GammaFontRenderer.cpp revision 9a8245629d69d81e0b62e52970feaf9c02580e75 
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// Constructors/destructor
28///////////////////////////////////////////////////////////////////////////////
29
30GammaFontRenderer::GammaFontRenderer() {
31    INIT_LOGD("Creating gamma font renderer");
32
33    // Get the renderer properties
34    char property[PROPERTY_VALUE_MAX];
35
36    // Get the gamma
37    float gamma = DEFAULT_TEXT_GAMMA;
38    if (property_get(PROPERTY_TEXT_GAMMA, property, NULL) > 0) {
39        INIT_LOGD("  Setting text gamma to %s", property);
40        gamma = atof(property);
41    } else {
42        INIT_LOGD("  Using default text gamma of %.2f", DEFAULT_TEXT_GAMMA);
43    }
44
45    // Get the black gamma threshold
46    mBlackThreshold = DEFAULT_TEXT_BLACK_GAMMA_THRESHOLD;
47    if (property_get(PROPERTY_TEXT_BLACK_GAMMA_THRESHOLD, property, NULL) > 0) {
48        INIT_LOGD("  Setting text black gamma threshold to %s", property);
49        mBlackThreshold = atoi(property);
50    } else {
51        INIT_LOGD("  Using default text black gamma threshold of %d",
52                DEFAULT_TEXT_BLACK_GAMMA_THRESHOLD);
53    }
54
55    // Get the white gamma threshold
56    mWhiteThreshold = DEFAULT_TEXT_WHITE_GAMMA_THRESHOLD;
57    if (property_get(PROPERTY_TEXT_WHITE_GAMMA_THRESHOLD, property, NULL) > 0) {
58        INIT_LOGD("  Setting text white gamma threshold to %s", property);
59        mWhiteThreshold = atoi(property);
60    } else {
61        INIT_LOGD("  Using default white black gamma threshold of %d",
62                DEFAULT_TEXT_WHITE_GAMMA_THRESHOLD);
63    }
64
65    // Compute the gamma tables
66    const float blackGamma = gamma;
67    const float whiteGamma = 1.0f / gamma;
68
69    for (uint32_t i = 0; i <= 255; i++) {
70        mGammaTable[i] = i;
71
72        const float v = i / 255.0f;
73        const float black = pow(v, blackGamma);
74        const float white = pow(v, whiteGamma);
75
76        mGammaTable[256 + i] = uint8_t((float)::floor(black * 255.0f + 0.5f));
77        mGammaTable[512 + i] = uint8_t((float)::floor(white * 255.0f + 0.5f));
78    }
79
80    memset(mRenderers, 0, sizeof(FontRenderer*) * kGammaCount);
81    memset(mRenderersUsageCount, 0, sizeof(uint32_t) * kGammaCount);
82}
83
84GammaFontRenderer::~GammaFontRenderer() {
85    for (int i = 0; i < kGammaCount; i++) {
86        delete mRenderers[i];
87    }
88}
89
90void GammaFontRenderer::clear() {
91    for (int i = 0; i < kGammaCount; i++) {
92        delete mRenderers[i];
93        mRenderers[i] = NULL;
94    }
95}
96
97void GammaFontRenderer::flush() {
98    int count = 0;
99    int min = -1;
100    uint32_t minCount = UINT_MAX;
101
102    for (int i = 0; i < kGammaCount; i++) {
103        if (mRenderers[i]) {
104            count++;
105            if (mRenderersUsageCount[i] < minCount) {
106                minCount = mRenderersUsageCount[i];
107                min = i;
108            }
109        }
110    }
111
112    if (count <= 1 || min < 0) return;
113
114    delete mRenderers[min];
115    mRenderers[min] = NULL;
116
117    // Also eliminate the caches for large glyphs, as they consume significant memory
118    for (int i = 0; i < kGammaCount; ++i) {
119        if (mRenderers[i]) {
120            mRenderers[i]->flushLargeCaches();
121        }
122    }
123}
124
125FontRenderer* GammaFontRenderer::getRenderer(Gamma gamma) {
126    FontRenderer* renderer = mRenderers[gamma];
127    if (!renderer) {
128        renderer = new FontRenderer();
129        mRenderers[gamma] = renderer;
130        renderer->setGammaTable(&mGammaTable[gamma * 256]);
131    }
132    mRenderersUsageCount[gamma]++;
133    return renderer;
134}
135
136FontRenderer& GammaFontRenderer::getFontRenderer(const SkPaint* paint) {
137    if (paint->getShader() == NULL) {
138        uint32_t c = paint->getColor();
139        const int r = (c >> 16) & 0xFF;
140        const int g = (c >>  8) & 0xFF;
141        const int b = (c      ) & 0xFF;
142        const int luminance = (r * 2 + g * 5 + b) >> 3;
143
144        if (luminance <= mBlackThreshold) {
145            return *getRenderer(kGammaBlack);
146        } else if (luminance >= mWhiteThreshold) {
147            return *getRenderer(kGammaWhite);
148        }
149    }
150    return *getRenderer(kGammaDefault);
151}
152
153}; // namespace uirenderer
154}; // namespace android
155