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Adding isOpaque method to skia shader classes

Browse Source 
REVIEW=http://codereview.appspot.com/5451102/
TEST=unit test ShaderOpacity



git-svn-id: http://skia.googlecode.com/svn/trunk@2840 2bbb7eff-a529-9590-31e7-b0007b416f81
This commit is contained in:
junov@chromium.org 2011-12-09 15:48:03 +00:00
parent e23f194bf9
commit b6e161937b
8 changed files with 163 additions and 14 deletions
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1
gyp/tests.gyp
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@ -53,6 +53,7 @@
'../tests/RefDictTest.cpp',
'../tests/RegionTest.cpp',
'../tests/ScalarTest.cpp',
'../tests/ShaderOpacityTest.cpp',
'../tests/Sk64Test.cpp',
'../tests/skia_test.cpp',
'../tests/SortTest.cpp',

1
include/core/SkColorShader.h
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@ -34,6 +34,7 @@ public:
virtual uint32_t getFlags() SK_OVERRIDE;
virtual uint8_t getSpan16Alpha() const SK_OVERRIDE;
virtual bool isOpaque() const SK_OVERRIDE;
virtual bool setContext(const SkBitmap& device, const SkPaint& paint,
const SkMatrix& matrix) SK_OVERRIDE;
virtual void shadeSpan(int x, int y, SkPMColor span[], int count) SK_OVERRIDE;

9
include/core/SkShader.h
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@ -96,6 +96,15 @@ public:
*/
virtual uint32_t getFlags() { return 0; }
/**
* Returns true if the shader is guaranteed to produce only opaque
* colors, subject to the SkPaint using the shader to apply an opaque
* alpha value. Subclasses should override this to allow some
* optimizations. isOpaque() can be called at any time, unlike getFlags,
* which only works properly when the context is set.
*/
virtual bool isOpaque() const { return false; }
/**
* Return the alpha associated with the data returned by shadeSpan16(). If
* kHasSpan16_Flag is not set, this value is meaningless.

4
src/core/SkBitmapProcShader.cpp
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@ -81,6 +81,10 @@ static bool only_scale_and_translate(const SkMatrix& matrix) {
return (matrix.getType() & ~mask) == 0;
}
bool SkBitmapProcShader::isOpaque() const {
return fRawBitmap.isOpaque();
}
bool SkBitmapProcShader::setContext(const SkBitmap& device,
const SkPaint& paint,
const SkMatrix& matrix) {

1
src/core/SkBitmapProcShader.h
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@ -18,6 +18,7 @@ public:
SkBitmapProcShader(const SkBitmap& src, TileMode tx, TileMode ty);
// overrides from SkShader
virtual bool isOpaque() const SK_OVERRIDE;
virtual bool setContext(const SkBitmap&, const SkPaint&, const SkMatrix&);
virtual uint32_t getFlags() { return fFlags; }
virtual void shadeSpan(int x, int y, SkPMColor dstC[], int count);

7
src/core/SkShader.cpp
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@ -221,6 +221,13 @@ SkColorShader::SkColorShader(SkColor c) {
SkColorShader::~SkColorShader() {}
bool SkColorShader::isOpaque() const {
if (fInheritColor) {
return true; // using paint's alpha
}
return SkColorGetA(fColor) == 255;
}
SkColorShader::SkColorShader(SkFlattenableReadBuffer& b) : INHERITED(b) {
fFlags = 0; // computed in setContext

35
src/effects/SkGradientShader.cpp
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@ -119,6 +119,7 @@ public:
// overrides
virtual bool setContext(const SkBitmap&, const SkPaint&, const SkMatrix&) SK_OVERRIDE;
virtual uint32_t getFlags() SK_OVERRIDE { return fFlags; }
virtual bool isOpaque() const SK_OVERRIDE;
protected:
Gradient_Shader(SkFlattenableReadBuffer& );
@ -161,7 +162,8 @@ private:
kStorageSize = kColorStorageCount * (sizeof(SkColor) + sizeof(Rec))
};
SkColor fStorage[(kStorageSize + 3) >> 2];
SkColor* fOrigColors;
SkColor* fOrigColors; // original colors, before modulation by paint in setContext
bool fColorsAreOpaque;
mutable uint16_t* fCache16; // working ptr. If this is NULL, we need to recompute the cache values
mutable SkPMColor* fCache32; // working ptr. If this is NULL, we need to recompute the cache values
@ -174,6 +176,7 @@ private:
static void Build32bitCache(SkPMColor[], SkColor c0, SkColor c1, int count,
U8CPU alpha);
void setCacheAlpha(U8CPU alpha) const;
void initCommon();
typedef SkShader INHERITED;
};
@ -302,7 +305,7 @@ Gradient_Shader::Gradient_Shader(const SkColor colors[], const SkScalar pos[],
}
}
}
fFlags = 0;
this->initCommon();
}
Gradient_Shader::Gradient_Shader(SkFlattenableReadBuffer& buffer) :
@ -336,7 +339,7 @@ Gradient_Shader::Gradient_Shader(SkFlattenableReadBuffer& buffer) :
}
}
SkReadMatrix(&buffer, &fPtsToUnit);
fFlags = 0;
this->initCommon();
}
Gradient_Shader::~Gradient_Shader() {
@ -350,6 +353,15 @@ Gradient_Shader::~Gradient_Shader() {
SkSafeUnref(fMapper);
}
void Gradient_Shader::initCommon() {
fFlags = 0;
unsigned colorAlpha = 0xFF;
for (int i = 0; i < fColorCount; i++) {
colorAlpha &= SkColorGetA(fOrigColors[i]);
}
fColorsAreOpaque = colorAlpha == 0xFF;
}
void Gradient_Shader::flatten(SkFlattenableWriteBuffer& buffer) {
this->INHERITED::flatten(buffer);
buffer.writeFlattenable(fMapper);
@ -366,6 +378,10 @@ void Gradient_Shader::flatten(SkFlattenableWriteBuffer& buffer) {
SkWriteMatrix(&buffer, fPtsToUnit);
}
bool Gradient_Shader::isOpaque() const {
return fColorsAreOpaque;
}
bool Gradient_Shader::setContext(const SkBitmap& device,
const SkPaint& paint,
const SkMatrix& matrix) {
@ -384,23 +400,14 @@ bool Gradient_Shader::setContext(const SkBitmap& device,
// now convert our colors in to PMColors
unsigned paintAlpha = this->getPaintAlpha();
unsigned colorAlpha = 0xFF;
// FIXME: record colorAlpha in constructor, since this is not affected
// by setContext()
for (int i = 0; i < fColorCount; i++) {
SkColor src = fOrigColors[i];
unsigned sa = SkColorGetA(src);
colorAlpha &= sa;
}
fFlags = this->INHERITED::getFlags();
if ((colorAlpha & paintAlpha) == 0xFF) {
if (fColorsAreOpaque && paintAlpha == 0xFF) {
fFlags |= kOpaqueAlpha_Flag;
}
// we can do span16 as long as our individual colors are opaque,
// regardless of the paint's alpha
if (0xFF == colorAlpha) {
if (fColorsAreOpaque) {
fFlags |= kHasSpan16_Flag;
}

119
tests/ShaderOpacityTest.cpp Normal file
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@ -0,0 +1,119 @@
/*
* Copyright 2011 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "Test.h"
#include "SkShader.h"
#include "SkGradientShader.h"
#include "SkColorShader.h"
static void test_bitmap(skiatest::Reporter* reporter) {
SkBitmap bmp;
bmp.setConfig(SkBitmap::kARGB_8888_Config, 2, 2);
// test 1: bitmap without pixel data
SkShader* shader = SkShader::CreateBitmapShader(bmp,
SkShader::kClamp_TileMode, SkShader::kClamp_TileMode);
REPORTER_ASSERT(reporter, shader);
REPORTER_ASSERT(reporter, !shader->isOpaque());
shader->unref();
// From this point on, we have pixels
bmp.allocPixels();
// test 2: not opaque by default
shader = SkShader::CreateBitmapShader(bmp,
SkShader::kClamp_TileMode, SkShader::kClamp_TileMode);
REPORTER_ASSERT(reporter, shader);
REPORTER_ASSERT(reporter, !shader->isOpaque());
shader->unref();
// test 3: explicitly opaque
bmp.setIsOpaque(true);
shader = SkShader::CreateBitmapShader(bmp,
SkShader::kClamp_TileMode, SkShader::kClamp_TileMode);
REPORTER_ASSERT(reporter, shader);
REPORTER_ASSERT(reporter, shader->isOpaque());
shader->unref();
// test 4: explicitly not opaque
bmp.setIsOpaque(false);
shader = SkShader::CreateBitmapShader(bmp,
SkShader::kClamp_TileMode, SkShader::kClamp_TileMode);
REPORTER_ASSERT(reporter, shader);
REPORTER_ASSERT(reporter, !shader->isOpaque());
shader->unref();
}
static void test_gradient(skiatest::Reporter* reporter)
{
SkPoint pts[2];
pts[0].iset(0, 0);
pts[1].iset(1, 0);
SkColor colors[2];
SkScalar pos[2] = {SkIntToScalar(0), SkIntToScalar(1)};
int count = 2;
SkShader::TileMode mode = SkShader::kClamp_TileMode;
// test 1: all opaque
colors[0] = SkColorSetARGB(0xFF, 0, 0, 0);
colors[1] = SkColorSetARGB(0xFF, 0, 0, 0);
SkShader* grad = SkGradientShader::CreateLinear(pts, colors, pos, count,
mode);
REPORTER_ASSERT(reporter, grad);
REPORTER_ASSERT(reporter, grad->isOpaque());
grad->unref();
// test 2: all 0 alpha
colors[0] = SkColorSetARGB(0, 0, 0, 0);
colors[1] = SkColorSetARGB(0, 0, 0, 0);
grad = SkGradientShader::CreateLinear(pts, colors, pos, count, mode);
REPORTER_ASSERT(reporter, grad);
REPORTER_ASSERT(reporter, !grad->isOpaque());
grad->unref();
// test 3: one opaque, one transparent
colors[0] = SkColorSetARGB(0xFF, 0, 0, 0);
colors[1] = SkColorSetARGB(0x40, 0, 0, 0);
grad = SkGradientShader::CreateLinear(pts, colors, pos, count, mode);
REPORTER_ASSERT(reporter, grad);
REPORTER_ASSERT(reporter, !grad->isOpaque());
grad->unref();
// test 4: test 3, swapped
colors[0] = SkColorSetARGB(0x40, 0, 0, 0);
colors[1] = SkColorSetARGB(0xFF, 0, 0, 0);
grad = SkGradientShader::CreateLinear(pts, colors, pos, count, mode);
REPORTER_ASSERT(reporter, grad);
REPORTER_ASSERT(reporter, !grad->isOpaque());
grad->unref();
}
static void test_color(skiatest::Reporter* reporter)
{
SkColorShader colorShader1(SkColorSetARGB(0,0,0,0));
REPORTER_ASSERT(reporter, !colorShader1.isOpaque());
SkColorShader colorShader2(SkColorSetARGB(0xFF,0,0,0));
REPORTER_ASSERT(reporter, colorShader2.isOpaque());
SkColorShader colorShader3(SkColorSetARGB(0x7F,0,0,0));
REPORTER_ASSERT(reporter, !colorShader3.isOpaque());
// with inherrited color, shader must declare itself as opaque,
// since lack of opacity will depend solely on the paint
SkColorShader colorShader4;
REPORTER_ASSERT(reporter, colorShader4.isOpaque());
}
static void test_shader_opacity(skiatest::Reporter* reporter)
{
test_gradient(reporter);
test_color(reporter);
test_bitmap(reporter);
}
#include "TestClassDef.h"
DEFINE_TESTCLASS("ShaderOpacity", ShaderOpacityTestClass, test_shader_opacity)