John P. Pfost wrote:
I thought that the intention of FL_WHEN_CHANGED was to allow a user to push and hold a button to start an action which then stops when they released the button.
I wrote a small example that does something like this. I derived a class
Fl_Timer_Button from Fl_Box (!) that only calls its callback in a
settable interval, as long as the button is pushed. The callback then
changes the button's color. Have fun ...
Albrecht
// This example program creates a Fl_Timer_Button. This button calls
// its callback, as long as a mouse button is pressed.
// The class is intentionally derived from Fl_Box and not from Fl_Button.
// Compile with: fltk-config --compile timer_button.cxx
#include <FL/Fl.H>
#include <FL/Fl_Double_Window.H>
#include <FL/Fl_Button.H>
#include <FL/Fl_Box.H>
#include <FL/fl_draw.H>
#include <stdio.h>
// *** Class Fl_Timer_Button:
class Fl_Timer_Button: public Fl_Box {
int ci_ ;
int active_ ;
double timeout_ ;
static void Timer_CB (void *);
public:
Fl_Timer_Button(int X, int Y, int W, int H, char *L=0)
: Fl_Box (X,Y,W,H,L)
{
active_ = 0;
ci_ = 0;
timeout_ = 0.25;
box (FL_UP_BOX);
};
int Fl_Timer_Button::ci() { return ci_; }
void Fl_Timer_Button::ci(int i) { ci_ = i; }
double Fl_Timer_Button::timeout() { return timeout_; }
void Fl_Timer_Button::timeout(double t) { timeout_ = t; }
protected:
int handle (int ev);
}; // Fl_Timer_Button
int Fl_Timer_Button::handle (int ev)
{
switch (ev) {
case FL_PUSH:
if (!active_) {
active_++;
box(FL_DOWN_BOX);
Fl::add_timeout(timeout_,Timer_CB,this);
}
Fl_Box::handle(ev);
redraw();
return 1;
case FL_RELEASE:
if (active_) {
active_ = 0;
box(FL_UP_BOX);
Fl::remove_timeout(Timer_CB);
}
Fl_Box::handle(ev);
redraw();
return 1;
default:
return Fl_Box::handle(ev);
}
}
void Fl_Timer_Button::Timer_CB (void *v) {
Fl_Timer_Button *b = (Fl_Timer_Button *)v;
b->do_callback(b,(void *)0);
Fl::repeat_timeout(b->timeout(),Timer_CB,b);
}
// *** End of class Fl_Timer_Button
// *** Application code:
static Fl_Color colors [] = {
FL_RED,FL_YELLOW,FL_GREEN,FL_BLUE,
FL_BLACK,FL_WHITE };
void button_cb(Fl_Widget *w, void *) {
Fl_Timer_Button *b = (Fl_Timer_Button *)w;
int x = b->ci();
if (++x>5) x=0;
b->ci(x);
b->color(colors[x]);
b->redraw();
}
int main(int argc, char **argv) {
Fl_Double_Window *win1 = new Fl_Double_Window(400, 200, "Window #1");
Fl_Timer_Button *but1 = new Fl_Timer_Button(50,50,300,100,
"Push for test\n\nand keep the mouse button pressed");
but1->callback(button_cb);
win1->end();
win1->show(argc, argv);
return Fl::run();
}
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