GammaFontRenderer.cpp revision 4121063313ac0d6f69f6253cac821d0c1c122086 
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 "Debug.h"
20#include "GammaFontRenderer.h"
21#include "Properties.h"
22
23namespace android {
24namespace uirenderer {
25
26///////////////////////////////////////////////////////////////////////////////
27// Utils
28///////////////////////////////////////////////////////////////////////////////
29
30static int luminance(const SkPaint* paint) {
31    uint32_t c = paint->getColor();
32    const int r = (c >> 16) & 0xFF;
33    const int g = (c >>  8) & 0xFF;
34    const int b = (c      ) & 0xFF;
35    return (r * 2 + g * 5 + b) >> 3;
36}
37
38///////////////////////////////////////////////////////////////////////////////
39// Base class GammaFontRenderer
40///////////////////////////////////////////////////////////////////////////////
41
42GammaFontRenderer* GammaFontRenderer::createRenderer() {
43    // Choose the best renderer
44    char property[PROPERTY_VALUE_MAX];
45    if (property_get(PROPERTY_TEXT_GAMMA_SHADER, property, DEFAULT_TEXT_GAMMA_SHADER) > 0) {
46        if (!strcasecmp(property, "true")) {
47            return new ShaderGammaFontRenderer();
48        }
49    }
50
51#if DEBUG_FONT_RENDERER_FORCE_SHADER_GAMMA
52    return new ShaderGammaFontRenderer();
53#else
54    return new LookupGammaFontRenderer();
55#endif
56}
57
58GammaFontRenderer::GammaFontRenderer() {
59    // Get the renderer properties
60    char property[PROPERTY_VALUE_MAX];
61
62    // Get the gamma
63    mGamma = DEFAULT_TEXT_GAMMA;
64    if (property_get(PROPERTY_TEXT_GAMMA, property, NULL) > 0) {
65        INIT_LOGD("  Setting text gamma to %s", property);
66        mGamma = atof(property);
67    } else {
68        INIT_LOGD("  Using default text gamma of %.2f", DEFAULT_TEXT_GAMMA);
69    }
70
71    // Get the black gamma threshold
72    mBlackThreshold = DEFAULT_TEXT_BLACK_GAMMA_THRESHOLD;
73    if (property_get(PROPERTY_TEXT_BLACK_GAMMA_THRESHOLD, property, NULL) > 0) {
74        INIT_LOGD("  Setting text black gamma threshold to %s", property);
75        mBlackThreshold = atoi(property);
76    } else {
77        INIT_LOGD("  Using default text black gamma threshold of %d",
78                DEFAULT_TEXT_BLACK_GAMMA_THRESHOLD);
79    }
80
81    // Get the white gamma threshold
82    mWhiteThreshold = DEFAULT_TEXT_WHITE_GAMMA_THRESHOLD;
83    if (property_get(PROPERTY_TEXT_WHITE_GAMMA_THRESHOLD, property, NULL) > 0) {
84        INIT_LOGD("  Setting text white gamma threshold to %s", property);
85        mWhiteThreshold = atoi(property);
86    } else {
87        INIT_LOGD("  Using default white black gamma threshold of %d",
88                DEFAULT_TEXT_WHITE_GAMMA_THRESHOLD);
89    }
90}
91
92GammaFontRenderer::~GammaFontRenderer() {
93}
94
95///////////////////////////////////////////////////////////////////////////////
96// Shader-based renderer
97///////////////////////////////////////////////////////////////////////////////
98
99ShaderGammaFontRenderer::ShaderGammaFontRenderer(): GammaFontRenderer() {
100    INIT_LOGD("Creating shader gamma font renderer");
101    mRenderer = NULL;
102}
103
104void ShaderGammaFontRenderer::describe(ProgramDescription& description,
105        const SkPaint* paint) const {
106    if (paint->getShader() == NULL) {
107        const int l = luminance(paint);
108
109        if (l <= mBlackThreshold) {
110            description.hasGammaCorrection = true;
111            description.gamma = mGamma;
112        } else if (l >= mWhiteThreshold) {
113            description.hasGammaCorrection = true;
114            description.gamma = 1.0f / mGamma;
115        }
116    }
117}
118
119void ShaderGammaFontRenderer::setupProgram(ProgramDescription& description,
120        Program* program) const {
121    if (description.hasGammaCorrection) {
122        glUniform1f(program->getUniform("gamma"), description.gamma);
123    }
124}
125
126///////////////////////////////////////////////////////////////////////////////
127// Lookup-based renderer
128///////////////////////////////////////////////////////////////////////////////
129
130LookupGammaFontRenderer::LookupGammaFontRenderer(): GammaFontRenderer() {
131    INIT_LOGD("Creating lookup gamma font renderer");
132
133    // Compute the gamma tables
134    const float blackGamma = mGamma;
135    const float whiteGamma = 1.0f / mGamma;
136
137    for (uint32_t i = 0; i <= 255; i++) {
138        mGammaTable[i] = i;
139
140        const float v = i / 255.0f;
141        const float black = pow(v, blackGamma);
142        const float white = pow(v, whiteGamma);
143
144        mGammaTable[256 + i] = uint8_t((float)::floor(black * 255.0f + 0.5f));
145        mGammaTable[512 + i] = uint8_t((float)::floor(white * 255.0f + 0.5f));
146    }
147
148    memset(mRenderers, 0, sizeof(FontRenderer*) * kGammaCount);
149    memset(mRenderersUsageCount, 0, sizeof(uint32_t) * kGammaCount);
150}
151
152LookupGammaFontRenderer::~LookupGammaFontRenderer() {
153    for (int i = 0; i < kGammaCount; i++) {
154        delete mRenderers[i];
155    }
156}
157
158void LookupGammaFontRenderer::clear() {
159    for (int i = 0; i < kGammaCount; i++) {
160        delete mRenderers[i];
161        mRenderers[i] = NULL;
162    }
163}
164
165void LookupGammaFontRenderer::flush() {
166    int count = 0;
167    int min = -1;
168    uint32_t minCount = UINT_MAX;
169
170    for (int i = 0; i < kGammaCount; i++) {
171        if (mRenderers[i]) {
172            count++;
173            if (mRenderersUsageCount[i] < minCount) {
174                minCount = mRenderersUsageCount[i];
175                min = i;
176            }
177        }
178    }
179
180    if (count <= 1 || min < 0) return;
181
182    delete mRenderers[min];
183    mRenderers[min] = NULL;
184
185    // Also eliminate the caches for large glyphs, as they consume significant memory
186    for (int i = 0; i < kGammaCount; ++i) {
187        if (mRenderers[i]) {
188            mRenderers[i]->flushLargeCaches();
189        }
190    }
191}
192
193FontRenderer* LookupGammaFontRenderer::getRenderer(Gamma gamma) {
194    FontRenderer* renderer = mRenderers[gamma];
195    if (!renderer) {
196        renderer = new FontRenderer();
197        mRenderers[gamma] = renderer;
198        renderer->setGammaTable(&mGammaTable[gamma * 256]);
199    }
200    mRenderersUsageCount[gamma]++;
201    return renderer;
202}
203
204FontRenderer& LookupGammaFontRenderer::getFontRenderer(const SkPaint* paint) {
205    if (paint->getShader() == NULL) {
206        const int l = luminance(paint);
207
208        if (l <= mBlackThreshold) {
209            return *getRenderer(kGammaBlack);
210        } else if (l >= mWhiteThreshold) {
211            return *getRenderer(kGammaWhite);
212        }
213    }
214    return *getRenderer(kGammaDefault);
215}
216
217}; // namespace uirenderer
218}; // namespace android
219