/*
 *  Brian's Theme
 *  -------------
 *  This version copyright (c) 1996 by Lachlan Patrick.
 *  Written using GraphApp.
 *
 *  This is a complex example not for beginners. It makes use of
 *  the timer functions, colour, windows and keyboard call-backs.
 */

#include <graphapp.h>

#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <time.h>

/*
 *  Global variables.
 */
int width = 400;
int height = 240;
int banner_height = 40;
char *banner = "Press a number to change the step size, Q to stop, R,G,B,C,M,Y,K for colours.";

window w;

int step_size = 3;
int step_location = 0;
point origin;

rgb colour = Blue;

/*
 *  Functions.
 */
void change_location(void)
{
	time_t t;

	srand((unsigned) time(&t));

	origin.x = rand() % width;
	origin.y = rand() % height;

	step_location = 0;
}

void handle_mouse(window w, int buttons, point xy)
{
	origin = xy;
	step_location = 0;
	redraw(w);
}

void handle_keydown(window w, int key)
{
	if (isdigit(key))
		step_size = key - '0';
	else if ((key == 'q') || (key == 'Q') || (key == ESC))
		exitapp();
	else switch (key) {
		case 'r': case 'R': colour = Red; break;
		case 'g': case 'G': colour = Green; break;
		case 'b': case 'B': colour = Blue; break;
		case 'c': case 'C': colour = Cyan; break;
		case 'm': case 'M': colour = Magenta; break;
		case 'y': case 'Y': colour = Yellow; break;
		case 'k': case 'K': colour = Black; break;
		default: break;
	}
}

void draw_window(window w, rect r)
{
	if (banner_height > 0)
	{
		r.y = height;
		r.height = banner_height;

		setcolour(Black);
		drawtext(r, Center + VCenter, banner);
	}
}

void resize_window(window w, rect r)
{
	banner_height = getheight(SystemFont)*2+8;

	if (r.height < 4*banner_height) /* too small for banner */
		banner_height = 0;

	height = r.height - banner_height;
	width = r.width;

	change_location();
}

/* create and display the window */
window init_window(void)
{
	banner_height = getheight(SystemFont)*2+8;

	w = newwindow("Brian's Theme",
			rect(0,0,width,height+banner_height),
			StandardWindow | Centered );
	setmouseup(w, handle_mouse);
	setkeydown(w, handle_keydown);
	setredraw(w, draw_window);
	setresize(w, resize_window);
	show(w);
	return w;
}

void draw_and_step(window w)
{
	drawto(w);
	setcolour(colour);

	if (step_location <= height) {
		drawline(origin, pt(0, height-step_location));
		drawline(origin, pt(width, step_location));
	}
	if (step_location <= width) {
		drawline(origin, pt(step_location, 0));
		drawline(origin, pt(width-step_location, height));
	}

	step_location += step_size;

	if ((step_location > width+100)
		&& (step_location > height+100))
	{
		change_location();
		redraw(w);
	}
}

void main(void)
{
	window win;

	initapp(0,0);
	win = init_window();
	settimerfn(draw_and_step, win);
	settimer(80);
	mainloop();
}