1 package com.android.server.accessibility; 2 3 import android.util.MathUtils; 4 import android.view.MotionEvent; 5 6 /** 7 * Some helper functions for gesture detection. 8 */ 9 final class GestureUtils { 10 GestureUtils()11 private GestureUtils() { 12 /* cannot be instantiated */ 13 } 14 isMultiTap(MotionEvent firstUp, MotionEvent secondUp, int multiTapTimeSlop, int multiTapDistanceSlop)15 public static boolean isMultiTap(MotionEvent firstUp, MotionEvent secondUp, 16 int multiTapTimeSlop, int multiTapDistanceSlop) { 17 if (firstUp == null || secondUp == null) return false; 18 return eventsWithinTimeAndDistanceSlop(firstUp, secondUp, multiTapTimeSlop, 19 multiTapDistanceSlop); 20 } 21 eventsWithinTimeAndDistanceSlop(MotionEvent first, MotionEvent second, int timeout, int distance)22 private static boolean eventsWithinTimeAndDistanceSlop(MotionEvent first, MotionEvent second, 23 int timeout, int distance) { 24 if (isTimedOut(first, second, timeout)) { 25 return false; 26 } 27 final double deltaMove = distance(first, second); 28 if (deltaMove >= distance) { 29 return false; 30 } 31 return true; 32 } 33 distance(MotionEvent first, MotionEvent second)34 public static double distance(MotionEvent first, MotionEvent second) { 35 return MathUtils.dist(first.getX(), first.getY(), second.getX(), second.getY()); 36 } 37 isTimedOut(MotionEvent firstUp, MotionEvent secondUp, int timeout)38 public static boolean isTimedOut(MotionEvent firstUp, MotionEvent secondUp, int timeout) { 39 final long deltaTime = secondUp.getEventTime() - firstUp.getEventTime(); 40 return (deltaTime >= timeout); 41 } 42 43 /** 44 * Determines whether a two pointer gesture is a dragging one. 45 * 46 * @return True if the gesture is a dragging one. 47 */ isDraggingGesture(float firstPtrDownX, float firstPtrDownY, float secondPtrDownX, float secondPtrDownY, float firstPtrX, float firstPtrY, float secondPtrX, float secondPtrY, float maxDraggingAngleCos)48 public static boolean isDraggingGesture(float firstPtrDownX, float firstPtrDownY, 49 float secondPtrDownX, float secondPtrDownY, float firstPtrX, float firstPtrY, 50 float secondPtrX, float secondPtrY, float maxDraggingAngleCos) { 51 52 // Check if the pointers are moving in the same direction. 53 final float firstDeltaX = firstPtrX - firstPtrDownX; 54 final float firstDeltaY = firstPtrY - firstPtrDownY; 55 56 if (firstDeltaX == 0 && firstDeltaY == 0) { 57 return true; 58 } 59 60 final float firstMagnitude = (float) Math.hypot(firstDeltaX, firstDeltaY); 61 final float firstXNormalized = 62 (firstMagnitude > 0) ? firstDeltaX / firstMagnitude : firstDeltaX; 63 final float firstYNormalized = 64 (firstMagnitude > 0) ? firstDeltaY / firstMagnitude : firstDeltaY; 65 66 final float secondDeltaX = secondPtrX - secondPtrDownX; 67 final float secondDeltaY = secondPtrY - secondPtrDownY; 68 69 if (secondDeltaX == 0 && secondDeltaY == 0) { 70 return true; 71 } 72 73 final float secondMagnitude = (float) Math.hypot(secondDeltaX, secondDeltaY); 74 final float secondXNormalized = 75 (secondMagnitude > 0) ? secondDeltaX / secondMagnitude : secondDeltaX; 76 final float secondYNormalized = 77 (secondMagnitude > 0) ? secondDeltaY / secondMagnitude : secondDeltaY; 78 79 final float angleCos = 80 firstXNormalized * secondXNormalized + firstYNormalized * secondYNormalized; 81 82 if (angleCos < maxDraggingAngleCos) { 83 return false; 84 } 85 86 return true; 87 } 88 } 89