Stabilize empty rect handling in EnclosingRect.

ui/gfx/geometry/size_unittest.cc

Index: ui/gfx/geometry/size_unittest.cc
diff --git a/ui/gfx/geometry/size_unittest.cc b/ui/gfx/geometry/size_unittest.cc
index 16b1ddceaec9ed6b96e8bebc5c1173627edc7a7e..eb16d4aaa46bbf4b3538e99e6ec53fe219e3e8c6 100644
--- a/ui/gfx/geometry/size_unittest.cc
+++ b/ui/gfx/geometry/size_unittest.cc
@@ -153,4 +153,84 @@ TEST(SizeTest, IntegerOverflow) {
   EXPECT_EQ(test, min_size);
 }
 
+// This checks that we set IsEmpty appropriately.
+TEST(SizeTest, TrivialDimensionTests) {
+  // First, using the constructor.
+  EXPECT_TRUE(SizeF(kTrivial / 2.f, 1.f).IsEmpty());
+  EXPECT_TRUE(SizeF(.01f, kTrivial / 2.f).IsEmpty());
+  EXPECT_TRUE(SizeF(0.f, 0.f).IsEmpty());
+  EXPECT_FALSE(SizeF(.01f, .01f).IsEmpty());
+
+  // Then use the setter.
+  SizeF test(2.f, 1.f);
+  EXPECT_FALSE(test.IsEmpty());
+
+  test.SetSize(kTrivial / 2.f, 1.f);
+  EXPECT_TRUE(test.IsEmpty());
+
+  test.SetSize(.01f, kTrivial / 2.f);
+  EXPECT_TRUE(test.IsEmpty());
+
+  test.SetSize(0.f, 0.f);
+  EXPECT_TRUE(test.IsEmpty());
+
+  test.SetSize(.01f, .01f);
+  EXPECT_FALSE(test.IsEmpty());
+
+  // Now just one dimension at a time.
+  test.set_width(kTrivial / 2.f);
+  EXPECT_TRUE(test.IsEmpty());
+
+  test.set_width(4e13f);
+  test.set_height(kTrivial / 2.f);
+  EXPECT_TRUE(test.IsEmpty());
+
+  test.set_width(kTrivial / 2.f);
+  test.set_height(4e13f);
+  EXPECT_TRUE(test.IsEmpty());
+
+  test.set_width(2.f);
+  EXPECT_FALSE(test.IsEmpty());
+}
+
+// These are the ramifications of the decision to keep the recorded size
+// at zero for trivial sizes.
+TEST(SizeTest, ClampsToZero) {
+  SizeF test(kTrivial / 2.f, 1.f);
+
+  EXPECT_EQ(test.width(), 0.f);
+  EXPECT_EQ(test.height(), 1.f);
+
+  test.SetSize(.01f, kTrivial / 2.f);
+
+  EXPECT_EQ(test.width(), .01f);
+  EXPECT_EQ(test.height(), 0.f);
+
+  test.SetSize(kTrivial, kTrivial);
+  test.Scale(0.5f);
+
+  EXPECT_EQ(test.width(), 0.f);
+  EXPECT_EQ(test.height(), 0.f);
+
+  test.SetSize(0.f, 0.f);
+  test.Enlarge(kTrivial / 2.f, kTrivial / 2.f);
+  test.Enlarge(kTrivial / 2.f, kTrivial / 2.f);
+  test.Enlarge(kTrivial / 2.f, kTrivial / 2.f);
+
+  EXPECT_EQ(test, SizeF(0.f, 0.f));
+}
+
+// These make sure the constructor and setter have the same effect on the
+// boundary case. This claims to know the boundary, but not which way it goes.
+TEST(SizeTest, ConsistentClamping) {
+  SizeF left(kTrivial, 0.f);
+  SizeF top(0.f, kTrivial);
+  SizeF right, bottom;

[danakj, 2017/03/23 20:12:06]

Not sure that |right| and |bottom| express these, or |left| and |top|. I'd maybe
suggest with_constructed_width, with_constructed_height, with_set_width,
with_set_height or something?

[Peter Mayo, 2017/03/23 23:58:41]

I have a better way I'll propose with the next edits.

+  right.SetSize(kTrivial, 0.f);
+  bottom.SetSize(0.f, kTrivial);
+
+  EXPECT_EQ(left, right);
+  EXPECT_EQ(top, bottom);
+}
+
 }  // namespace gfx