1 /*
2 * Copyright (c) 2020-2021 Huawei Device Co., Ltd.
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
14 */
15
16 #include "draw/draw_triangle.h"
17 #include "draw/draw_utils.h"
18
19 namespace OHOS {
Draw(BufferInfo & gfxDstBuffer,const Point * points,uint8_t count,const Rect & mask,const ColorType & color,OpacityType opa)20 void DrawTriangle::Draw(BufferInfo& gfxDstBuffer,
21 const Point* points,
22 uint8_t count,
23 const Rect& mask,
24 const ColorType& color,
25 OpacityType opa)
26 {
27 if ((points == nullptr) || (count != VERTEX_NUM)) {
28 return;
29 }
30 // sort vertex according to y axis
31 Point p1 = points[0]; // 0: point index
32 Point p2 = points[1]; // 1: point index
33 Point p3 = points[2]; // 2: point index
34 // return if vertexs are invalid.
35 if ((p1.x == p2.x) && ((p1.y == p2.y) || (p1.x == p3.x))) {
36 return;
37 }
38 if ((p2.x == p3.x) && (p2.y == p3.y)) {
39 return;
40 }
41 if (((p1.x == p3.x) || (p1.y == p2.y)) && (p1.y == p3.y)) {
42 return;
43 }
44 SortVertexs(p1, p2, p3);
45 Edge edge1 = InitEdge(p1, p2);
46 Edge edge2 = InitEdge(p1, p3);
47 Rect area;
48 int16_t lastY = p1.y;
49
50 while (edge1.curPoint.y <= p3.y) {
51 // change edge1 from p1-p2 to p2-p3
52 if (edge1.curPoint.y == p2.y) {
53 edge1 = InitEdge(p2, p3);
54 if (edge1.dPoint.y == 0) {
55 return;
56 }
57 }
58
59 area.SetLeft(MATH_MIN(edge1.curPoint.x, edge2.curPoint.x));
60 area.SetRight(MATH_MAX(edge1.curPoint.x, edge2.curPoint.x));
61 area.SetTop(MATH_MIN(edge1.curPoint.y, edge2.curPoint.y));
62 area.SetBottom(MATH_MAX(edge1.curPoint.y, edge2.curPoint.y));
63 DrawUtils::GetInstance()->DrawColorArea(gfxDstBuffer, area, mask, color, opa);
64
65 while (edge1.curPoint.y == lastY) {
66 // use Bresenham algorithm to get next point on edge1
67 StepToNextPointOnEdge(edge1);
68 }
69 while (edge2.curPoint.y == lastY) {
70 // use Bresenham algorithm to get next point on edge2
71 StepToNextPointOnEdge(edge2);
72 }
73 lastY = edge1.curPoint.y;
74 }
75 }
76
SortVertexs(Point & p1,Point & p2,Point & p3)77 void DrawTriangle::SortVertexs(Point& p1, Point& p2, Point& p3)
78 {
79 SortPoint(p1, p2);
80 SortPoint(p2, p3);
81 SortPoint(p1, p2);
82 }
83
SortPoint(Point & p1,Point & p2)84 void DrawTriangle::SortPoint(Point& p1, Point& p2)
85 {
86 Point temp;
87 if (p1.y > p2.y) {
88 temp = p1;
89 p1 = p2;
90 p2 = temp;
91 }
92 }
93
StepToNextPointOnEdge(Edge & edge)94 void DrawTriangle::StepToNextPointOnEdge(Edge& edge)
95 {
96 if (edge.dPoint.x > edge.dPoint.y) {
97 edge.curPoint.x += edge.uPoint.x;
98 edge.eps += edge.dPoint.y;
99 if ((edge.eps << 1) >= edge.dPoint.x) {
100 edge.curPoint.y += edge.uPoint.y;
101 edge.eps -= edge.dPoint.x;
102 }
103 } else {
104 edge.curPoint.y += edge.uPoint.y;
105 edge.eps += edge.dPoint.x;
106 if ((edge.eps << 1) >= edge.dPoint.y) {
107 edge.curPoint.x += edge.uPoint.x;
108 edge.eps -= edge.dPoint.y;
109 }
110 }
111 }
112
InitEdge(const Point & startP,const Point & endP)113 DrawTriangle::Edge DrawTriangle::InitEdge(const Point& startP, const Point& endP)
114 {
115 Edge edge = { {0, 0}, {0, 0}, {0, 0}, 0 };
116 edge.curPoint = startP;
117 edge.dPoint.x = startP.x - endP.x;
118 edge.dPoint.y = startP.y - endP.y;
119 edge.uPoint.x = (edge.dPoint.x < 0) ? 1 : -1;
120 edge.uPoint.y = (edge.dPoint.y < 0) ? 1 : -1;
121 edge.eps = 0;
122 edge.dPoint.x = MATH_ABS(edge.dPoint.x);
123 edge.dPoint.y = MATH_ABS(edge.dPoint.y);
124 return edge;
125 }
126 } // namespace OHOS
127