fltk/src/Fl_Roller.cxx

//
// "$Id"
//
// Roller widget for the Fast Light Tool Kit (FLTK).
//
// Copyright 1998 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 to "fltk-bugs@easysw.com".
//

// 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:
    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;
  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;
  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;
    }
    // draw ridges:
    double junk;
    for (double y = -ARC+modf(offset*sin(ARC)/(W/2)/delta,&junk)*delta;;
	 y += delta) {
      int y1 = int((sin(y)/sin(ARC)+1)*W/2);
      if (y1 <= 0) continue; else if (y1 >= W-1) break;
      fl_color(FL_DARK3); fl_yxline(X+y1,Y+1,Y+H-1);
      if (y < 0) y1--; else y1++;
      fl_color(FL_LIGHT1);fl_yxline(X+y1,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;
    }
    // draw ridges:
    double junk;
    for (double y = -ARC+modf(offset*sin(ARC)/(H/2)/delta,&junk)*delta;
	 ; y += delta) {
      int y1 = int((sin(y)/sin(ARC)+1)*H/2);
      if (y1 <= 0) continue; else if (y1 >= H-1) break;
      fl_color(FL_DARK3); fl_xyline(X+1,Y+y1,X+W-1);
      if (y < 0) y1--; else y1++;
      fl_color(FL_LIGHT1);fl_xyline(X+1,Y+y1,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);
  }
}

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_FRAME);
  step(1,1000);
}

//
// End of "$Id: Fl_Roller.cxx,v 1.3 1998/10/19 20:46:00 mike Exp $".
//