/// <summary> /// Loads packets from the input stream. For example, packets are all of the x's in a stroke /// </summary> #endif static uint LoadPackets(Stream inputStream, uint totalBytesInStrokeBlockOfIsfStream, #if OLD_ISF Compressor compressor, #endif StylusPointDescription stylusPointDescription, Matrix transform, out StylusPointCollection stylusPoints) { stylusPoints = null; if (0 == totalBytesInStrokeBlockOfIsfStream) return 0; uint locallyDecodedBytesRemaining = totalBytesInStrokeBlockOfIsfStream; uint localBytesRead; // First read the no of packets uint pointCount; localBytesRead = SerializationHelper.Decode(inputStream, out pointCount); if (locallyDecodedBytesRemaining < localBytesRead) throw new ArgumentException(StrokeCollectionSerializer.ISFDebugMessage("Invalid ISF data")); locallyDecodedBytesRemaining -= localBytesRead; if (0 == locallyDecodedBytesRemaining) return localBytesRead; // Allocate packet properties int intsPerPoint = stylusPointDescription.GetInputArrayLengthPerPoint(); int buttonCount = stylusPointDescription.ButtonCount; int buttonIntsPerPoint = (buttonCount > 0 ? 1 : 0); int valueIntsPerPoint = intsPerPoint - buttonIntsPerPoint; //add one int per point for button data if it exists int[] rawPointData = new int[pointCount * intsPerPoint]; int[] packetDataSet = new int[pointCount]; // copy the rest of the data from the stroke data byte[] inputBuffer = new byte[locallyDecodedBytesRemaining]; // Read the input data into the byte array uint bytesRead = StrokeCollectionSerializer.ReliableRead(inputStream, inputBuffer, locallyDecodedBytesRemaining); if ( bytesRead != locallyDecodedBytesRemaining ) { // Make sure the bytes read are expected. If not, we should bail out. // An exception will be thrown. throw new ArgumentException(StrokeCollectionSerializer.ISFDebugMessage("Invalid ISF data")); } // at this point, we have read all of the bytes remaining in the input // stream's packet block, and while we will keep the bytes remaining // variable for positioning within the local byte buffer, we should // not read from the stream again, or we risk reading into another // ISF tag's block. int originalPressureIndex = stylusPointDescription.OriginalPressureIndex; for (int i = 0; i < valueIntsPerPoint && locallyDecodedBytesRemaining > 0; i++) { localBytesRead = locallyDecodedBytesRemaining; Compressor.DecompressPacketData( #if OLD_ISF compressor, #endif inputBuffer, ref localBytesRead, packetDataSet); if (localBytesRead > locallyDecodedBytesRemaining) throw new ArgumentException(StrokeCollectionSerializer.ISFDebugMessage("Invalid ISF data")); // // packetDataSet is like this: // ------------- // |X|X|X|X|X|X| // ------------- // // we need to copy into rawPointData at // // ------------- // |X| |X| |X| | // ------------- // // additionally, for NormalPressure, if it exists and was // reordered in the StylusPointDescription, we need to account for that here // int tempi = i; if (tempi > 1 && originalPressureIndex != -1 && originalPressureIndex != StylusPointDescription.RequiredPressureIndex/*2*/) { // // NormalPressure exists in the packet stream and was not at index 2 // StylusPointDescription enforces that NormalPressure is at index 2 // so we need to copy packet data beyond X and Y into a different location // // take the example of the original StylusPointDescription // |X|Y|XTilt|YTilt|NormalPressure|Rotation| // // originalPressureIndex is 4, and we know it is now 2 // which means that everything before index 4 has been shifted one // and everything after index 4 is still good. Index 4 should be copied to index 2 if (tempi == originalPressureIndex) { tempi = 2; } else if (tempi < originalPressureIndex) { tempi++; } } locallyDecodedBytesRemaining -= localBytesRead; for (int j = 0, x = 0; j < pointCount; j++, x += intsPerPoint) { rawPointData[x + tempi] = packetDataSet[j]; } // Move the array elements to point to next set of compressed data for (uint u = 0; u < locallyDecodedBytesRemaining; u++) { inputBuffer[u] = inputBuffer[u + (int)localBytesRead]; } } // Now that we've read packet data, we must read button data if it is there byte[] buttonData = null; // since the button state is a simple bit value (either down or up), the button state // for a series of packets is packed into an array of bits rather than integers // For example, if there are 16 packets, and 2 buttons, then 32 bits can be used (e.g. 1 32-bit integer) if (0 != locallyDecodedBytesRemaining && buttonCount > 0) { // calculate the number of full bytes used for buttons per packet // Example: 10 buttons would require 1 full byte int fullBytesForButtonsPerPacket = buttonCount / Native.BitsPerByte; // calculate the number of bits that spill beyond the full byte boundary // Example: 10 buttons would require 2 extra bits (8 fit in a full byte) int partialBitsForButtonsPerPacket = buttonCount % Native.BitsPerByte; // Now figure out how many bytes we need to read for the button data localBytesRead = (uint)((buttonCount * pointCount + 7) / Native.BitsPerByte); if (localBytesRead > locallyDecodedBytesRemaining) { throw new ArgumentException(StrokeCollectionSerializer.ISFDebugMessage("Buffer range is smaller than expected expected size")); } locallyDecodedBytesRemaining -= localBytesRead; int buttonSizeInBytes = (buttonCount + 7)/Native.BitsPerByte; buttonData = new byte[pointCount * buttonSizeInBytes]; // Create a bit reader to unpack the bits from the ISF stream into // loosely packed byte buffer (e.g. button data aligned on full byte // boundaries only) BitStreamReader bitReader = new BitStreamReader(inputBuffer, (uint)buttonCount * pointCount); // unpack the button data into each packet int byteCounter = 0; while (!bitReader.EndOfStream) { // unpack the fully bytes first for (int fullBytes = 0; fullBytes < fullBytesForButtonsPerPacket; fullBytes++) { buttonData[byteCounter++] = bitReader.ReadByte(Native.BitsPerByte); } // then unpack a single partial byte if necessary if (partialBitsForButtonsPerPacket > 0) { buttonData[byteCounter++] = bitReader.ReadByte((int)partialBitsForButtonsPerPacket); } } // if the number of bytes allocated != necessary byte amount then an error occurred if (byteCounter != buttonData.Length) { throw new ArgumentException(StrokeCollectionSerializer.ISFDebugMessage("Button data length not equal to expected length")); } // // set the point data in the raw array // FillButtonData( (int)pointCount, buttonCount, valueIntsPerPoint, //gives the first button index rawPointData, buttonData); } stylusPoints = new StylusPointCollection(stylusPointDescription, rawPointData, null, transform); // if we read too far into the stream (e.g. the packets were compressed) // then move the stream pointer back to the end of the actual packet // data before returning. This keeps the return value on the function // (representing bytes read) honest and consistent with the stream // position movement in this function. if (0 != locallyDecodedBytesRemaining) { inputStream.Seek(0 - (long)locallyDecodedBytesRemaining, SeekOrigin.Current); } return totalBytesInStrokeBlockOfIsfStream - locallyDecodedBytesRemaining; }
/// <summary> /// Uncompress /// </summary> /// <param name="input"></param> /// <param name="inputIndex"></param> /// <returns></returns> internal byte[] Uncompress(byte[] input, int inputIndex) { //first things first Debug.Assert(input != null); Debug.Assert(input.Length > 1); Debug.Assert(inputIndex < input.Length); Debug.Assert(inputIndex >= 0); List<byte> output = new List<byte>(); BitStreamWriter writer = new BitStreamWriter(output); BitStreamReader reader = new BitStreamReader(input, inputIndex); //decode int index = 0, countBytes = 0, start = 0; byte byte1 = 0, byte2 = 0; _maxMatchLength = FirstMaxMatchLength; // initialize the ring buffer for (index = 0; index < RingBufferLength - _maxMatchLength; index++) { _ringBuffer[index] = 0; } //initialize decoding globals _flags = 0; _currentRingBufferPosition = RingBufferLength - _maxMatchLength; while (!reader.EndOfStream) { byte1 = reader.ReadByte(Native.BitsPerByte); // High order byte counts the number of bits used in the low order // byte. if (((_flags >>= 1) & 0x100) == 0) { // Set bit mask describing the next 8 bytes. _flags = (((int)byte1) | 0xff00); byte1 = reader.ReadByte(Native.BitsPerByte); } if ((_flags & 1) != 0) { // Just store the literal byte in the buffer. writer.Write(byte1, Native.BitsPerByte); _ringBuffer[_currentRingBufferPosition++] = byte1; _currentRingBufferPosition &= RingBufferLength - 1; } else { // Extract the offset and count to copy from the ring buffer. byte2 = reader.ReadByte(Native.BitsPerByte); countBytes = (int)byte2; start = (countBytes & 0xf0) << 4 | (int)byte1; countBytes = (countBytes & 0x0f) + MaxLiteralLength; for (index = 0; index <= countBytes; index++) { byte1 = _ringBuffer[(start + index) & (RingBufferLength - 1)]; writer.Write(byte1, Native.BitsPerByte); _ringBuffer[_currentRingBufferPosition++] = byte1; _currentRingBufferPosition &= RingBufferLength - 1; } } } return output.ToArray(); }