PhoneTabSwitcherLayout.java 文件源码

/**
 * Animates a tab to be swiped horizontally.
 *
 * @param tabItem
 *         The tab item, which corresponds to the tab, which should be swiped, as an instance of
 *         the class {@link TabItem}. The tab item may not be null
 * @param targetPosition
 *         The position on the x-axis, the tab should be moved to, in pixels as a {@link Float}
 *         value
 * @param selected
 *         True, if the tab should become the selected one, false otherwise
 * @param animationDuration
 *         The duration of the animation in milliseconds as a {@link Long} value
 * @param velocity
 *         The velocity of the drag gesture, which caused the tab to be swiped, in pixels per
 *         second as a {@link Float} value
 */
private void animateSwipe(@NonNull final TabItem tabItem, final float targetPosition,
                          final boolean selected, final long animationDuration,
                          final float velocity) {
    View view = tabItem.getView();
    float currentPosition = getArithmetics().getPosition(Axis.X_AXIS, tabItem);
    float distance = Math.abs(targetPosition - currentPosition);
    float maxDistance = getArithmetics().getSize(Axis.X_AXIS, tabItem) + swipedTabDistance;
    long duration = velocity > 0 ? Math.round((distance / velocity) * 1000) :
            Math.round(animationDuration * (distance / maxDistance));
    ViewPropertyAnimator animation = view.animate();
    animation.setListener(new AnimationListenerWrapper(
            selected ? createSwipeSelectedTabAnimationListener(tabItem) :
                    createSwipeNeighborAnimationListener(tabItem)));
    animation.setInterpolator(new AccelerateDecelerateInterpolator());
    animation.setDuration(duration);
    animation.setStartDelay(0);
    getArithmetics().animatePosition(Axis.X_AXIS, animation, tabItem, targetPosition, true);
    animation.start();
}