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/* libs/graphics/effects/SkShaderExtras.cpp
**
** Copyright 2006, 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 "SkComposeShader.h"
#include "SkColorFilter.h"
#include "SkColorPriv.h"
#include "SkXfermode.h"
//////////////////////////////////////////////////////////////////////////////////////
SkComposeShader::SkComposeShader(SkShader* sA, SkShader* sB, SkXfermode* mode)
{
fShaderA = sA; sA->ref();
fShaderB = sB; sB->ref();
// mode may be null
fMode = mode; mode->safeRef();
}
SkComposeShader::SkComposeShader(SkFlattenableReadBuffer& buffer) :
INHERITED(buffer)
{
fShaderA = static_cast<SkShader*>(buffer.readFlattenable());
fShaderB = static_cast<SkShader*>(buffer.readFlattenable());
fMode = static_cast<SkXfermode*>(buffer.readFlattenable());
}
SkComposeShader::~SkComposeShader()
{
fMode->safeUnref(); // may be null
fShaderB->unref();
fShaderA->unref();
}
void SkComposeShader::beginSession()
{
this->INHERITED::beginSession();
fShaderA->beginSession();
fShaderB->beginSession();
}
void SkComposeShader::endSession()
{
fShaderA->endSession();
fShaderB->endSession();
this->INHERITED::endSession();
}
class SkAutoAlphaRestore {
public:
SkAutoAlphaRestore(SkPaint* paint, uint8_t newAlpha)
{
fAlpha = paint->getAlpha();
fPaint = paint;
paint->setAlpha(newAlpha);
}
~SkAutoAlphaRestore()
{
fPaint->setAlpha(fAlpha);
}
private:
SkPaint* fPaint;
uint8_t fAlpha;
};
void SkComposeShader::flatten(SkFlattenableWriteBuffer& buffer)
{
this->INHERITED::flatten(buffer);
buffer.writeFlattenable(fShaderA);
buffer.writeFlattenable(fShaderB);
buffer.writeFlattenable(fMode);
}
/* We call setContext on our two worker shaders. However, we
always let them see opaque alpha, and if the paint really
is translucent, then we apply that after the fact.
*/
bool SkComposeShader::setContext(const SkBitmap& device,
const SkPaint& paint,
const SkMatrix& matrix)
{
if (!this->INHERITED::setContext(device, paint, matrix))
return false;
// we preconcat our localMatrix (if any) with the device matrix
// before calling our sub-shaders
SkMatrix tmpM;
(void)this->getLocalMatrix(&tmpM);
tmpM.setConcat(matrix, tmpM);
SkAutoAlphaRestore restore(const_cast<SkPaint*>(&paint), 0xFF);
return fShaderA->setContext(device, paint, tmpM) &&
fShaderB->setContext(device, paint, tmpM);
}
// larger is better (fewer times we have to loop), but we shouldn't
// take up too much stack-space (each element is 4 bytes)
#define TMP_COLOR_COUNT 64
void SkComposeShader::shadeSpan(int x, int y, SkPMColor result[], int count)
{
SkShader* shaderA = fShaderA;
SkShader* shaderB = fShaderB;
SkXfermode* mode = fMode;
unsigned scale = SkAlpha255To256(this->getPaintAlpha());
SkPMColor tmp[TMP_COLOR_COUNT];
if (NULL == mode) // implied SRC_OVER
{
// TODO: when we have a good test-case, should use SkBlitRow::Proc32
// for these loops
do {
int n = count;
if (n > TMP_COLOR_COUNT)
n = TMP_COLOR_COUNT;
shaderA->shadeSpan(x, y, result, n);
shaderB->shadeSpan(x, y, tmp, n);
if (256 == scale)
{
for (int i = 0; i < n; i++)
result[i] = SkPMSrcOver(tmp[i], result[i]);
}
else
{
for (int i = 0; i < n; i++)
result[i] = SkAlphaMulQ(SkPMSrcOver(tmp[i], result[i]), scale);
}
result += n;
x += n;
count -= n;
} while (count > 0);
}
else // use mode for the composition
{
do {
int n = count;
if (n > TMP_COLOR_COUNT)
n = TMP_COLOR_COUNT;
shaderA->shadeSpan(x, y, result, n);
shaderB->shadeSpan(x, y, tmp, n);
mode->xfer32(result, tmp, n, NULL);
if (256 == scale)
{
for (int i = 0; i < n; i++)
result[i] = SkAlphaMulQ(result[i], scale);
}
result += n;
x += n;
count -= n;
} while (count > 0);
}
}
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