/**
* Constructs a new swipe-to-dismiss touch listener for the given list view.
*
* @param recyclerView The list view whose items should be dismissable.
* @param callbacks The callback to trigger when the user has indicated that she would like to
* dismiss one or more list items.
*/
public SwipeToDismissTouchListener(
SomeCollectionView recyclerView, DismissCallbacks<SomeCollectionView> callbacks) {
ViewConfiguration vc = ViewConfiguration.get(recyclerView.getContext());
mSlop = vc.getScaledTouchSlop();
mMinFlingVelocity = vc.getScaledMinimumFlingVelocity() * 16;
mMaxFlingVelocity = vc.getScaledMaximumFlingVelocity();
mAnimationTime =
recyclerView.getContext().getResources().getInteger(android.R.integer.config_shortAnimTime);
mRecyclerView = recyclerView;
mCallbacks = callbacks;
mHandler = new Handler();
}
/**
* Returns an {@link android.widget.AbsListView.OnScrollListener} to be added to the {@link
* android.widget.ListView} using {@link
* android.widget.ListView#setOnScrollListener(android.widget.AbsListView.OnScrollListener)}. If a
* scroll listener is already assigned, the caller should still pass scroll changes through to
* this listener. This will ensure that this {@link SwipeToDismissTouchListener} is paused during
* list view scrolling.
*
* @see SwipeToDismissTouchListener
*/
public Object makeScrollListener() {
return mRecyclerView.makeScrollListener(
new AbsListView.OnScrollListener() {
@Override
public void onScrollStateChanged(AbsListView absListView, int scrollState) {
processPendingDismisses();
setEnabled(scrollState != AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL);
}
@Override
public void onScroll(AbsListView absListView, int i, int i1, int i2) {}
});
}
@Override
public boolean onTouch(View view, MotionEvent motionEvent) {
if (mViewWidth < 2) {
mViewWidth = mRecyclerView.getWidth();
}
switch (motionEvent.getActionMasked()) {
case MotionEvent.ACTION_DOWN:
{
if (mPaused) {
return false;
}
// TODO: ensure this is a finger, and set a flag
// Find the child view that was touched (perform a hit test)
Rect rect = new Rect();
int childCount = mRecyclerView.getChildCount();
int[] listViewCoords = new int[2];
mRecyclerView.getLocationOnScreen(listViewCoords);
int x = (int) motionEvent.getRawX() - listViewCoords[0];
int y = (int) motionEvent.getRawY() - listViewCoords[1];
View child;
for (int i = 0; i < childCount; i++) {
child = mRecyclerView.getChildAt(i);
child.getHitRect(rect);
if (rect.contains(x, y)) {
assert (child instanceof ViewGroup && ((ViewGroup) child).getChildCount() == 2)
: "Each child needs to extend from ViewGroup and have two children";
boolean dataContainerHasBeenDismissed =
mPendingDismiss != null
&& mPendingDismiss.position == mRecyclerView.getChildPosition(child)
&& mPendingDismiss.rowContainer.dataContainerHasBeenDismissed;
mRowContainer = new RowContainer((ViewGroup) child);
mRowContainer.dataContainerHasBeenDismissed = dataContainerHasBeenDismissed;
break;
}
}
if (mRowContainer != null) {
mDownX = motionEvent.getRawX();
mDownY = motionEvent.getRawY();
mDownPosition = mRecyclerView.getChildPosition(mRowContainer.container);
if (mCallbacks.canDismiss(mDownPosition)) {
mVelocityTracker = VelocityTracker.obtain();
mVelocityTracker.addMovement(motionEvent);
} else {
mRowContainer = null;
}
}
return false;
}
case MotionEvent.ACTION_CANCEL:
{
if (mVelocityTracker == null) {
break;
}
if (mRowContainer != null && mSwiping) {
// cancel
mRowContainer
.getCurrentSwipingView()
.animate()
.translationX(0)
.alpha(1)
.setDuration(mAnimationTime)
.setListener(null);
}
mVelocityTracker.recycle();
mVelocityTracker = null;
mDownX = 0;
mDownY = 0;
mRowContainer = null;
mDownPosition = ListView.INVALID_POSITION;
mSwiping = false;
break;
}
case MotionEvent.ACTION_UP:
{
if (mVelocityTracker == null) {
break;
}
float deltaX = motionEvent.getRawX() - mDownX;
mVelocityTracker.addMovement(motionEvent);
mVelocityTracker.computeCurrentVelocity(1000);
float velocityX = mVelocityTracker.getXVelocity();
float absVelocityX = Math.abs(velocityX);
float absVelocityY = Math.abs(mVelocityTracker.getYVelocity());
boolean dismiss = false;
boolean dismissRight = false;
if (Math.abs(deltaX) > mViewWidth / 2 && mSwiping) {
dismiss = true;
dismissRight = deltaX > 0;
} else if (mMinFlingVelocity <= absVelocityX
&& absVelocityX <= mMaxFlingVelocity
&& absVelocityY < absVelocityX
&& mSwiping) {
// dismiss only if flinging in the same direction as dragging
dismiss = (velocityX < 0) == (deltaX < 0);
dismissRight = mVelocityTracker.getXVelocity() > 0;
}
if (dismiss && mDownPosition != ListView.INVALID_POSITION) {
// dismiss
final RowContainer downView =
mRowContainer; // mDownView gets null'd before animation ends
final int downPosition = mDownPosition;
mRowContainer
.getCurrentSwipingView()
.animate()
.translationX(dismissRight ? mViewWidth : -mViewWidth)
.alpha(0)
.setDuration(mAnimationTime)
.setListener(
new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
performDismiss(downView, downPosition);
}
});
} else {
// cancel
mRowContainer
.getCurrentSwipingView()
.animate()
.translationX(0)
.alpha(1)
.setDuration(mAnimationTime)
.setListener(null);
}
mVelocityTracker.recycle();
mVelocityTracker = null;
mDownX = 0;
mDownY = 0;
mRowContainer = null;
mDownPosition = ListView.INVALID_POSITION;
mSwiping = false;
break;
}
case MotionEvent.ACTION_MOVE:
{
if (mVelocityTracker == null || mPaused) {
break;
}
mVelocityTracker.addMovement(motionEvent);
float deltaX = motionEvent.getRawX() - mDownX;
float deltaY = motionEvent.getRawY() - mDownY;
if (Math.abs(deltaX) > mSlop && Math.abs(deltaY) < Math.abs(deltaX) / 2) {
mSwiping = true;
mSwipingSlop = (deltaX > 0 ? mSlop : -mSlop);
mRecyclerView.requestDisallowInterceptTouchEvent(true);
// Cancel ListView's touch (un-highlighting the item)
MotionEvent cancelEvent = MotionEvent.obtain(motionEvent);
cancelEvent.setAction(
MotionEvent.ACTION_CANCEL
| (motionEvent.getActionIndex() << MotionEvent.ACTION_POINTER_INDEX_SHIFT));
mRecyclerView.onTouchEvent(cancelEvent);
cancelEvent.recycle();
}
if (mSwiping) {
mRowContainer.getCurrentSwipingView().setTranslationX(deltaX - mSwipingSlop);
// Comment line below to disable alpha fade on initial swipe
mRowContainer
.getCurrentSwipingView()
.setAlpha(Math.max(0f, Math.min(1f, 1f - 2f * Math.abs(deltaX) / mViewWidth)));
return true;
}
break;
}
}
return false;
}