Example usage for android.view VelocityTracker addMovement

Introduction

In this page you can find the example usage for android.view VelocityTracker addMovement.

Prototype

public void addMovement(MotionEvent event) 

Source Link

Document

Add a user's movement to the tracker.

Usage

From source file:com.oguzbabaoglu.cardpager.CardPager.java

@Override
public boolean onTouchEvent(@NonNull MotionEvent ev) {

    if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0) {
        // Don't handle edge touches immediately -- they may actually belong to one of our descendants.
        return false;
    }/*from   w ww . j  ava2  s . c o  m*/

    if (pagerAdapter == null || pagerAdapter.getCount() == 0) {
        // Nothing to present or scroll; nothing to touch.
        return false;
    }

    if (velocityTracker == null) {
        velocityTracker = VelocityTracker.obtain();
    }
    velocityTracker.addMovement(ev);

    final int action = ev.getAction();

    switch (action & MotionEventCompat.ACTION_MASK) {

    case MotionEvent.ACTION_DOWN:

        // Do not interfere with the settling action.
        if (scrollState != SCROLL_STATE_SETTLING) {
            scroller.abortAnimation();
            populatePending = false;
            populate();
        }

        // Remember where the motion event started
        lastMotionX = initialMotionX = ev.getX();
        lastMotionY = initialMotionY = ev.getY();
        activePointerId = MotionEventCompat.getPointerId(ev, 0);
        break;

    case MotionEvent.ACTION_MOVE:
        if (!dragInProgress) {
            final int pointerIndex = MotionEventCompat.findPointerIndex(ev, activePointerId);
            final float x = MotionEventCompat.getX(ev, pointerIndex);
            final float xDiff = Math.abs(x - lastMotionX);
            final float y = MotionEventCompat.getY(ev, pointerIndex);
            final float yDiff = Math.abs(y - lastMotionY);

            if (xDiff > touchSlop && xDiff > yDiff) {

                dragInProgress = true;
                lastMotionX = x - initialMotionX > 0 ? initialMotionX + touchSlop : initialMotionX - touchSlop;
                lastMotionY = y;
                setScrollState(SCROLL_STATE_DRAGGING);

                // Disallow Parent Intercept, just in case
                requestParentDisallowInterceptTouchEvent(true);
            }
        }
        // Not else! Note that dragInProgress can be set above.
        if (dragInProgress) {
            // Scroll to follow the motion event
            final int activePointerIndex = MotionEventCompat.findPointerIndex(ev, activePointerId);
            final float x = MotionEventCompat.getX(ev, activePointerIndex);
            performDrag(x);
        }
        break;

    case MotionEvent.ACTION_UP:

        if (!dragInProgress) {
            break;
        }

        final VelocityTracker velocityTracker = this.velocityTracker;
        velocityTracker.computeCurrentVelocity(1000, maximumVelocity);
        final int initialVelocity = (int) VelocityTrackerCompat.getXVelocity(velocityTracker, activePointerId);

        populatePending = true;

        final int width = getClientWidth();
        final int scrollX = getScrollX();
        final ItemInfo ii = infoForCurrentScrollPosition();
        final int currentPage = ii.position;
        final float pageOffset = ((float) scrollX / width) - ii.offset;
        final int activePointerIndex = MotionEventCompat.findPointerIndex(ev, activePointerId);
        final float x = MotionEventCompat.getX(ev, activePointerIndex);
        final int totalDelta = (int) (x - initialMotionX);
        final int nextPage = determineTargetPage(currentPage, pageOffset, initialVelocity, totalDelta);

        setCurrentItemInternal(nextPage, true, true, initialVelocity);
        activePointerId = INVALID_POINTER;
        endDrag();
        break;

    case MotionEvent.ACTION_CANCEL:

        if (!dragInProgress) {
            break;
        }

        scrollToItem(currentItem, true, 0);
        activePointerId = INVALID_POINTER;
        endDrag();
        break;

    case MotionEventCompat.ACTION_POINTER_DOWN:
        final int index = MotionEventCompat.getActionIndex(ev);
        lastMotionX = MotionEventCompat.getX(ev, index);
        activePointerId = MotionEventCompat.getPointerId(ev, index);
        break;

    case MotionEventCompat.ACTION_POINTER_UP:
        onSecondaryPointerUp(ev);
        lastMotionX = MotionEventCompat.getX(ev, MotionEventCompat.findPointerIndex(ev, activePointerId));
        break;
    }

    return true;
}

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