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// Commands for manipulating rects.
const Rect = {
// Create a rect given the top left and bottom right corners.
create(x1, y1, x2, y2) {
return {
bottom: y2,
top: y1,
left: x1,
right: x2,
width: x2 - x1,
height: y2 - y1,
};
},
copy(rect) {
return {
bottom: rect.bottom,
top: rect.top,
left: rect.left,
right: rect.right,
width: rect.width,
height: rect.height,
};
},
// Translate a rect by x horizontally and y vertically.
translate(rect, x, y) {
if (x == null) x = 0;
if (y == null) y = 0;
return {
bottom: rect.bottom + y,
top: rect.top + y,
left: rect.left + x,
right: rect.right + x,
width: rect.width,
height: rect.height,
};
},
// Subtract rect2 from rect1, returning an array of rects which are in rect1 but not rect2.
subtract(rect1, rect2) {
// Bound rect2 by rect1
rect2 = this.create(
Math.max(rect1.left, rect2.left),
Math.max(rect1.top, rect2.top),
Math.min(rect1.right, rect2.right),
Math.min(rect1.bottom, rect2.bottom),
);
// If bounding rect2 has made the width or height negative, rect1 does not contain rect2.
if ((rect2.width < 0) || (rect2.height < 0)) return [Rect.copy(rect1)];
//
// All the possible rects, in the order
// +-+-+-+
// |1|2|3|
// +-+-+-+
// |4| |5|
// +-+-+-+
// |6|7|8|
// +-+-+-+
// where the outer rectangle is rect1 and the inner rectangle is rect 2. Note that the rects may
// be of width or height 0.
//
const rects = [
// Top row.
this.create(rect1.left, rect1.top, rect2.left, rect2.top),
this.create(rect2.left, rect1.top, rect2.right, rect2.top),
this.create(rect2.right, rect1.top, rect1.right, rect2.top),
// Middle row.
this.create(rect1.left, rect2.top, rect2.left, rect2.bottom),
this.create(rect2.right, rect2.top, rect1.right, rect2.bottom),
// Bottom row.
this.create(rect1.left, rect2.bottom, rect2.left, rect1.bottom),
this.create(rect2.left, rect2.bottom, rect2.right, rect1.bottom),
this.create(rect2.right, rect2.bottom, rect1.right, rect1.bottom),
];
return rects.filter((rect) => (rect.height > 0) && (rect.width > 0));
},
// Determine whether two rects overlap.
intersects(rect1, rect2) {
return (rect1.right > rect2.left) &&
(rect1.left < rect2.right) &&
(rect1.bottom > rect2.top) &&
(rect1.top < rect2.bottom);
},
// Determine whether two rects overlap, including 0-width intersections at borders.
intersectsStrict(rect1, rect2) {
return (rect1.right >= rect2.left) && (rect1.left <= rect2.right) &&
(rect1.bottom >= rect2.top) && (rect1.top <= rect2.bottom);
},
equals(rect1, rect2) {
for (const property of ["top", "bottom", "left", "right", "width", "height"]) {
if (rect1[property] !== rect2[property]) return false;
}
return true;
},
intersect(rect1, rect2) {
return this.create(
Math.max(rect1.left, rect2.left),
Math.max(rect1.top, rect2.top),
Math.min(rect1.right, rect2.right),
Math.min(rect1.bottom, rect2.bottom),
);
},
};
window.Rect = Rect;
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