internal APNGFrame(GraphicsDevice graphicsDevice, Frame frame)
{
if (frame.fcTLChunk != null)
{
X = (int) frame.fcTLChunk.XOffset;
Y = (int) frame.fcTLChunk.YOffset;
Width = (int) frame.fcTLChunk.Width;
Height = (int) frame.fcTLChunk.Height;
BlendOp = frame.fcTLChunk.BlendOp;
DisposeOp = frame.fcTLChunk.DisposeOp;
DelayTime = new TimeSpan(
TimeSpan.TicksPerSecond*frame.fcTLChunk.DelayNum/frame.fcTLChunk.DelayDen);
}
else
{
X = 0;
Y = 0;
Width = frame.IHDRChunk.Width;
Height = frame.IHDRChunk.Height;
BlendOp = BlendOps.APNGBlendOpSource;
DisposeOp = DisposeOps.APNGDisposeOpNone;
DelayTime = TimeSpan.Zero;
}
// frame.GetStream() is not seekable, so we build a new MemoryStream.
FrameTexture = Texture2D.FromStream(
graphicsDevice, new MemoryStream(frame.GetStream().ToArray()));
MultiplyAlpha(FrameTexture);
}
public APNG(byte[] fileBytes)
{
ms = new MemoryStream(fileBytes);
// check file signature.
if (!Helper.IsBytesEqual(ms.ReadBytes(Frame.Signature.Length), Frame.Signature))
throw new Exception("File signature incorrect.");
// Read IHDR chunk.
IHDRChunk = new IHDRChunk(ms);
if (IHDRChunk.ChunkType != "IHDR")
throw new Exception("IHDR chunk must located before any other chunks.");
// Now let's loop in chunks
Chunk chunk;
Frame frame = null;
List<ITextChunk> text_chunks = new List<ITextChunk>();
bool isIDATAlreadyParsed = false;
do
{
if (ms.Position == ms.Length)
throw new Exception("IEND chunk expected.");
chunk = new Chunk(ms);
switch (chunk.ChunkType)
{
case "IHDR":
throw new Exception("Only single IHDR is allowed.");
break;
case "acTL":
if (IsSimplePNG)
throw new Exception("acTL chunk must located before any IDAT and fdAT");
TextChunks = text_chunks.ToArray();
text_chunks.Clear();
acTLChunk = new acTLChunk(chunk);
break;
case "IDAT":
// To be an APNG, acTL must located before any IDAT and fdAT.
if (acTLChunk == null)
{
TextChunks = text_chunks.ToArray();
text_chunks.Clear();
IsSimplePNG = true;
}
// Only default image has IDAT.
defaultImage.IHDRChunk = IHDRChunk;
defaultImage.AddIDATChunk(new IDATChunk(chunk));
isIDATAlreadyParsed = true;
break;
case "fcTL":
// Simple PNG should ignore this.
if (IsSimplePNG)
continue;
if (frame != null && frame.IDATChunks.Count == 0)
throw new Exception("One frame must have only one fcTL chunk.");
// IDAT already parsed means this fcTL is used by FRAME IMAGE.
if (isIDATAlreadyParsed)
{
// register current frame object and build a new frame object
// for next use
if (frame != null)
{
frame.TextChunks = text_chunks.ToArray();
frames.Add(frame);
text_chunks.Clear();
}
frame = new Frame
{
IHDRChunk = IHDRChunk,
fcTLChunk = new fcTLChunk(chunk)
};
}
// Otherwise this fcTL is used by the DEFAULT IMAGE.
else
{
defaultImage.fcTLChunk = new fcTLChunk(chunk);
}
break;
case "fdAT":
// Simple PNG should ignore this.
if (IsSimplePNG)
continue;
// fdAT is only used by frame image.
if (frame == null || frame.fcTLChunk == null)
throw new Exception("fcTL chunk expected.");
frame.AddIDATChunk(new fdATChunk(chunk).ToIDATChunk());
break;
case "IEND":
// register last frame object
if (frame != null)
{
frame.TextChunks = text_chunks.ToArray();
frames.Add(frame);
text_chunks.Clear();
}
if (DefaultImage.IDATChunks.Count != 0)
DefaultImage.IENDChunk = new IENDChunk(chunk);
foreach (Frame f in frames)
{
f.IENDChunk = new IENDChunk(chunk);
}
break;
case "iTXt":
text_chunks.Add(new iTXtChunk(chunk));
break;
case "tEXt":
text_chunks.Add(new tEXtChunk(chunk));
break;
case "zTXt":
text_chunks.Add(new zTXtChunk(chunk));
break;
default:
//TODO: Handle other chunks.
break;
}
} while (chunk.ChunkType != "IEND");
// We have one more thing to do:
// If the default image if part of the animation,
// we should insert it into frames list.
if (defaultImage.fcTLChunk != null)
{
frames.Insert(0, defaultImage);
DefaultImageIsAnimeated = true;
}
}