fltk/src/Fl_Valuator.cxx

//
// "$Id$"
//
// Valuator widget for the Fast Light Tool Kit (FLTK).
//
// Copyright 1998-2008 by Bill Spitzak and others.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Library General Public
// License as published by the Free Software Foundation; either
// version 2 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Library General Public License for more details.
//
// You should have received a copy of the GNU Library General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
// USA.
//
// Please report all bugs and problems on the following page:
//
//     http://www.fltk.org/str.php
//

/** \fn int Fl_Valuator::changed() const
  This value is true if the user has moved the slider. It is
  turned off by value(x) and just before doing a callback
  (the callback can turn it back on if desired).
*/

// Base class for sliders and all other one-value "knobs"

#include <FL/Fl.H>
#include <FL/Fl_Valuator.H>
#include <FL/math.h>
#include <stdio.h>
#include "flstring.h"

Fl_Valuator::Fl_Valuator(int X, int Y, int W, int H, const char* L)
/**
  Creates a new Fl_Valuator widget using the given position,
  size, and label string. The default boxtype is FL_NO_BOX.
*/
: Fl_Widget(X,Y,W,H,L) {
  align(FL_ALIGN_BOTTOM);
  when(FL_WHEN_CHANGED);
  value_ = 0;
  previous_value_ = 1;
  min = 0;
  max = 1;
  A = 0.0;
  B = 1;
}

const double epsilon = 4.66e-10;

/**  See double Fl_Valuator::step() const */
void Fl_Valuator::step(double s) {
  if (s < 0) s = -s;
  A = rint(s);
  B = 1;
  while (fabs(s-A/B) > epsilon && B<=(0x7fffffff/10)) {B *= 10; A = rint(s*B);}
}

/**  Sets the step value to 1/10<SUP>digits.*/
void Fl_Valuator::precision(int p) {
  A = 1.0;
  for (B = 1; p--;) B *= 10;
}
/** Asks for partial redraw */
void Fl_Valuator::value_damage() {damage(FL_DAMAGE_EXPOSE);} // by default do partial-redraw

/**  See double Fl_Valuator::value() const */
int Fl_Valuator::value(double v) {
  clear_changed();
  if (v == value_) return 0;
  value_ = v;
  value_damage();
  return 1;
}

double Fl_Valuator::softclamp(double v) {
  int which = (min<=max);
  double p = previous_value_;
  if ((v<min)==which && p!=min && (p<min)!=which) return min;
  else if ((v>max)==which && p!=max && (p>max)!=which) return max;
  else return v;
}

// inline void Fl_Valuator::handle_push() {previous_value_ = value_;}

void Fl_Valuator::handle_drag(double v) {
  if (v != value_) {
    value_ = v;
    value_damage();
    set_changed();
    if (when() & FL_WHEN_CHANGED) do_callback();
  }
}

void Fl_Valuator::handle_release() {
  if (when()&FL_WHEN_RELEASE) {
    // insure changed() is off even if no callback is done.  It may have
    // been turned on by the drag, and then the slider returned to it's
    // initial position:
    clear_changed();
    // now do the callback only if slider in new position or always is on:
    if (value_ != previous_value_ || when() & FL_WHEN_NOT_CHANGED) {
      do_callback();
    }
  }
}

/**
  Round the passed value to the nearest step increment.  Does
  nothing if step is zero.
*/
double Fl_Valuator::round(double v) {
  if (A) return rint(v*B/A)*A/B;
  else return v;
}

/**  Clamps the passed value to the valuator range.*/
double Fl_Valuator::clamp(double v) {
  if ((v<min)==(min<=max)) return min;
  else if ((v>max)==(min<=max)) return max;
  else return v;
}

/**
  Adds n times the step value to the passed value. If
  step was set to zero it uses fabs(maximum() - minimum()) /
  100.
*/
double Fl_Valuator::increment(double v, int n) {
  if (!A) return v+n*(max-min)/100;
  if (min > max) n = -n;
  return (rint(v*B/A)+n)*A/B;
}

/**
  Uses internal rules to format the fields numerical value into
  the character array pointed to by the passed parameter.</P>
  
  <P>The actual format used depends on the current step value. If
  the step value has been set to zero then a %g format is used.
  If the step value is non-zero, then a %.*f format is used,
  where the precision is calculated to show sufficient digits
  for the current step value. An integer step value, such as 1
  or 1.0, gives a precision of 0, so the formatted value will
  appear as an integer.</P>
  
  <P>This method is used by the Fl_Value_... group of widgets to 
  format the current value into a text string. 
  The return value is the length of the formatted text.
  The formatted value is written into in <i>buffer</i>. 
  <i>buffer</i> should have space for at least 128 bytes.</P>
  
  <P>You may override this function to create your own text formatting.
*/
int Fl_Valuator::format(char* buffer) {
  double v = value();
  // MRS: THIS IS A HACK - RECOMMEND ADDING BUFFER SIZE ARGUMENT
  if (!A || !B) return snprintf(buffer, 128, "%g", v);

  // Figure out how many digits are required to correctly format the
  // value.
  int i, c = 0;
  char temp[32];
  // output a number with many digits after the decimal point. This
  // seems to be needed to get high precission
  snprintf(temp, sizeof(temp), "%.12f", A/B);
  // strip all trailing 0's
  for (i=strlen(temp)-1; i>0; i--) {
    if (temp[i]!='0') break;
  }
  // count digits until we find the decimal point (or comma or whatever
  // letter is set in the current locale)
  for (; i>0; i--, c++) {
    if (!isdigit(temp[i])) break;
  }

  // MRS: THIS IS A HACK - RECOMMEND ADDING BUFFER SIZE ARGUMENT
  return snprintf(buffer, 128, "%.*f", c, v);
}

//
// End of "$Id$".
//