private void prepareAnimation() {
yMap.clear();
positionMap.clear();
beforeVisible.clear();
afterVisible.clear();
adapter.setMayNotify(false);
final int childCount = getChildCount();
final int firstVisiblePosition = getFirstVisiblePosition();
for (int i = 0; i < childCount; i++) {
final View child = getChildAt(i);
final long id = adapter.getItemId(firstVisiblePosition + i);
yMap.put(id, ViewHelper.getY(child));
positionMap.put(id, firstVisiblePosition + i);
}
for (int i = 0; i < firstVisiblePosition; i++) {
final long id = adapter.getItemId(i);
beforeVisible.add(id);
}
final int count = adapter.getCount();
for (int i = firstVisiblePosition + childCount; i < count; i++) {
final long id = adapter.getItemId(i);
afterVisible.add(id);
}
}
/** Animate items that just appeared and items that move within the screen. */
private void animatePostLayout(final float durationUnit) {
final AnimatorSet animatorSet = new AnimatorSet();
for (int i = 0; i < getChildCount(); i++) {
final View child = getChildAt(i);
final long id = getItemIdAtPosition(getFirstVisiblePosition() + i);
ObjectAnimator anim = null;
ViewHelper.setAlpha(child, 1f);
if (yMap.containsKey(id)) {
// moved within visible area
// log("Moved within visible area id: " + id);
final float oldY = yMap.remove(id);
final float newY = ViewHelper.getY(child);
if (oldY != newY) {
anim = animateY(child, oldY, newY, durationUnit);
}
} else {
// moved into visible area or new
if (beforeVisible.contains(id)) {
// moved from top
final float newY = ViewHelper.getY(child);
final float oldY = -child.getHeight();
anim = animateY(child, oldY, newY, durationUnit);
} else if (afterVisible.contains(id)) {
// moved from bottom
final float newY = ViewHelper.getY(child);
final float oldY = getHeight();
anim = animateY(child, oldY, newY, durationUnit);
} else {
// entirely new
ViewHelper.setAlpha(child, 0f);
anim = animateAlpha(child, true);
anim.setStartDelay(MIN_ANIM_DURATION);
}
}
if (anim != null) {
animatorSet.play(anim);
}
}
animatorSet.addListener(
new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(final Animator animation) {
finishAnimation();
};
});
animatorSet.start();
}