box.c

#include <math.h>
#include <stdlib.h>

#include "box.h"

#include <stdio.h>

bool parse_box(struct grim_box *box, const char *str) {
	char *end = NULL;
	box->x = strtol(str, &end, 10);
	if (end[0] != ',') {
		return false;
	}

	char *next = end + 1;
	box->y = strtol(next, &end, 10);
	if (end[0] != ' ') {
		return false;
	}

	next = end + 1;
	box->width = strtol(next, &end, 10);
	if (end[0] != 'x') {
		return false;
	}

	next = end + 1;
	box->height = strtol(next, &end, 10);
	if (end[0] != '\0') {
		return false;
	}

	return true;
}

bool is_empty_box(struct grim_box *box) {
	return box->width <= 0 || box->height <= 0;
}

bool intersect_box(struct grim_box *a, struct grim_box *b) {
	if (is_empty_box(a) || is_empty_box(b)) {
		return false;
	}

	int x1 = fmax(a->x, b->x);
	int y1 = fmax(a->y, b->y);
	int x2 = fmin(a->x + a->width, b->x + b->width);
	int y2 = fmin(a->y + a->height, b->y + b->height);

	struct grim_box box = {
		.x = x1,
		.y = y1,
		.width = x2 - x1,
		.height = y2 - y1,
	};
	return !is_empty_box(&box);
}