Add unittest for matrix reverse

This Cl adds some unit tests for the CFX_Matrix Reverse method.

Bug: chromium:702041
Change-Id: I9598d3eb48d6b86a3e192d313fe1091bd29a4701
Reviewed-on: https://pdfium-review.googlesource.com/4492
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: dsinclair <dsinclair@chromium.org>

2 files changed, 90 insertions, 0 deletions

diff --git a/BUILD.gn b/BUILD.gn
index e513b37e05..a11c2c179e 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -1872,6 +1872,7 @@ test("pdfium_unittests") {
     "core/fxcrt/fx_basic_gcc_unittest.cpp",
     "core/fxcrt/fx_basic_util_unittest.cpp",
     "core/fxcrt/fx_bidi_unittest.cpp",
+    "core/fxcrt/fx_coordinates_unittest.cpp",
     "core/fxcrt/fx_extension_unittest.cpp",
     "core/fxcrt/fx_memory_unittest.cpp",
     "core/fxcrt/fx_system_unittest.cpp",
diff --git a/core/fxcrt/fx_coordinates_unittest.cpp b/core/fxcrt/fx_coordinates_unittest.cpp
new file mode 100644
index 0000000000..12ddb97330
--- /dev/null
+++ b/core/fxcrt/fx_coordinates_unittest.cpp
@@ -0,0 +1,89 @@
+// Copyright 2017 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "core/fxcrt/fx_coordinates.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+TEST(CFX_Matrix, ReverseIdentity) {
+  CFX_Matrix m;
+  CFX_Matrix rev;
+
+  m.SetIdentity();
+  rev.SetReverse(m);
+  EXPECT_FLOAT_EQ(1.0, rev.a);
+  EXPECT_FLOAT_EQ(0.0, rev.b);
+  EXPECT_FLOAT_EQ(0.0, rev.c);
+  EXPECT_FLOAT_EQ(1.0, rev.d);
+  EXPECT_FLOAT_EQ(0.0, rev.e);
+  EXPECT_FLOAT_EQ(0.0, rev.f);
+
+  CFX_PointF expected(2, 3);
+  CFX_PointF result = rev.Transform(m.Transform(CFX_PointF(2, 3)));
+  EXPECT_FLOAT_EQ(expected.x, result.x);
+  EXPECT_FLOAT_EQ(expected.y, result.y);
+}
+
+TEST(CFX_Matrix, Reverse) {
+  float data[6] = {3, 0, 2, 3, 1, 4};
+  CFX_Matrix m(data);
+  CFX_Matrix rev;
+
+  rev.SetReverse(m);
+  EXPECT_FLOAT_EQ(0.33333334f, rev.a);
+  EXPECT_FLOAT_EQ(0.0f, rev.b);
+  EXPECT_FLOAT_EQ(-0.22222222f, rev.c);
+  EXPECT_FLOAT_EQ(0.33333334f, rev.d);
+  EXPECT_FLOAT_EQ(0.55555556f, rev.e);
+  EXPECT_FLOAT_EQ(-1.3333334f, rev.f);
+
+  CFX_PointF expected(2, 3);
+  CFX_PointF result = rev.Transform(m.Transform(CFX_PointF(2, 3)));
+  EXPECT_FLOAT_EQ(expected.x, result.x);
+  EXPECT_FLOAT_EQ(expected.y, result.y);
+}
+
+// Note, I think these are a bug and the matrix should be the identity.
+TEST(CFX_Matrix, ReverseCR702041) {
+  // The determinate is < std::numeric_limits<float>::epsilon()
+  float data[6] = {0.947368443f, -0.108947366f, -0.923076928f,
+                   0.106153846f, 18.0f,         787.929993f};
+  CFX_Matrix m(data);
+  CFX_Matrix rev;
+
+  rev.SetReverse(m);
+  EXPECT_FLOAT_EQ(14247728.0f, rev.a);
+  EXPECT_FLOAT_EQ(14622668.0f, rev.b);
+  EXPECT_FLOAT_EQ(1.2389329e+08f, rev.c);
+  EXPECT_FLOAT_EQ(1.2715364e+08f, rev.d);
+  EXPECT_FLOAT_EQ(-9.7875698e+10f, rev.e);
+  EXPECT_FLOAT_EQ(-1.0045138e+11f, rev.f);
+
+  // Should be 2, 3
+  CFX_PointF expected(0, 0);
+  CFX_PointF result = rev.Transform(m.Transform(CFX_PointF(2, 3)));
+  EXPECT_FLOAT_EQ(expected.x, result.x);
+  EXPECT_FLOAT_EQ(expected.y, result.y);
+}
+
+TEST(CFX_Matrix, ReverseCR714187) {
+  // The determinate is < std::numeric_limits<float>::epsilon()
+  float data[6] = {0.000037f, 0.0f, 0.0f, -0.000037f, 182.413101f, 136.977646f};
+  CFX_Matrix m(data);
+  CFX_Matrix rev;
+
+  rev.SetReverse(m);
+  EXPECT_FLOAT_EQ(27027.025f, rev.a);
+  EXPECT_FLOAT_EQ(0.0f, rev.b);
+  EXPECT_FLOAT_EQ(0.0f, rev.c);
+  EXPECT_FLOAT_EQ(-27027.025f, rev.d);
+  EXPECT_FLOAT_EQ(-4930083.5f, rev.e);
+  EXPECT_FLOAT_EQ(3702098.2f, rev.f);
+
+  // Should be 3 ....
+  CFX_PointF expected(2, 2.75);
+  CFX_PointF result = rev.Transform(m.Transform(CFX_PointF(2, 3)));
+  EXPECT_FLOAT_EQ(expected.x, result.x);
+  EXPECT_FLOAT_EQ(expected.y, result.y);
+}