# color matrix from 13.10 [fltk]

Bjarne Stroustrup “Programming Principles and Practice Using C++”
Chapter 13 Exercise 13
Using GUI library called FLTK (Fast Light Tool Kit, “full tick”).

```Output:

```

[code language=”cpp”]
// Philipp Siedler
// Bjarne Stroustrup’s PP
// Chapter 13 Exercise 13

#define _USE_MATH_DEFINES
#include "Simple_window.h"
#include "Graph.h"
#include <cmath>

using namespace Graph_lib;

ostream& operator<<(ostream& out, Point& a) {
out << "(" << a.x << "," << a.y << ")";
return out;
}

int main()
try
{
Point tl(100, 100);
Simple_window win(tl, 720, 400, "Simple Window");
Point center(win.x_max() / 2, win.y_max() / 2);

Vector_ref<Graph_lib::Rectangle> rect;
Graph_lib::Rectangle x(Point(100, 200), Point(200, 300));

rect.push_back(x);
rect.push_back(new Graph_lib::Rectangle(Point(50, 60), Point(80, 90)));

for (int i = 0; i < rect.size(); i++) rect[i].move(10, 10);

Vector_ref<Graph_lib::Rectangle> vr;
for (int i = 0; i < 16; i++) {
for (int j = 0; j < 16; j++) {
vr.push_back(new Graph_lib::Rectangle(Point(i * 20, j * 20), 20, 20));
vr[vr.size() – 1].set_fill_color(Color(i * 16 + j));
win.attach(vr[vr.size() – 1]);
}
}

win.wait_for_button();
}
catch (exception& e) {
cout << e.what() << endl;
return 1;
}
catch (…) {
cout << "Exiting" << endl;
return 2;
}
[/code]