/// <summary>
/// Writes a Graphic Control Extension to the supplied output stream.
/// </summary>
/// <param name="frame">
/// The GifFrame to which this graphic control extension relates.
/// </param>
/// <param name="transparentColourIndex">
/// The index within the active colour table of the transparent colour.
/// </param>
/// <param name="outputStream">
/// The stream to write to.
/// </param>
private void WriteGraphicCtrlExt(GifFrame frame,
int transparentColourIndex,
Stream outputStream)
{
outputStream.WriteByte(GifComponent.CodeExtensionIntroducer);
outputStream.WriteByte(GifComponent.CodeGraphicControlLabel);
// The frame doesn't have have a graphic control extension yet, so we
// need to work out what it would contain.
DisposalMethod disposalMethod;
bool hasTransparentColour;
if (_transparent == Color.Empty) // TODO: remove reference to _transparent - parameterise?
{
hasTransparentColour = false;
disposalMethod = DisposalMethod.NotSpecified; // dispose = no action
}
else
{
// TESTME: WriteGraphicCtrlExt - _transparent != Color.Empty
hasTransparentColour = true;
disposalMethod = DisposalMethod.RestoreToBackgroundColour; // force clear if using transparent color
}
int blockSize = 4;
GraphicControlExtension gce
= new GraphicControlExtension(blockSize,
disposalMethod,
frame.ExpectsUserInput,
hasTransparentColour,
frame.Delay,
transparentColourIndex);
gce.WriteToStream(outputStream);
}
public void WriteToStreamTest()
{
ReportStart();
int blockSize = 4;
DisposalMethod disposalMethod = DisposalMethod.DoNotDispose;
bool expectsUserInput = false;
bool hasTransparentColour = true;
int delayTime = 10;
int transparentColourIndex = 6;
_gce = new GraphicControlExtension(blockSize,
disposalMethod,
expectsUserInput,
hasTransparentColour,
delayTime,
transparentColourIndex);
MemoryStream s = new MemoryStream();
_gce.WriteToStream(s);
s.Seek(0, SeekOrigin.Begin);
_gce = new GraphicControlExtension(s);
Assert.AreEqual(ErrorState.Ok, _gce.ConsolidatedState);
Assert.AreEqual(blockSize, _gce.BlockSize);
Assert.AreEqual(disposalMethod, _gce.DisposalMethod);
Assert.AreEqual(expectsUserInput, _gce.ExpectsUserInput);
Assert.AreEqual(hasTransparentColour, _gce.HasTransparentColour);
Assert.AreEqual(delayTime, _gce.DelayTime);
Assert.AreEqual(transparentColourIndex, _gce.TransparentColourIndex);
ReportEnd();
}
