public static GifExtension ReadExtension(Stream stream, IEnumerable <GifExtension> controlExtensions, bool metadataOnly)
{
//Note: at this point, the Extension Introducer (0x21) has already been read
var label = stream.ReadByte();
if (label < 0)
{
throw GifHelpers.UnexpectedEndOfStreamException();
}
switch (label)
{
case GifGraphicControlExtension.ExtensionLabel:
return(GifGraphicControlExtension.ReadGraphicsControl(stream));
case GifCommentExtension.ExtensionLabel:
return(GifCommentExtension.ReadComment(stream));
case GifPlainTextExtension.ExtensionLabel:
return(GifPlainTextExtension.ReadPlainText(stream, controlExtensions, metadataOnly));
case GifApplicationExtension.ExtensionLabel:
return(GifApplicationExtension.ReadApplication(stream));
default:
throw GifHelpers.UnknownExtensionTypeException(label);
}
}
public static GifApplicationExtension ReadApplication(Stream stream)
{
var ext = new GifApplicationExtension();
ext.Read(stream);
return(ext);
}
public static ushort GetRepeatCount(GifApplicationExtension ext)
{
if (ext.Data.Length >= 3)
{
return(BitConverter.ToUInt16(ext.Data, 1));
}
return(1);
}
/// <summary>
/// Initializes the module.
/// </summary>
public static void Initialize()
{
GraphicControlGifExtension.registerSelfAsGifExtension();
GifApplicationExtension.registerSelfAsGifExtension();
LoopingGifApplicationExtension.registerSelfAsAppExtension();
}
public static GifBitmapCoder ConvertStciIndexedToGif(
StciIndexed aStci, UInt16 aDelay, bool aUseTransparent, int aForeshotingNumber)
{
var _stciPalette = aStci.Palette;
var _colors = new List <Color>(StciIndexed.NUMBER_OF_COLORS);
for (int i = 0; i < StciIndexed.NUMBER_OF_COLORS; i++)
{
_colors.Add(Color.FromRgb(_stciPalette[i * 3], _stciPalette[i * 3 + 1], _stciPalette[i * 3 + 2]));
}
var _palette = new BitmapPalette(_colors);
var _gifCoder = new GifBitmapCoder(_palette);
_gifCoder.Extensions.Add(new GifCommentExtension("Egorov A. V. for ja2.su"));
Int16 _minOffsetX = Int16.MaxValue;
Int16 _minOffsetY = Int16.MaxValue;
int foreshotingCount = 0;
foreach (var _subImage in aStci.Images)
{
if (_subImage.AuxData != null && _subImage.AuxData.NumberOfFrames > 0)
{
foreshotingCount++;
}
if (aForeshotingNumber > 0 && aForeshotingNumber != foreshotingCount)
{
continue;
}
var _header = _subImage.Header;
_minOffsetX = Math.Min(_minOffsetX, _header.OffsetX);
_minOffsetY = Math.Min(_minOffsetY, _header.OffsetY);
}
if (_minOffsetX < 0 || _minOffsetY < 0)
{
var _shiftData = new List <byte>(4);
_shiftData.AddRange(BitConverter.GetBytes(_minOffsetX));
_shiftData.AddRange(BitConverter.GetBytes(_minOffsetY));
var _shiftExtension = new GifApplicationExtension(ApplicationId, _shiftData.ToArray());
_gifCoder.Extensions.Add(_shiftExtension);
}
foreshotingCount = 0;
foreach (var _subImage in aStci.Images)
{
if (_subImage.AuxData != null && _subImage.AuxData.NumberOfFrames > 0)
{
foreshotingCount++;
}
if (aForeshotingNumber > 0 && aForeshotingNumber != foreshotingCount)
{
continue;
}
var _header = _subImage.Header;
var _imageSource = BitmapSource.Create(
_header.Width,
_header.Height,
96, 96,
PixelFormats.Indexed8,
_palette,
_subImage.ImageData,
_header.Width);
var _frame = BitmapFrame.Create(_imageSource);
var _offsetX = _header.OffsetX;
var _offsetY = _header.OffsetY;
if (_minOffsetX < 0 || _minOffsetY < 0)
{
// GIF format suports only positive offsets
_offsetX = (short)(_offsetX - _minOffsetX);
_offsetY = (short)(_offsetY - _minOffsetY);
}
var _bf = new GifBitmapFrame(_frame, (ushort)_offsetX, (ushort)_offsetY);
if (_subImage.AuxData != null)
{
var _auxData = new byte[AuxObjectData.SIZE];
_subImage.AuxData.Save(new MemoryStream(_auxData));
_bf.Extensions.Add(new GifApplicationExtension(ApplicationId, _auxData));
}
_bf.DisposalMethod = GifFrameDisposalMethod.RestoreToBackgroundColor;
_bf.UseGlobalPalette = true;
_bf.UseTransparency = aUseTransparent;
_bf.Delay = aDelay;
if (aUseTransparent)
{
_bf.TransparentColorIndex = (byte)aStci.Header.TransparentColorIndex;
}
_gifCoder.AddFrame(_bf);
}
return(_gifCoder);
}
public static bool IsNetscapeExtension(GifApplicationExtension ext)
{
return(ext.ApplicationIdentifier == "NETSCAPE" && Encoding.ASCII.GetString(ext.AuthenticationCode) == "2.0");
}
