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 SkXfermode::Mode 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 == SkXfermode::kClear_Mode, "SkXfermode enums have changed"); 35 static_assert(1 == SkXfermode::kSrc_Mode, "SkXfermode enums have changed"); 36 static_assert(2 == SkXfermode::kDst_Mode, "SkXfermode enums have changed"); 37 static_assert(3 == SkXfermode::kSrcOver_Mode, "SkXfermode enums have changed"); 38 static_assert(4 == SkXfermode::kDstOver_Mode, "SkXfermode enums have changed"); 39 static_assert(5 == SkXfermode::kSrcIn_Mode, "SkXfermode enums have changed"); 40 static_assert(6 == SkXfermode::kDstIn_Mode, "SkXfermode enums have changed"); 41 static_assert(7 == SkXfermode::kSrcOut_Mode, "SkXfermode enums have changed"); 42 static_assert(8 == SkXfermode::kDstOut_Mode, "SkXfermode enums have changed"); 43 static_assert(9 == SkXfermode::kSrcATop_Mode, "SkXfermode enums have changed"); 44 static_assert(10 == SkXfermode::kDstATop_Mode, "SkXfermode enums have changed"); 45 static_assert(11 == SkXfermode::kXor_Mode, "SkXfermode enums have changed"); 46 static_assert(12 == SkXfermode::kPlus_Mode, "SkXfermode enums have changed"); 47 static_assert(13 == SkXfermode::kModulate_Mode, "SkXfermode enums have changed"); 48 static_assert(14 == SkXfermode::kScreen_Mode, "SkXfermode enums have changed"); 49 static_assert(15 == SkXfermode::kOverlay_Mode, "SkXfermode enums have changed"); 50 static_assert(16 == SkXfermode::kDarken_Mode, "SkXfermode enums have changed"); 51 static_assert(17 == SkXfermode::kLighten_Mode, "SkXfermode 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[SkXfermode::kSrc_Mode] 55 const Blender kBlends[] = { 56 { SkXfermode::kClear_Mode, GL_ZERO, GL_ONE_MINUS_SRC_ALPHA }, 57 { SkXfermode::kSrc_Mode, GL_ONE, GL_ZERO }, 58 { SkXfermode::kDst_Mode, GL_ZERO, GL_ONE }, 59 { SkXfermode::kSrcOver_Mode, GL_ONE, GL_ONE_MINUS_SRC_ALPHA }, 60 { SkXfermode::kDstOver_Mode, GL_ONE_MINUS_DST_ALPHA, GL_ONE }, 61 { SkXfermode::kSrcIn_Mode, GL_DST_ALPHA, GL_ZERO }, 62 { SkXfermode::kDstIn_Mode, GL_ZERO, GL_SRC_ALPHA }, 63 { SkXfermode::kSrcOut_Mode, GL_ONE_MINUS_DST_ALPHA, GL_ZERO }, 64 { SkXfermode::kDstOut_Mode, GL_ZERO, GL_ONE_MINUS_SRC_ALPHA }, 65 { SkXfermode::kSrcATop_Mode, GL_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA }, 66 { SkXfermode::kDstATop_Mode, GL_ONE_MINUS_DST_ALPHA, GL_SRC_ALPHA }, 67 { SkXfermode::kXor_Mode, GL_ONE_MINUS_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA }, 68 { SkXfermode::kPlus_Mode, GL_ONE, GL_ONE }, 69 { SkXfermode::kModulate_Mode, GL_ZERO, GL_SRC_COLOR }, 70 { SkXfermode::kScreen_Mode, GL_ONE, GL_ONE_MINUS_SRC_COLOR } 71 }; 72 73 // This array contains the swapped version of each SkXfermode. For instance 74 // this array's SrcOver blending mode is actually DstOver. You can refer to 75 // createLayer() for more information on the purpose of this array. 76 const Blender kBlendsSwap[] = { 77 { SkXfermode::kClear_Mode, GL_ONE_MINUS_DST_ALPHA, GL_ZERO }, 78 { SkXfermode::kSrc_Mode, GL_ZERO, GL_ONE }, 79 { SkXfermode::kDst_Mode, GL_ONE, GL_ZERO }, 80 { SkXfermode::kSrcOver_Mode, GL_ONE_MINUS_DST_ALPHA, GL_ONE }, 81 { SkXfermode::kDstOver_Mode, GL_ONE, GL_ONE_MINUS_SRC_ALPHA }, 82 { SkXfermode::kSrcIn_Mode, GL_ZERO, GL_SRC_ALPHA }, 83 { SkXfermode::kDstIn_Mode, GL_DST_ALPHA, GL_ZERO }, 84 { SkXfermode::kSrcOut_Mode, GL_ZERO, GL_ONE_MINUS_SRC_ALPHA }, 85 { SkXfermode::kDstOut_Mode, GL_ONE_MINUS_DST_ALPHA, GL_ZERO }, 86 { SkXfermode::kSrcATop_Mode, GL_ONE_MINUS_DST_ALPHA, GL_SRC_ALPHA }, 87 { SkXfermode::kDstATop_Mode, GL_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA }, 88 { SkXfermode::kXor_Mode, GL_ONE_MINUS_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA }, 89 { SkXfermode::kPlus_Mode, GL_ONE, GL_ONE }, 90 { SkXfermode::kModulate_Mode, GL_DST_COLOR, GL_ZERO }, 91 { SkXfermode::kScreen_Mode, GL_ONE_MINUS_DST_COLOR, GL_ONE } 92 }; 93 94 Blend::Blend() 95 : mEnabled(false) 96 , mSrcMode(GL_ZERO) 97 , mDstMode(GL_ZERO) { 98 // gl blending off by default 99 } 100 101 void Blend::invalidate() { 102 syncEnabled(); 103 mSrcMode = mDstMode = GL_ZERO; 104 } 105 106 void Blend::syncEnabled() { 107 if (mEnabled) { 108 glEnable(GL_BLEND); 109 } else { 110 glDisable(GL_BLEND); 111 } 112 } 113 114 void Blend::getFactors(SkXfermode::Mode mode, ModeOrderSwap modeUsage, GLenum* outSrc, GLenum* outDst) { 115 *outSrc = (modeUsage == ModeOrderSwap::Swap) ? kBlendsSwap[mode].src : kBlends[mode].src; 116 *outDst = (modeUsage == ModeOrderSwap::Swap) ? kBlendsSwap[mode].dst : kBlends[mode].dst; 117 } 118 119 void Blend::setFactors(GLenum srcMode, GLenum dstMode) { 120 if (srcMode == GL_ZERO && dstMode == GL_ZERO) { 121 // disable blending 122 if (mEnabled) { 123 glDisable(GL_BLEND); 124 mEnabled = false; 125 } 126 } else { 127 // enable blending 128 if (!mEnabled) { 129 glEnable(GL_BLEND); 130 mEnabled = true; 131 } 132 133 if (srcMode != mSrcMode || dstMode != mDstMode) { 134 glBlendFunc(srcMode, dstMode); 135 mSrcMode = srcMode; 136 mDstMode = dstMode; 137 } 138 } 139 } 140 141 void Blend::dump() { 142 ALOGD("Blend: enabled %d, func src %d, dst %d", mEnabled, mSrcMode, mDstMode); 143 } 144 145 } /* namespace uirenderer */ 146 } /* namespace android */ 147 148
