/// <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="ImageFrame{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));
this.width = image.Width;
this.height = image.Height;
ImageMetadata metadata = image.Metadata;
PngMetadata pngMetadata = metadata.GetPngMetadata();
PngEncoderOptionsHelpers.AdjustOptions <TPixel>(this.options, pngMetadata, out this.use16Bit, out this.bytesPerPixel);
IndexedImageFrame <TPixel> quantized = PngEncoderOptionsHelpers.CreateQuantizedFrame(this.options, image);
this.bitDepth = PngEncoderOptionsHelpers.CalculateBitDepth(this.options, image, quantized);
stream.Write(PngConstants.HeaderBytes);
this.WriteHeaderChunk(stream);
this.WritePaletteChunk(stream, quantized);
this.WriteTransparencyChunk(stream, pngMetadata);
this.WritePhysicalChunk(stream, metadata);
this.WriteGammaChunk(stream);
this.WriteExifChunk(stream, metadata);
this.WriteTextChunks(stream, pngMetadata);
this.WriteDataChunks(image.Frames.RootFrame, quantized, stream);
this.WriteEndChunk(stream);
stream.Flush();
quantized?.Dispose();
}
private void EncodeLocal <TPixel>(Image <TPixel> image, IndexedImageFrame <TPixel> quantized, Stream stream)
where TPixel : unmanaged, IPixel <TPixel>
{
ImageFrame <TPixel> previousFrame = null;
GifFrameMetadata previousMeta = null;
for (int i = 0; i < image.Frames.Count; i++)
{
ImageFrame <TPixel> frame = image.Frames[i];
ImageFrameMetadata metadata = frame.Metadata;
GifFrameMetadata frameMetadata = metadata.GetGifMetadata();
if (quantized is null)
{
// Allow each frame to be encoded at whatever color depth the frame designates if set.
if (previousFrame != null && previousMeta.ColorTableLength != frameMetadata.ColorTableLength &&
frameMetadata.ColorTableLength > 0)
{
var options = new QuantizerOptions
{
Dither = this.quantizer.Options.Dither,
DitherScale = this.quantizer.Options.DitherScale,
MaxColors = frameMetadata.ColorTableLength
};
using IQuantizer <TPixel> frameQuantizer = this.quantizer.CreatePixelSpecificQuantizer <TPixel>(this.configuration, options);
quantized = frameQuantizer.BuildPaletteAndQuantizeFrame(frame, frame.Bounds());
}
else
{
using IQuantizer <TPixel> frameQuantizer = this.quantizer.CreatePixelSpecificQuantizer <TPixel>(this.configuration);
quantized = frameQuantizer.BuildPaletteAndQuantizeFrame(frame, frame.Bounds());
}
}
this.bitDepth = ImageMaths.GetBitsNeededForColorDepth(quantized.Palette.Length);
this.WriteGraphicalControlExtension(frameMetadata, this.GetTransparentIndex(quantized), stream);
this.WriteImageDescriptor(frame, true, stream);
this.WriteColorTable(quantized, stream);
this.WriteImageData(quantized, stream);
quantized.Dispose();
quantized = null; // So next frame can regenerate it
previousFrame = frame;
previousMeta = frameMetadata;
}
}
/// <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="ImageFrame{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));
this.width = image.Width;
this.height = image.Height;
ImageMetadata metadata = image.Metadata;
PngMetadata pngMetadata = metadata.GetFormatMetadata(PngFormat.Instance);
PngEncoderOptionsHelpers.AdjustOptions <TPixel>(this.options, pngMetadata, out this.use16Bit, out this.bytesPerPixel);
Image <TPixel> clonedImage = null;
bool clearTransparency = this.options.TransparentColorMode == PngTransparentColorMode.Clear;
if (clearTransparency)
{
clonedImage = image.Clone();
ClearTransparentPixels(clonedImage);
}
IndexedImageFrame <TPixel> quantized = this.CreateQuantizedImage(image, clonedImage);
stream.Write(PngConstants.HeaderBytes);
this.WriteHeaderChunk(stream);
this.WriteGammaChunk(stream);
this.WritePaletteChunk(stream, quantized);
this.WriteTransparencyChunk(stream, pngMetadata);
this.WritePhysicalChunk(stream, metadata);
this.WriteExifChunk(stream, metadata);
this.WriteTextChunks(stream, pngMetadata);
this.WriteDataChunks(clearTransparency ? clonedImage : image, quantized, stream);
this.WriteEndChunk(stream);
stream.Flush();
quantized?.Dispose();
clonedImage?.Dispose();
}