/**
* this should be called only for ancillary chunks and PLTE (groups 1 - 3 - 5)
**/
static bool ShouldWrite(PngChunk chunk, int currentGroup)
{
if (currentGroup == CHUNK_GROUP_2_PLTE)
{
return(chunk.Id.Equals(ChunkHelper.PLTE));
}
if (currentGroup % 2 == 0)
{
throw new System.IO.IOException("bad chunk group?");
}
int minChunkGroup, maxChunkGroup;
if (chunk.MustGoBeforePLTE())
{
minChunkGroup = maxChunkGroup = ChunksList.CHUNK_GROUP_1_AFTERIDHR;
}
else if (chunk.MustGoBeforeIDAT())
{
maxChunkGroup = ChunksList.CHUNK_GROUP_3_AFTERPLTE;
minChunkGroup = chunk.MustGoAfterPLTE()
? ChunksList.CHUNK_GROUP_3_AFTERPLTE
: ChunksList.CHUNK_GROUP_1_AFTERIDHR;
}
else
{
maxChunkGroup = ChunksList.CHUNK_GROUP_5_AFTERIDAT;
minChunkGroup = ChunksList.CHUNK_GROUP_1_AFTERIDHR;
}
int preferred = maxChunkGroup;
if (chunk.Priority)
{
preferred = minChunkGroup;
}
if (ChunkHelper.IsUnknown(chunk) && chunk.ChunkGroup > 0)
{
preferred = chunk.ChunkGroup;
}
if (currentGroup == preferred)
{
return(true);
}
if (currentGroup > preferred && currentGroup <= maxChunkGroup)
{
return(true);
}
return(false);
}