fltk/src/Fl_Roller.cxx

//
// Roller widget for the Fast Light Tool Kit (FLTK).
//
// Copyright 1998-2010 by Bill Spitzak and others.
//
// This library is free software. Distribution and use rights are outlined in
// the file "COPYING" which should have been included with this file.  If this
// file is missing or damaged, see the license at:
//
//     https://www.fltk.org/COPYING.php
//
// Please see the following page on how to report bugs and issues:
//
//     https://www.fltk.org/bugs.php
//

// Rapid-App style knob

#include <FL/Fl.H>
#include <FL/Fl_Roller.H>
#include <FL/fl_draw.H>
#include <math.h>

int Fl_Roller::handle(int event) {
  static int ipos;
  int newpos = horizontal() ? Fl::event_x() : Fl::event_y();
  switch (event) {
    case FL_PUSH:
      if (Fl::visible_focus()) {
        Fl::focus(this);
        redraw();
      }
      handle_push();
      ipos = newpos;
      return 1;
    case FL_DRAG:
      handle_drag(clamp(round(increment(previous_value(),newpos-ipos))));
      return 1;
    case FL_RELEASE:
      handle_release();
      return 1;
    case FL_MOUSEWHEEL :
      if (Fl::belowmouse()==this) {
        if (horizontal()) {
          if (Fl::e_dx!=0) {
            handle_drag(clamp(round(increment(value(),-Fl::e_dx))));
          }
        } else {
          if (Fl::e_dy!=0) {
            handle_drag(clamp(round(increment(value(),-Fl::e_dy))));
          }
        }
        return 1;
      } else {
        return 0;
      }
    case FL_KEYBOARD :
      switch (Fl::event_key()) {
        case FL_Up:
          if (horizontal()) return 0;
          handle_drag(clamp(increment(value(),-1)));
          return 1;
        case FL_Down:
          if (horizontal()) return 0;
          handle_drag(clamp(increment(value(),1)));
          return 1;
        case FL_Left:
          if (!horizontal()) return 0;
          handle_drag(clamp(increment(value(),-1)));
          return 1;
        case FL_Right:
          if (!horizontal()) return 0;
          handle_drag(clamp(increment(value(),1)));
          return 1;
        default:
          return 0;
      }
      // break not required because of switch...
    case FL_FOCUS :
    case FL_UNFOCUS :
      if (Fl::visible_focus()) {
        redraw();
        return 1;
      } else return 0;
    case FL_ENTER :
    case FL_LEAVE :
      return 1;
    default:
      return 0;
  }
}

void Fl_Roller::draw() {
  if (damage()&FL_DAMAGE_ALL) draw_box();
  int X = x()+Fl::box_dx(box());
  int Y = y()+Fl::box_dy(box());
  int W = w()-Fl::box_dw(box())-1;
  int H = h()-Fl::box_dh(box())-1;
  if (W<=0 || H <=0) return;
  int offset = step() ? int(value()/step()) : 0;
  const double ARC = 1.5; // 1/2 the number of radians visible
  const double delta = .2; // radians per knurl
  if (horizontal()) { // horizontal one
    // draw shaded ends of wheel:
    int h1 = W/4+1; // distance from end that shading starts
    fl_color(color()); fl_rectf(X+h1,Y,W-2*h1,H);
    for (int i=0; h1; i++) {
      fl_color((Fl_Color)(FL_GRAY-i-1));
      int h2 = FL_GRAY-i-1 > FL_DARK3 ? 2*h1/3+1 : 0;
      fl_rectf(X+h2,Y,h1-h2,H);
      fl_rectf(X+W-h1,Y,h1-h2,H);
      h1 = h2;
    }
    if (active_r()) {
      // draw ridges:
      double junk;
      for (double yy = -ARC+modf(offset*sin(ARC)/(W/2)/delta,&junk)*delta;;
           yy += delta) {
        int yy1 = int((sin(yy)/sin(ARC)+1)*W/2);
        if (yy1 <= 0) continue; else if (yy1 >= W-1) break;
        fl_color(FL_DARK3); fl_yxline(X+yy1,Y+1,Y+H-1);
        if (yy < 0) yy1--; else yy1++;
        fl_color(FL_LIGHT1);fl_yxline(X+yy1,Y+1,Y+H-1);
      }
      // draw edges:
      h1 = W/8+1; // distance from end the color inverts
      fl_color(FL_DARK2);
      fl_xyline(X+h1,Y+H-1,X+W-h1);
      fl_color(FL_DARK3);
      fl_yxline(X,Y+H,Y,X+h1);
      fl_xyline(X+W-h1,Y,X+W);
      fl_color(FL_LIGHT2);
      fl_xyline(X+h1,Y-1,X+W-h1);
      fl_yxline(X+W,Y,Y+H,X+W-h1);
      fl_xyline(X+h1,Y+H,X);
    }
  } else { // vertical one
    // draw shaded ends of wheel:
    int h1 = H/4+1; // distance from end that shading starts
    fl_color(color()); fl_rectf(X,Y+h1,W,H-2*h1);
    for (int i=0; h1; i++) {
      fl_color((Fl_Color)(FL_GRAY-i-1));
      int h2 = FL_GRAY-i-1 > FL_DARK3 ? 2*h1/3+1 : 0;
      fl_rectf(X,Y+h2,W,h1-h2);
      fl_rectf(X,Y+H-h1,W,h1-h2);
      h1 = h2;
    }
    if (active_r()) {
      // draw ridges:
      double junk;
      for (double yy = -ARC+modf(offset*sin(ARC)/(H/2)/delta,&junk)*delta;
           ; yy += delta) {
        int yy1 = int((sin(yy)/sin(ARC)+1)*H/2);
        if (yy1 <= 0) continue; else if (yy1 >= H-1) break;
        fl_color(FL_DARK3); fl_xyline(X+1,Y+yy1,X+W-1);
        if (yy < 0) yy1--; else yy1++;
        fl_color(FL_LIGHT1);fl_xyline(X+1,Y+yy1,X+W-1);
      }
      // draw edges:
      h1 = H/8+1; // distance from end the color inverts
      fl_color(FL_DARK2);
      fl_yxline(X+W-1,Y+h1,Y+H-h1);
      fl_color(FL_DARK3);
      fl_xyline(X+W,Y,X,Y+h1);
      fl_yxline(X,Y+H-h1,Y+H);
      fl_color(FL_LIGHT2);
      fl_yxline(X,Y+h1,Y+H-h1);
      fl_xyline(X,Y+H,X+W,Y+H-h1);
      fl_yxline(X+W,Y+h1,Y);
    }
  }

  if (Fl::focus() == this) draw_focus(FL_THIN_UP_FRAME, x(), y(), w(), h());
}

/**
  Creates a new Fl_Roller widget using the given position,
  size, and label string. The default boxtype is FL_NO_BOX.
  <P>Inherited destructor destroys the valuator.
*/
Fl_Roller::Fl_Roller(int X,int Y,int W,int H,const char* L)
  : Fl_Valuator(X,Y,W,H,L) {
  box(FL_UP_BOX);
  step(1,1000);
}