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package com.android.server.accessibility;
import android.util.MathUtils;
import android.view.MotionEvent;
/**
* Some helper functions for gesture detection.
*/
final class GestureUtils {
private GestureUtils() {
/* cannot be instantiated */
}
public static boolean isTap(MotionEvent down, MotionEvent up, int tapTimeSlop,
int tapDistanceSlop, int actionIndex) {
return eventsWithinTimeAndDistanceSlop(down, up, tapTimeSlop, tapDistanceSlop, actionIndex);
}
public static boolean isMultiTap(MotionEvent firstUp, MotionEvent secondUp,
int multiTapTimeSlop, int multiTapDistanceSlop, int actionIndex) {
return eventsWithinTimeAndDistanceSlop(firstUp, secondUp, multiTapTimeSlop,
multiTapDistanceSlop, actionIndex);
}
private static boolean eventsWithinTimeAndDistanceSlop(MotionEvent first, MotionEvent second,
int timeout, int distance, int actionIndex) {
if (isTimedOut(first, second, timeout)) {
return false;
}
final double deltaMove = computeDistance(first, second, actionIndex);
if (deltaMove >= distance) {
return false;
}
return true;
}
public static double computeDistance(MotionEvent first, MotionEvent second, int pointerIndex) {
return MathUtils.dist(first.getX(pointerIndex), first.getY(pointerIndex),
second.getX(pointerIndex), second.getY(pointerIndex));
}
public static boolean isTimedOut(MotionEvent firstUp, MotionEvent secondUp, int timeout) {
final long deltaTime = secondUp.getEventTime() - firstUp.getEventTime();
return (deltaTime >= timeout);
}
public static boolean isSamePointerContext(MotionEvent first, MotionEvent second) {
return (first.getPointerIdBits() == second.getPointerIdBits()
&& first.getPointerId(first.getActionIndex())
== second.getPointerId(second.getActionIndex()));
}
/**
* Determines whether a two pointer gesture is a dragging one.
*
* @param event The event with the pointer data.
* @return True if the gesture is a dragging one.
*/
public static boolean isDraggingGesture(float firstPtrDownX, float firstPtrDownY,
float secondPtrDownX, float secondPtrDownY, float firstPtrX, float firstPtrY,
float secondPtrX, float secondPtrY, float maxDraggingAngleCos) {
// Check if the pointers are moving in the same direction.
final float firstDeltaX = firstPtrX - firstPtrDownX;
final float firstDeltaY = firstPtrY - firstPtrDownY;
if (firstDeltaX == 0 && firstDeltaY == 0) {
return true;
}
final float firstMagnitude =
(float) Math.sqrt(firstDeltaX * firstDeltaX + firstDeltaY * firstDeltaY);
final float firstXNormalized =
(firstMagnitude > 0) ? firstDeltaX / firstMagnitude : firstDeltaX;
final float firstYNormalized =
(firstMagnitude > 0) ? firstDeltaY / firstMagnitude : firstDeltaY;
final float secondDeltaX = secondPtrX - secondPtrDownX;
final float secondDeltaY = secondPtrY - secondPtrDownY;
if (secondDeltaX == 0 && secondDeltaY == 0) {
return true;
}
final float secondMagnitude =
(float) Math.sqrt(secondDeltaX * secondDeltaX + secondDeltaY * secondDeltaY);
final float secondXNormalized =
(secondMagnitude > 0) ? secondDeltaX / secondMagnitude : secondDeltaX;
final float secondYNormalized =
(secondMagnitude > 0) ? secondDeltaY / secondMagnitude : secondDeltaY;
final float angleCos =
firstXNormalized * secondXNormalized + firstYNormalized * secondYNormalized;
if (angleCos < maxDraggingAngleCos) {
return false;
}
return true;
}
}
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