Patch.cpp revision 759ea80dca64ad652110a129e0d8bf93fea79f61 
1/*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#define LOG_TAG "OpenGLRenderer"
18
19#include <cmath>
20
21#include "Patch.h"
22
23namespace android {
24namespace uirenderer {
25
26///////////////////////////////////////////////////////////////////////////////
27// Constructors/destructor
28///////////////////////////////////////////////////////////////////////////////
29
30Patch::Patch(const uint32_t xCount, const uint32_t yCount) {
31    // 2 triangles per patch, 3 vertices per triangle
32    verticesCount = (xCount + 1) * (yCount + 1) * 2 * 3;
33    vertices = new TextureVertex[verticesCount];
34}
35
36Patch::~Patch() {
37    delete vertices;
38}
39
40///////////////////////////////////////////////////////////////////////////////
41// Vertices management
42///////////////////////////////////////////////////////////////////////////////
43
44void Patch::updateVertices(const float bitmapWidth, const float bitmapHeight,
45        float left, float top, float right, float bottom,
46        const int32_t* xDivs, const int32_t* yDivs, const uint32_t width, const uint32_t height) {
47    const uint32_t xStretchCount = (width + 1) >> 1;
48    const uint32_t yStretchCount = (height + 1) >> 1;
49
50    float stretchX = 0.0f;
51    float stretchY = 0.0;
52
53    const float meshWidth = right - left;
54
55    if (xStretchCount > 0) {
56        uint32_t stretchSize = 0;
57        for (uint32_t i = 1; i < width; i += 2) {
58            stretchSize += xDivs[i] - xDivs[i - 1];
59        }
60        const float xStretchTex = stretchSize;
61        const float fixed = bitmapWidth - stretchSize;
62        const float xStretch = right - left - fixed;
63        stretchX = xStretch / xStretchTex;
64    }
65
66    if (yStretchCount > 0) {
67        uint32_t stretchSize = 0;
68        for (uint32_t i = 1; i < height; i += 2) {
69            stretchSize += yDivs[i] - yDivs[i - 1];
70        }
71        const float yStretchTex = stretchSize;
72        const float fixed = bitmapHeight - stretchSize;
73        const float yStretch = bottom - top - fixed;
74        stretchY = yStretch / yStretchTex;
75    }
76
77    TextureVertex* vertex = vertices;
78
79    float previousStepY = 0.0f;
80
81    float y1 = 0.0f;
82    float v1 = 0.0f;
83
84    for (uint32_t i = 0; i < height; i++) {
85        float stepY = yDivs[i];
86
87        float y2 = 0.0f;
88        if (i & 1) {
89            const float segment = stepY - previousStepY;
90            y2 = y1 + segment * stretchY;
91        } else {
92            y2 = y1 + stepY - previousStepY;
93        }
94        float v2 = fmax(0.0f, stepY - 0.5f) / bitmapHeight;
95
96        generateRow(vertex, y1, y2, v1, v2, xDivs, width, stretchX,
97                right - left, bitmapWidth);
98
99        y1 = y2;
100        v1 = (stepY + 0.5f) / bitmapHeight;
101
102        previousStepY = stepY;
103    }
104
105    generateRow(vertex, y1, bottom - top, v1, 1.0f, xDivs, width, stretchX,
106            right - left, bitmapWidth);
107}
108
109inline void Patch::generateRow(TextureVertex*& vertex, float y1, float y2, float v1, float v2,
110        const int32_t xDivs[], uint32_t xCount, float stretchX, float width, float bitmapWidth) {
111    float previousStepX = 0.0f;
112
113    float x1 = 0.0f;
114    float u1 = 0.0f;
115
116    // Generate the row quad by quad
117    for (uint32_t i = 0; i < xCount; i++) {
118        float stepX = xDivs[i];
119
120        float x2 = 0.0f;
121        if (i & 1) {
122            const float segment = stepX - previousStepX;
123            x2 = x1 + segment * stretchX;
124        } else {
125            x2 = x1 + stepX - previousStepX;
126        }
127        float u2 = fmax(0.0f, stepX - 0.5f) / bitmapWidth;
128
129        generateQuad(vertex, x1, y1, x2, y2, u1, v1, u2, v2);
130
131        x1 = x2;
132        u1 = (stepX + 0.5f) / bitmapWidth;
133
134        previousStepX = stepX;
135    }
136
137    generateQuad(vertex, x1, y1, width, y2, u1, v1, 1.0f, v2);
138}
139
140inline void Patch::generateQuad(TextureVertex*& vertex, float x1, float y1, float x2, float y2,
141            float u1, float v1, float u2, float v2) {
142    // Left triangle
143    TextureVertex::set(vertex++, x1, y1, u1, v1);
144    TextureVertex::set(vertex++, x2, y1, u2, v1);
145    TextureVertex::set(vertex++, x1, y2, u1, v2);
146
147    // Right triangle
148    TextureVertex::set(vertex++, x1, y2, u1, v2);
149    TextureVertex::set(vertex++, x2, y1, u2, v1);
150    TextureVertex::set(vertex++, x2, y2, u2, v2);
151}
152
153}; // namespace uirenderer
154}; // namespace android
155