GammaFontRenderer.cpp revision 11718bc17bcfc56dfb9f4362eebf640b025c4415 
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#include "Debug.h"
18#include "GammaFontRenderer.h"
19#include "Properties.h"
20
21namespace android {
22namespace uirenderer {
23
24///////////////////////////////////////////////////////////////////////////////
25// Utils
26///////////////////////////////////////////////////////////////////////////////
27
28static int luminance(const SkPaint* paint) {
29    uint32_t c = paint->getColor();
30    const int r = (c >> 16) & 0xFF;
31    const int g = (c >>  8) & 0xFF;
32    const int b = (c      ) & 0xFF;
33    return (r * 2 + g * 5 + b) >> 3;
34}
35
36///////////////////////////////////////////////////////////////////////////////
37// Base class GammaFontRenderer
38///////////////////////////////////////////////////////////////////////////////
39
40GammaFontRenderer* GammaFontRenderer::createRenderer() {
41    // Choose the best renderer
42    char property[PROPERTY_VALUE_MAX];
43    if (property_get(PROPERTY_TEXT_GAMMA_METHOD, property, DEFAULT_TEXT_GAMMA_METHOD) > 0) {
44        if (!strcasecmp(property, "lookup")) {
45            return new LookupGammaFontRenderer();
46        }
47    }
48
49    return new Lookup3GammaFontRenderer();
50}
51
52GammaFontRenderer::GammaFontRenderer() {
53    // Get the renderer properties
54    char property[PROPERTY_VALUE_MAX];
55
56    // Get the gamma
57    mGamma = DEFAULT_TEXT_GAMMA;
58    if (property_get(PROPERTY_TEXT_GAMMA, property, nullptr) > 0) {
59        INIT_LOGD("  Setting text gamma to %s", property);
60        mGamma = atof(property);
61    } else {
62        INIT_LOGD("  Using default text gamma of %.2f", DEFAULT_TEXT_GAMMA);
63    }
64
65    // Get the black gamma threshold
66    mBlackThreshold = DEFAULT_TEXT_BLACK_GAMMA_THRESHOLD;
67    if (property_get(PROPERTY_TEXT_BLACK_GAMMA_THRESHOLD, property, nullptr) > 0) {
68        INIT_LOGD("  Setting text black gamma threshold to %s", property);
69        mBlackThreshold = atoi(property);
70    } else {
71        INIT_LOGD("  Using default text black gamma threshold of %d",
72                DEFAULT_TEXT_BLACK_GAMMA_THRESHOLD);
73    }
74
75    // Get the white gamma threshold
76    mWhiteThreshold = DEFAULT_TEXT_WHITE_GAMMA_THRESHOLD;
77    if (property_get(PROPERTY_TEXT_WHITE_GAMMA_THRESHOLD, property, nullptr) > 0) {
78        INIT_LOGD("  Setting text white gamma threshold to %s", property);
79        mWhiteThreshold = atoi(property);
80    } else {
81        INIT_LOGD("  Using default white black gamma threshold of %d",
82                DEFAULT_TEXT_WHITE_GAMMA_THRESHOLD);
83    }
84}
85
86GammaFontRenderer::~GammaFontRenderer() {
87}
88
89///////////////////////////////////////////////////////////////////////////////
90// Lookup-based renderer
91///////////////////////////////////////////////////////////////////////////////
92
93LookupGammaFontRenderer::LookupGammaFontRenderer()
94        : GammaFontRenderer() {
95    INIT_LOGD("Creating lookup gamma font renderer");
96
97    // Compute the gamma tables
98    const float gamma = 1.0f / mGamma;
99
100    for (uint32_t i = 0; i <= 255; i++) {
101        mGammaTable[i] = uint8_t((float)::floor(pow(i / 255.0f, gamma) * 255.0f + 0.5f));
102    }
103
104    mRenderer = nullptr;
105}
106
107void LookupGammaFontRenderer::endPrecaching() {
108    if (mRenderer) {
109        mRenderer->endPrecaching();
110    }
111}
112
113///////////////////////////////////////////////////////////////////////////////
114// Lookup-based renderer, using 3 different correction tables
115///////////////////////////////////////////////////////////////////////////////
116
117Lookup3GammaFontRenderer::Lookup3GammaFontRenderer()
118        : GammaFontRenderer() {
119    INIT_LOGD("Creating lookup3 gamma font renderer");
120
121    // Compute the gamma tables
122    const float blackGamma = mGamma;
123    const float whiteGamma = 1.0f / mGamma;
124
125    for (uint32_t i = 0; i <= 255; i++) {
126        const float v = i / 255.0f;
127        const float black = pow(v, blackGamma);
128        const float white = pow(v, whiteGamma);
129
130        mGammaTable[i] = i;
131        mGammaTable[256 + i] = uint8_t((float)::floor(black * 255.0f + 0.5f));
132        mGammaTable[512 + i] = uint8_t((float)::floor(white * 255.0f + 0.5f));
133    }
134
135    memset(mRenderers, 0, sizeof(FontRenderer*) * kGammaCount);
136    memset(mRenderersUsageCount, 0, sizeof(uint32_t) * kGammaCount);
137}
138
139void Lookup3GammaFontRenderer::endPrecaching() {
140    for (int i = 0; i < kGammaCount; i++) {
141        if (mRenderers[i]) {
142            mRenderers[i]->endPrecaching();
143        }
144    }
145}
146
147void Lookup3GammaFontRenderer::clear() {
148    for (int i = 0; i < kGammaCount; i++) {
149        mRenderers[i].release();
150    }
151}
152
153void Lookup3GammaFontRenderer::flush() {
154    int count = 0;
155    int min = -1;
156    uint32_t minCount = UINT_MAX;
157
158    for (int i = 0; i < kGammaCount; i++) {
159        if (mRenderers[i]) {
160            count++;
161            if (mRenderersUsageCount[i] < minCount) {
162                minCount = mRenderersUsageCount[i];
163                min = i;
164            }
165        }
166    }
167
168    if (count <= 1 || min < 0) return;
169
170    mRenderers[min].release();
171
172    // Also eliminate the caches for large glyphs, as they consume significant memory
173    for (int i = 0; i < kGammaCount; ++i) {
174        if (mRenderers[i]) {
175            mRenderers[i]->flushLargeCaches();
176        }
177    }
178}
179
180FontRenderer* Lookup3GammaFontRenderer::getRenderer(Gamma gamma) {
181    if (!mRenderers[gamma]) {
182        mRenderers[gamma].reset(new FontRenderer());
183        mRenderers[gamma]->setGammaTable(&mGammaTable[gamma * 256]);
184    }
185    mRenderersUsageCount[gamma]++;
186    return mRenderers[gamma].get();
187}
188
189FontRenderer& Lookup3GammaFontRenderer::getFontRenderer(const SkPaint* paint) {
190    if (paint->getShader() == nullptr) {
191        const int l = luminance(paint);
192
193        if (l <= mBlackThreshold) {
194            return *getRenderer(kGammaBlack);
195        } else if (l >= mWhiteThreshold) {
196            return *getRenderer(kGammaWhite);
197        }
198    }
199    return *getRenderer(kGammaDefault);
200}
201
202}; // namespace uirenderer
203}; // namespace android
204