Add ColorMatrix filter tests from Android CTS.

tests/ColorMatrixTest.cpp

Index: tests/ColorMatrixTest.cpp
diff --git a/tests/ColorMatrixTest.cpp b/tests/ColorMatrixTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..885fef9de065dcfaeb267439e56090cd0b584283
--- /dev/null
+++ b/tests/ColorMatrixTest.cpp
@@ -0,0 +1,95 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkBitmap.h"
+#include "SkCanvas.h"
+#include "SkColor.h"
+#include "SkColorMatrixFilter.h"
+#include "SkPaint.h"
+
+#include "Test.h"
+
+static inline void assert_color(skiatest::Reporter* reporter, SkColor expected, SkColor actual) {
+    const int TOLERANCE = 1;
+    REPORTER_ASSERT(reporter, abs(SkColorGetA(expected) - SkColorGetA(actual)) <= TOLERANCE);
+    REPORTER_ASSERT(reporter, abs(SkColorGetR(expected) - SkColorGetR(actual)) <= TOLERANCE);
+    REPORTER_ASSERT(reporter, abs(SkColorGetG(expected) - SkColorGetG(actual)) <= TOLERANCE);
+    REPORTER_ASSERT(reporter, abs(SkColorGetB(expected) - SkColorGetB(actual)) <= TOLERANCE);
+}
+
+/**
+ * This test case is a mirror of the Android CTS tests for MatrixColorFilter
+ * found in the android.graphics.ColorMatrixColorFilterTest class.
+ */
+static inline void test_colorMatrix(skiatest::Reporter* reporter) {

[scroggo, 2015/05/19 20:10:44]

Why is this its own function? Why not just use DEF_TEST here?

[djsollen, 2015/05/19 20:24:29]

Personal preference.  My intention was that this method would just replicate the
CTS test and additional methods could be added for other colorMatrix tests. 
However, I should have named this test_colorMatrix_CTS or something like that.  

+
+    SkBitmap bitmap;
+    bitmap.allocN32Pixels(1,1);
+
+    SkCanvas canvas(bitmap);
+    SkPaint paint;
+
+    SkScalar blueToCyan[20] = {
+            1.0f, 0.0f, 0.0f, 0.0f, 0.0f,
+            0.0f, 1.0f, 1.0f, 0.0f, 0.0f,
+            0.0f, 0.0f, 1.0f, 0.0f, 0.0f,
+            0.0f, 0.0f, 0.0f, 1.0f, 0.0f };
+    paint.setColorFilter(SkColorMatrixFilter::Create(blueToCyan))->unref();
+
+    paint.setColor(SK_ColorBLUE);
+    canvas.drawPoint(0, 0, paint);
+    assert_color(reporter, SK_ColorCYAN, bitmap.getColor(0, 0));
+
+    paint.setColor(SK_ColorGREEN);
+    canvas.drawPoint(0, 0, paint);
+    assert_color(reporter, SK_ColorGREEN, bitmap.getColor(0, 0));
+
+    paint.setColor(SK_ColorRED);
+    canvas.drawPoint(0, 0, paint);
+    assert_color(reporter, SK_ColorRED, bitmap.getColor(0, 0));
+
+    // color components are clipped, not scaled
+    paint.setColor(SK_ColorMAGENTA);
+    canvas.drawPoint(0, 0, paint);
+    assert_color(reporter, SK_ColorWHITE, bitmap.getColor(0, 0));
+
+    SkScalar transparentRedAddBlue[20] = {
+            1.0f, 0.0f, 0.0f, 0.0f, 0.0f,
+            0.0f, 1.0f, 0.0f, 0.0f, 0.0f,
+            0.0f, 0.0f, 1.0f, 0.0f, 64.0f,
+           -0.5f, 0.0f, 0.0f, 1.0f, 0.0f
+    };
+    paint.setColorFilter(SkColorMatrixFilter::Create(transparentRedAddBlue))->unref();
+    bitmap.eraseColor(SK_ColorTRANSPARENT);
+
+    paint.setColor(SK_ColorRED);
+    canvas.drawPoint(0, 0, paint);
+    // Temporarily disabled assert until skbug.com/3848 is resolved.
+    // assert_color(reporter, SkColorSetARGB(128, 255, 0, 64), bitmap.getColor(0, 0));
+
+    paint.setColor(SK_ColorCYAN);
+    canvas.drawPoint(0, 0, paint);
+    // blue gets clipped
+    assert_color(reporter, SK_ColorCYAN, bitmap.getColor(0, 0));
+
+    // change array to filter out green
+    REPORTER_ASSERT(reporter, 1.0f == transparentRedAddBlue[6]);
+    transparentRedAddBlue[6] = 0.0f;
+
+    // check that changing the array has no effect
+    canvas.drawPoint(0, 0, paint);
+    assert_color(reporter, SK_ColorCYAN, bitmap.getColor(0, 0));
+
+    // create a new filter with the changed matrix
+    paint.setColorFilter(SkColorMatrixFilter::Create(transparentRedAddBlue))->unref();
+    canvas.drawPoint(0, 0, paint);
+    assert_color(reporter, SK_ColorBLUE, bitmap.getColor(0, 0));
+}
+
+DEF_TEST(ColorMatrix, reporter) {
+    test_colorMatrix(reporter);
+}