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
19namespace OHOS {
20void 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
77void DrawTriangle::SortVertexs(Point& p1, Point& p2, Point& p3)
78{
79    SortPoint(p1, p2);
80    SortPoint(p2, p3);
81    SortPoint(p1, p2);
82}
83
84void 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
94void 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
113DrawTriangle::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