splash/SplashScreen.h

//========================================================================
//
// SplashScreen.h
//
//========================================================================

//========================================================================
//
// Modified under the Poppler project - http://poppler.freedesktop.org
//
// All changes made under the Poppler project to this file are licensed
// under GPL version 2 or later
//
// Copyright (C) 2009, 2018 Albert Astals Cid <aacid@kde.org>
//
// To see a description of the changes please see the Changelog file that
// came with your tarball or type make ChangeLog if you are building from git
//
//========================================================================

#ifndef SPLASHSCREEN_H
#define SPLASHSCREEN_H

#include "SplashTypes.h"

#include <stdlib.h>

//------------------------------------------------------------------------
// SplashScreen
//------------------------------------------------------------------------

class SplashScreen {
public:

  SplashScreen(SplashScreenParams *params);
  SplashScreen(SplashScreen *screen);
  ~SplashScreen();

  SplashScreen(const SplashScreen&) = delete;
  SplashScreen& operator=(const SplashScreen&) = delete;

  SplashScreen *copy() { return new SplashScreen(this); }

  // Return the computed pixel value (0=black, 1=white) for the gray
  // level <value> at (<x>, <y>).
  int test(int x, int y, unsigned char value) {
    int xx, yy;
    if (mat == nullptr) createMatrix();
    xx = x & sizeM1;
    yy = y & sizeM1;
    return value < mat[(yy << log2Size) + xx] ? 0 : 1;
  }

  // Returns true if value is above the white threshold or below the
  // black threshold, i.e., if the corresponding halftone will be
  // solid white or black.
  bool isStatic(unsigned char value) { if (mat == nullptr) createMatrix(); return value < minVal || value >= maxVal; }

private:
  void createMatrix();

  void buildDispersedMatrix(int i, int j, int val,
			    int delta, int offset);
  void buildClusteredMatrix();
  int distance(int x0, int y0, int x1, int y1);
  void buildSCDMatrix(int r);

  SplashScreenParams *screenParams;	// params to create the other members
  unsigned char *mat;			// threshold matrix
  int size;			// size of the threshold matrix
  int sizeM1;			// size - 1
  int log2Size;			// log2(size)
  unsigned char minVal;		// any pixel value below minVal generates
				//   solid black
  unsigned char maxVal;		// any pixel value above maxVal generates
				//   solid white
};

#endif