1 /*
2 * Copyright 2012 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 #include "CubicUtilities.h"
9 #include "CurveIntersection.h"
10 #include "TestUtilities.h"
11
quad_to_cubic(const Quadratic & quad,Cubic & cubic)12 void quad_to_cubic(const Quadratic& quad, Cubic& cubic) {
13 cubic[0] = quad[0];
14 cubic[1].x = quad[0].x / 3 + quad[1].x * 2 / 3;
15 cubic[1].y = quad[0].y / 3 + quad[1].y * 2 / 3;
16 cubic[2].x = quad[2].x / 3 + quad[1].x * 2 / 3;
17 cubic[2].y = quad[2].y / 3 + quad[1].y * 2 / 3;
18 cubic[3] = quad[2];
19 }
20
tiny(const Cubic & cubic)21 static bool tiny(const Cubic& cubic) {
22 int index, minX, maxX, minY, maxY;
23 minX = maxX = minY = maxY = 0;
24 for (index = 1; index < 4; ++index) {
25 if (cubic[minX].x > cubic[index].x) {
26 minX = index;
27 }
28 if (cubic[minY].y > cubic[index].y) {
29 minY = index;
30 }
31 if (cubic[maxX].x < cubic[index].x) {
32 maxX = index;
33 }
34 if (cubic[maxY].y < cubic[index].y) {
35 maxY = index;
36 }
37 }
38 return approximately_equal(cubic[maxX].x, cubic[minX].x)
39 && approximately_equal(cubic[maxY].y, cubic[minY].y);
40 }
41
find_tight_bounds(const Cubic & cubic,_Rect & bounds)42 void find_tight_bounds(const Cubic& cubic, _Rect& bounds) {
43 CubicPair cubicPair;
44 chop_at(cubic, cubicPair, 0.5);
45 if (!tiny(cubicPair.first()) && !controls_inside(cubicPair.first())) {
46 find_tight_bounds(cubicPair.first(), bounds);
47 } else {
48 bounds.add(cubicPair.first()[0]);
49 bounds.add(cubicPair.first()[3]);
50 }
51 if (!tiny(cubicPair.second()) && !controls_inside(cubicPair.second())) {
52 find_tight_bounds(cubicPair.second(), bounds);
53 } else {
54 bounds.add(cubicPair.second()[0]);
55 bounds.add(cubicPair.second()[3]);
56 }
57 }
58
controls_inside(const Cubic & cubic)59 bool controls_inside(const Cubic& cubic) {
60 return
61 ((cubic[0].x <= cubic[1].x && cubic[0].x <= cubic[2].x && cubic[1].x <= cubic[3].x && cubic[2].x <= cubic[3].x)
62 || (cubic[0].x >= cubic[1].x && cubic[0].x >= cubic[2].x && cubic[1].x >= cubic[3].x && cubic[2].x >= cubic[3].x))
63 && ((cubic[0].y <= cubic[1].y && cubic[0].y <= cubic[2].y && cubic[1].y <= cubic[3].y && cubic[2].y <= cubic[3].y)
64 || (cubic[0].y >= cubic[1].y && cubic[0].y >= cubic[2].y && cubic[1].y >= cubic[3].y && cubic[2].x >= cubic[3].y));
65 }
66