> I have an app with a dial on it and would like to have it wrap around, so
> I can just keep turning it, but can't see how to do it. Is there a way?
Hmm, this works (see attached) though was more of a hassle than I'd expected...
------------------
//
// Test a demo of a roller that wraps over...
//
#include <FL/Fl.H>
#include <FL/Fl_Double_Window.H>
#include <FL/Fl_Button.H>
#include <FL/Fl_Roller.H>
#include <FL/Fl_Dial.H>
#include <stdio.h>
#include <math.h>
static Fl_Double_Window *main_win = NULL;
/******************************************************************************/
static double wrap_clamp(Fl_Valuator *w, double v) {
double min = w->minimum();
double max = w->maximum();
double res = v;
if ((v<min)==(min<=max)) res = (max - (min - v));
else if ((v>max)==(min<=max)) res = (min + (v - max));
return res;
}
/******************************************************************************/
class Roll_Over : public Fl_Roller {
public:
Roll_Over(int X, int Y, int W, int H) : Fl_Roller(X, Y, W, H) { };
double clamp(double v) {return wrap_clamp(this,v);};
int handle(int event);
};
int Roll_Over::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_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;
}
}
static Roll_Over *roller = NULL;
/******************************************************************************/
class Wrap_Dial : public Fl_Dial {
public:
Wrap_Dial(int X, int Y, int W, int H) : Fl_Dial(X, Y, W, H)
{angle1(360);angle2(0); };
double clamp(double v) {return wrap_clamp(this,v);};
int handle(int event, int X, int Y, int W, int H);
int handle(int e) {return handle(e, x(), y(), w(), h());};
};
int Wrap_Dial::handle(int event, int X, int Y, int W, int H) {
short a1 = angle1();
short a2 = angle2();
switch (event) {
case FL_PUSH: {
Fl_Widget_Tracker wp(this);
handle_push();
if (wp.deleted()) return 1; }
case FL_DRAG: {
int mx = (Fl::event_x()-X-W/2)*H;
int my = (Fl::event_y()-Y-H/2)*W;
if (!mx && !my) return 1;
double angle = 270-atan2((float)-my, (float)mx)*180/M_PI;
double oldangle = (a2-a1)*(value()-minimum())/(maximum()-minimum()) + a1;
while (angle < oldangle-180) angle += 360;
while (angle > oldangle+180) angle -= 360;
double val = minimum() + (maximum()-minimum())*(angle-a1)/(a2-a1);
handle_drag(clamp(round(val)));
} return 1;
case FL_RELEASE:
handle_release();
return 1;
case FL_ENTER : /* FALLTHROUGH */
case FL_LEAVE :
return 1;
default:
return 0;
}
}
static Wrap_Dial *dial = NULL;
/******************************************************************************/
static void cb_Exit(Fl_Button*, void*) {
main_win->hide();
}
static void cb_roller(Roll_Over *rl, void *) {
int val = (int)rl->value();
printf("roll-to %3d\n", val); fflush(stdout);
}
static void cb_dial(Wrap_Dial *rl, void *) {
int val = (int)(rl->value() * 100.0);
printf("dial-to %3d\n", val); fflush(stdout);
}
int main(int argc, char **argv)
{
main_win = new Fl_Double_Window(551, 366, "Endless Roller Demo");
main_win->begin();
Fl_Button* exit_bt = new Fl_Button(476, 326, 64, 28, "Exit");
exit_bt->callback((Fl_Callback*)cb_Exit);
roller = new Roll_Over(35, 100, 40, 170);
roller->step(0.25);
roller->maximum(50);
roller->callback((Fl_Callback*)cb_roller);
roller->clear_visible_focus();
dial = new Wrap_Dial(100, 100, 100, 100);
dial->callback((Fl_Callback*)cb_dial);
main_win->end();
main_win->show(argc, argv);
return Fl::run();
}
/* end of file */
------------------
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