/// <summary>
/// Gets the frame as PNG FileStream.
/// </summary>
public MemoryStream GetStream()
{
var ihdrChunk = new IHDRChunk(IHDRChunk);
if (fcTLChunk != null)
{
// Fix frame size with fcTL data.
ihdrChunk.ModifyChunkData(0, Helper.ConvertEndian(fcTLChunk.Width));
ihdrChunk.ModifyChunkData(4, Helper.ConvertEndian(fcTLChunk.Height));
}
// Write image data
var ms = new MemoryStream();
ms.WriteBytes(Signature);
ms.WriteBytes(ihdrChunk.RawData);
otherChunks.ForEach(o => ms.WriteBytes(o.RawData));
idatChunks.ForEach(i => ms.WriteBytes(i.RawData));
ms.WriteBytes(IENDChunk.RawData);
ms.Position = 0;
return(ms);
}
/// <summary>
/// Load the specified stream.
/// </summary>
/// <param name="stream">Streamrepresentation of the png file.</param>
internal void Load(MemoryStream stream)
{
ms = stream;
// 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.");
}
viewSize = new Size(IHDRChunk.Width, IHDRChunk.Height);
// Now let's loop in chunks
Chunk chunk;
Frame frame = null;
var otherChunks = new List <OtherChunk>();
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.");
case "acTL":
if (IsSimplePNG)
{
throw new Exception("acTL chunk must located before any IDAT and fdAT");
}
acTLChunk = new acTLChunk(chunk);
break;
case "IDAT":
// To be an APNG, acTL must located before any IDAT and fdAT.
if (acTLChunk == null)
{
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)
{
frames.Add(frame);
}
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)
{
frames.Add(frame);
}
if (DefaultImage.IDATChunks.Count != 0)
{
DefaultImage.IENDChunk = new IENDChunk(chunk);
}
foreach (Frame f in frames)
{
f.IENDChunk = new IENDChunk(chunk);
}
break;
default:
otherChunks.Add(new OtherChunk(chunk));
break;
}
} while (chunk.ChunkType != "IEND");
// We have one more thing to do:
// If the default image is part of the animation,
// we should insert it into frames list.
if (defaultImage.fcTLChunk != null)
{
frames.Insert(0, defaultImage);
DefaultImageIsAnimated = true;
}
else //If it isn't animated it still needs the other chunks.
{
otherChunks.ForEach(defaultImage.AddOtherChunk);
}
// Now we should apply every chunk in otherChunks to every frame.
frames.ForEach(f => otherChunks.ForEach(f.AddOtherChunk));
}
