private static void FillUncompressedColorIndexBuffer(byte[] data, ref int currentEntrySize, ref bool firstRead)
{
BitReader reader = new BitReader(data);
List<int> nextDictionaryEntry = new List<int>();
while ((reader.BitPosition + currentEntrySize) <= reader.BitLength)
{
int result = reader.Read(currentEntrySize);
bool addToDictionary =
!firstRead &&// don't add on the first read
(mDictionary.Count < (1 << 12)); // dictionary capped at 12 bits
List<int> pattern;
if (result < mDictionary.Count)
{
pattern = mDictionary[result];
}
else if (result == mDictionary.Count)
{
// special case for LZW
pattern = new List<int>(nextDictionaryEntry);
// pattern.Add(nextDictionaryEntry[nextDictionaryEntry.Count - 1]);
pattern.Add(nextDictionaryEntry[0]);
}
else
{
int index = mUncompressedColorIndexBuffer.Count - 1;
string error = "Error when reading pixel number " + (mUncompressedColorIndexBuffer.Count - 1);
int row = (mUncompressedColorIndexBuffer.Count) / mGifInfo.Width + 1;
int column = (mUncompressedColorIndexBuffer.Count) % mGifInfo.Width;
error += "\n On the image that's (" + column + ", " + row + ").";
throw new Exception(error);
}
firstRead = false;
// Check for constant values
if (result == ClrConstant)
{
// Clear dictionary
addToDictionary = false;
firstRead = true;
nextDictionaryEntry = new List<int>();
currentEntrySize = mGifInfo.LzwMin + 1;
FillDictionary();
}
else if (result == EndConstant)
{
// End of image
break;
}
else
{
// It's just image data
for (int i = 0; i < pattern.Count; i++)
{
mUncompressedColorIndexBuffer.Add((byte)pattern[i]);
}
#if DEBUG
if (mUncompressedColorIndexBuffer.Count > mGifInfo.Width * mGifInfo.Height)
{
throw new InvalidOperationException("The uncompressed buffer is too big!");
}
#endif
}
if (addToDictionary)
{
// add to dictionary
List<int> newPattern = new List<int>(nextDictionaryEntry);
// newPattern.Add(pattern[pattern.Count - 1]);
newPattern.Add(pattern[0]);
mDictionary.Add(newPattern);
currentEntrySize = CurrentEntrySize;
if (currentEntrySize == 13)
{
currentEntrySize = 12;
}
}
if (result != ClrConstant)
{
nextDictionaryEntry = pattern;
}
}
}
private static void FillUncompressedColorIndexBuffer(byte[] data, ref int currentEntrySize, ref bool firstRead)
{
BitReader reader = new BitReader(data);
List <int> nextDictionaryEntry = new List <int>();
while ((reader.BitPosition + currentEntrySize) <= reader.BitLength)
{
int result = reader.Read(currentEntrySize);
bool addToDictionary =
!firstRead && // don't add on the first read
(mDictionary.Count < (1 << 12)); // dictionary capped at 12 bits
List <int> pattern;
if (result < mDictionary.Count)
{
pattern = mDictionary[result];
}
else if (result == mDictionary.Count)
{
// special case for LZW
pattern = new List <int>(nextDictionaryEntry);
// pattern.Add(nextDictionaryEntry[nextDictionaryEntry.Count - 1]);
pattern.Add(nextDictionaryEntry[0]);
}
else
{
int index = mUncompressedColorIndexBuffer.Count - 1;
string error = "Error when reading pixel number " + (mUncompressedColorIndexBuffer.Count - 1);
int row = (mUncompressedColorIndexBuffer.Count) / mGifInfo.Width + 1;
int column = (mUncompressedColorIndexBuffer.Count) % mGifInfo.Width;
error += "\n On the image that's (" + column + ", " + row + ").";
throw new Exception(error);
}
firstRead = false;
// Check for constant values
if (result == ClrConstant)
{
// Clear dictionary
addToDictionary = false;
firstRead = true;
nextDictionaryEntry = new List <int>();
currentEntrySize = mGifInfo.LzwMin + 1;
FillDictionary();
}
else if (result == EndConstant)
{
// End of image
break;
}
else
{
// It's just image data
for (int i = 0; i < pattern.Count; i++)
{
mUncompressedColorIndexBuffer.Add((byte)pattern[i]);
}
#if DEBUG
if (mUncompressedColorIndexBuffer.Count > mGifInfo.Width * mGifInfo.Height)
{
throw new InvalidOperationException("The uncompressed buffer is too big!");
}
#endif
}
if (addToDictionary)
{
// add to dictionary
List <int> newPattern = new List <int>(nextDictionaryEntry);
// newPattern.Add(pattern[pattern.Count - 1]);
newPattern.Add(pattern[0]);
mDictionary.Add(newPattern);
currentEntrySize = CurrentEntrySize;
if (currentEntrySize == 13)
{
currentEntrySize = 12;
}
}
if (result != ClrConstant)
{
nextDictionaryEntry = pattern;
}
}
}
