From mboxrd@z Thu Jan  1 00:00:00 1970
To: 9fans@cse.psu.edu
From: andrey mirtchovski <andrey@lanl.gov>
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	boundary="upas-zwucqaziljqhynhafwwwopmzkm"
Message-Id: <20020117172218.2BECC1998C@mail.cse.psu.edu>
Subject: [9fans] people who write little useless graphical programs should be shot
Date: Thu, 17 Jan 2002 09:09:20 -0700
Topicbox-Message-UUID: 3e833022-eaca-11e9-9e20-41e7f4b1d025

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i have a laptop here running plan9.. i'm quite happy with it most of the time and
i'm not happy with it when it hangs during window resize (when running p9 locally)..

i suspected the vga driver so i wrote a small graphical program to see if it will force
it to hang by displaying lines on the screen over and over again. i indeed succeeded
in crashing it.

then, last night, i decided to 'beautify' the program and foo.c was born..

it displays moving lines in a window.. it provides the user with the wonderful
options to do 'more', 'less' and 'exit'.. it was hacked rather quickly to accomodate
more than one line at a time, and this shows in the code quality...

the performance is satisfactory even when running on a pure terminal (8bpp)...
of course higher bpp means more visually pleasing lines, but the performance
tradeoff is something you should decide for yourselves :)

enjoy (if you enjoy such things :)

andrey

ps: could someone please explain how to use '|fmt' in acme mail? i have to press
enter every line in order to make the mail somewhat readable :)


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#include <u.h>
#include <libc.h>
#include <draw.h>
#include <event.h>


Rectangle r;
Image *img[256];

typedef struct {
	Point p1;
	Point p2;
	int b;
	int db;

	int p1dx;
	int p1dy;
	int p2dx;
	int p2dy;

} mline;

typedef struct mq mq;
struct mq {
	mline *node;
	mq *next;
};

void
eresized(int new)
{
	if(new && getwindow(display, Refnone) < 0) {
		fprint(2, "bez: can't reattach to window: %r\n");
		exits("resized");
	}

	draw(screen, screen->r, display->black, nil, ZP);
	r = screen->r;

}

char *buttons[] =
{
	"more",
	"less",
	"exit",
	0
};

Menu menu =
{
	buttons
};

void
init(mline *m) {
	m->p1.x = r.min.x + nrand(r.max.x - r.min.x);
	m->p2.x = r.min.x + nrand(r.max.x - r.min.x);
	m->p1.y = r.min.y + nrand(r.max.y - r.min.y);
	m->p2.y = r.min.y + nrand(r.max.y - r.min.y);

	m->p1dx = (int)((frand() - 0.5)*5);
	m->p1dy = (int)((frand() - 0.5)*5);
	m->p2dx = (int)((frand() - 0.5)*5);
	m->p2dy = (int)((frand() - 0.5)*5);

	m->b = 1;
	m->db = 1;

}

void main(int argc, char **argv) {
	int i, b = 1, db = 1;
	Mouse ms;
	Point p1, p2;
	mq q;
	mq *p;
	mline *m;

	srand(time(0));




	if(initdraw(nil, nil, "bez") < 0)
		sysfatal("initdraw failed: %r");

	/* allocate colors */
	for(i = 0; i < 256; i++) {
		img[i] = allocimage(display, Rect(0, 0, 1, 1), screen->chan, 1, (i<<24)|(i<<16)|(i<<8)|0xFF);
	}

	r = screen->r;

	q.node = (mline *)malloc(sizeof (mline));
	q.next = nil;

	init(q.node);



	einit(Emouse);

	eresized(0);
	for(;;) {
		if(ecanmouse()) {
			ms = emouse();
			if(ms.buttons&4)
				switch(emenuhit(3, &ms, &menu)) {
					case 0: 	/* more */
						p=&q;
						while(p->next != nil)
							p = p->next;

						p->next = (mq *)malloc(sizeof (mq));
						p->next->node = (mline *)malloc(sizeof(mline));
						init(p->next->node);
						p->next->next = nil;
						break;
					case 1:
						if(q.next == nil)
							break;
						p = &q;
						while(p->next->next != nil)
							p = p->next;
						free(p->next->node);
						free(p->next);
						p->next = nil;

						break;
					case 2:
						exits(0);
				}
		}




		p = &q;
		while(p != nil) {

			m = p->node;
			m->p1.x += m->p1dx;
			if(m->p1.x < r.min.x || m->p1.x > r.max.x)
				m->p1dx = -m->p1dx;
			m->p1.y += m->p1dy;
			if(m->p1.y < r.min.y || m->p1.y > r.max.y)
				m->p1dy = -m->p1dy;
			m->p2.x += m->p2dx;
			if(m->p2.x < r.min.x || m->p2.x > r.max.x)
				m->p2dx = -m->p2dx;
			m->p2.y += m->p2dy;
			if(m->p2.y < r.min.y || m->p2.y > r.max.y)
				m->p2dy = -m->p2dy;

			line(screen, m->p1, m->p2, Endsquare, Endsquare,2, img[m->b], ZP);

			if(m->b <= 0 || m->b >= 255)
				m->db *= -1;
			m->b+= m->db;

			p = p->next;
		}
	}
}
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