Fl_Button widget

This example shows how to create Fl_Button widget.

The program produces the following picture:

 1 #pragma package ".."
 2 
 3 #include "chfltk.h"
 4 #include <stdio.h>
 5 #include <stdlib.h>
 6 
 7 void change_color_cb(Fl_Widget *g, void *v) {
 8   static int i=0;
 9   i=(i+1)%2;
10   if (i) {
11     g->labelcolor((unsigned)FL_RED);
12   } else {
13     g->labelcolor((unsigned)FL_GREEN);
14   }
15 }
16 
17 int main(int argc, char *argv[])
18 {
19   Fl_Window *window = new Fl_Window(300, 180);
20   Fl_Button *box = new Fl_Button(20, 40, 260, 100, "Hello World");
21   box->box(FL_UP_BOX);
22   box->callback((ChFl_Callback)change_color_cb, (void*)0);
23   box->labelsize((uchar)36);
24   box->labelfont((uchar)(FL_BOLD+FL_ITALIC));
25   window->end();
26   window->show(argc, argv);
27   Fl::run();
28   exit(1);
29   return 0;
30 }

Code description

11: Argument type of overloaded methods must be set by explicit casting
22: Overloaded methods need exlicit casting of parameters
23: Type uchar is defined by FLTK to unsigned char. See also the * comment above about overloaded methods
27: Start FLTK event loop
28: This shouldn't be necessary if future releases of ChFLTK but at the moment one needs to call exit() to terminate application smoothly