+//------------------------------------------------------------------------
+// BaseStream
+//------------------------------------------------------------------------
+
+BaseStream::BaseStream(Object *dict) {
+ this->dict = *dict;
+}
+
+BaseStream::~BaseStream() {
+ dict.free();
+}
+
+//------------------------------------------------------------------------
+// FilterStream
+//------------------------------------------------------------------------
+
+FilterStream::FilterStream(Stream *str) {
+ this->str = str;
+}
+
+FilterStream::~FilterStream() {
+}
+
+void FilterStream::setPos(int pos) {
+ error(-1, "Internal: called setPos() on FilterStream");
+}
+
+//------------------------------------------------------------------------
+// ImageStream
+//------------------------------------------------------------------------
+
+ImageStream::ImageStream(Stream *str, int width, int nComps, int nBits) {
+ int imgLineSize;
+
+ this->str = str;
+ this->width = width;
+ this->nComps = nComps;
+ this->nBits = nBits;
+
+ nVals = width * nComps;
+ if (nBits == 1) {
+ imgLineSize = (nVals + 7) & ~7;
+ } else {
+ imgLineSize = nVals;
+ }
+ imgLine = (Guchar *)gmalloc(imgLineSize * sizeof(Guchar));
+ imgIdx = nVals;
+}
+
+ImageStream::~ImageStream() {
+ gfree(imgLine);
+}
+
+void ImageStream::reset() {
+ str->reset();
+}
+
+GBool ImageStream::getPixel(Guchar *pix) {
+ Gulong buf, bitMask;
+ int bits;
+ int c;
+ int i;
+
+ if (imgIdx >= nVals) {
+
+ // read one line of image pixels
+ if (nBits == 1) {
+ for (i = 0; i < nVals; i += 8) {
+ c = str->getChar();
+ imgLine[i+0] = (Guchar)((c >> 7) & 1);
+ imgLine[i+1] = (Guchar)((c >> 6) & 1);
+ imgLine[i+2] = (Guchar)((c >> 5) & 1);
+ imgLine[i+3] = (Guchar)((c >> 4) & 1);
+ imgLine[i+4] = (Guchar)((c >> 3) & 1);
+ imgLine[i+5] = (Guchar)((c >> 2) & 1);
+ imgLine[i+6] = (Guchar)((c >> 1) & 1);
+ imgLine[i+7] = (Guchar)(c & 1);
+ }
+ } else if (nBits == 8) {
+ for (i = 0; i < nVals; ++i) {
+ imgLine[i] = str->getChar();
+ }
+ } else {
+ bitMask = (1 << nBits) - 1;
+ buf = 0;
+ bits = 0;
+ for (i = 0; i < nVals; ++i) {
+ if (bits < nBits) {
+ buf = (buf << 8) | (str->getChar() & 0xff);
+ bits += 8;
+ }
+ imgLine[i] = (Guchar)((buf >> (bits - nBits)) & bitMask);
+ bits -= nBits;
+ }
+ }
+
+ // reset to start of line
+ imgIdx = 0;
+ }
+
+ for (i = 0; i < nComps; ++i)
+ pix[i] = imgLine[imgIdx++];
+ return gTrue;
+}
+
+void ImageStream::skipLine() {
+ int n, i;
+
+ n = (nVals * nBits + 7) >> 3;
+ for (i = 0; i < n; ++i) {
+ str->getChar();
+ }
+}
+
+//------------------------------------------------------------------------
+// StreamPredictor
+//------------------------------------------------------------------------
+
+StreamPredictor::StreamPredictor(Stream *str, int predictor,
+ int width, int nComps, int nBits) {
+ this->str = str;
+ this->predictor = predictor;
+ this->width = width;
+ this->nComps = nComps;
+ this->nBits = nBits;
+
+ nVals = width * nComps;
+ pixBytes = (nComps * nBits + 7) >> 3;
+ rowBytes = ((nVals * nBits + 7) >> 3) + pixBytes;
+ predLine = (Guchar *)gmalloc(rowBytes);
+ memset(predLine, 0, rowBytes);
+ predIdx = rowBytes;
+}
+
+StreamPredictor::~StreamPredictor() {
+ gfree(predLine);
+}
+
+int StreamPredictor::lookChar() {
+ if (predIdx >= rowBytes) {
+ if (!getNextLine()) {
+ return EOF;
+ }
+ }
+ return predLine[predIdx];
+}
+
+int StreamPredictor::getChar() {
+ if (predIdx >= rowBytes) {
+ if (!getNextLine()) {
+ return EOF;
+ }
+ }
+ return predLine[predIdx++];
+}
+
+GBool StreamPredictor::getNextLine() {
+ int curPred;
+ Guchar upLeftBuf[4];
+ int left, up, upLeft, p, pa, pb, pc;
+ int c;
+ Gulong inBuf, outBuf, bitMask;
+ int inBits, outBits;
+ int i, j, k;
+
+ // get PNG optimum predictor number
+ if (predictor == 15) {
+ if ((curPred = str->getRawChar()) == EOF) {
+ return gFalse;
+ }
+ curPred += 10;
+ } else {
+ curPred = predictor;
+ }
+
+ // read the raw line, apply PNG (byte) predictor
+ upLeftBuf[0] = upLeftBuf[1] = upLeftBuf[2] = upLeftBuf[3] = 0;
+ for (i = pixBytes; i < rowBytes; ++i) {
+ upLeftBuf[3] = upLeftBuf[2];
+ upLeftBuf[2] = upLeftBuf[1];
+ upLeftBuf[1] = upLeftBuf[0];
+ upLeftBuf[0] = predLine[i];
+ if ((c = str->getRawChar()) == EOF) {
+ break;
+ }
+ switch (curPred) {
+ case 11: // PNG sub
+ predLine[i] = predLine[i - pixBytes] + (Guchar)c;
+ break;
+ case 12: // PNG up
+ predLine[i] = predLine[i] + (Guchar)c;
+ break;
+ case 13: // PNG average
+ predLine[i] = ((predLine[i - pixBytes] + predLine[i]) >> 1) +
+ (Guchar)c;
+ break;
+ case 14: // PNG Paeth
+ left = predLine[i - pixBytes];
+ up = predLine[i];
+ upLeft = upLeftBuf[pixBytes];
+ p = left + up - upLeft;
+ if ((pa = p - left) < 0)
+ pa = -pa;
+ if ((pb = p - up) < 0)
+ pb = -pb;
+ if ((pc = p - upLeft) < 0)
+ pc = -pc;
+ if (pa <= pb && pa <= pc)
+ predLine[i] = pa + (Guchar)c;
+ else if (pb <= pc)
+ predLine[i] = pb + (Guchar)c;
+ else
+ predLine[i] = pc + (Guchar)c;
+ break;
+ case 10: // PNG none
+ default: // no predictor or TIFF predictor
+ predLine[i] = (Guchar)c;
+ break;
+ }
+ }
+
+ // apply TIFF (component) predictor
+ //~ this is completely untested
+ if (predictor == 2) {
+ if (nBits == 1) {
+ inBuf = predLine[pixBytes - 1];
+ for (i = pixBytes; i < rowBytes; i += 8) {
+ // 1-bit add is just xor
+ inBuf = (inBuf << 8) | predLine[i];
+ predLine[i] ^= inBuf >> nComps;
+ }
+ } else if (nBits == 8) {
+ for (i = pixBytes; i < rowBytes; ++i) {
+ predLine[i] += predLine[i - nComps];
+ }
+ } else {
+ upLeftBuf[0] = upLeftBuf[1] = upLeftBuf[2] = upLeftBuf[3] = 0;
+ bitMask = (1 << nBits) - 1;
+ inBuf = outBuf = 0;
+ inBits = outBits = 0;
+ j = k = pixBytes;
+ for (i = 0; i < nVals; ++i) {
+ if (inBits < nBits) {
+ inBuf = (inBuf << 8) | (predLine[j++] & 0xff);
+ inBits += 8;
+ }
+ upLeftBuf[3] = upLeftBuf[2];
+ upLeftBuf[2] = upLeftBuf[1];
+ upLeftBuf[1] = upLeftBuf[0];
+ upLeftBuf[0] = (upLeftBuf[nComps] +
+ (inBuf >> (inBits - nBits))) & bitMask;
+ outBuf = (outBuf << nBits) | upLeftBuf[0];
+ inBits -= nBits;
+ outBits += nBits;
+ if (outBits > 8) {
+ predLine[k++] = (Guchar)(outBuf >> (outBits - 8));
+ }
+ }
+ if (outBits > 0) {
+ predLine[k++] = (Guchar)(outBuf << (8 - outBits));
+ }
+ }
+ }
+
+ // reset to start of line
+ predIdx = pixBytes;
+
+ return gTrue;
+}
+