Fix matrix similarity test on arm64

Addresses precision issue by using a simpler test.
Also fixes issues with IvMatrix::preservesRightAngles, and adds unit tests.

BUG=skia:2405
R=robertphillips@google.com, egdaniel@google.com, djsollen@google.com, reed@google.com

Author: jvanverth@google.com

Review URL: https://codereview.chromium.org/520123002

1 files changed, 39 insertions, 9 deletions

diff --git a/tests/MatrixTest.cpp b/tests/MatrixTest.cpp
index cbec021b40..fc7ac42a99 100644
--- a/tests/MatrixTest.cpp
+++ b/tests/MatrixTest.cpp
@@ -245,88 +245,96 @@ static void test_matrix_min_max_scale(skiatest::Reporter* reporter) {
     }
 }
 
-static void test_matrix_is_similarity(skiatest::Reporter* reporter) {
+static void test_matrix_preserve_shape(skiatest::Reporter* reporter) {
     SkMatrix mat;
 
     // identity
     mat.setIdentity();
     REPORTER_ASSERT(reporter, mat.isSimilarity());
+    REPORTER_ASSERT(reporter, mat.preservesRightAngles());
 
     // translation only
     mat.reset();
     mat.setTranslate(SkIntToScalar(100), SkIntToScalar(100));
     REPORTER_ASSERT(reporter, mat.isSimilarity());
+    REPORTER_ASSERT(reporter, mat.preservesRightAngles());
 
     // scale with same size
     mat.reset();
     mat.setScale(SkIntToScalar(15), SkIntToScalar(15));
     REPORTER_ASSERT(reporter, mat.isSimilarity());
+    REPORTER_ASSERT(reporter, mat.preservesRightAngles());
 
     // scale with one negative
     mat.reset();
     mat.setScale(SkIntToScalar(-15), SkIntToScalar(15));
     REPORTER_ASSERT(reporter, mat.isSimilarity());
+    REPORTER_ASSERT(reporter, mat.preservesRightAngles());
 
     // scale with different size
     mat.reset();
     mat.setScale(SkIntToScalar(15), SkIntToScalar(20));
     REPORTER_ASSERT(reporter, !mat.isSimilarity());
+    REPORTER_ASSERT(reporter, mat.preservesRightAngles());
 
     // scale with same size at a pivot point
     mat.reset();
     mat.setScale(SkIntToScalar(15), SkIntToScalar(15),
                  SkIntToScalar(2), SkIntToScalar(2));
     REPORTER_ASSERT(reporter, mat.isSimilarity());
+    REPORTER_ASSERT(reporter, mat.preservesRightAngles());
 
     // scale with different size at a pivot point
     mat.reset();
     mat.setScale(SkIntToScalar(15), SkIntToScalar(20),
                  SkIntToScalar(2), SkIntToScalar(2));
     REPORTER_ASSERT(reporter, !mat.isSimilarity());
+    REPORTER_ASSERT(reporter, mat.preservesRightAngles());
 
     // skew with same size
     mat.reset();
     mat.setSkew(SkIntToScalar(15), SkIntToScalar(15));
     REPORTER_ASSERT(reporter, !mat.isSimilarity());
+    REPORTER_ASSERT(reporter, !mat.preservesRightAngles());
 
     // skew with different size
     mat.reset();
     mat.setSkew(SkIntToScalar(15), SkIntToScalar(20));
     REPORTER_ASSERT(reporter, !mat.isSimilarity());
+    REPORTER_ASSERT(reporter, !mat.preservesRightAngles());
 
     // skew with same size at a pivot point
     mat.reset();
     mat.setSkew(SkIntToScalar(15), SkIntToScalar(15),
                 SkIntToScalar(2), SkIntToScalar(2));
     REPORTER_ASSERT(reporter, !mat.isSimilarity());
+    REPORTER_ASSERT(reporter, !mat.preservesRightAngles());
 
     // skew with different size at a pivot point
     mat.reset();
     mat.setSkew(SkIntToScalar(15), SkIntToScalar(20),
                 SkIntToScalar(2), SkIntToScalar(2));
     REPORTER_ASSERT(reporter, !mat.isSimilarity());
+    REPORTER_ASSERT(reporter, !mat.preservesRightAngles());
 
     // perspective x
     mat.reset();
     mat.setPerspX(SkScalarToPersp(SK_Scalar1 / 2));
     REPORTER_ASSERT(reporter, !mat.isSimilarity());
+    REPORTER_ASSERT(reporter, !mat.preservesRightAngles());
 
     // perspective y
     mat.reset();
     mat.setPerspY(SkScalarToPersp(SK_Scalar1 / 2));
     REPORTER_ASSERT(reporter, !mat.isSimilarity());
+    REPORTER_ASSERT(reporter, !mat.preservesRightAngles());
 
     // rotate
     for (int angle = 0; angle < 360; ++angle) {
         mat.reset();
         mat.setRotate(SkIntToScalar(angle));
-#ifndef SK_CPU_ARM64
         REPORTER_ASSERT(reporter, mat.isSimilarity());
-#else
-        // 64-bit ARM devices built with -O2 and -ffp-contract=fast have a loss
-        // of precision and require that we have a higher tolerance
-        REPORTER_ASSERT(reporter, mat.isSimilarity(SK_ScalarNearlyZero + 0.00010113f));
-#endif
+        REPORTER_ASSERT(reporter, mat.preservesRightAngles());
     }
 
     // see if there are any accumulated precision issues
@@ -335,38 +343,60 @@ static void test_matrix_is_similarity(skiatest::Reporter* reporter) {
         mat.postRotate(SkIntToScalar(1));
     }
     REPORTER_ASSERT(reporter, mat.isSimilarity());
+    REPORTER_ASSERT(reporter, mat.preservesRightAngles());
 
     // rotate + translate
     mat.reset();
     mat.setRotate(SkIntToScalar(30));
     mat.postTranslate(SkIntToScalar(10), SkIntToScalar(20));
     REPORTER_ASSERT(reporter, mat.isSimilarity());
+    REPORTER_ASSERT(reporter, mat.preservesRightAngles());
 
     // rotate + uniform scale
     mat.reset();
     mat.setRotate(SkIntToScalar(30));
     mat.postScale(SkIntToScalar(2), SkIntToScalar(2));
     REPORTER_ASSERT(reporter, mat.isSimilarity());
+    REPORTER_ASSERT(reporter, mat.preservesRightAngles());
 
     // rotate + non-uniform scale
     mat.reset();
     mat.setRotate(SkIntToScalar(30));
     mat.postScale(SkIntToScalar(3), SkIntToScalar(2));
     REPORTER_ASSERT(reporter, !mat.isSimilarity());
+    REPORTER_ASSERT(reporter, !mat.preservesRightAngles());
+
+    // non-uniform scale + rotate
+    mat.reset();
+    mat.setScale(SkIntToScalar(3), SkIntToScalar(2));
+    mat.postRotate(SkIntToScalar(30));
+    REPORTER_ASSERT(reporter, !mat.isSimilarity());
+    REPORTER_ASSERT(reporter, mat.preservesRightAngles());
 
     // all zero
     mat.setAll(0, 0, 0, 0, 0, 0, 0, 0, 0);
     REPORTER_ASSERT(reporter, !mat.isSimilarity());
+    REPORTER_ASSERT(reporter, !mat.preservesRightAngles());
 
     // all zero except perspective
+    mat.reset();
     mat.setAll(0, 0, 0, 0, 0, 0, 0, 0, SK_Scalar1);
     REPORTER_ASSERT(reporter, !mat.isSimilarity());
+    REPORTER_ASSERT(reporter, !mat.preservesRightAngles());
+
+    // scales zero, only skews (rotation)
+    mat.setAll(0, SK_Scalar1, 0,
+               -SK_Scalar1, 0, 0,
+               0, 0, SkMatrix::I()[8]);
+    REPORTER_ASSERT(reporter, mat.isSimilarity());
+    REPORTER_ASSERT(reporter, mat.preservesRightAngles());
 
-    // scales zero, only skews
+    // scales zero, only skews (reflection)
     mat.setAll(0, SK_Scalar1, 0,
                SK_Scalar1, 0, 0,
                0, 0, SkMatrix::I()[8]);
     REPORTER_ASSERT(reporter, mat.isSimilarity());
+    REPORTER_ASSERT(reporter, mat.preservesRightAngles());
 }
 
 // For test_matrix_decomposition, below.
@@ -815,7 +845,7 @@ DEF_TEST(Matrix, reporter) {
     REPORTER_ASSERT(reporter, !are_equal(reporter, mat, mat2));
 
     test_matrix_min_max_scale(reporter);
-    test_matrix_is_similarity(reporter);
+    test_matrix_preserve_shape(reporter);
     test_matrix_recttorect(reporter);
     test_matrix_decomposition(reporter);
     test_matrix_homogeneous(reporter);