137 lines
4.9 KiB
C++
137 lines
4.9 KiB
C++
/*
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <renderstate/Blend.h>
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#include "Program.h"
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#include "ShadowTessellator.h"
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namespace android {
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namespace uirenderer {
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/**
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* Structure mapping Skia xfermodes to OpenGL blending factors.
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*/
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struct Blender {
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SkXfermode::Mode mode;
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GLenum src;
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GLenum dst;
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};
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// In this array, the index of each Blender equals the value of the first
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// entry. For instance, gBlends[1] == gBlends[SkXfermode::kSrc_Mode]
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const Blender kBlends[] = {
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{ SkXfermode::kClear_Mode, GL_ZERO, GL_ONE_MINUS_SRC_ALPHA },
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{ SkXfermode::kSrc_Mode, GL_ONE, GL_ZERO },
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{ SkXfermode::kDst_Mode, GL_ZERO, GL_ONE },
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{ SkXfermode::kSrcOver_Mode, GL_ONE, GL_ONE_MINUS_SRC_ALPHA },
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{ SkXfermode::kDstOver_Mode, GL_ONE_MINUS_DST_ALPHA, GL_ONE },
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{ SkXfermode::kSrcIn_Mode, GL_DST_ALPHA, GL_ZERO },
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{ SkXfermode::kDstIn_Mode, GL_ZERO, GL_SRC_ALPHA },
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{ SkXfermode::kSrcOut_Mode, GL_ONE_MINUS_DST_ALPHA, GL_ZERO },
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{ SkXfermode::kDstOut_Mode, GL_ZERO, GL_ONE_MINUS_SRC_ALPHA },
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{ SkXfermode::kSrcATop_Mode, GL_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA },
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{ SkXfermode::kDstATop_Mode, GL_ONE_MINUS_DST_ALPHA, GL_SRC_ALPHA },
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{ SkXfermode::kXor_Mode, GL_ONE_MINUS_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA },
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{ SkXfermode::kPlus_Mode, GL_ONE, GL_ONE },
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{ SkXfermode::kModulate_Mode, GL_ZERO, GL_SRC_COLOR },
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{ SkXfermode::kScreen_Mode, GL_ONE, GL_ONE_MINUS_SRC_COLOR }
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};
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// This array contains the swapped version of each SkXfermode. For instance
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// this array's SrcOver blending mode is actually DstOver. You can refer to
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// createLayer() for more information on the purpose of this array.
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const Blender kBlendsSwap[] = {
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{ SkXfermode::kClear_Mode, GL_ONE_MINUS_DST_ALPHA, GL_ZERO },
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{ SkXfermode::kSrc_Mode, GL_ZERO, GL_ONE },
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{ SkXfermode::kDst_Mode, GL_ONE, GL_ZERO },
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{ SkXfermode::kSrcOver_Mode, GL_ONE_MINUS_DST_ALPHA, GL_ONE },
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{ SkXfermode::kDstOver_Mode, GL_ONE, GL_ONE_MINUS_SRC_ALPHA },
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{ SkXfermode::kSrcIn_Mode, GL_ZERO, GL_SRC_ALPHA },
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{ SkXfermode::kDstIn_Mode, GL_DST_ALPHA, GL_ZERO },
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{ SkXfermode::kSrcOut_Mode, GL_ZERO, GL_ONE_MINUS_SRC_ALPHA },
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{ SkXfermode::kDstOut_Mode, GL_ONE_MINUS_DST_ALPHA, GL_ZERO },
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{ SkXfermode::kSrcATop_Mode, GL_ONE_MINUS_DST_ALPHA, GL_SRC_ALPHA },
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{ SkXfermode::kDstATop_Mode, GL_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA },
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{ SkXfermode::kXor_Mode, GL_ONE_MINUS_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA },
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{ SkXfermode::kPlus_Mode, GL_ONE, GL_ONE },
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{ SkXfermode::kModulate_Mode, GL_DST_COLOR, GL_ZERO },
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{ SkXfermode::kScreen_Mode, GL_ONE_MINUS_DST_COLOR, GL_ONE }
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};
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Blend::Blend()
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: mEnabled(false)
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, mSrcMode(GL_ZERO)
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, mDstMode(GL_ZERO) {
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// gl blending off by default
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}
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void Blend::enable(SkXfermode::Mode mode, bool swapSrcDst) {
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GLenum srcMode;
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GLenum dstMode;
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getFactors(mode, swapSrcDst, &srcMode, &dstMode);
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setFactors(srcMode, dstMode);
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}
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void Blend::disable() {
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if (mEnabled) {
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glDisable(GL_BLEND);
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mEnabled = false;
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}
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}
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void Blend::invalidate() {
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syncEnabled();
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mSrcMode = mDstMode = GL_ZERO;
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}
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void Blend::syncEnabled() {
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if (mEnabled) {
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glEnable(GL_BLEND);
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} else {
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glDisable(GL_BLEND);
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}
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}
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void Blend::getFactors(SkXfermode::Mode mode, bool swapSrcDst, GLenum* outSrc, GLenum* outDst) {
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*outSrc = swapSrcDst ? kBlendsSwap[mode].src : kBlends[mode].src;
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*outDst = swapSrcDst ? kBlendsSwap[mode].dst : kBlends[mode].dst;
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}
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void Blend::setFactors(GLenum srcMode, GLenum dstMode) {
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if (srcMode == GL_ZERO && dstMode == GL_ZERO) {
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disable();
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} else {
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if (!mEnabled) {
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glEnable(GL_BLEND);
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mEnabled = true;
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}
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if (srcMode != mSrcMode || dstMode != mDstMode) {
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glBlendFunc(srcMode, dstMode);
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mSrcMode = srcMode;
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mDstMode = dstMode;
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}
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}
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}
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void Blend::dump() {
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ALOGD("Blend: enabled %d, func src %d, dst %d", mEnabled, mSrcMode, mDstMode);
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}
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} /* namespace uirenderer */
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} /* namespace android */
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