function.cc

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//========================================================================
//
// Function.cc
//
// Copyright 2001-2002 Glyph & Cog, LLC
//
//========================================================================

#include <aconf.h>

#ifdef USE_GCC_PRAGMAS
#pragma implementation
#endif

#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <math.h>
#include "gmem.h"
#include "Object.h"
#include "Dict.h"
#include "Stream.h"
#include "Error.h"
#include "Function.h"

//------------------------------------------------------------------------
// Function
//------------------------------------------------------------------------

Function::Function() {
}

Function::~Function() {
}

Function *Function::parse(Object *funcObj) {
  Function *func;
  Dict *dict;
  int funcType;
  Object obj1;

  if (funcObj->isStream()) {
    dict = funcObj->streamGetDict();
  } else if (funcObj->isDict()) {
    dict = funcObj->getDict();
  } else if (funcObj->isName("Identity")) {
    return new IdentityFunction();
  } else {
    error(-1, "Expected function dictionary or stream");
    return NULL;
  }

  if (!dict->lookup("FunctionType", &obj1)->isInt()) {
    error(-1, "Function type is missing or wrong type");
    obj1.free();
    return NULL;
  }
  funcType = obj1.getInt();
  obj1.free();

  if (funcType == 0) {
    func = new SampledFunction(funcObj, dict);
  } else if (funcType == 2) {
    func = new ExponentialFunction(funcObj, dict);
  } else if (funcType == 3) {
    func = new StitchingFunction(funcObj, dict);
  } else if (funcType == 4) {
    func = new PostScriptFunction(funcObj, dict);
  } else {
    error(-1, "Unimplemented function type (%d)", funcType);
    return NULL;
  }
  if (!func->isOk()) {
    delete func;
    return NULL;
  }

  return func;
}

GBool Function::init(Dict *dict) {
  Object obj1, obj2;
  int i;

  //----- Domain
  if (!dict->lookup("Domain", &obj1)->isArray()) {
    error(-1, "Function is missing domain");
    goto err2;
  }
  m = obj1.arrayGetLength() / 2;
  if (m > funcMaxInputs) {
    error(-1, "Functions with more than %d inputs are unsupported",
	  funcMaxInputs);
    goto err2;
  }
  for (i = 0; i < m; ++i) {
    obj1.arrayGet(2*i, &obj2);
    if (!obj2.isNum()) {
      error(-1, "Illegal value in function domain array");
      goto err1;
    }
    domain[i][0] = obj2.getNum();
    obj2.free();
    obj1.arrayGet(2*i+1, &obj2);
    if (!obj2.isNum()) {
      error(-1, "Illegal value in function domain array");
      goto err1;
    }
    domain[i][1] = obj2.getNum();
    obj2.free();
  }
  obj1.free();

  //----- Range
  hasRange = gFalse;
  n = 0;
  if (dict->lookup("Range", &obj1)->isArray()) {
    hasRange = gTrue;
    n = obj1.arrayGetLength() / 2;
    if (n > funcMaxOutputs) {
      error(-1, "Functions with more than %d outputs are unsupported",
	    funcMaxOutputs);
      goto err2;
    }
    for (i = 0; i < n; ++i) {
      obj1.arrayGet(2*i, &obj2);
      if (!obj2.isNum()) {
	error(-1, "Illegal value in function range array");
	goto err1;
      }
      range[i][0] = obj2.getNum();
      obj2.free();
      obj1.arrayGet(2*i+1, &obj2);
      if (!obj2.isNum()) {
	error(-1, "Illegal value in function range array");
	goto err1;
      }
      range[i][1] = obj2.getNum();
      obj2.free();
    }
  }
  obj1.free();

  return gTrue;

 err1:
  obj2.free();
 err2:
  obj1.free();
  return gFalse;
}

//------------------------------------------------------------------------
// IdentityFunction
//------------------------------------------------------------------------

IdentityFunction::IdentityFunction() {
  int i;

  // fill these in with arbitrary values just in case they get used
  // somewhere
  m = funcMaxInputs;
  n = funcMaxOutputs;
  for (i = 0; i < funcMaxInputs; ++i) {
    domain[i][0] = 0;
    domain[i][1] = 1;
  }
  hasRange = gFalse;
}

IdentityFunction::~IdentityFunction() {
}

void IdentityFunction::transform(double *in, double *out) {
  int i;

  for (i = 0; i < funcMaxOutputs; ++i) {
    out[i] = in[i];
  }
}

//------------------------------------------------------------------------
// SampledFunction
//------------------------------------------------------------------------

SampledFunction::SampledFunction(Object *funcObj, Dict *dict) {
  Stream *str;
  int nSamples, sampleBits;
  double sampleMul;
  Object obj1, obj2;
  Guint buf, bitMask;
  int bits;
  int s;
  int i;

  samples = NULL;
  ok = gFalse;

  //----- initialize the generic stuff
  if (!init(dict)) {
    goto err1;
  }
  if (!hasRange) {
    error(-1, "Type 0 function is missing range");
    goto err1;
  }

  //----- get the stream
  if (!funcObj->isStream()) {
    error(-1, "Type 0 function isn't a stream");
    goto err1;
  }
  str = funcObj->getStream();

  //----- Size
  if (!dict->lookup("Size", &obj1)->isArray() ||
      obj1.arrayGetLength() != m) {
    error(-1, "Function has missing or invalid size array");
    goto err2;
  }
  for (i = 0; i < m; ++i) {
    obj1.arrayGet(i, &obj2);
    if (!obj2.isInt()) {
      error(-1, "Illegal value in function size array");
      goto err3;
    }
    sampleSize[i] = obj2.getInt();
    obj2.free();
  }
  obj1.free();

  //----- BitsPerSample
  if (!dict->lookup("BitsPerSample", &obj1)->isInt()) {
    error(-1, "Function has missing or invalid BitsPerSample");
    goto err2;
  }
  sampleBits = obj1.getInt();
  sampleMul = 1.0 / (double)((1 << sampleBits) - 1);
  obj1.free();

  //----- Encode
  if (dict->lookup("Encode", &obj1)->isArray() &&
      obj1.arrayGetLength() == 2*m) {
    for (i = 0; i < m; ++i) {
      obj1.arrayGet(2*i, &obj2);
      if (!obj2.isNum()) {
	error(-1, "Illegal value in function encode array");
	goto err3;
      }
      encode[i][0] = obj2.getNum();
      obj2.free();
      obj1.arrayGet(2*i+1, &obj2);
      if (!obj2.isNum()) {
	error(-1, "Illegal value in function encode array");
	goto err3;
      }
      encode[i][1] = obj2.getNum();
      obj2.free();
    }
  } else {
    for (i = 0; i < m; ++i) {
      encode[i][0] = 0;
      encode[i][1] = sampleSize[i] - 1;
    }
  }
  obj1.free();

  //----- Decode
  if (dict->lookup("Decode", &obj1)->isArray() &&
      obj1.arrayGetLength() == 2*n) {
    for (i = 0; i < n; ++i) {
      obj1.arrayGet(2*i, &obj2);
      if (!obj2.isNum()) {
	error(-1, "Illegal value in function decode array");
	goto err3;
      }
      decode[i][0] = obj2.getNum();
      obj2.free();
      obj1.arrayGet(2*i+1, &obj2);
      if (!obj2.isNum()) {
	error(-1, "Illegal value in function decode array");
	goto err3;
      }
      decode[i][1] = obj2.getNum();
      obj2.free();
    }
  } else {
    for (i = 0; i < n; ++i) {
      decode[i][0] = range[i][0];
      decode[i][1] = range[i][1];
    }
  }
  obj1.free();

  //----- samples
  nSamples = n;
  for (i = 0; i < m; ++i)
    nSamples *= sampleSize[i];
  samples = (double *)gmalloc(nSamples * sizeof(double));
  buf = 0;
  bits = 0;
  bitMask = (1 << sampleBits) - 1;
  str->reset();
  for (i = 0; i < nSamples; ++i) {
    if (sampleBits == 8) {
      s = str->getChar();
    } else if (sampleBits == 16) {
      s = str->getChar();
      s = (s << 8) + str->getChar();
    } else if (sampleBits == 32) {
      s = str->getChar();
      s = (s << 8) + str->getChar();
      s = (s << 8) + str->getChar();
      s = (s << 8) + str->getChar();
    } else {
      while (bits < sampleBits) {
	buf = (buf << 8) | (str->getChar() & 0xff);
	bits += 8;
      }
      s = (buf >> (bits - sampleBits)) & bitMask;
      bits -= sampleBits;
    }
    samples[i] = (double)s * sampleMul;
  }
  str->close();

  ok = gTrue;
  return;

 err3:
  obj2.free();
 err2:
  obj1.free();
 err1:
  return;
}

SampledFunction::~SampledFunction() {
  if (samples) {
    gfree(samples);
  }
}

SampledFunction::SampledFunction(SampledFunction *func) {
  int nSamples, i;

  memcpy(this, func, sizeof(SampledFunction));

  nSamples = n;
  for (i = 0; i < m; ++i) {
    nSamples *= sampleSize[i];
  }
  samples = (double *)gmalloc(nSamples * sizeof(double));
  memcpy(samples, func->samples, nSamples * sizeof(double));
}

void SampledFunction::transform(double *in, double *out) {
  double x;
  int e[2][funcMaxInputs];
  double efrac[funcMaxInputs];
  double s0[1 << funcMaxInputs], s1[1 << funcMaxInputs];
  int i, j, k, idx;

  // map input values into sample array
  for (i = 0; i < m; ++i) {
    x = ((in[i] - domain[i][0]) / (domain[i][1] - domain[i][0])) *
        (encode[i][1] - encode[i][0]) + encode[i][0];
    if (x < 0) {
      x = 0;
    } else if (x > sampleSize[i] - 1) {
      x = sampleSize[i] - 1;
    }
    e[0][i] = (int)floor(x);
    e[1][i] = (int)ceil(x);
    efrac[i] = x - e[0][i];
  }

  // for each output, do m-linear interpolation
  for (i = 0; i < n; ++i) {

    // pull 2^m values out of the sample array
    for (j = 0; j < (1<<m); ++j) {
      idx = e[j & 1][m - 1];
      for (k = m - 2; k >= 0; --k) {
	idx = idx * sampleSize[k] + e[(j >> k) & 1][k];
      }
      idx = idx * n + i;
      s0[j] = samples[idx];
    }

    // do m sets of interpolations
    for (j = 0; j < m; ++j) {
      for (k = 0; k < (1 << (m - j)); k += 2) {
	s1[k >> 1] = (1 - efrac[j]) * s0[k] + efrac[j] * s0[k+1];
      }
      memcpy(s0, s1, (1 << (m - j - 1)) * sizeof(double));
    }

    // map output value to range
    out[i] = s0[0] * (decode[i][1] - decode[i][0]) + decode[i][0];
    if (out[i] < range[i][0]) {
      out[i] = range[i][0];
    } else if (out[i] > range[i][1]) {
      out[i] = range[i][1];
    }
  }
}

//------------------------------------------------------------------------
// ExponentialFunction
//------------------------------------------------------------------------

ExponentialFunction::ExponentialFunction(Object *funcObj, Dict *dict) {
  Object obj1, obj2;
  GBool hasN;
  int i;

  ok = gFalse;

  //----- initialize the generic stuff
  if (!init(dict)) {
    goto err1;
  }
  if (m != 1) {
    error(-1, "Exponential function with more than one input");
    goto err1;
  }
  hasN = hasRange;

  //----- default values
  for (i = 0; i < funcMaxOutputs; ++i) {
    c0[i] = 0;
    c1[i] = 1;
  }

  //----- C0
  if (dict->lookup("C0", &obj1)->isArray()) {
    if (!hasN) {
      n = obj1.arrayGetLength();
      hasN = gTrue;
    } else if (obj1.arrayGetLength() != n) {
      error(-1, "Function's C0 array is wrong length");
      goto err2;
    }
    for (i = 0; i < n; ++i) {
      obj1.arrayGet(i, &obj2);
      if (!obj2.isNum()) {
	error(-1, "Illegal value in function C0 array");
	goto err3;
      }
      c0[i] = obj2.getNum();
      obj2.free();
    }
  }
  obj1.free();

  //----- C1
  if (dict->lookup("C1", &obj1)->isArray()) {
    if (!hasN) {
      n = obj1.arrayGetLength();
      hasN = gTrue;
    } else if (obj1.arrayGetLength() != n) {
      error(-1, "Function's C1 array is wrong length");
      goto err2;
    }
    for (i = 0; i < n; ++i) {
      obj1.arrayGet(i, &obj2);
      if (!obj2.isNum()) {
	error(-1, "Illegal value in function C1 array");
	goto err3;
      }
      c1[i] = obj2.getNum();
      obj2.free();
    }
  }
  obj1.free();

  //----- N (exponent)
  if (!dict->lookup("N", &obj1)->isNum()) {
    error(-1, "Function has missing or invalid N");
    goto err2;
  }
  e = obj1.getNum();
  obj1.free();

  // this isn't supposed to happen, but I've run into (broken) PDF
  // files where it does
  if (!hasN) {
    error(-1, "Exponential function does not define number of output values");
    n = 1;
  }

  ok = gTrue;
  return;

 err3:
  obj2.free();
 err2:
  obj1.free();
 err1:
  return;
}

ExponentialFunction::~ExponentialFunction() {
}

ExponentialFunction::ExponentialFunction(ExponentialFunction *func) {
  memcpy(this, func, sizeof(ExponentialFunction));