/// <summary>
/// Decodes the specified stream.
/// </summary>
/// <param name="stream">The stream.</param>
/// <returns>This.</returns>
public override FileBase Decode(Stream stream)
{
Header = FileHeader.Read(stream);
ScreenDescriptor = LogicalScreenDescriptor.Read(stream);
if (ScreenDescriptor.GlobalColorTablePresent)
{
ColorTable = ColorTable.Read(stream, ScreenDescriptor.GlobalColorTableSize);
}
var Flag = stream.ReadByte();
while (Flag != SectionTypes.Terminator)
{
if (Flag == SectionTypes.ImageLabel)
{
Frames.Add(Frame.Read(stream, ColorTable, GraphicsControlExtension, ScreenDescriptor, Frames));
}
else if (Flag == SectionTypes.ExtensionIntroducer)
{
var Label = (SectionTypes)stream.ReadByte();
if (Label == SectionTypes.GraphicControlLabel)
{
GraphicsControlExtension = GraphicsControl.Read(stream);
}
else if (Label == SectionTypes.CommentLabel)
{
Comment.Read(stream);
}
else if (Label == SectionTypes.ApplicationExtensionLabel)
{
ApplicationExtension.Read(stream);
}
else if (Label == SectionTypes.PlainTextLabel)
{
PlainText.Read(stream);
}
}
else if (Flag == SectionTypes.EndIntroducer)
{
break;
}
Flag = stream.ReadByte();
}
return(this);
}
/// <summary>
/// Loads the animation.
/// </summary>
/// <param name="animation">The animation.</param>
/// <param name="quantizedImage">The quantized image.</param>
private void LoadAnimation(Animation animation, QuantizedImage quantizedImage)
{
var TempImage = animation[0];
var TransparencyIndex = quantizedImage.TransparentIndex;
Header = new FileHeader();
ScreenDescriptor = new LogicalScreenDescriptor(TempImage, TransparencyIndex, BitDepth);
Frames.Add(new Frame(TempImage, quantizedImage, BitDepth, animation.Delay));
if (animation.Count > 1)
{
AppExtension = new ApplicationExtension(animation.RepeatCount, animation.Count);
for (int x = 1; x < animation.Count; ++x)
{
quantizedImage = Quantizer.Quantize(animation[x], Quality);
TempImage = animation[x];
Frames.Add(new Frame(TempImage, quantizedImage, BitDepth, animation.Delay));
}
}
}
/// <summary>
/// Loads the image.
/// </summary>
/// <param name="image">The image.</param>
/// <param name="quantizedImage">The quantized image.</param>
private void LoadImage(Image image, QuantizedImage quantizedImage)
{
Header = new FileHeader();
ScreenDescriptor = new LogicalScreenDescriptor(image, quantizedImage.TransparentIndex, BitDepth);
Frames.Add(new Frame(image, quantizedImage, BitDepth, 150));
}
private static byte[] ReadFrameColors(FrameIndices indices, ColorTable colorTable, GraphicsControl graphicsControl, ImageDescriptor descriptor, LogicalScreenDescriptor screenDescriptor, List <Frame> frames)
{
int imageWidth = screenDescriptor.Width;
int imageHeight = screenDescriptor.Height;
byte[] CurrentFrame = null;
byte[] LastFrame = null;
if (frames.Count > 0 &&
graphicsControl != null &&
graphicsControl.DisposalMethod == DisposalMethod.RestoreToPrevious)
{
CurrentFrame = new byte[imageWidth * imageHeight * 4];
Array.Copy(frames[frames.Count - 1].Data, CurrentFrame, CurrentFrame.Length);
LastFrame = new byte[imageWidth * imageHeight * 4];
Array.Copy(CurrentFrame, LastFrame, LastFrame.Length);
}
else
{
CurrentFrame = new byte[imageWidth * imageHeight * 4];
}
int offset, i = 0;
int interlacePass = 0;
int interlaceIncrement = 8;
int interlaceY = 0;
for (int y = descriptor.Top; y < descriptor.Top + descriptor.Height; y++)
{
int writeY;
if (descriptor.Interlace)
{
if (interlaceY >= descriptor.Height)
{
interlacePass++;
switch (interlacePass)
{
case 1:
interlaceY = 4;
break;
case 2:
interlaceY = 2;
interlaceIncrement = 4;
break;
case 3:
interlaceY = 1;
interlaceIncrement = 2;
break;
}
}
writeY = interlaceY + descriptor.Top;
interlaceY += interlaceIncrement;
}
else
{
writeY = y;
}
for (int x = descriptor.Left; x < descriptor.Left + descriptor.Width; x++)
{
offset = ((writeY * imageWidth) + x) * 4;
int index = indices.Indices[i];
if (graphicsControl == null ||
graphicsControl.TransparencyFlag == false ||
graphicsControl.TransparencyIndex != index)
{
int indexOffset = index * 3;
CurrentFrame[offset + 0] = colorTable.Data[indexOffset];
CurrentFrame[offset + 1] = colorTable.Data[indexOffset + 1];
CurrentFrame[offset + 2] = colorTable.Data[indexOffset + 2];
CurrentFrame[offset + 3] = 255;
}
i++;
}
}
return(CurrentFrame);
}
/// <summary>
/// Reads from the specified stream.
/// </summary>
/// <param name="stream">The stream.</param>
/// <param name="globalColorTable">The global color table.</param>
/// <param name="graphicsControl">The graphics control.</param>
/// <param name="screenDescriptor">The screen descriptor.</param>
/// <param name="frames">The frames.</param>
/// <returns>
/// The resulting frame.
/// </returns>
public static Frame Read(Stream stream, ColorTable globalColorTable, GraphicsControl graphicsControl, LogicalScreenDescriptor screenDescriptor, List <Frame> frames)
{
var TempDescriptor = ImageDescriptor.Read(stream);
ColorTable LocalColorTable = TempDescriptor.LocalColorTableExists ?
ColorTable.Read(stream, TempDescriptor.LocalColorTableSize) :
globalColorTable;
var TempIndices = FrameIndices.Read(stream, TempDescriptor);
var Data = ReadFrameColors(TempIndices, LocalColorTable, graphicsControl, TempDescriptor, screenDescriptor, frames);
Skip(stream, 0);
return(new Frame(graphicsControl, TempDescriptor, LocalColorTable, TempIndices, Data));
}
