I have a ListView which has an OnItemClickListener. On top of that, each row (CardView) has an OnTouchListener in order to implement a swiping gesture.
The OnTouchListener reacts to ACTION_DOWN, ACTION_CANCEL, ACTION_MOVE and ACTION_UP. I use performItemClick() when ACTION_UP happens, so that the OnItemClickListener is called when required.
If I return true in the OnTouchListener, the swiping movement I implemented via ACTION_MOVE works perfectly, clicking the item works as well. However, there is zero visual feedback. Usually, there would be a ripple on Lollipop or a background change on ICS.
If I return False (meaning I don't want to intercept the event), then there is a visual feedback and the clicking works... But my OnTouchListener never intercepts any ACTION_MOVE event. This prevents any swiping.
I tried a variety of solutions, such as using v.setpressed() but it had no effect.
I'm curious to know how I could preserve the ripple (or visual feedback in general) that would happen if my OnTouchListener wasn't intercepting the event.
Here's my OnTouchListener, if you're curious.
private final View.OnTouchListener mTouchListener = new View.OnTouchListener() {
float mDownX;
private int mSwipeSlop = -1;
private boolean mItemPressed;
private VelocityTracker mVelocityTracker = null;
private HashMap<Long, Integer> mItemIdTopMap = new HashMap<>();
@Override
public boolean onTouch(final View v, MotionEvent event) {
int index = event.getActionIndex();
int pointerId = event.getPointerId(index);
if (mSwipeSlop < 0) {
mSwipeSlop = ViewConfiguration.get(getActivity())
.getScaledTouchSlop();
}
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
if (mItemPressed) {
// Multi-item swipes not handled
return false;
}
mItemPressed = true;
mDownX = event.getX();
if (mVelocityTracker == null) {
// Retrieve a new VelocityTracker object to watch the velocity of a motion.
mVelocityTracker = VelocityTracker.obtain();
} else {
// Reset the velocity tracker back to its initial state.
mVelocityTracker.clear();
}
mVelocityTracker.addMovement(event);
break;
case MotionEvent.ACTION_CANCEL:
v.setAlpha(1);
v.setTranslationX(0);
mItemPressed = false;
mVelocityTracker.recycle();
mVelocityTracker = null;
break;
case MotionEvent.ACTION_MOVE: {
mVelocityTracker.addMovement(event);
float x = event.getX() + v.getTranslationX();
float deltaX = x - mDownX;
float deltaXAbs = Math.abs(deltaX);
if (!mSwiping) {
if (deltaXAbs > mSwipeSlop) {
mSwiping = true;
getListView().requestDisallowInterceptTouchEvent(true);
mBackgroundContainer.showBackground(v.getTop(), v.getHeight());
}
}
if (mSwiping) {
v.setTranslationX((x - mDownX));
v.setAlpha(1 - deltaXAbs / v.getWidth());
}
}
break;
case MotionEvent.ACTION_UP: {
// User let go - figure out whether to animate the view out, or back into place
if (mSwiping) {
float x = event.getX() + v.getTranslationX();
float deltaX = x - mDownX;
float deltaXAbs = Math.abs(deltaX);
float fractionCovered;
float endX;
float endAlpha;
final boolean remove;
mVelocityTracker.computeCurrentVelocity(1000);
float velocityX = Math.abs(VelocityTrackerCompat.getXVelocity(mVelocityTracker, pointerId));
if (velocityX > 700 || deltaXAbs > v.getWidth() / 4) {
// fixme
fractionCovered = deltaXAbs / v.getWidth();
endX = deltaX < 0 ? -v.getWidth() : v.getWidth();
endAlpha = 0;
remove = true;
} else {
// Not far enough - animate it back
fractionCovered = 1 - (deltaXAbs / v.getWidth());
endX = 0;
endAlpha = 1;
remove = false;
}
mVelocityTracker.clear();
int SWIPE_DURATION = 600;
long duration = (int) ((1 - fractionCovered) * SWIPE_DURATION);
getListView().setEnabled(false);
v.animate().setDuration(duration).
alpha(endAlpha).translationX(endX).
withEndAction(new Runnable() { // fixme replace with AnimationListener
@Override
public void run() {
// Restore animated values
v.setAlpha(1);
v.setTranslationX(0);
if (remove) {
animateRemoval(getListView(), v);
} else {
mBackgroundContainer.hideBackground();
mSwiping = false;
getListView().setEnabled(true);
}
}
});
} else {
int position = getListView().getPositionForView(v);
if (position != ListView.INVALID_POSITION)
getListView().performItemClick(v, position, getListView().getItemIdAtPosition(position));
}
}
mItemPressed = false;
break;
default:
return false;
}
return true;
}
private void animateRemoval(final ListView listview, View viewToRemove) {
// irrelevant
}
};
It's based on Chet Haase's demo from a couple of years back.
I really can't figure it out. Help?
Thanks!