private static void EncodeBitmapHeader(IcoFrame source, Dialect dialect, BitmapEncoding encoding, Rgba32[] colorTable, ByteWriter writer, out uint offsetToImageSize)
{
if (dialect != Dialect.Ico)
{
writer.AddUint16(FileFormatConstants._bitmapFileMagic);
writer.AddUint32(0); // Size will be filled in later
writer.AddUint32(0); // Reserved
writer.AddUint32(0); // Offset will be filled in later
}
writer.AddUint32(FileFormatConstants._bitmapInfoHeaderSize);
writer.AddUint32((uint)source.CookedData.Width);
writer.AddUint32((uint)source.CookedData.Height * ((dialect == Dialect.Ico) ? 2u : 1u));
writer.AddUint16(1); // biPlanes
writer.AddUint16((ushort)BmpUtil.GetBitDepthForPixelFormat(encoding)); // biBitCount
writer.AddUint32(FileFormatConstants.BI_RGB); // biCompression
offsetToImageSize = (uint)writer.SeekOffset;
writer.AddUint32(0); // biSizeImage
writer.AddUint32((dialect == Dialect.Ico) ? 0u : FileFormatConstants._72dpiInPixelsPerMeter); // biXPelsPerMeter
writer.AddUint32((dialect == Dialect.Ico) ? 0u : FileFormatConstants._72dpiInPixelsPerMeter); // biYPelsPerMeter
writer.AddUint32((uint)(colorTable?.Length ?? 0)); // biClrUsed
writer.AddUint32(0); // biClrImportant
if (colorTable != null)
{
foreach (var color in colorTable)
{
writer.AddUint8(color.B);
writer.AddUint8(color.G);
writer.AddUint8(color.R);
writer.AddUint8(0);
}
}
if (dialect != Dialect.Ico)
{
while (writer.Data.Count % 4 != 0)
{
writer.AddUint8(0);
}
}
}