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