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      1 package org.robolectric.shadows;
      2 
      3 import static org.assertj.core.api.Assertions.assertThat;
      4 
      5 import android.view.MotionEvent;
      6 import android.view.VelocityTracker;
      7 import org.junit.Before;
      8 import org.junit.Test;
      9 import org.junit.runner.RunWith;
     10 import org.robolectric.RobolectricTestRunner;
     11 import org.robolectric.Shadows;
     12 
     13 @RunWith(RobolectricTestRunner.class)
     14 public class VelocityTrackerTest {
     15   VelocityTracker velocityTracker;
     16 
     17   @Before
     18   public void setUp() {
     19     velocityTracker = VelocityTracker.obtain();
     20   }
     21 
     22   @Test
     23   public void handlesXMovement() {
     24     velocityTracker.addMovement(doMotion(0, 0, 0));
     25     velocityTracker.addMovement(doMotion(20, 20, 0));
     26     velocityTracker.computeCurrentVelocity(1);
     27 
     28     // active pointer
     29     assertThat(velocityTracker.getXVelocity()).isEqualTo(1);
     30     assertThat(velocityTracker.getXVelocity(0)).isEqualTo(1);
     31     // inactive pointer
     32     assertThat(velocityTracker.getXVelocity(10)).isEqualTo(0);
     33   }
     34 
     35   @Test
     36   public void handlesYMovement() {
     37     velocityTracker.addMovement(doMotion(0, 0, 0));
     38     velocityTracker.addMovement(doMotion(20, 0, 20));
     39     velocityTracker.computeCurrentVelocity(1);
     40 
     41     // active pointer
     42     assertThat(velocityTracker.getYVelocity()).isEqualTo(1);
     43     assertThat(velocityTracker.getYVelocity(0)).isEqualTo(1);
     44     // inactive pointer
     45     assertThat(velocityTracker.getYVelocity(10)).isEqualTo(0);
     46   }
     47 
     48   @Test
     49   public void handlesXAndYMovement() {
     50     velocityTracker.addMovement(doMotion(0, 0, 0));
     51     velocityTracker.addMovement(doMotion(20, 20, 40));
     52     velocityTracker.computeCurrentVelocity(1);
     53 
     54     assertThat(velocityTracker.getXVelocity()).isEqualTo(1);
     55     assertThat(velocityTracker.getYVelocity()).isEqualTo(2);
     56   }
     57 
     58   @Test
     59   public void handlesWindowing_positive() {
     60     velocityTracker.addMovement(doMotion(0, 0, 0));
     61     velocityTracker.addMovement(doMotion(20, 10000, 10000));
     62     velocityTracker.computeCurrentVelocity(1, 10);
     63 
     64     assertThat(velocityTracker.getXVelocity()).isEqualTo(10);
     65     assertThat(velocityTracker.getYVelocity()).isEqualTo(10);
     66   }
     67 
     68   @Test
     69   public void handlesWindowing_negative() {
     70     velocityTracker.addMovement(doMotion(0, 0, 0));
     71     velocityTracker.addMovement(doMotion(20, -10000, -10000));
     72     velocityTracker.computeCurrentVelocity(1, 10);
     73 
     74     assertThat(velocityTracker.getXVelocity()).isEqualTo(-10);
     75     assertThat(velocityTracker.getYVelocity()).isEqualTo(-10);
     76   }
     77 
     78   @Test
     79   public void handlesMultiplePointers() {
     80     // pointer 0 active
     81     velocityTracker.addMovement(doMotion(0, 0, 0));
     82     // pointer 1 active
     83     velocityTracker.addMovement(doMotion(20, 40, 40, 0, 0));
     84     velocityTracker.addMovement(doMotion(40, 80, 80, 20, 20));
     85     velocityTracker.computeCurrentVelocity(1);
     86 
     87     // active pointer
     88     assertThat(velocityTracker.getXVelocity()).isEqualTo(1);
     89     assertThat(velocityTracker.getXVelocity(1)).isEqualTo(1);
     90     // inactive pointer
     91     assertThat(velocityTracker.getXVelocity(0)).isEqualTo(2f);
     92   }
     93 
     94   @Test
     95   public void handlesClearing() {
     96     velocityTracker.addMovement(doMotion(0, 0, 0));
     97     velocityTracker.addMovement(doMotion(20, 20, 20));
     98     velocityTracker.computeCurrentVelocity(1);
     99     velocityTracker.clear();
    100 
    101     assertThat(velocityTracker.getXVelocity()).isEqualTo(0);
    102     assertThat(velocityTracker.getYVelocity()).isEqualTo(0);
    103     velocityTracker.computeCurrentVelocity(1);
    104     assertThat(velocityTracker.getXVelocity()).isEqualTo(0);
    105     assertThat(velocityTracker.getYVelocity()).isEqualTo(0);
    106   }
    107 
    108   @Test
    109   public void clearsOnDown() {
    110     velocityTracker.addMovement(doMotion(0, 0, 0));
    111     velocityTracker.addMovement(doMotion(20, 20, 20));
    112     velocityTracker.computeCurrentVelocity(1);
    113     velocityTracker.addMovement(doPointerDown(40, 40, 40));
    114     velocityTracker.computeCurrentVelocity(1);
    115 
    116     assertThat(velocityTracker.getXVelocity()).isEqualTo(0);
    117     assertThat(velocityTracker.getYVelocity()).isEqualTo(0);
    118   }
    119 
    120   private static MotionEvent doMotion(long time, float x, float y) {
    121     return MotionEvent.obtain(0, time, MotionEvent.ACTION_MOVE, x, y, 0);
    122   }
    123 
    124   private static MotionEvent doPointerDown(long time, float x, float y) {
    125     return MotionEvent.obtain(time, time, MotionEvent.ACTION_DOWN, x, y, 0);
    126   }
    127 
    128   /**
    129    * Construct a new MotionEvent involving two pointers at {@code time}. Pointer 2 will be
    130    * considered active.
    131    */
    132   private static MotionEvent doMotion(
    133       long time, float pointer1X, float pointer1Y, float pointer2X, float pointer2Y) {
    134     MotionEvent event =
    135         MotionEvent.obtain(0, time, MotionEvent.ACTION_MOVE, pointer2X, pointer2Y, 0);
    136     ShadowMotionEvent shadowEvent = Shadows.shadowOf(event);
    137     shadowEvent.setPointer2(pointer1X, pointer1Y);
    138     shadowEvent.setPointerIndex(0);
    139     // we put our active pointer (the second one down) first, so flip the IDs so that they match up
    140     // properly
    141     shadowEvent.setPointerIds(1, 0);
    142 
    143     return event;
    144   }
    145 }
    146