/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.view;
import junit.framework.Assert;
import android.test.InstrumentationTestCase;
import android.test.suitebuilder.annotation.MediumTest;
import android.view.animation.AccelerateInterpolator;
import android.view.animation.DecelerateInterpolator;
import android.view.animation.Interpolator;
import android.view.animation.LinearInterpolator;
/**
* Exercises {@link android.view.VelocityTracker} to compute correct velocity.<br>
* To launch this test, use :<br>
* <code>./development/testrunner/runtest.py framework -c android.view.VelocityTest</code>
*/
public class VelocityTest extends InstrumentationTestCase {
@MediumTest
public void testInitialCondiditions() {
VelocityTracker vt = VelocityTracker.obtain();
assertNotNull(vt);
vt.recycle();
}
/**
* Test that {@link android.view.VelocityTracker}.clear() clears
* the previous values after a call to computeCurrentVelocity()
*/
@MediumTest
public void testClear() {
long t = System.currentTimeMillis();
VelocityTracker vt = VelocityTracker.obtain();
drag(vt, 100, 200, 100, 200, 10, t, 300);
vt.computeCurrentVelocity(1);
assertFalse("Velocity should not be null", vt.getXVelocity() == 0.0f);
assertFalse("Velocity should not be null", vt.getYVelocity() == 0.0f);
vt.clear();
vt.computeCurrentVelocity(1);
assertEquals(0.0f, vt.getXVelocity());
assertEquals(0.0f, vt.getYVelocity());
vt.recycle();
}
@MediumTest
public void testDragAcceleration () {
long t = System.currentTimeMillis();
VelocityTracker vt = VelocityTracker.obtain();
drag(vt, 100, 200, 100, 200, 15, t, 400, new AccelerateInterpolator());
vt.computeCurrentVelocity(1000);
assertGreater(250.0f, vt.getXVelocity());
assertGreater(250.0f, vt.getYVelocity());
vt.recycle();
}
@MediumTest
public void testDragDeceleration () {
long t = System.currentTimeMillis();
VelocityTracker vt = VelocityTracker.obtain();
drag(vt, 100, 200, 100, 200, 15, t, 400, new DecelerateInterpolator());
vt.computeCurrentVelocity(1000);
assertLower(250.0f, vt.getXVelocity());
assertLower(250.0f, vt.getYVelocity());
vt.recycle();
}
@MediumTest
public void testDragLinearHorizontal() {
long t = System.currentTimeMillis();
VelocityTracker vt = VelocityTracker.obtain();
// 100px in 400ms => 250px/s
drag(vt, 100, 200, 200, 200, 15, t, 400);
vt.computeCurrentVelocity(1000);
assertEquals(0.0f, vt.getYVelocity());
assertEqualFuzzy(250.0f, vt.getXVelocity(), 4f);
vt.recycle();
}
@MediumTest
public void testDragLinearVertical() {
long t = System.currentTimeMillis();
VelocityTracker vt = VelocityTracker.obtain();
// 100px in 400ms => 250px/s
drag(vt, 200, 200, 100, 200, 15, t, 400);
vt.computeCurrentVelocity(1000);
assertEquals(0.0f, vt.getXVelocity());
assertEqualFuzzy(250.0f, vt.getYVelocity(), 4f);
vt.recycle();
}
/**
* Test dragging with two points only
* (velocity must be an exact value)
*/
@MediumTest
public void testDragWith2Points () {
long t = System.currentTimeMillis();
VelocityTracker vt = VelocityTracker.obtain();
// 100px, 2 steps, 100ms => 1000px/s
drag(vt, 100, 200, 100, 200, 2, t, 100);
vt.computeCurrentVelocity(1000);
assertEquals(1000.0f, vt.getXVelocity());
assertEquals(1000.0f, vt.getYVelocity());
vt.recycle();
}
/**
* Velocity is independent of the number of points used during
* the same interval
*/
@MediumTest
public void testStabilityInNbPoints () {
long t = System.currentTimeMillis();
VelocityTracker vt = VelocityTracker.obtain();
drag(vt, 100, 200, 100, 200, 10, t, 400); // 10 steps over 400ms
vt.computeCurrentVelocity(1);
float firstX = vt.getXVelocity();
float firstY = vt.getYVelocity();
vt.clear();
drag(vt, 100, 200, 100, 200, 20, t, 400); // 20 steps over 400ms
vt.computeCurrentVelocity(1);
float secondX = vt.getXVelocity();
float secondY = vt.getYVelocity();
assertEqualFuzzy(firstX, secondX, 0.1f);
assertEqualFuzzy(firstY, secondY, 0.1f);
vt.recycle();
}
/**
* Velocity is independent of the time when the events occurs,
* it only depends on delays between the events.
*/
@MediumTest
public void testStabilityInTime () {
long t = System.currentTimeMillis();
VelocityTracker vt = VelocityTracker.obtain();
drag(vt, 100, 200, 100, 200, 10, t, 400);
vt.computeCurrentVelocity(1);
float firstX = vt.getXVelocity();
float firstY = vt.getYVelocity();
vt.clear();
drag(vt, 100, 200, 100, 200, 10, t + 3600*1000, 400); // on hour later
vt.computeCurrentVelocity(1);
float secondX = vt.getXVelocity();
float secondY = vt.getYVelocity();
assertEqualFuzzy(firstX, secondX, 0.1f);
assertEqualFuzzy(firstY, secondY, 0.1f);
vt.recycle();
}
/**
* Velocity is independent of the position of the events,
* it only depends on their relative distance.
*/
@MediumTest
public void testStabilityInSpace () {
long t = System.currentTimeMillis();
VelocityTracker vt = VelocityTracker.obtain();
drag(vt, 100, 200, 100, 200, 10, t, 400);
vt.computeCurrentVelocity(1);
float firstX = vt.getXVelocity();
float firstY = vt.getYVelocity();
vt.clear();
drag(vt, 200, 300, 200, 300, 10, t, 400); // 100px further
vt.computeCurrentVelocity(1);
float secondX = vt.getXVelocity();
float secondY = vt.getYVelocity();
assertEqualFuzzy(firstX, secondX, 0.1f);
assertEqualFuzzy(firstY, secondY, 0.1f);
vt.recycle();
}
/**
* Test that calls to {@link android.view.VelocityTracker}.computeCurrentVelocity()
* will output same values when using the same data.
*/
@MediumTest
public void testStabilityOfComputation() {
long t = System.currentTimeMillis();
VelocityTracker vt = VelocityTracker.obtain();
drag(vt, 100, 200, 100, 200, 10, t, 300);
vt.computeCurrentVelocity(1);
float firstX = vt.getXVelocity();
float firstY = vt.getYVelocity();
vt.computeCurrentVelocity(1);
float secondX = vt.getXVelocity();
float secondY = vt.getYVelocity();
assertEquals(firstX, secondX);
assertEquals(firstY, secondY);
vt.recycle();
}
/**
* Test the units parameter of {@link android.view.VelocityTracker}.computeCurrentVelocity()
*/
@MediumTest
public void testStabilityOfUnits() {
long t = System.currentTimeMillis();
VelocityTracker vt = VelocityTracker.obtain();
drag(vt, 100, 200, 100, 200, 10, t, 300);
vt.computeCurrentVelocity(1);
float firstX = vt.getXVelocity();
float firstY = vt.getYVelocity();
vt.computeCurrentVelocity(1000);
float secondX = vt.getXVelocity();
float secondY = vt.getYVelocity();
assertEqualFuzzy(firstX, secondX / 1000.0f, 0.1f);
assertEqualFuzzy(firstY, secondY / 1000.0f, 0.1f);
vt.recycle();
}
/**
* Simulate a drag by giving directly MotionEvents to
* the VelocityTracker using a linear interpolator
*/
private void drag(VelocityTracker vt, int startX, int endX, int startY, int endY, int steps,
long startime, int duration) {
drag(vt, startX, endX, startY, endY, steps, startime, duration, new LinearInterpolator());
}
/**
* Simulate a drag by giving directly MotionEvents to
* the VelocityTracker using a given interpolator
*/
private void drag(VelocityTracker vt, int startX, int endX, int startY, int endY, int steps,
long startime, int duration, Interpolator interpolator) {
addMotionEvent(vt, startX, startY, startime, MotionEvent.ACTION_DOWN);
float dt = duration / (float)steps;
int distX = endX - startX;
int distY = endY - startY;
for (int i=1; i<steps-1; i++) {
float ii = interpolator.getInterpolation(i / (float)steps);
int x = (int) (startX + distX * ii);
int y = (int) (startY + distY * ii);
long time = startime + (int) (i * dt);
addMotionEvent(vt, x, y, time, MotionEvent.ACTION_MOVE);
}
addMotionEvent(vt, endX, endY, startime + duration, MotionEvent.ACTION_UP);
}
private void addMotionEvent(VelocityTracker vt, int x, int y, long time, int action) {
MotionEvent me = MotionEvent.obtain(time, time, action, x, y, 0);
vt.addMovement(me);
me.recycle();
}
/**
* Float imprecision of the average computations and filtering
* (removing last MotionEvent for N > 3) implies that tests
* accepts some approximated values.
*/
private void assertEqualFuzzy(float expected, float actual, float threshold) {
boolean fuzzyEqual = actual >= expected - threshold && actual <= expected + threshold;
Assert.assertTrue("Expected: <"+expected+"> but was: <"+actual+
"> while accepting a variation of: <"+threshold+">", fuzzyEqual);
}
private void assertGreater(float minExpected, float actual) {
Assert.assertTrue("Expected: minimum <"+minExpected+"> but was: <"+actual+">",
actual > minExpected);
}
private void assertLower(float maxExpected, float actual) {
Assert.assertTrue("Expected: maximum <"+maxExpected+"> but was: <"+actual+">",
actual < maxExpected);
}
}
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