, as the previous statement will throw a exception.
return(null);
}
}
/// <summary>
/// Decodes the stream to the image.
/// </summary>
/// <typeparam name="TPixel">The pixel format.</typeparam>
/// <param name="stream">The stream containing image data. </param>
/// <exception cref="ImageFormatException">
/// Thrown if the stream does not contain and end chunk.
/// </exception>
/// <exception cref="ArgumentOutOfRangeException">
/// Thrown if the image is larger than the maximum allowable size.
/// </exception>
/// <returns>The decoded image</returns>
public Image <TPixel> Decode <TPixel>(Stream stream)
where TPixel : struct, IPixel <TPixel>
{
var metadata = new ImageMetadata();
PngMetadata pngMetadata = metadata.GetFormatMetadata(PngFormat.Instance);
this.currentStream = stream;
this.currentStream.Skip(8);
Image <TPixel> image = null;
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:
if (image is null)
{
this.InitializeImage(metadata, out image);
}
this.ReadScanlines(chunk, image.Frames.RootFrame, pngMetadata);
break;
case PngChunkType.Palette:
var pal = new byte[chunk.Length];
Buffer.BlockCopy(chunk.Data.Array, 0, pal, 0, chunk.Length);
this.palette = pal;
break;
case PngChunkType.Transparency:
var alpha = new byte[chunk.Length];
Buffer.BlockCopy(chunk.Data.Array, 0, alpha, 0, chunk.Length);
this.paletteAlpha = alpha;
this.AssignTransparentMarkers(alpha, pngMetadata);
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()
}
}
if (image is null)
{
PngThrowHelper.ThrowNoData();
}
return(image);
}
finally
{
this.scanline?.Dispose();
this.previousScanline?.Dispose();
}
}
/// <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));
}