/// <summary>
/// Constructs a PngWriter from a outputStream, with optional filename or description
/// </summary>
/// <remarks>
/// After construction nothing is writen yet. You still can set some
/// parameters (compression, filters) and queue chunks before start writing the pixels.
///
/// See also <c>FileHelper.createPngWriter()</c>
/// </remarks>
/// <param name="outputStream">Opened stream for binary writing</param>
/// <param name="imgInfo">Basic image parameters</param>
/// <param name="filename">Optional, can be the filename or a description.</param>
public PngWriter(Stream outputStream, ImageInfo imgInfo,
string filename)
{
this.filename = filename ?? "";
this.outputStream = outputStream;
ImgInfo = imgInfo;
// defaults settings
CompLevel = 6;
ShouldCloseStream = true;
IdatMaxSize = 0; // use default
CompressionStrategy = EDeflateCompressStrategy.Filtered;
// prealloc
//scanline = new int[imgInfo.SamplesPerRowPacked];
rowb = new byte[imgInfo.BytesPerRow + 1];
rowbprev = new byte[rowb.Length];
rowbfilter = new byte[rowb.Length];
chunksList = new ChunksListForWrite(ImgInfo);
metadata = new PngMetadata(chunksList);
filterStrat = new FilterWriteStrategy(ImgInfo, FilterType.FILTER_DEFAULT);
IsUnpackedMode = false;
needsPack = IsUnpackedMode && imgInfo.Packed;
}
/// <summary> Sets internal prediction filter type, or strategy to choose it. </summary> /// <remarks> /// This must be called just after constructor, before starting writing. /// Recommended values: DEFAULT (default) or AGGRESIVE /// </remarks> /// <param name="filterType"> One of the five prediction types or strategy to choose it </param> public void SetFilterType(FilterType filterType) => filterStrat = new FilterWriteStrategy(ImgInfo, filterType);