1 /*
2 * Copyright (C) 2012 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 "Caches.h"
18 #include "Dither.h"
19
20 namespace android {
21 namespace uirenderer {
22
23 ///////////////////////////////////////////////////////////////////////////////
24 // Lifecycle
25 ///////////////////////////////////////////////////////////////////////////////
26
Dither()27 Dither::Dither(): mCaches(NULL), mInitialized(false), mDitherTexture(0) {
28 }
29
bindDitherTexture()30 void Dither::bindDitherTexture() {
31 if (!mInitialized) {
32 bool useFloatTexture = Extensions::getInstance().hasFloatTextures();
33
34 glGenTextures(1, &mDitherTexture);
35 mCaches->bindTexture(mDitherTexture);
36
37 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
38 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
39
40 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
41 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
42
43 if (useFloatTexture) {
44 // We use a R16F texture, let's remap the alpha channel to the
45 // red channel to avoid changing the shader sampling code on GL ES 3.0+
46 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_SWIZZLE_A, GL_RED);
47
48 float dither = 1.0f / (255.0f * DITHER_KERNEL_SIZE * DITHER_KERNEL_SIZE);
49 const GLfloat pattern[] = {
50 0 * dither, 8 * dither, 2 * dither, 10 * dither,
51 12 * dither, 4 * dither, 14 * dither, 6 * dither,
52 3 * dither, 11 * dither, 1 * dither, 9 * dither,
53 15 * dither, 7 * dither, 13 * dither, 5 * dither
54 };
55
56 glPixelStorei(GL_UNPACK_ALIGNMENT, sizeof(GLfloat));
57 glTexImage2D(GL_TEXTURE_2D, 0, GL_R16F, DITHER_KERNEL_SIZE, DITHER_KERNEL_SIZE, 0,
58 GL_RED, GL_FLOAT, &pattern);
59 } else {
60 const uint8_t pattern[] = {
61 0, 8, 2, 10,
62 12, 4, 14, 6,
63 3, 11, 1, 9,
64 15, 7, 13, 5
65 };
66
67 glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
68 glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, DITHER_KERNEL_SIZE, DITHER_KERNEL_SIZE, 0,
69 GL_ALPHA, GL_UNSIGNED_BYTE, &pattern);
70 }
71
72 mInitialized = true;
73 } else {
74 mCaches->bindTexture(mDitherTexture);
75 }
76 }
77
clear()78 void Dither::clear() {
79 if (mInitialized) {
80 mCaches->deleteTexture(mDitherTexture);
81 mInitialized = false;
82 }
83 }
84
85 ///////////////////////////////////////////////////////////////////////////////
86 // Program management
87 ///////////////////////////////////////////////////////////////////////////////
88
setupProgram(Program * program,GLuint * textureUnit)89 void Dither::setupProgram(Program* program, GLuint* textureUnit) {
90 if (!mCaches) mCaches = &Caches::getInstance();
91
92 GLuint textureSlot = (*textureUnit)++;
93 mCaches->activeTexture(textureSlot);
94
95 bindDitherTexture();
96
97 glUniform1i(program->getUniform("ditherSampler"), textureSlot);
98 }
99
100 }; // namespace uirenderer
101 }; // namespace android
102