Lomiri
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MathUtils.js
1/*
2 * Copyright (C) 2016 Canonical Ltd.
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; version 3.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License
14 * along with this program. If not, see <http://www.gnu.org/licenses/>.
15 */
16
17.pragma library
18
19/**
20 * From processing.js: https://raw.githubusercontent.com/processing-js/processing-js/v1.4.8/processing.js
21 *
22 * Re-map a number from one range to another. In the example above, the number
23 * '25' is converted from a value in the range 0..100 into a value that
24 * ranges from the left edge (0) to the right edge (width) of the screen.
25 * Numbers outside the range are not clamped to 0 and 1, because out-of-range
26 * values are often intentional and useful.
27 *
28 * @param {Number} value The incoming value to be converted
29 * @param {Number} istart Lower bound of the value's current range
30 * @param {Number} istop Upper bound of the value's current range
31 * @param {Number} ostart Lower bound of the value's target range
32 * @param {Number} ostop Upper bound of the value's target range
33 *
34 * @returns {Number}
35 */
36function map(value, istart, istop, ostart, ostop) {
37 return ostart + (ostop - ostart) * ((value - istart) / (istop - istart))
38}
39
40/**
41 * Return a value which is always between `min` and `max`
42 *
43 * @param {Number} value The current value
44 * @param {Number} min The minimum value
45 * @param {Number} max The maximum value
46 *
47 * @returns {Number}
48 */
49function clamp(value, min, max) {
50 if (value < min) return min
51 if (value > max) return max
52 return value
53}
54
55// calculates the distance from the middle of one rect to middle of other rect
56function rectDistance(rect1, rect2) {
57 return pointDistance(Qt.point(rect1.x + rect1.width / 2, rect1.y + rect1.height / 2),
58 Qt.point(rect2.x + rect2.width / 2, rect2.y + rect2.height / 2))
59}
60
61// calculates the distance between two points
62function pointDistance(point1, point2) {
63 return Math.sqrt(Math.pow(point1.x - point2.x, 2) +
64 Math.pow(point1.y - point2.y, 2)
65 )
66}
67
68// from http://stackoverflow.com/questions/14616829/java-method-to-find-the-rectangle-that-is-the-intersection-of-two-rectangles-usi
69function intersectionRect(r1, r2) {
70 var xmin = Math.max(r1.x, r2.x);
71 var xmax1 = r1.x + r1.width;
72 var xmax2 = r2.x + r2.width;
73 var xmax = Math.min(xmax1, xmax2);
74 var out = {x:0, y:0, width:0, height:0}
75 if (xmax > xmin) {
76 var ymin = Math.max(r1.y, r2.y);
77 var ymax1 = r1.y + r1.height;
78 var ymax2 = r2.y + r2.height;
79 var ymax = Math.min(ymax1, ymax2);
80 if (ymax > ymin) {
81 out.x = xmin;
82 out.y = ymin;
83 out.width = xmax - xmin;
84 out.height = ymax - ymin;
85 }
86 }
87 return out;
88}
89
90function easeOutCubic(t) { return (--t)*t*t+1 }
91
92function linearAnimation(startProgress, endProgress, startValue, endValue, progress) {
93 // progress : progressDiff = value : valueDiff => value = progress * valueDiff / progressDiff
94 return (progress - startProgress) * (endValue - startValue) / (endProgress - startProgress) + startValue;
95}