Java tutorial
/* * Copyright 2013 Google Inc. * Copyright 2015 Bruno Romeu Nunes * Copyright 2015 Katsuya Goto * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package br.com.devmix.baseapp.listener; import android.graphics.Rect; import android.os.SystemClock; import android.support.annotation.NonNull; import android.support.v4.animation.AnimatorCompatHelper; import android.support.v4.animation.AnimatorListenerCompat; import android.support.v4.animation.AnimatorUpdateListenerCompat; import android.support.v4.animation.ValueAnimatorCompat; import android.support.v4.view.ViewCompat; import android.support.v4.view.ViewPropertyAnimatorListenerAdapter; import android.support.v7.widget.RecyclerView; import android.view.MotionEvent; import android.view.VelocityTracker; import android.view.View; import android.view.ViewConfiguration; import android.view.ViewGroup; import android.widget.ListView; import java.util.ArrayList; import java.util.Collections; import java.util.List; public class OnSwipeableRecyclerViewTouchListener implements RecyclerView.OnItemTouchListener { // Cached ViewConfiguration and system-wide constant values private int mSlop; private int mMinFlingVelocity; private int mMaxFlingVelocity; private long mAnimationTime; // Fixed properties private RecyclerView mRecyclerView; private SwipeListener mSwipeListener; private int mViewWidth = 1; // 1 and not 0 to prevent dividing by zero // Transient properties private List<PendingDismissData> mPendingDismisses = new ArrayList<>(); private int mDismissAnimationRefCount = 0; private float mAlpha; private float mDownX; private float mDownY; private boolean mSwiping; private int mSwipingSlop; private VelocityTracker mVelocityTracker; private int mDownPosition; private int mAnimatingPosition = ListView.INVALID_POSITION; private View mDownView; private boolean mPaused; private float mFinalDelta; /** * Constructs a new swipe touch listener for the given {@link android.support.v7.widget.RecyclerView} * * @param recyclerView The recycler view whose items should be dismissable by swiping. * @param listener The listener for the swipe events. */ public OnSwipeableRecyclerViewTouchListener(RecyclerView recyclerView, SwipeListener listener) { 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; mSwipeListener = listener; /** * This will ensure that this SwipeableRecyclerViewTouchListener is paused during list view scrolling. * If a scroll listener is already assigned, the caller should still pass scroll changes through * to this listener. */ mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() { @Override public void onScrollStateChanged(RecyclerView recyclerView, int newState) { super.onScrollStateChanged(recyclerView, newState); setEnabled(newState != RecyclerView.SCROLL_STATE_DRAGGING); } @Override public void onScrolled(RecyclerView recyclerView, int dx, int dy) { super.onScrolled(recyclerView, dx, dy); } }); } /** * Enables or disables (pauses or resumes) watching for swipe-to-dismiss gestures. * * @param enabled Whether or not to watch for gestures. */ public void setEnabled(boolean enabled) { mPaused = !enabled; } @Override public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent motionEvent) { return handleTouchEvent(motionEvent); } @Override public void onTouchEvent(RecyclerView rv, MotionEvent motionEvent) { handleTouchEvent(motionEvent); } @Override public void onRequestDisallowInterceptTouchEvent(boolean b) { } private boolean handleTouchEvent(MotionEvent motionEvent) { if (mViewWidth < 2) { mViewWidth = mRecyclerView.getWidth(); } switch (motionEvent.getActionMasked()) { case MotionEvent.ACTION_DOWN: { if (mPaused) { break; } // 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)) { mDownView = child; break; } } if (mDownView != null && mAnimatingPosition != mRecyclerView.getChildAdapterPosition(mDownView)) { mAlpha = ViewCompat.getAlpha(mDownView); mDownX = motionEvent.getRawX(); mDownY = motionEvent.getRawY(); mDownPosition = mRecyclerView.getChildAdapterPosition(mDownView); if (mSwipeListener.canSwipe(mDownPosition)) { mVelocityTracker = VelocityTracker.obtain(); mVelocityTracker.addMovement(motionEvent); } else { mDownView = null; } } break; } case MotionEvent.ACTION_CANCEL: { if (mVelocityTracker == null) { break; } if (mDownView != null && mSwiping) { // cancel ViewCompat.animate(mDownView).translationX(0).alpha(mAlpha).setDuration(mAnimationTime) .setListener(null); } mVelocityTracker.recycle(); mVelocityTracker = null; mDownX = 0; mDownY = 0; mDownView = null; mDownPosition = ListView.INVALID_POSITION; mSwiping = false; break; } case MotionEvent.ACTION_UP: { if (mVelocityTracker == null) { break; } mFinalDelta = 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(mFinalDelta) > mViewWidth / 2 && mSwiping) { dismiss = true; dismissRight = mFinalDelta > 0; } else if (mMinFlingVelocity <= absVelocityX && absVelocityX <= mMaxFlingVelocity && absVelocityY < absVelocityX && mSwiping) { // dismiss only if flinging in the same direction as dragging dismiss = (velocityX < 0) == (mFinalDelta < 0); dismissRight = mVelocityTracker.getXVelocity() > 0; } if (dismiss && mDownPosition != mAnimatingPosition && mDownPosition != ListView.INVALID_POSITION) { // dismiss final View downView = mDownView; // mDownView gets null'd before animation ends final int downPosition = mDownPosition; ++mDismissAnimationRefCount; mAnimatingPosition = mDownPosition; ViewCompat.animate(mDownView).translationX(dismissRight ? mViewWidth : -mViewWidth).alpha(0) .setDuration(mAnimationTime).setListener(new ViewPropertyAnimatorListenerAdapter() { @Override public void onAnimationEnd(View view) { performDismiss(downView, downPosition); } }); } else { // cancel ViewCompat.animate(mDownView).translationX(0).alpha(mAlpha).setDuration(mAnimationTime) .setListener(null); } mVelocityTracker.recycle(); mVelocityTracker = null; mDownX = 0; mDownY = 0; mDownView = 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 (!mSwiping && Math.abs(deltaX) > mSlop && Math.abs(deltaY) < Math.abs(deltaX) / 2) { mSwiping = true; mSwipingSlop = (deltaX > 0 ? mSlop : -mSlop); } if (mSwiping) { ViewCompat.setTranslationX(mDownView, deltaX - mSwipingSlop); ViewCompat.setAlpha(mDownView, Math.max(0f, Math.min(mAlpha, mAlpha * (1f - Math.abs(deltaX) / mViewWidth)))); return true; } break; } } return false; } private void performDismiss(final View dismissView, final int dismissPosition) { // Animate the dismissed list item to zero-height and fire the dismiss callback when // all dismissed list item animations have completed. This triggers layout on each animation // frame; in the future we may want to do something smarter and more performant. final ViewGroup.LayoutParams lp = dismissView.getLayoutParams(); final int originalLayoutParamsHeight = lp.height; final int originalHeight = dismissView.getHeight(); ValueAnimatorCompat animatorCompat = AnimatorCompatHelper.emptyValueAnimator(); animatorCompat.setDuration(mAnimationTime); animatorCompat.addListener(new AnimatorListenerCompat() { @Override public void onAnimationStart(ValueAnimatorCompat animation) { } @Override public void onAnimationEnd(ValueAnimatorCompat animation) { --mDismissAnimationRefCount; if (mDismissAnimationRefCount == 0) { // No active animations, process all pending dismisses. // Sort by descending position Collections.sort(mPendingDismisses); int[] dismissPositions = new int[mPendingDismisses.size()]; for (int i = mPendingDismisses.size() - 1; i >= 0; i--) { dismissPositions[i] = mPendingDismisses.get(i).position; } if (mFinalDelta > 0) { mSwipeListener.onDismissedBySwipeRight(mRecyclerView, dismissPositions); } else { mSwipeListener.onDismissedBySwipeLeft(mRecyclerView, dismissPositions); } // Reset mDownPosition to avoid MotionEvent.ACTION_UP trying to start a dismiss // animation with a stale position mDownPosition = ListView.INVALID_POSITION; ViewGroup.LayoutParams lp; for (PendingDismissData pendingDismiss : mPendingDismisses) { // Reset view presentation ViewCompat.setAlpha(pendingDismiss.view, mAlpha); ViewCompat.setTranslationX(pendingDismiss.view, 0); lp = pendingDismiss.view.getLayoutParams(); lp.height = originalLayoutParamsHeight; pendingDismiss.view.setLayoutParams(lp); } // Send a cancel event long time = SystemClock.uptimeMillis(); MotionEvent cancelEvent = MotionEvent.obtain(time, time, MotionEvent.ACTION_CANCEL, 0, 0, 0); mRecyclerView.dispatchTouchEvent(cancelEvent); mPendingDismisses.clear(); mAnimatingPosition = ListView.INVALID_POSITION; } } @Override public void onAnimationCancel(ValueAnimatorCompat animation) { } @Override public void onAnimationRepeat(ValueAnimatorCompat animation) { } }); animatorCompat.addUpdateListener(new AnimatorUpdateListenerCompat() { @Override public void onAnimationUpdate(ValueAnimatorCompat animation) { float fraction = animation.getAnimatedFraction(); lp.height = (int) (originalHeight * (1 - fraction)); dismissView.setLayoutParams(lp); } }); mPendingDismisses.add(new PendingDismissData(dismissPosition, dismissView)); animatorCompat.start(); } /** * The callback interface used by {@link OnSwipeableRecyclerViewTouchListener} to inform its client * about a swipe of one or more list item positions. */ public interface SwipeListener { /** * Called to determine whether the given position can be swiped. */ boolean canSwipe(int position); /** * Called when the item has been dismissed by swiping to the left. * * @param recyclerView The originating {@link android.support.v7.widget.RecyclerView}. * @param reverseSortedPositions An array of positions to dismiss, sorted in descending * order for convenience. */ void onDismissedBySwipeLeft(RecyclerView recyclerView, int[] reverseSortedPositions); /** * Called when the item has been dismissed by swiping to the right. * * @param recyclerView The originating {@link android.support.v7.widget.RecyclerView}. * @param reverseSortedPositions An array of positions to dismiss, sorted in descending * order for convenience. */ void onDismissedBySwipeRight(RecyclerView recyclerView, int[] reverseSortedPositions); } class PendingDismissData implements Comparable<PendingDismissData> { public int position; public View view; public PendingDismissData(int position, View view) { this.position = position; this.view = view; } @Override public int compareTo(@NonNull PendingDismissData other) { // Sort by descending position return other.position - position; } } }