1 /*
2 * Copyright (C) 2015 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 #include <renderstate/Blend.h>
17 #include "Program.h"
18
19 #include "ShadowTessellator.h"
20
21 namespace android {
22 namespace uirenderer {
23
24 /**
25 * Structure mapping Skia xfermodes to OpenGL blending factors.
26 */
27 struct Blender {
28 SkBlendMode mode;
29 GLenum src;
30 GLenum dst;
31 };
32
33 // assumptions made by lookup tables in either this file or ProgramCache
34 static_assert(0 == static_cast<int>(SkBlendMode::kClear), "SkBlendMode enums have changed");
35 static_assert(1 == static_cast<int>(SkBlendMode::kSrc), "SkBlendMode enums have changed");
36 static_assert(2 == static_cast<int>(SkBlendMode::kDst), "SkBlendMode enums have changed");
37 static_assert(3 == static_cast<int>(SkBlendMode::kSrcOver), "SkBlendMode enums have changed");
38 static_assert(4 == static_cast<int>(SkBlendMode::kDstOver), "SkBlendMode enums have changed");
39 static_assert(5 == static_cast<int>(SkBlendMode::kSrcIn), "SkBlendMode enums have changed");
40 static_assert(6 == static_cast<int>(SkBlendMode::kDstIn), "SkBlendMode enums have changed");
41 static_assert(7 == static_cast<int>(SkBlendMode::kSrcOut), "SkBlendMode enums have changed");
42 static_assert(8 == static_cast<int>(SkBlendMode::kDstOut), "SkBlendMode enums have changed");
43 static_assert(9 == static_cast<int>(SkBlendMode::kSrcATop), "SkBlendMode enums have changed");
44 static_assert(10 == static_cast<int>(SkBlendMode::kDstATop), "SkBlendMode enums have changed");
45 static_assert(11 == static_cast<int>(SkBlendMode::kXor), "SkBlendMode enums have changed");
46 static_assert(12 == static_cast<int>(SkBlendMode::kPlus), "SkBlendMode enums have changed");
47 static_assert(13 == static_cast<int>(SkBlendMode::kModulate), "SkBlendMode enums have changed");
48 static_assert(14 == static_cast<int>(SkBlendMode::kScreen), "SkBlendMode enums have changed");
49 static_assert(15 == static_cast<int>(SkBlendMode::kOverlay), "SkBlendMode enums have changed");
50 static_assert(16 == static_cast<int>(SkBlendMode::kDarken), "SkBlendMode enums have changed");
51 static_assert(17 == static_cast<int>(SkBlendMode::kLighten), "SkBlendMode enums have changed");
52
53 // In this array, the index of each Blender equals the value of the first
54 // entry. For instance, gBlends[1] == gBlends[SkBlendMode::kSrc]
55 const Blender kBlends[] = {{SkBlendMode::kClear, GL_ZERO, GL_ONE_MINUS_SRC_ALPHA},
56 {SkBlendMode::kSrc, GL_ONE, GL_ZERO},
57 {SkBlendMode::kDst, GL_ZERO, GL_ONE},
58 {SkBlendMode::kSrcOver, GL_ONE, GL_ONE_MINUS_SRC_ALPHA},
59 {SkBlendMode::kDstOver, GL_ONE_MINUS_DST_ALPHA, GL_ONE},
60 {SkBlendMode::kSrcIn, GL_DST_ALPHA, GL_ZERO},
61 {SkBlendMode::kDstIn, GL_ZERO, GL_SRC_ALPHA},
62 {SkBlendMode::kSrcOut, GL_ONE_MINUS_DST_ALPHA, GL_ZERO},
63 {SkBlendMode::kDstOut, GL_ZERO, GL_ONE_MINUS_SRC_ALPHA},
64 {SkBlendMode::kSrcATop, GL_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA},
65 {SkBlendMode::kDstATop, GL_ONE_MINUS_DST_ALPHA, GL_SRC_ALPHA},
66 {SkBlendMode::kXor, GL_ONE_MINUS_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA},
67 {SkBlendMode::kPlus, GL_ONE, GL_ONE},
68 {SkBlendMode::kModulate, GL_ZERO, GL_SRC_COLOR},
69 {SkBlendMode::kScreen, GL_ONE, GL_ONE_MINUS_SRC_COLOR}};
70
71 // This array contains the swapped version of each SkBlendMode. For instance
72 // this array's SrcOver blending mode is actually DstOver. You can refer to
73 // createLayer() for more information on the purpose of this array.
74 const Blender kBlendsSwap[] = {{SkBlendMode::kClear, GL_ONE_MINUS_DST_ALPHA, GL_ZERO},
75 {SkBlendMode::kSrc, GL_ZERO, GL_ONE},
76 {SkBlendMode::kDst, GL_ONE, GL_ZERO},
77 {SkBlendMode::kSrcOver, GL_ONE_MINUS_DST_ALPHA, GL_ONE},
78 {SkBlendMode::kDstOver, GL_ONE, GL_ONE_MINUS_SRC_ALPHA},
79 {SkBlendMode::kSrcIn, GL_ZERO, GL_SRC_ALPHA},
80 {SkBlendMode::kDstIn, GL_DST_ALPHA, GL_ZERO},
81 {SkBlendMode::kSrcOut, GL_ZERO, GL_ONE_MINUS_SRC_ALPHA},
82 {SkBlendMode::kDstOut, GL_ONE_MINUS_DST_ALPHA, GL_ZERO},
83 {SkBlendMode::kSrcATop, GL_ONE_MINUS_DST_ALPHA, GL_SRC_ALPHA},
84 {SkBlendMode::kDstATop, GL_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA},
85 {SkBlendMode::kXor, GL_ONE_MINUS_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA},
86 {SkBlendMode::kPlus, GL_ONE, GL_ONE},
87 {SkBlendMode::kModulate, GL_DST_COLOR, GL_ZERO},
88 {SkBlendMode::kScreen, GL_ONE_MINUS_DST_COLOR, GL_ONE}};
89
Blend()90 Blend::Blend() : mEnabled(false), mSrcMode(GL_ZERO), mDstMode(GL_ZERO) {
91 // gl blending off by default
92 }
93
invalidate()94 void Blend::invalidate() {
95 syncEnabled();
96 mSrcMode = mDstMode = GL_ZERO;
97 }
98
syncEnabled()99 void Blend::syncEnabled() {
100 if (mEnabled) {
101 glEnable(GL_BLEND);
102 } else {
103 glDisable(GL_BLEND);
104 }
105 }
106
getFactors(SkBlendMode mode,ModeOrderSwap modeUsage,GLenum * outSrc,GLenum * outDst)107 void Blend::getFactors(SkBlendMode mode, ModeOrderSwap modeUsage, GLenum* outSrc, GLenum* outDst) {
108 int index = static_cast<int>(mode);
109 *outSrc = (modeUsage == ModeOrderSwap::Swap) ? kBlendsSwap[index].src : kBlends[index].src;
110 *outDst = (modeUsage == ModeOrderSwap::Swap) ? kBlendsSwap[index].dst : kBlends[index].dst;
111 }
112
setFactors(GLenum srcMode,GLenum dstMode)113 void Blend::setFactors(GLenum srcMode, GLenum dstMode) {
114 if ((srcMode == GL_ZERO || srcMode == GL_ONE) && dstMode == GL_ZERO) {
115 // disable blending
116 if (mEnabled) {
117 glDisable(GL_BLEND);
118 mEnabled = false;
119 }
120 } else {
121 // enable blending
122 if (!mEnabled) {
123 glEnable(GL_BLEND);
124 mEnabled = true;
125 }
126
127 if (srcMode != mSrcMode || dstMode != mDstMode) {
128 glBlendFunc(srcMode, dstMode);
129 mSrcMode = srcMode;
130 mDstMode = dstMode;
131 }
132 }
133 }
134
dump()135 void Blend::dump() {
136 ALOGD("Blend: enabled %d, func src %d, dst %d", mEnabled, mSrcMode, mDstMode);
137 }
138
139 } /* namespace uirenderer */
140 } /* namespace android */
141