androidx.recyclerview.widget.RecyclerView#OnScrollListener ( )源码实例Demo

/**
 * Set edge effect or glow color for recycler view.
 *
 * @param recyclerView The recycler view to set the edge effect color.
 * @param color The edge effect color to be set.
 * @param scrollListener Scroll listener to set color on over scroll.
 */
public static void setEdgeEffectColor(@Nullable RecyclerView recyclerView,
        final @ColorInt int color, @Nullable RecyclerView.OnScrollListener scrollListener) {
    if (recyclerView == null) {
        return;
    }

    if (scrollListener == null) {
        scrollListener =
                new RecyclerView.OnScrollListener() {
                    @Override
                    public void onScrollStateChanged(@NonNull RecyclerView recyclerView,
                            int newState) {
                        super.onScrollStateChanged(recyclerView, newState);

                        setEdgeEffectColor(recyclerView, color);
                    }
                };

        recyclerView.removeOnScrollListener(scrollListener);
        recyclerView.addOnScrollListener(scrollListener);
    }

    setEdgeEffectColor(recyclerView, color);
}
 

public TitleBarViewHelper setRecyclerView(RecyclerView recyclerView) {
    mRecyclerView = recyclerView;
    if (mRecyclerView == null) {
        return this;
    }
    if (mScrollListener == null) {
        mScrollListener = new RecyclerView.OnScrollListener() {
            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);
                //滚动到顶部了
                if (recyclerView.computeVerticalScrollOffset() == 0) {
                    LoggerManager.i("mScrollY:" + mScrollY + ";mAlpha:" + mAlpha);
                    mScrollY = 0;
                } else {
                    mScrollY += dy;
                }
                mAlpha = setChange(mScrollY);
            }

        };
    }
    mRecyclerView.addOnScrollListener(mScrollListener);
    return this;
}
 

protected void init() {
    if (isInitialized) {
        return;
    }
    isInitialized = true;
    setClipChildren(false);
    onScrollListener = new RecyclerView.OnScrollListener() {
        @Override
        public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
            if (!isEnabled() || bubble == null || handle.isSelected()) {
                return;
            }
            int verticalScrollOffset = recyclerView.computeVerticalScrollOffset();
            int verticalScrollRange = recyclerView.computeVerticalScrollRange();
            float proportion = (float) verticalScrollOffset / (float) (verticalScrollRange - height);
            setBubbleAndHandlePosition(height * proportion);
            // If scroll amount is small, don't show it
            if (minimumScrollThreshold == 0 || dy == 0 || Math.abs(dy) > minimumScrollThreshold || scrollbarAnimator.isAnimating()) {
                showScrollbar();
                autoHideScrollbar();
            }
        }
    };
}
 

@Test
public void testRecyclerSpecOnBind() {
  EventHandler refreshHandler = mock(EventHandler.class);
  Binder<RecyclerView> binder = mock(Binder.class);

  SnapHelper snapHelper = mock(SnapHelper.class);

  final int size = 3;
  List<RecyclerView.OnScrollListener> scrollListeners = createListOfScrollListeners(size);

  LithoRecylerView.TouchInterceptor touchInterceptor =
      mock(LithoRecylerView.TouchInterceptor.class);

  RecyclerSpec.onBind(
      mComponentContext,
      mSectionsRecyclerView,
      binder,
      null,
      scrollListeners,
      snapHelper,
      true,
      touchInterceptor,
      refreshHandler);

  assertThat(mSectionsRecyclerView.isEnabled()).isTrue();

  assertThat(mSectionsRecyclerView.getRecyclerView()).isSameAs(mRecyclerView);

  verifyAddOnScrollListenerWasCalledNTimes(mRecyclerView, size);
  assertThat(mRecyclerView.getTouchInterceptor()).isSameAs(touchInterceptor);

  verify(binder).bind(mRecyclerView);
  assertThat(mRecyclerView.isLayoutRequested()).isTrue();
  assertThat(mSectionsRecyclerView.hasBeenDetachedFromWindow()).isFalse();
  verify(snapHelper).attachToRecyclerView(mRecyclerView);
}
 

@Test
public void testRecyclerSpecOnUnbind() {
  mSectionsRecyclerView.setHasBeenDetachedFromWindow(true);

  Binder<RecyclerView> binder = mock(Binder.class);

  final int size = 3;
  List<RecyclerView.OnScrollListener> scrollListeners = createListOfScrollListeners(size);

  RecyclerSpec.onUnbind(mComponentContext, mSectionsRecyclerView, binder, null, scrollListeners);

  verify(binder).unbind(mRecyclerView);
  verifyRemoveOnScrollListenerWasCalledNTimes(mRecyclerView, size);
  assertThat(mSectionsRecyclerView.getOnRefreshListener()).isNull();
}
 

private static List<RecyclerView.OnScrollListener> createListOfScrollListeners(int size) {
  List<RecyclerView.OnScrollListener> onScrollListeners = new ArrayList<>(size);
  for (int i = 0; i < size; i++) {
    onScrollListeners.add(mock(RecyclerView.OnScrollListener.class));
  }

  return onScrollListeners;
}
 

protected void onDown(MotionEvent event) {
    if(indicator != null && indicator.getVisibility() == INVISIBLE && recyclerView.getAdapter() != null && !hiddenByNotEnoughElements) {
        indicator.setVisibility(VISIBLE);
        indicator.setAlpha(0F);
        indicator.animate().alpha(1F).setDuration(150).setListener(new AnimatorListenerAdapter() {
            @TargetApi(Build.VERSION_CODES.HONEYCOMB)
            @Override
            public void onAnimationEnd(Animator animation) {
                super.onAnimationEnd(animation);

                indicator.setAlpha(1F);
            }
        });
    }

    int top = handleThumb.getHeight() / 2;
    int bottom = recyclerView.getHeight() - Utils.getDP(72, recyclerView.getContext());
    float boundedY = Math.max(top, Math.min(bottom, event.getY() - getHandleOffset()));

    currentScrollPercent = (boundedY - top) / (bottom - top);
    if(isScrollChangeLargeEnoughForFastScroll(currentScrollPercent) ||
            currentScrollPercent == 0 || currentScrollPercent == 1) {
        previousScrollPercent = currentScrollPercent;
        int dy = scrollUtils.scrollToPositionAtProgress(currentScrollPercent);
        scrollUtils.scrollHandleAndIndicator();
        if(dy != 0) {
            for(RecyclerView.OnScrollListener listener : listeners) {
                listener.onScrolled(recyclerView, 0, dy);
            }
        }
    }

    if(lightOnTouch) {
        handleThumb.setBackgroundColor(handleColor);
    }
}
 

@Override
public void attachToPager(@NonNull final ScrollingPagerIndicator indicator, @NonNull final RecyclerView pager) {
    if (!(pager.getLayoutManager() instanceof LinearLayoutManager)) {
        throw new IllegalStateException("Only LinearLayoutManager is supported");
    }
    if (pager.getAdapter() == null) {
        throw new IllegalStateException("RecyclerView has not Adapter attached");
    }
    this.layoutManager = (LinearLayoutManager) pager.getLayoutManager();
    this.recyclerView = pager;
    this.attachedAdapter = pager.getAdapter();
    this.indicator = indicator;

    dataObserver = new RecyclerView.AdapterDataObserver() {
        @Override
        public void onChanged() {
            indicator.setDotCount(attachedAdapter.getItemCount());
            updateCurrentOffset();
        }

        @Override
        public void onItemRangeChanged(int positionStart, int itemCount) {
            onChanged();
        }

        @Override
        public void onItemRangeChanged(int positionStart, int itemCount, Object payload) {
            onChanged();
        }

        @Override
        public void onItemRangeInserted(int positionStart, int itemCount) {
            onChanged();
        }

        @Override
        public void onItemRangeRemoved(int positionStart, int itemCount) {
            onChanged();
        }

        @Override
        public void onItemRangeMoved(int fromPosition, int toPosition, int itemCount) {
            onChanged();
        }
    };
    attachedAdapter.registerAdapterDataObserver(dataObserver);
    indicator.setDotCount(attachedAdapter.getItemCount());
    updateCurrentOffset();

    scrollListener = new RecyclerView.OnScrollListener() {
        @Override
        public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {
            if (newState == RecyclerView.SCROLL_STATE_IDLE && isInIdleState()) {
                int newPosition = findCompletelyVisiblePosition();
                if (newPosition != RecyclerView.NO_POSITION) {
                    indicator.setDotCount(attachedAdapter.getItemCount());
                    if (newPosition < attachedAdapter.getItemCount()) {
                        indicator.setCurrentPosition(newPosition);
                    }
                }
            }
        }

        @Override
        public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
            updateCurrentOffset();
        }
    };

    recyclerView.addOnScrollListener(scrollListener);
}
 

public void setOnScrollListener(RecyclerView.OnScrollListener onScrollListener) {
        mOnScrollListener = onScrollListener;
}
 

@Override
public void removeOnScrollListener(RecyclerView.OnScrollListener onScrollListener) {
  removeOnScrollListeners.add(onScrollListener);
  super.removeOnScrollListener(onScrollListener);
}
 

/**
 * Remove a listener for scroll events triggered by the scroll bar.
 */
public void removeScrollListener(RecyclerView.OnScrollListener scrollListener) {
    listeners.remove(scrollListener);
}
 

public void setOnScrollListener(RecyclerView.OnScrollListener recyclerScrollListener) {
    this.recyclerScrollListener = recyclerScrollListener;
}
 

@Implementation
public void addOnScrollListener(RecyclerView.OnScrollListener scrollListener) {
    this.scrollListener = scrollListener;
}
 

public void removeOnScrollListener(RecyclerView.OnScrollListener listener) {
    if (scrollListener == listener) {
        scrollListener = null;
    }
}
 

public RecyclerView.OnScrollListener getScrollListener() {
    return scrollListener;
}
 

public void removeOnScrollListener(RecyclerView.OnScrollListener customOnScrollListener) {
    mRecyclerView.removeOnScrollListener(customOnScrollListener);
}
 

/**
     * Return ScrollListener for ListView
     *
     * @return OnScrollListener
     */
    public RecyclerView.OnScrollListener makeScrollListener() {
        return new RecyclerView.OnScrollListener() {

            private boolean isFirstItem = false;
            private boolean isLastItem = false;

            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                setEnabled(newState != recyclerView.SCROLL_STATE_DRAGGING);
                if (swipeClosesAllItemsWhenListMoves && newState == recyclerView.SCROLL_STATE_DRAGGING) {
                    closeOpenedItems();
                }
                if (newState == recyclerView.SCROLL_STATE_DRAGGING) {
                    listViewMoving = true;
                    setEnabled(false);
                }
                if (newState != recyclerView.SCROLL_STATE_SETTLING && newState != recyclerView.SCROLL_STATE_DRAGGING) {
                    listViewMoving = false;
                    downPosition = ListView.INVALID_POSITION;
                    swipeListView.resetScrolling();
                    new Handler().postDelayed(new Runnable() {
                        public void run() {
                            setEnabled(true);
                        }
                    }, 500);
                }
            }

            @Override
            public void onScrolled(RecyclerView view, int dx, int dy) {
//                if (isFirstItem) {
//                    boolean onSecondItemList = firstVisibleItem == 1;
//                    if (onSecondItemList) {
//                        isFirstItem = false;
//                    }
//                } else {
//                    boolean onFirstItemList = firstVisibleItem == 0;
//                    if (onFirstItemList)
//                        isFirstItem = true;
//                        swipeListView.onFirstListItem();
//                    }
//                }
//                if (isLastItem) {
//                    boolean onBeforeLastItemList = firstVisibleItem + visibleItemCount == totalItemCount - 1;
//                    if (onBeforeLastItemList) {
//                        isLastItem = false;
//                    }
//                } else {
//                    boolean onLastItemList = firstVisibleItem + visibleItemCount >= totalItemCount;
//                    if (onLastItemList) {
//                        isLastItem = true;
//                        swipeListView.onLastListItem();
//                    }
//                }
            }
        };
    }
 

public void addOnScrollListener(RecyclerView.OnScrollListener customOnScrollListener) {
    mRecyclerView.addOnScrollListener(customOnScrollListener);
}
 

/**
 * Add a listener to wrapped RecyclerView that will be notified of any changes in scroll state or position.
 * <p>
 * <p>Components that add a listener should take care to remove it when finished.
 * Other components that take ownership of a view may call {@link #clearOnScrollListeners()}
 * to remove all attached listeners.</p>
 *
 * @param listener listener to set or null to clear
 */
@SuppressWarnings("unused")
public final void addOnScrollListener(RecyclerView.OnScrollListener listener) {
    getRvCategories().addOnScrollListener(listener);
}
 

/**
 * Remove a listener from wrapped RecyclerView that was notified of any changes in scroll state or position.
 *
 * @param listener listener to set or null to clear
 */
@SuppressWarnings("unused")
public final void removeOnScrollListener(RecyclerView.OnScrollListener listener) {
    getRvCategories().removeOnScrollListener(listener);
}