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/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <renderstate/Blend.h>
#include "Program.h"
#include "ShadowTessellator.h"
namespace android {
namespace uirenderer {
/**
* Structure mapping Skia xfermodes to OpenGL blending factors.
*/
struct Blender {
SkBlendMode mode;
GLenum src;
GLenum dst;
};
// assumptions made by lookup tables in either this file or ProgramCache
static_assert(0 == static_cast<int>(SkBlendMode::kClear), "SkBlendMode enums have changed");
static_assert(1 == static_cast<int>(SkBlendMode::kSrc), "SkBlendMode enums have changed");
static_assert(2 == static_cast<int>(SkBlendMode::kDst), "SkBlendMode enums have changed");
static_assert(3 == static_cast<int>(SkBlendMode::kSrcOver), "SkBlendMode enums have changed");
static_assert(4 == static_cast<int>(SkBlendMode::kDstOver), "SkBlendMode enums have changed");
static_assert(5 == static_cast<int>(SkBlendMode::kSrcIn), "SkBlendMode enums have changed");
static_assert(6 == static_cast<int>(SkBlendMode::kDstIn), "SkBlendMode enums have changed");
static_assert(7 == static_cast<int>(SkBlendMode::kSrcOut), "SkBlendMode enums have changed");
static_assert(8 == static_cast<int>(SkBlendMode::kDstOut), "SkBlendMode enums have changed");
static_assert(9 == static_cast<int>(SkBlendMode::kSrcATop), "SkBlendMode enums have changed");
static_assert(10 == static_cast<int>(SkBlendMode::kDstATop), "SkBlendMode enums have changed");
static_assert(11 == static_cast<int>(SkBlendMode::kXor), "SkBlendMode enums have changed");
static_assert(12 == static_cast<int>(SkBlendMode::kPlus), "SkBlendMode enums have changed");
static_assert(13 == static_cast<int>(SkBlendMode::kModulate), "SkBlendMode enums have changed");
static_assert(14 == static_cast<int>(SkBlendMode::kScreen), "SkBlendMode enums have changed");
static_assert(15 == static_cast<int>(SkBlendMode::kOverlay), "SkBlendMode enums have changed");
static_assert(16 == static_cast<int>(SkBlendMode::kDarken), "SkBlendMode enums have changed");
static_assert(17 == static_cast<int>(SkBlendMode::kLighten), "SkBlendMode enums have changed");
// In this array, the index of each Blender equals the value of the first
// entry. For instance, gBlends[1] == gBlends[SkBlendMode::kSrc]
const Blender kBlends[] = {
{ SkBlendMode::kClear, GL_ZERO, GL_ONE_MINUS_SRC_ALPHA },
{ SkBlendMode::kSrc, GL_ONE, GL_ZERO },
{ SkBlendMode::kDst, GL_ZERO, GL_ONE },
{ SkBlendMode::kSrcOver, GL_ONE, GL_ONE_MINUS_SRC_ALPHA },
{ SkBlendMode::kDstOver, GL_ONE_MINUS_DST_ALPHA, GL_ONE },
{ SkBlendMode::kSrcIn, GL_DST_ALPHA, GL_ZERO },
{ SkBlendMode::kDstIn, GL_ZERO, GL_SRC_ALPHA },
{ SkBlendMode::kSrcOut, GL_ONE_MINUS_DST_ALPHA, GL_ZERO },
{ SkBlendMode::kDstOut, GL_ZERO, GL_ONE_MINUS_SRC_ALPHA },
{ SkBlendMode::kSrcATop, GL_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA },
{ SkBlendMode::kDstATop, GL_ONE_MINUS_DST_ALPHA, GL_SRC_ALPHA },
{ SkBlendMode::kXor, GL_ONE_MINUS_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA },
{ SkBlendMode::kPlus, GL_ONE, GL_ONE },
{ SkBlendMode::kModulate, GL_ZERO, GL_SRC_COLOR },
{ SkBlendMode::kScreen, GL_ONE, GL_ONE_MINUS_SRC_COLOR }
};
// This array contains the swapped version of each SkBlendMode. For instance
// this array's SrcOver blending mode is actually DstOver. You can refer to
// createLayer() for more information on the purpose of this array.
const Blender kBlendsSwap[] = {
{ SkBlendMode::kClear, GL_ONE_MINUS_DST_ALPHA, GL_ZERO },
{ SkBlendMode::kSrc, GL_ZERO, GL_ONE },
{ SkBlendMode::kDst, GL_ONE, GL_ZERO },
{ SkBlendMode::kSrcOver, GL_ONE_MINUS_DST_ALPHA, GL_ONE },
{ SkBlendMode::kDstOver, GL_ONE, GL_ONE_MINUS_SRC_ALPHA },
{ SkBlendMode::kSrcIn, GL_ZERO, GL_SRC_ALPHA },
{ SkBlendMode::kDstIn, GL_DST_ALPHA, GL_ZERO },
{ SkBlendMode::kSrcOut, GL_ZERO, GL_ONE_MINUS_SRC_ALPHA },
{ SkBlendMode::kDstOut, GL_ONE_MINUS_DST_ALPHA, GL_ZERO },
{ SkBlendMode::kSrcATop, GL_ONE_MINUS_DST_ALPHA, GL_SRC_ALPHA },
{ SkBlendMode::kDstATop, GL_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA },
{ SkBlendMode::kXor, GL_ONE_MINUS_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA },
{ SkBlendMode::kPlus, GL_ONE, GL_ONE },
{ SkBlendMode::kModulate, GL_DST_COLOR, GL_ZERO },
{ SkBlendMode::kScreen, GL_ONE_MINUS_DST_COLOR, GL_ONE }
};
Blend::Blend()
: mEnabled(false)
, mSrcMode(GL_ZERO)
, mDstMode(GL_ZERO) {
// gl blending off by default
}
void Blend::invalidate() {
syncEnabled();
mSrcMode = mDstMode = GL_ZERO;
}
void Blend::syncEnabled() {
if (mEnabled) {
glEnable(GL_BLEND);
} else {
glDisable(GL_BLEND);
}
}
void Blend::getFactors(SkBlendMode mode, ModeOrderSwap modeUsage, GLenum* outSrc, GLenum* outDst) {
int index = static_cast<int>(mode);
*outSrc = (modeUsage == ModeOrderSwap::Swap) ? kBlendsSwap[index].src : kBlends[index].src;
*outDst = (modeUsage == ModeOrderSwap::Swap) ? kBlendsSwap[index].dst : kBlends[index].dst;
}
void Blend::setFactors(GLenum srcMode, GLenum dstMode) {
if ((srcMode == GL_ZERO || srcMode == GL_ONE) && dstMode == GL_ZERO) {
// disable blending
if (mEnabled) {
glDisable(GL_BLEND);
mEnabled = false;
}
} else {
// enable blending
if (!mEnabled) {
glEnable(GL_BLEND);
mEnabled = true;
}
if (srcMode != mSrcMode || dstMode != mDstMode) {
glBlendFunc(srcMode, dstMode);
mSrcMode = srcMode;
mDstMode = dstMode;
}
}
}
void Blend::dump() {
ALOGD("Blend: enabled %d, func src %d, dst %d", mEnabled, mSrcMode, mDstMode);
}
} /* namespace uirenderer */
} /* namespace android */
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