/// <summary>
/// Initializes a new instance of the <see cref="Frame" /> class.
/// </summary>
/// <param name="graphicsControl">The graphics control.</param>
/// <param name="descriptor">The descriptor.</param>
/// <param name="localColorTable">The local color table.</param>
/// <param name="indices">The indices.</param>
/// <param name="data">The data.</param>
public Frame(GraphicsControl graphicsControl, ImageDescriptor descriptor, ColorTable localColorTable, FrameIndices indices, byte[] data)
{
Data = data;
Indices = indices;
Descriptor = descriptor;
LocalColorTable = localColorTable;
GraphicsControl = graphicsControl;
}
/// <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));
}
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);
}
