/// <summary>
/// Ad-hoc criteria for 'equivalent' chunks.
/// </summary>
/// <remarks>
/// Two chunks are equivalent if they have the same Id AND either:
/// 1. they are Single
/// 2. both are textual and have the same key
/// 3. both are SPLT and have the same palette name
/// Bear in mind that this is an ad-hoc, non-standard, nor required (nor wrong)
/// criterion. Use it only if you find it useful. Notice that PNG allows to have
/// repeated textual keys with same keys.
/// </remarks>
/// <param name="c1">Chunk1</param>
/// <param name="c2">Chunk1</param>
/// <returns>true if equivalent</returns>
public static bool Equivalent(PngChunk c1, PngChunk c2)
{
if (c1 == c2)
{
return(true);
}
if (c1 == null || c2 == null || !c1.Id.Equals(c2.Id))
{
return(false);
}
// same id
if (c1.GetType() != c2.GetType())
{
return(false); // should not happen
}
if (!c2.AllowsMultiple())
{
return(true);
}
if (c1 is PngChunkTextVar)
{
return(((PngChunkTextVar)c1).GetKey().Equals(((PngChunkTextVar)c2).GetKey()));
}
if (c1 is PngChunkSPLT)
{
return(((PngChunkSPLT)c1).PalName.Equals(((PngChunkSPLT)c2).PalName));
}
// unknown chunks that allow multiple? consider they don't match
return(false);
}
internal int writeChunks(Stream os, int currentGroup)
{
List <int> written = new List <int>();
for (int i = 0; i < queuedChunks.Count; i++)
{
PngChunk c = queuedChunks[i];
if (!shouldWrite(c, currentGroup))
{
continue;
}
if (ChunkHelper.IsCritical(c.Id) && !c.Id.Equals(ChunkHelper.PLTE))
{
throw new PngjOutputException("bad chunk queued: " + c);
}
if (alreadyWrittenKeys.ContainsKey(c.Id) && !c.AllowsMultiple())
{
throw new PngjOutputException("duplicated chunk does not allow multiple: " + c);
}
c.write(os);
chunks.Add(c);
alreadyWrittenKeys[c.Id] = alreadyWrittenKeys.ContainsKey(c.Id) ? alreadyWrittenKeys[c.Id] + 1 : 1;
written.Add(i);
c.ChunkGroup = currentGroup;
}
for (int k = written.Count - 1; k >= 0; k--)
{
queuedChunks.RemoveAt(written[k]);
}
return(written.Count);
}
internal int WriteChunks(IO.Stream os, int currentGroup)
{
List <int> written = new List <int>();
for (int i = 0; i < queuedChunks.Count; i++)
{
PngChunk chunk = queuedChunks[i];
if (!ShouldWrite(chunk, currentGroup))
{
continue;
}
if (ChunkHelper.IsCritical(chunk.Id) && !chunk.Id.Equals(ChunkHelper.PLTE))
{
throw new System.IO.IOException($"bad chunk queued: {chunk}");
}
if (alreadyWrittenKeys.ContainsKey(chunk.Id) && !chunk.AllowsMultiple())
{
throw new System.IO.IOException($"duplicated chunk does not allow multiple: {chunk}");
}
chunk.Write(os);
chunks.Add(chunk);
alreadyWrittenKeys[chunk.Id] = alreadyWrittenKeys.ContainsKey(chunk.Id) ? alreadyWrittenKeys[chunk.Id] + 1 : 1;
written.Add(i);
chunk.ChunkGroup = currentGroup;
}
for (int k = written.Count - 1; k != -1; k--)
{
queuedChunks.RemoveAt(written[k]);
}
return(written.Count);
}
