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

1 files changed, 119 insertions, 0 deletions

diff --git a/tests/ShaderOpacityTest.cpp b/tests/ShaderOpacityTest.cpp
new file mode 100644
index 0000000000..a8177eeb8b
--- /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)