quspline.h

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/**********************************************************************
 * File:        quspline.h  (Formerly qspline.h)
 * Description: Code for the QSPLINE class.
 * Author:      Ray Smith
 * Created:     Tue Oct 08 17:16:12 BST 1991
 *
 * (C) Copyright 1991, Hewlett-Packard Ltd.
 ** 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.
 *
 **********************************************************************/
 
#ifndef QUSPLINE_H
#define QUSPLINE_H
 
#include "scrollview.h" // for ScrollView, ScrollView::Color
 
#include <cstdint> // for int32_t
 
struct Pix;
 
namespace tesseract {
 
class ICOORD;
class QUAD_COEFFS;
class ROW;
class TBOX;
 
class TESS_API QSPLINE {
  friend void make_first_baseline(TBOX *, int, int *, int *, QSPLINE *, QSPLINE *, float);
  friend void make_holed_baseline(TBOX *, int, QSPLINE *, QSPLINE *, float);
  friend void tweak_row_baseline(ROW *, double, double);
 
public:
  QSPLINE() { // empty constructor
    segments = 0;
    xcoords = nullptr; // everything empty
    quadratics = nullptr;
  }
  QSPLINE( // copy constructor
      const QSPLINE &src);
  QSPLINE(                          // constructor
      int32_t count,                // number of segments
      int32_t *xstarts,             // segment starts
      double *coeffs);              // coefficients
  ~QSPLINE();                       // destructor
  QSPLINE(                          // least squares fit
      int xstarts[],                // spline boundaries
      int segcount,                 // no of segments
      int xcoords[],                // points to fit
      int ycoords[], int blobcount, // no of coords
      int degree);                  // function
 
  double step(   // step change
      double x1, // between coords
      double x2);
  double y(            // evaluate
      double x) const; // at x
 
  void move(            // reposition spline
      ICOORD vec);      // by vector
  bool overlap(         // test overlap
      QSPLINE *spline2, // 2 cannot be smaller
      double fraction); // by more than this
  void extrapolate(     // linear extrapolation
      double gradient,  // gradient to use
      int left,         // new left edge
      int right);       // new right edge
 
#ifndef GRAPHICS_DISABLED
  void plot(                           // draw it
      ScrollView *window,              // in window
      ScrollView::Color colour) const; // in colour
#endif
 
  // Paint the baseline over pix. If pix has depth of 32, then the line will
  // be painted in red. Otherwise it will be painted in black.
  void plot(Image pix) const;
 
  QSPLINE &operator=(const QSPLINE &source); // from this
 
private:
  int32_t spline_index(    // binary search
      double x) const;     // for x
  int32_t segments;        // no of segments
  int32_t *xcoords;        // no of coords
  QUAD_COEFFS *quadratics; // spline pieces
};
 
} // namespace tesseract
 
#endif