/// <summary>
/// Encodes the image to the specified stream from the <see cref="Image{TPixel}"/>.
/// </summary>
/// <typeparam name="TPixel">The pixel format.</typeparam>
/// <param name="image">The <see cref="Image{TPixel}"/> to encode from.</param>
/// <param name="stream">The <see cref="Stream"/> to encode the image data to.</param>
public void Encode <TPixel>(Image <TPixel> image, Stream stream)
where TPixel : unmanaged, IPixel <TPixel>
{
Guard.NotNull(image, nameof(image));
Guard.NotNull(stream, nameof(stream));
ImageMetadata metadata = image.Metadata;
GifMetadata gifMetadata = metadata.GetGifMetadata();
this.colorTableMode ??= gifMetadata.ColorTableMode;
bool useGlobalTable = this.colorTableMode == GifColorTableMode.Global;
// Quantize the image returning a palette.
IndexedImageFrame <TPixel> quantized;
using (IFrameQuantizer <TPixel> frameQuantizer = this.quantizer.CreateFrameQuantizer <TPixel>(this.configuration))
{
quantized = frameQuantizer.QuantizeFrame(image.Frames.RootFrame, image.Bounds());
}
// Get the number of bits.
this.bitDepth = ImageMaths.GetBitsNeededForColorDepth(quantized.Palette.Length);
// Write the header.
this.WriteHeader(stream);
// Write the LSD.
int index = this.GetTransparentIndex(quantized);
this.WriteLogicalScreenDescriptor(metadata, image.Width, image.Height, index, useGlobalTable, stream);
if (useGlobalTable)
{
this.WriteColorTable(quantized, stream);
}
// Write the comments.
this.WriteComments(gifMetadata, stream);
// Write application extension to allow additional frames.
if (image.Frames.Count > 1)
{
this.WriteApplicationExtension(stream, gifMetadata.RepeatCount);
}
if (useGlobalTable)
{
this.EncodeGlobal(image, quantized, index, stream);
}
else
{
this.EncodeLocal(image, quantized, stream);
}
// Clean up.
quantized.Dispose();
// TODO: Write extension etc
stream.WriteByte(GifConstants.EndIntroducer);
}
/// <summary>
/// Initializes a new instance of the <see cref="GifMetadata"/> class.
/// </summary>
/// <param name="other">The metadata to create an instance from.</param>
private GifMetadata(GifMetadata other)
{
this.RepeatCount = other.RepeatCount;
this.ColorTableMode = other.ColorTableMode;
this.GlobalColorTableLength = other.GlobalColorTableLength;
for (int i = 0; i < other.Comments.Count; i++)
{
this.Comments.Add(other.Comments[i]);
}
}
/// <summary>
/// Encodes the image to the specified stream from the <see cref="Image{TPixel}"/>.
/// </summary>
/// <typeparam name="TPixel">The pixel format.</typeparam>
/// <param name="image">The <see cref="Image{TPixel}"/> to encode from.</param>
/// <param name="stream">The <see cref="Stream"/> to encode the image data to.</param>
/// <param name="cancellationToken">The token to request cancellation.</param>
public void Encode <TPixel>(Image <TPixel> image, Stream stream, CancellationToken cancellationToken)
where TPixel : unmanaged, IPixel <TPixel>
{
Guard.NotNull(image, nameof(image));
Guard.NotNull(stream, nameof(stream));
ImageMetadata metadata = image.Metadata;
GifMetadata gifMetadata = metadata.GetGifMetadata();
this.colorTableMode ??= gifMetadata.ColorTableMode;
bool useGlobalTable = this.colorTableMode == GifColorTableMode.Global;
// Quantize the image returning a palette.
IndexedImageFrame <TPixel> quantized;
using (IQuantizer <TPixel> frameQuantizer = this.quantizer.CreatePixelSpecificQuantizer <TPixel>(this.configuration))
{
if (useGlobalTable)
{
frameQuantizer.BuildPalette(this.pixelSamplingStrategy, image);
quantized = frameQuantizer.QuantizeFrame(image.Frames.RootFrame, image.Bounds());
}
else
{
quantized = frameQuantizer.BuildPaletteAndQuantizeFrame(image.Frames.RootFrame, image.Bounds());
}
}
// Get the number of bits.
this.bitDepth = ColorNumerics.GetBitsNeededForColorDepth(quantized.Palette.Length);
// Write the header.
this.WriteHeader(stream);
// Write the LSD.
int index = this.GetTransparentIndex(quantized);
this.WriteLogicalScreenDescriptor(metadata, image.Width, image.Height, index, useGlobalTable, stream);
if (useGlobalTable)
{
this.WriteColorTable(quantized, stream);
}
// Write the comments.
this.WriteComments(gifMetadata, stream);
// Write application extensions.
XmpProfile xmpProfile = image.Metadata.XmpProfile ?? image.Frames.RootFrame.Metadata.XmpProfile;
this.WriteApplicationExtensions(stream, image.Frames.Count, gifMetadata.RepeatCount, xmpProfile);
if (useGlobalTable)
{
this.EncodeGlobal(image, quantized, index, stream);
}
else
{
this.EncodeLocal(image, quantized, stream);
}
// Clean up.
quantized.Dispose();
stream.WriteByte(GifConstants.EndIntroducer);
}
