stream.cc

这是一个做pdf阅读器的源代码文件,是大家学习阅读器资料的很好参考

//========================================================================
//
// Stream.cc
//
// Copyright 1996-2003 Glyph & Cog, LLC
//
//========================================================================

#include <aconf.h>

#ifdef USE_GCC_PRAGMAS
#pragma implementation
#endif

#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <limits.h>
#ifndef WIN32
#include <unistd.h>
#endif
#include <string.h>
#include <ctype.h>
#include "gmem.h"
#include "gfile.h"
#include "config.h"
#include "Error.h"
#include "Object.h"
#include "Lexer.h"
#include "GfxState.h"
#include "Stream.h"
#include "JBIG2Stream.h"
#include "JPXStream.h"
#include "Stream-CCITT.h"

#ifdef __DJGPP__
static GBool setDJSYSFLAGS = gFalse;
#endif

#ifdef VMS
#ifdef __GNUC__
#define SEEK_SET 0
#define SEEK_CUR 1
#define SEEK_END 2
#endif
#endif

//------------------------------------------------------------------------
// Stream (base class)
//------------------------------------------------------------------------

Stream::Stream() {
  ref = 1;
}

Stream::~Stream() {
}

void Stream::close() {
}

int Stream::getRawChar() {
  error(-1, "Internal: called getRawChar() on non-predictor stream");
  return EOF;
}

char *Stream::getLine(char *buf, int size) {
  int i;
  int c;

  if (lookChar() == EOF)
    return NULL;
  for (i = 0; i < size - 1; ++i) {
    c = getChar();
    if (c == EOF || c == '\n')
      break;
    if (c == '\r') {
      if ((c = lookChar()) == '\n')
	getChar();
      break;
    }
    buf[i] = c;
  }
  buf[i] = '\0';
  return buf;
}

GString *Stream::getPSFilter(int psLevel, char *indent) {
  return new GString();
}

Stream *Stream::addFilters(Object *dict) {
  Object obj, obj2;
  Object params, params2;
  Stream *str;
  int i;

  str = this;
  dict->dictLookup("Filter", &obj);
  if (obj.isNull()) {
    obj.free();
    dict->dictLookup("F", &obj);
  }
  dict->dictLookup("DecodeParms", &params);
  if (params.isNull()) {
    params.free();
    dict->dictLookup("DP", &params);
  }
  if (obj.isName()) {
    str = makeFilter(obj.getName(), str, &params);
  } else if (obj.isArray()) {
    for (i = 0; i < obj.arrayGetLength(); ++i) {
      obj.arrayGet(i, &obj2);
      if (params.isArray())
	params.arrayGet(i, &params2);
      else
	params2.initNull();
      if (obj2.isName()) {
	str = makeFilter(obj2.getName(), str, &params2);
      } else {
	error(getPos(), "Bad filter name");
	str = new EOFStream(str);
      }
      obj2.free();
      params2.free();
    }
  } else if (!obj.isNull()) {
    error(getPos(), "Bad 'Filter' attribute in stream");
  }
  obj.free();
  params.free();

  return str;
}

Stream *Stream::makeFilter(char *name, Stream *str, Object *params) {
  int pred;			// parameters
  int colors;
  int bits;
  int early;
  int encoding;
  GBool endOfLine, byteAlign, endOfBlock, black;
  int columns, rows;
  int colorXform;
  Object globals, obj;

  if (!strcmp(name, "ASCIIHexDecode") || !strcmp(name, "AHx")) {
    str = new ASCIIHexStream(str);
  } else if (!strcmp(name, "ASCII85Decode") || !strcmp(name, "A85")) {
    str = new ASCII85Stream(str);
  } else if (!strcmp(name, "LZWDecode") || !strcmp(name, "LZW")) {
    pred = 1;
    columns = 1;
    colors = 1;
    bits = 8;
    early = 1;
    if (params->isDict()) {
      params->dictLookup("Predictor", &obj);
      if (obj.isInt())
	pred = obj.getInt();
      obj.free();
      params->dictLookup("Columns", &obj);
      if (obj.isInt())
	columns = obj.getInt();
      obj.free();
      params->dictLookup("Colors", &obj);
      if (obj.isInt())
	colors = obj.getInt();
      obj.free();
      params->dictLookup("BitsPerComponent", &obj);
      if (obj.isInt())
	bits = obj.getInt();
      obj.free();
      params->dictLookup("EarlyChange", &obj);
      if (obj.isInt())
	early = obj.getInt();
      obj.free();
    }
    str = new LZWStream(str, pred, columns, colors, bits, early);
  } else if (!strcmp(name, "RunLengthDecode") || !strcmp(name, "RL")) {
    str = new RunLengthStream(str);
  } else if (!strcmp(name, "CCITTFaxDecode") || !strcmp(name, "CCF")) {
    encoding = 0;
    endOfLine = gFalse;
    byteAlign = gFalse;
    columns = 1728;
    rows = 0;
    endOfBlock = gTrue;
    black = gFalse;
    if (params->isDict()) {
      params->dictLookup("K", &obj);
      if (obj.isInt()) {
	encoding = obj.getInt();
      }
      obj.free();
      params->dictLookup("EndOfLine", &obj);
      if (obj.isBool()) {
	endOfLine = obj.getBool();
      }
      obj.free();
      params->dictLookup("EncodedByteAlign", &obj);
      if (obj.isBool()) {
	byteAlign = obj.getBool();
      }
      obj.free();
      params->dictLookup("Columns", &obj);
      if (obj.isInt()) {
	columns = obj.getInt();
      }
      obj.free();
      params->dictLookup("Rows", &obj);
      if (obj.isInt()) {
	rows = obj.getInt();
      }
      obj.free();
      params->dictLookup("EndOfBlock", &obj);
      if (obj.isBool()) {
	endOfBlock = obj.getBool();
      }
      obj.free();
      params->dictLookup("BlackIs1", &obj);
      if (obj.isBool()) {
	black = obj.getBool();
      }
      obj.free();
    }
    str = new CCITTFaxStream(str, encoding, endOfLine, byteAlign,
			     columns, rows, endOfBlock, black);
  } else if (!strcmp(name, "DCTDecode") || !strcmp(name, "DCT")) {
    colorXform = -1;
    if (params->isDict()) {
      if (params->dictLookup("ColorTransform", &obj)->isInt()) {
	colorXform = obj.getInt();
      }
      obj.free();
    }
    str = new DCTStream(str, colorXform);
  } else if (!strcmp(name, "FlateDecode") || !strcmp(name, "Fl")) {
    pred = 1;
    columns = 1;
    colors = 1;
    bits = 8;
    if (params->isDict()) {
      params->dictLookup("Predictor", &obj);
      if (obj.isInt())
	pred = obj.getInt();
      obj.free();
      params->dictLookup("Columns", &obj);
      if (obj.isInt())
	columns = obj.getInt();
      obj.free();
      params->dictLookup("Colors", &obj);
      if (obj.isInt())
	colors = obj.getInt();
      obj.free();
      params->dictLookup("BitsPerComponent", &obj);
      if (obj.isInt())
	bits = obj.getInt();
      obj.free();
    }
    str = new FlateStream(str, pred, columns, colors, bits);
  } else if (!strcmp(name, "JBIG2Decode")) {
    if (params->isDict()) {
      params->dictLookup("JBIG2Globals", &globals);
    }
    str = new JBIG2Stream(str, &globals);
    globals.free();
  } else if (!strcmp(name, "JPXDecode")) {
    str = new JPXStream(str);
  } else {
    error(getPos(), "Unknown filter '%s'", name);
    str = new EOFStream(str);
  }
  return str;
}

//------------------------------------------------------------------------
// BaseStream
//------------------------------------------------------------------------

BaseStream::BaseStream(Object *dictA) {
  dict = *dictA;
}

BaseStream::~BaseStream() {
  dict.free();
}

//------------------------------------------------------------------------
// FilterStream
//------------------------------------------------------------------------

FilterStream::FilterStream(Stream *strA) {
  str = strA;
}

FilterStream::~FilterStream() {
}

void FilterStream::close() {
  str->close();
}

void FilterStream::setPos(Guint pos, int dir) {
  error(-1, "Internal: called setPos() on FilterStream");
}

//------------------------------------------------------------------------
// ImageStream
//------------------------------------------------------------------------

ImageStream::ImageStream(Stream *strA, int widthA, int nCompsA, int nBitsA) {
  int imgLineSize;

  str = strA;
  width = widthA;
  nComps = nCompsA;
  nBits = nBitsA;

  nVals = width * nComps;
  if (nBits == 1) {
    imgLineSize = (nVals + 7) & ~7;
  } else {
    imgLineSize = nVals;
  }
  imgLine = (Guchar *)gmallocn(imgLineSize, sizeof(Guchar));
  imgIdx = nVals;
}

ImageStream::~ImageStream() {
  gfree(imgLine);
}

void ImageStream::reset() {
  str->reset();
}

GBool ImageStream::getPixel(Guchar *pix) {
  int i;

  if (imgIdx >= nVals) {
    getLine();
    imgIdx = 0;
  }
  for (i = 0; i < nComps; ++i) {
    pix[i] = imgLine[imgIdx++];
  }
  return gTrue;
}

Guchar *ImageStream::getLine() {
  Gulong buf, bitMask;
  int bits;
  int c;
  int i;

  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;
    }
  }
  return imgLine;
}

void ImageStream::skipLine() {
  int n, i;

  n = (nVals * nBits + 7) >> 3;
  for (i = 0; i < n; ++i) {
    str->getChar();
  }
}

//------------------------------------------------------------------------
// StreamPredictor
//------------------------------------------------------------------------

StreamPredictor::StreamPredictor(Stream *strA, int predictorA,
				 int widthA, int nCompsA, int nBitsA) {
  str = strA;
  predictor = predictorA;
  width = widthA;
  nComps = nCompsA;
  nBits = nBitsA;
  predLine = NULL;
  ok = gFalse;

  nVals = width * nComps;
  if (width <= 0 || nComps <= 0 || nBits <= 0 ||
      nComps >= INT_MAX / nBits ||
      width >= INT_MAX / nComps / nBits ||
      nVals * nBits + 7 < 0) {
    return;
  }
  pixBytes = (nComps * nBits + 7) >> 3;
  rowBytes = ((nVals * nBits + 7) >> 3) + pixBytes;
  if (rowBytes <= 0) {
    return;
  }
  predLine = (Guchar *)gmalloc(rowBytes);
  memset(predLine, 0, rowBytes);
  predIdx = rowBytes;

  ok = gTrue;
}

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[gfxColorMaxComps * 2 + 1];
  int left, up, upLeft, p, pa, pb, pc;
  int c;
  Gulong inBuf, outBuf, bitMask;
  int inBits, outBits;
  int i, j, k, kk;

  // get PNG optimum predictor number
  if (predictor >= 10) {
    if ((curPred = str->getRawChar()) == EOF) {
      return gFalse;
    }
    curPred += 10;
  } else {
    curPred = predictor;
  }

  // read the raw line, apply PNG (byte) predictor
  memset(upLeftBuf, 0, pixBytes + 1);
  for (i = pixBytes; i < rowBytes; ++i) {
    for (j = pixBytes; j > 0; --j) {
      upLeftBuf[j] = upLeftBuf[j-1];
    }
    upLeftBuf[0] = predLine[i];
    if ((c = str->getRawChar()) == EOF) {
      if (i > pixBytes) {
	// this ought to return false, but some (broken) PDF files
	// contain truncated image data, and Adobe apparently reads the
	// last partial line
	break;
      }
      return gFalse;
    }
    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] = left + (Guchar)c;
      else if (pb <= pc)
	predLine[i] = up + (Guchar)c;
      else
	predLine[i] = upLeft + (Guchar)c;
      break;
    case 10:			// PNG none
    default:			// no predictor or TIFF predictor
      predLine[i] = (Guchar)c;
      break;
    }
  }

  // apply TIFF (component) predictor
  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 {
      memset(upLeftBuf, 0, nComps + 1);
      bitMask = (1 << nBits) - 1;
      inBuf = outBuf = 0;
      inBits = outBits = 0;
      j = k = pixBytes;
      for (i = 0; i < width; ++i) {
	for (kk = 0; kk < nComps; ++kk) {
	  if (inBits < nBits) {
	    inBuf = (inBuf << 8) | (predLine[j++] & 0xff);
	    inBits += 8;
	  }
	  upLeftBuf[kk] = (Guchar)((upLeftBuf[kk] +
				    (inBuf >> (inBits - nBits))) & bitMask);
	  inBits -= nBits;
	  outBuf = (outBuf << nBits) | upLeftBuf[kk];
	  outBits += nBits;
	  if (outBits >= 8) {
	    predLine[k++] = (Guchar)(outBuf >> (outBits - 8));
	    outBits -= 8;
	  }
	}
      }
      if (outBits > 0) {
	predLine[k++] = (Guchar)((outBuf << (8 - outBits)) +
				 (inBuf & ((1 << (8 - outBits)) - 1)));
      }
    }
  }

  // reset to start of line
  predIdx = pixBytes;

  return gTrue;
}

//------------------------------------------------------------------------
// FileStream
//------------------------------------------------------------------------

FileStream::FileStream(FILE *fA, Guint startA, GBool limitedA,
		       Guint lengthA, Object *dictA):
    BaseStream(dictA) {
  f = fA;
  start = startA;
  limited = limitedA;
  length = lengthA;