I don't understand how to make buttons in FLTK - c++

Question

#include "std_lib_facilities_4.h"
#include "Window.h"
#include "Graph.h"
#include "GUI.h"
#include <FL/Fl_Image.H>
using namespace Graph_lib;
using namespace std;
struct Lines_window:Graph_lib::Window{
Lines_window(Point xy, int w, int h, const string& title);
Button button_1;
Button button_2;
static void cb_change_color(Address, Address);
static void cb_change_picture(Address, Address);
};
Lines_window::Lines_window(Point xy, int w, int h, const string& title) :
Window(xy, w, h, title),
button_1(Point(x_max()/2, y_max()/2), 200, 100, "Button 1", cb_change_color),
button_2(Point(x_max()/3, y_max()/3), 200, 100, "Button 2", cb_change_picture)
{
attach(button_1);
attach(button_2);
}
void Lines_window::cb_change_color(Address, Address pw)
{
}
void Lines_window::cb_change_picture(Address, Address pw)
{
}
int main()
try {
if(H112 != 201401L)error("Error: incorrect std_lib_facilities_4.h version ", H112);
using namespace Graph_lib;
Lines_window win(Point(100,100),600,400,"Buttons");
return gui_main();
return 0;
}
catch(exception& e) {
cerr << "exception: " << e.what() << '\n';
return 1;
}
catch (...) {
cerr << "Some exception\n";
return 2;
}
This is my button code. I am trying to make two buttons, one that changes color when you press it and another that puts an image on the button when you press it. I haven't made a callback yet because this won't compile. Errors are:
GUI.cpp:16:6: error: prototype for ‘void Graph_lib::Button::attach(Graph_lib::Window&, Fl_Color)’ does not match any in class ‘Graph_lib::Button’
void Button::attach(Window& win, Fl_Color color)
^
In file included from GUI.cpp:10:0:
GUI.h:66:14: error: candidate is: virtual void Graph_lib::Button::attach(Graph_lib::Window&)
void attach(Window&);
^
Do I need callbacks to compile? I am basing this code off of my professor's code here. I took everything out except for the buttons so I could make them. The GUI.cpp and GUI.h were given to us. What am I doing wrong?
GUI.cpp
//
// This is a GUI support code to the chapters 12-16 of the book
// "Programming -- Principles and Practice Using C++" by Bjarne Stroustrup
//
#include <FL/Fl.H>
#include <FL/Fl_Button.H>
#include <FL/Fl_Output.H>
#include "GUI.h"
namespace Graph_lib {
//------------------------------------------------------------------------------
void Button::attach(Window& win, Fl_Color color)
{
pw = new Fl_Button(loc.x, loc.y, width, height, label.c_str());
pw->color(BLUE);
pw->callback(reinterpret_cast<Fl_Callback*>(do_it), &win); // pass the window
own = &win;
}
//------------------------------------------------------------------------------
int In_box::get_int()
{
Fl_Input& pi = reference_to<Fl_Input>(pw);
// return atoi(pi.value());
const char* p = pi.value();
if (!isdigit(p[0])) return -999999;
return atoi(p);
}
//------------------------------------------------------------------------------
string In_box::get_string()
{
Fl_Input& pi = reference_to<Fl_Input>(pw);
return string(pi.value());
}
//------------------------------------------------------------------------------
void In_box::attach(Window& win)
{
pw = new Fl_Input(loc.x, loc.y, width, height, label.c_str());
own = &win;
}
//------------------------------------------------------------------------------
void Out_box::put(const string& s)
{
reference_to<Fl_Output>(pw).value(s.c_str());
}
//------------------------------------------------------------------------------
void Out_box::attach(Window& win)
{
pw = new Fl_Output(loc.x, loc.y, width, height, label.c_str());
own = &win;
}
//------------------------------------------------------------------------------
int Menu::attach(Button& b)
{
b.width = width;
b.height = height;
switch(k) {
case horizontal:
b.loc = Point(loc.x+offset,loc.y);
offset+=b.width;
break;
case vertical:
b.loc = Point(loc.x,loc.y+offset);
offset+=b.height;
break;
}
selection.push_back(b); // b is NOT OWNED: pass by reference
return int(selection.size()-1);
}
//------------------------------------------------------------------------------
int Menu::attach(Button* p)
{
Button& b = *p;
b.width = width;
b.height = height;
switch(k) {
case horizontal:
b.loc = Point(loc.x+offset,loc.y);
offset+=b.width;
break;
case vertical:
b.loc = Point(loc.x,loc.y+offset);
offset+=b.height;
break;
}
selection.push_back(&b); // b is OWNED: pass by pointer
return int(selection.size()-1);
}
//------------------------------------------------------------------------------
} // of namespace Graph_lib
GUI.h
//
// This is a GUI support code to the chapters 12-16 of the book
// "Programming -- Principles and Practice Using C++" by Bjarne Stroustrup
//
#ifndef GUI_GUARD
#define GUI_GUARD
#include "Window.h"
#include "Graph.h"
namespace Graph_lib {
//------------------------------------------------------------------------------
typedef void* Address; // Address is a synonym for void*
typedef void(*Callback)(Address, Address); // FLTK's required function type for all callbacks
//------------------------------------------------------------------------------
template<class W> W& reference_to(Address pw)
// treat an address as a reference to a W
{
return *static_cast<W*>(pw);
}
//------------------------------------------------------------------------------
class Widget {
// Widget is a handle to an Fl_widget - it is *not* an Fl_widget
// We try to keep our interface classes at arm's length from FLTK
public:
Widget(Point xy, int w, int h, const string& s, Callback cb)
: loc(xy), width(w), height(h), label(s), do_it(cb)
{}
virtual void move(int dx,int dy) { hide(); pw->position(loc.x+=dx, loc.y+=dy); show(); }
virtual void hide() { pw->hide(); }
virtual void show() { pw->show(); }
virtual void attach(Window&) = 0;
Point loc;
int width;
int height;
string label;
Callback do_it;
virtual ~Widget() { }
protected:
Window* own; // every Widget belongs to a Window
Fl_Widget* pw; // connection to the FLTK Widget
private:
Widget& operator=(const Widget&); // don't copy Widgets
Widget(const Widget&);
};
//------------------------------------------------------------------------------
struct Button : Widget {
Button(Point xy, int w, int h, const string& label, Callback cb)
: Widget(xy,w,h,label,cb)
{}
void attach(Window&);
};
//------------------------------------------------------------------------------
struct In_box : Widget {
In_box(Point xy, int w, int h, const string& s)
:Widget(xy,w,h,s,0) { }
int get_int();
string get_string();
void attach(Window& win);
};
//------------------------------------------------------------------------------
struct Out_box : Widget {
Out_box(Point xy, int w, int h, const string& s)
:Widget(xy,w,h,s,0) { }
void put(int);
void put(const string&);
void attach(Window& win);
};
//------------------------------------------------------------------------------
struct Menu : Widget {
enum Kind { horizontal, vertical };
Menu(Point xy, int w, int h, Kind kk, const string& label)
: Widget(xy,w,h,label,0), k(kk), offset(0)
{}
Vector_ref<Button> selection;
Kind k;
int offset;
int attach(Button& b); // Menu does not delete &b
int attach(Button* p); // Menu deletes p
void show() // show all buttons
{
for (unsigned int i = 0; i<selection.size(); ++i)
selection[i].show();
}
void hide() // hide all buttons
{
for (unsigned int i = 0; i<selection.size(); ++i)
selection[i].hide();
}
void move(int dx, int dy) // move all buttons
{
for (unsigned int i = 0; i<selection.size(); ++i)
selection[i].move(dx,dy);
}
void attach(Window& win) // attach all buttons
{
for (int i=0; i<selection.size(); ++i) win.attach(selection[i]);
own = &win;
}
};
//------------------------------------------------------------------------------
} // of namespace Graph_lib
#endif // GUI_GUARD

Answer 1

I found the answer. It wouldn't compile because I added an argument to be passed to button (the Fl_Color). I will have to figure out a way to pass a value to the button to change the color.