Adding isOpaque method to skia shader classes
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
diff --git a/gyp/tests.gyp b/gyp/tests.gyp
index 46c5ac5..a9c152d 100644
--- a/gyp/tests.gyp
+++ b/gyp/tests.gyp
@@ -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',
diff --git a/include/core/SkColorShader.h b/include/core/SkColorShader.h
index c68617a..9b1fed3 100644
--- a/include/core/SkColorShader.h
+++ b/include/core/SkColorShader.h
@@ -34,6 +34,7 @@
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;
diff --git a/include/core/SkShader.h b/include/core/SkShader.h
index db737c9..7c5be06 100644
--- a/include/core/SkShader.h
+++ b/include/core/SkShader.h
@@ -97,6 +97,15 @@
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.
*/
diff --git a/src/core/SkBitmapProcShader.cpp b/src/core/SkBitmapProcShader.cpp
index 85f9645..65387e4 100644
--- a/src/core/SkBitmapProcShader.cpp
+++ b/src/core/SkBitmapProcShader.cpp
@@ -81,6 +81,10 @@
return (matrix.getType() & ~mask) == 0;
}
+bool SkBitmapProcShader::isOpaque() const {
+ return fRawBitmap.isOpaque();
+}
+
bool SkBitmapProcShader::setContext(const SkBitmap& device,
const SkPaint& paint,
const SkMatrix& matrix) {
diff --git a/src/core/SkBitmapProcShader.h b/src/core/SkBitmapProcShader.h
index 9af9d2e..cd70279 100644
--- a/src/core/SkBitmapProcShader.h
+++ b/src/core/SkBitmapProcShader.h
@@ -18,6 +18,7 @@
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);
diff --git a/src/core/SkShader.cpp b/src/core/SkShader.cpp
index b832f95..44ec62d 100644
--- a/src/core/SkShader.cpp
+++ b/src/core/SkShader.cpp
@@ -221,6 +221,13 @@
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
diff --git a/src/effects/SkGradientShader.cpp b/src/effects/SkGradientShader.cpp
index bc7f8a3..af357a6 100644
--- a/src/effects/SkGradientShader.cpp
+++ b/src/effects/SkGradientShader.cpp
@@ -119,6 +119,7 @@
// 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 @@
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 @@
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 @@
}
}
}
- fFlags = 0;
+ this->initCommon();
}
Gradient_Shader::Gradient_Shader(SkFlattenableReadBuffer& buffer) :
@@ -336,7 +339,7 @@
}
}
SkReadMatrix(&buffer, &fPtsToUnit);
- fFlags = 0;
+ this->initCommon();
}
Gradient_Shader::~Gradient_Shader() {
@@ -350,6 +353,15 @@
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 @@
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 @@
// 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;
}
diff --git a/tests/ShaderOpacityTest.cpp b/tests/ShaderOpacityTest.cpp
new file mode 100644
index 0000000..a8177ee
--- /dev/null
+++ b/tests/ShaderOpacityTest.cpp
@@ -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)