Event smoothing in CrOS gesture recognizer.

ui/aura/gestures/velocity_calculator_unittest.cc

+// Copyright (c) 2012 The Chromium 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 "testing/gtest/include/gtest/gtest.h"
+#include "ui/aura/gestures/velocity_calculator.h"
+#include "ui/aura/test/aura_test_base.h"
+
+namespace aura {
+namespace test {
+
+namespace {
+static void AddPoints(VelocityCalculator* velocityCalculator,
+                      float x_increment,
+                      float y_increment,
+                      float time_increment,
+                      int num_points) {
+  float x = 0;
+  float y = 0;
+  double time = 0;
+
+  for (int i = 0; i < num_points; ++i) {
+    velocityCalculator->PointSeen(x, y, time);
+    x += x_increment;
+    y += y_increment;
+    time += time_increment;
+  }
+}
+}  // namespace
+
+typedef AuraTestBase VelocityCalculatorTest;
+
+// Test that the velocity returned is reasonable
+TEST_F(VelocityCalculatorTest, ReturnsReasonableVelocity) {
+  float vx;
+  float vy;
+
+  VelocityCalculator velocityCalculator(5);
+  AddPoints(&velocityCalculator, 10, -10, 1, 7);
+  velocityCalculator.Velocity(&vx, &vy);
+  EXPECT_GT(vx, 9.9);
+  EXPECT_LT(vx, 10.1);
+  EXPECT_GT(vy, -10.1);
+  EXPECT_LT(vy, -9.9);
+
+  velocityCalculator.PointSeen(9, -11, 5.5);
+  velocityCalculator.PointSeen(21, -19, 6);
+  velocityCalculator.PointSeen(30, -32, 6.5);
+  velocityCalculator.PointSeen(38, -40, 7);
+  velocityCalculator.PointSeen(50, -51, 7.5);
+  velocityCalculator.Velocity(&vx, &vy);
+  EXPECT_GT(vx, 19);
+  EXPECT_LT(vx, 21);
+  EXPECT_GT(vy, -21);
+  EXPECT_LT(vy, -19);
+
+  // Significantly larger difference in position
+  velocityCalculator.PointSeen(70, -70, 8);
+  velocityCalculator.Velocity(&vx, &vy);
+  EXPECT_GT(vx, 20);
+  EXPECT_LT(vx, 25);
+  EXPECT_GT(vy, -25);
+  EXPECT_LT(vy, -20);
+}
+
+// Check that the velocity returned is 0 if the velocity calculator
+// doesn't have enough data
+TEST_F(VelocityCalculatorTest, RequiresEnoughData) {
+  float vx = 5;
+  float vy = 5;
+  VelocityCalculator velocityCalculator(5);
+  velocityCalculator.Velocity(&vx, &vy);
+  EXPECT_EQ(vx, 0);
+  EXPECT_EQ(vy, 0);
+
+  AddPoints(&velocityCalculator, 10, 10, 1, 4);
+
+  // We've only seen 4 points, the buffer size is 5
+  // Since the buffer isn't full, return 0
+  velocityCalculator.Velocity(&vx, &vy);
+  EXPECT_EQ(vx, 0);
+  EXPECT_EQ(vy, 0);
+
+  AddPoints(&velocityCalculator, 10, 10, 1, 1);
+
+  velocityCalculator.Velocity(&vx, &vy);
+  EXPECT_GT(vx, 9.9);
+  EXPECT_GT(vy, 9.9);
+}
+
+// Ensures ClearHistory behaves correctly
+TEST_F(VelocityCalculatorTest, ClearsHistory) {
+  float vx;
+  float vy;
+
+  VelocityCalculator velocityCalculator(5);
+  AddPoints(&velocityCalculator, 10, -10, 1, 7);
+
+  velocityCalculator.Velocity(&vx, &vy);
+  EXPECT_GT(vx, 9.9);
+  EXPECT_LT(vy, -9.9);
+
+  velocityCalculator.ClearHistory();
+
+  velocityCalculator.Velocity(&vx, &vy);
+  EXPECT_EQ(vx, 0);
+  EXPECT_EQ(vy, 0);
+}
+
+// Ensure data older than the buffer size is ignored
+TEST_F(VelocityCalculatorTest, IgnoresOldData) {
+  float vx;
+  float vy;
+
+  VelocityCalculator velocityCalculator(5);
+  AddPoints(&velocityCalculator, 10, -10, 1, 7);
+  velocityCalculator.Velocity(&vx, &vy);
+  EXPECT_GT(vx, 9.9);
+  EXPECT_LT(vy, -9.9);
+
+  AddPoints(&velocityCalculator, 0, 0, 1, 5);
+
+  velocityCalculator.Velocity(&vx, &vy);
+  EXPECT_EQ(vx, 0);
+  EXPECT_EQ(vy, 0);
+}
+
+}  // namespace test
+}  // namespace aura