mfx.cpp

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/******************************************************************************
 ** Filename:       mfx.c
 ** Purpose:        Micro feature extraction routines
 ** Author:         Dan Johnson
 **
 ** (c) Copyright Hewlett-Packard Company, 1988.
 ** Licensed under the Apache License, Version 2.0 (the "License");
 ** you may not use this file except in compliance with the License.
 ** You may obtain a copy of the License at
 ** http://www.apache.org/licenses/LICENSE-2.0
 ** Unless required by applicable law or agreed to in writing, software
 ** distributed under the License is distributed on an "AS IS" BASIS,
 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 ** See the License for the specific language governing permissions and
 ** limitations under the License.
 *****************************************************************************/
 
#include "mfx.h"
 
#include "clusttool.h" //NEEDED
#include "intfx.h"
#include "mfdefs.h"
#include "mfoutline.h"
#include "normalis.h"
#include "params.h"
 
namespace tesseract {
 
/* old numbers corresponded to 10.0 degrees and 80.0 degrees */
double_VAR(classify_min_slope, 0.414213562, "Slope below which lines are called horizontal");
double_VAR(classify_max_slope, 2.414213562, "Slope above which lines are called vertical");
 
/*----------------------------------------------------------------------------
          Private Function Prototypes
-----------------------------------------------------------------------------*/
 
MICROFEATURES ConvertToMicroFeatures(MFOUTLINE Outline, MICROFEATURES MicroFeatures);
 
MicroFeature ExtractMicroFeature(MFOUTLINE Start, MFOUTLINE End);
 
/*----------------------------------------------------------------------------
            Public Code
----------------------------------------------------------------------------*/
 
MICROFEATURES BlobMicroFeatures(TBLOB *Blob, const DENORM &cn_denorm) {
  MICROFEATURES MicroFeatures;
  LIST Outlines;
  LIST RemainingOutlines;
 
  if (Blob != nullptr) {
    Outlines = ConvertBlob(Blob);
 
    RemainingOutlines = Outlines;
    iterate(RemainingOutlines) {
      auto Outline = static_cast<MFOUTLINE>(RemainingOutlines->first_node());
      CharNormalizeOutline(Outline, cn_denorm);
    }
 
    RemainingOutlines = Outlines;
    iterate(RemainingOutlines) {
      auto Outline = static_cast<MFOUTLINE>(RemainingOutlines->first_node());
      FindDirectionChanges(Outline, classify_min_slope, classify_max_slope);
      MarkDirectionChanges(Outline);
      MicroFeatures = ConvertToMicroFeatures(Outline, MicroFeatures);
    }
    FreeOutlines(Outlines);
  }
  return MicroFeatures;
} /* BlobMicroFeatures */
 
/*---------------------------------------------------------------------------
            Private Code
---------------------------------------------------------------------------*/
 
MICROFEATURES ConvertToMicroFeatures(MFOUTLINE Outline, MICROFEATURES MicroFeatures) {
  MFOUTLINE Current;
  MFOUTLINE Last;
  MFOUTLINE First;
 
  if (DegenerateOutline(Outline)) {
    return (MicroFeatures);
  }
 
  First = NextExtremity(Outline);
  Last = First;
  do {
    Current = NextExtremity(Last);
    if (!PointAt(Current)->Hidden) {
      auto NewFeature = ExtractMicroFeature(Last, Current);
      MicroFeatures.push_front(NewFeature);
    }
    Last = Current;
  } while (Last != First);
 
  return MicroFeatures;
} /* ConvertToMicroFeatures */
 
MicroFeature ExtractMicroFeature(MFOUTLINE Start, MFOUTLINE End) {
  MFEDGEPT *P1, *P2;
 
  P1 = PointAt(Start);
  P2 = PointAt(End);
 
  MicroFeature NewFeature;
  NewFeature[(int)MicroFeatureParameter::MFXPosition] = AverageOf(P1->Point.x, P2->Point.x);
  NewFeature[(int)MicroFeatureParameter::MFYPosition] = AverageOf(P1->Point.y, P2->Point.y);
  NewFeature[(int)MicroFeatureParameter::MFLength] = DistanceBetween(P1->Point, P2->Point);
  NewFeature[(int)MicroFeatureParameter::MFDirection] = NormalizedAngleFrom(&P1->Point, &P2->Point, 1.0);
  NewFeature[(int)MicroFeatureParameter::MFBulge1] = 0.0f;  // deprecated
  NewFeature[(int)MicroFeatureParameter::MFBulge2] = 0.0f; // deprecated
 
  return NewFeature;
} /* ExtractMicroFeature */
 
} // namespace tesseract