DO NOT MERGE Update scroll up and down behavior
Scroll up was not scrolling. For example in cases where the available
space for recyclerview was too small and the recyclerview had insets
top. Scroll down also neded a similar improvement.
Bug: 168827981
Test: manual
Change-Id: I833bec10e94bb9dc4d5e6cfc5574d3f596a3757d
diff --git a/car-ui-lib/src/com/android/car/ui/recyclerview/DefaultScrollBar.java b/car-ui-lib/src/com/android/car/ui/recyclerview/DefaultScrollBar.java
index 912dda3..fec2618 100644
--- a/car-ui-lib/src/com/android/car/ui/recyclerview/DefaultScrollBar.java
+++ b/car-ui-lib/src/com/android/car/ui/recyclerview/DefaultScrollBar.java
@@ -19,12 +19,14 @@
import android.content.res.Resources;
import android.os.Handler;
+import android.util.SparseArray;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.AccelerateDecelerateInterpolator;
import android.view.animation.Interpolator;
import androidx.annotation.IntRange;
+import androidx.annotation.Nullable;
import androidx.recyclerview.widget.OrientationHelper;
import androidx.recyclerview.widget.RecyclerView;
@@ -299,13 +301,93 @@
}
}
+ private boolean mIsAdapterChangeObserverRegistered = false;
+ @Nullable
+ private RecyclerView.Adapter mCurrentAdapter;
private final RecyclerView.OnScrollListener mRecyclerViewOnScrollListener =
new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
updatePaginationButtons(false);
+ cacheChildrenHeight(recyclerView.getLayoutManager());
+ if (mCurrentAdapter != recyclerView.getAdapter()) {
+ mIsAdapterChangeObserverRegistered = false;
+ if (mCurrentAdapter != null) {
+ mCurrentAdapter.unregisterAdapterDataObserver(mAdapterChangeObserver);
+ }
+ }
+ if (!mIsAdapterChangeObserverRegistered
+ && recyclerView.getAdapter() != null) {
+ mIsAdapterChangeObserverRegistered = true;
+ mCurrentAdapter = recyclerView.getAdapter();
+ mCurrentAdapter.registerAdapterDataObserver(mAdapterChangeObserver);
+ }
}
};
+ private final SparseArray<Integer> mChildHeightByAdapterPosition = new SparseArray();
+
+ private final RecyclerView.AdapterDataObserver mAdapterChangeObserver =
+ new RecyclerView.AdapterDataObserver() {
+ @Override
+ public void onChanged() {
+ clearCachedHeights();
+ }
+ @Override
+ public void onItemRangeChanged(int positionStart, int itemCount, Object payload) {
+ clearCachedHeights();
+ }
+ @Override
+ public void onItemRangeChanged(int positionStart, int itemCount) {
+ clearCachedHeights();
+ }
+ @Override
+ public void onItemRangeInserted(int positionStart, int itemCount) {
+ clearCachedHeights();
+ }
+ @Override
+ public void onItemRangeMoved(int fromPosition, int toPosition, int itemCount) {
+ clearCachedHeights();
+ }
+ @Override
+ public void onItemRangeRemoved(int positionStart, int itemCount) {
+ clearCachedHeights();
+ }
+ };
+
+ private void clearCachedHeights() {
+ mChildHeightByAdapterPosition.clear();
+ cacheChildrenHeight(mRecyclerView.getLayoutManager());
+ }
+
+ private void cacheChildrenHeight(RecyclerView.LayoutManager layoutManager) {
+ for (int i = 0; i < layoutManager.getChildCount(); i++) {
+ View child = layoutManager.getChildAt(i);
+ int childPosition = layoutManager.getPosition(child);
+ if (mChildHeightByAdapterPosition.indexOfKey(childPosition) < 0) {
+ mChildHeightByAdapterPosition.put(childPosition, child.getHeight());
+ }
+ }
+ }
+
+ private int estimateNextPositionScrollUp(int currentPos, int scrollDistance,
+ OrientationHelper orientationHelper) {
+ int nextPos = 0;
+ int distance = 0;
+ for (int i = currentPos - 1; i >= 0; i--) {
+ if (mChildHeightByAdapterPosition.indexOfKey(i) < 0) {
+ // Use the average height estimate when there is not enough data
+ nextPos = mSnapHelper.estimateNextPositionDiffForScrollDistance(orientationHelper,
+ -scrollDistance);
+ break;
+ }
+ if ((distance + mChildHeightByAdapterPosition.get(i)) > Math.abs(scrollDistance)) {
+ nextPos = i - currentPos + 1;
+ break;
+ }
+ distance += mChildHeightByAdapterPosition.get(i);
+ }
+ return nextPos;
+ }
/**
* Returns the page the given position is on, starting with page 0.
@@ -347,52 +429,38 @@
OrientationHelper orientationHelper = getOrientationHelper(layoutManager);
int screenSize = orientationHelper.getTotalSpace();
int scrollDistance = screenSize;
- boolean isPageUpOverLongItem;
- // The iteration order matters. In case where there are 2 items longer than screen size, we
- // want to focus on upcoming view.
- for (int i = 0; i < layoutManager.getChildCount(); i++) {
- /*
- * We treat child View longer than screen size differently:
- * 1) When it enters screen, next pageUp will align its bottom with parent bottom;
- * 2) When it leaves screen, next pageUp will align its top with parent top.
- */
- View child = layoutManager.getChildAt(i);
- if (child.getHeight() > screenSize) {
- if (orientationHelper.getDecoratedEnd(child) < screenSize) {
- // Child view bottom is entering screen. Align its bottom with parent bottom.
- scrollDistance = screenSize - orientationHelper.getDecoratedEnd(child);
- } else if (-screenSize < orientationHelper.getDecoratedStart(child)
- && orientationHelper.getDecoratedStart(child) < 0) {
- // Child view top is about to enter screen - its distance to parent top
- // is less than a full scroll. Align child top with parent top.
- scrollDistance = Math.abs(orientationHelper.getDecoratedStart(child));
- }
- // There can be two items that are longer than the screen. We stop at the first one.
- // This is affected by the iteration order.
- // Distance should always be positive. Negate its value to scroll up.
- mRecyclerView.smoothScrollBy(0, -scrollDistance);
- return;
- }
- }
-
- int nextPos = mSnapHelper.estimateNextPositionDiffForScrollDistance(orientationHelper,
- -scrollDistance);
- View currentPosView = getFirstFullyVisibleChild(orientationHelper);
+ View currentPosView = getFirstMostVisibleChild(orientationHelper);
int currentPos = currentPosView != null ? mRecyclerView.getLayoutManager().getPosition(
currentPosView) : 0;
- mRecyclerView.smoothScrollToPosition(Math.max(0, currentPos + nextPos));
+ int nextPos = estimateNextPositionScrollUp(currentPos,
+ scrollDistance - Math.max(0, orientationHelper.getStartAfterPadding()
+ - orientationHelper.getDecoratedStart(currentPosView)), orientationHelper);
+ if (nextPos == 0) {
+ // Distance should always be positive. Negate its value to scroll up.
+ mRecyclerView.smoothScrollBy(0, -scrollDistance);
+ } else {
+ mRecyclerView.smoothScrollToPosition(Math.max(0, currentPos + nextPos));
+ }
}
- private View getFirstFullyVisibleChild(OrientationHelper helper) {
- for (int i = 0; i < getRecyclerView().getChildCount(); i++) {
- View child = getRecyclerView().getChildAt(i);
- if (CarUiSnapHelper.getPercentageVisible(child, helper) == 1f) {
- return getRecyclerView().getChildAt(i);
+ private View getFirstMostVisibleChild(OrientationHelper helper) {
+ float mostVisiblePercent = 0;
+ View mostVisibleView = null;
+
+ for (int i = 0; i < getRecyclerView().getLayoutManager().getChildCount(); i++) {
+ View child = getRecyclerView().getLayoutManager().getChildAt(i);
+ float visiblePercentage = CarUiSnapHelper.getPercentageVisible(child, helper);
+ if (visiblePercentage == 1f) {
+ mostVisibleView = child;
+ break;
+ } else if (visiblePercentage > mostVisiblePercent) {
+ mostVisiblePercent = visiblePercentage;
+ mostVisibleView = child;
}
}
- return null;
+ return mostVisibleView;
}
/**
@@ -413,43 +481,46 @@
int screenSize = orientationHelper.getTotalSpace();
int scrollDistance = screenSize;
- // If the last item is partially visible, page down should bring it to the top.
- View lastChild = layoutManager.getChildAt(layoutManager.getChildCount() - 1);
- if (layoutManager.isViewPartiallyVisible(lastChild,
- /* completelyVisible= */ false, /* acceptEndPointInclusion= */ false)) {
- scrollDistance = orientationHelper.getDecoratedStart(lastChild)
- - orientationHelper.getStartAfterPadding();
- if (scrollDistance <= 0) {
- // - Scroll value is zero if the top of last item is aligned with top of the screen;
- // - Scroll value can be negative if the child is longer than the screen size and
- // the visible area of the screen does not show the start of the child.
- // Scroll to the next screen in both cases.
- scrollDistance = screenSize;
- }
+ View currentPosView = getFirstMostVisibleChild(orientationHelper);
+
+ // If current view is partially visible and bottom of the view is below visible area of
+ // the recyclerview either scroll down one page (screenSize) or enough to align the bottom
+ // of the view with the bottom of the recyclerview. Note that this will not cause a snap,
+ // because the current view is already snapped to the top or it wouldn't be the most
+ // visible view.
+ if (layoutManager.isViewPartiallyVisible(currentPosView,
+ /* completelyVisible= */ false, /* acceptEndPointInclusion= */ false)
+ && orientationHelper.getDecoratedEnd(currentPosView)
+ > orientationHelper.getEndAfterPadding()) {
+ scrollDistance = Math.min(screenSize,
+ orientationHelper.getDecoratedEnd(currentPosView)
+ - orientationHelper.getEndAfterPadding());
}
- // The iteration order matters. In case where there are 2 items longer than screen size, we
- // want to focus on upcoming view (the one at the bottom of screen).
+ // Iterate over the childview (bottom to top) and stop when we find the first
+ // view that we can snap to and the scroll size is less than max scroll size (screenSize)
for (int i = layoutManager.getChildCount() - 1; i >= 0; i--) {
- /* We treat child View longer than screen size differently:
- * 1) When it enters screen, next pageDown will align its top with parent top;
- * 2) When it leaves screen, next pageDown will align its bottom with parent bottom.
- */
View child = layoutManager.getChildAt(i);
- if (child.getHeight() > screenSize) {
- if (orientationHelper.getDecoratedStart(child)
- - orientationHelper.getStartAfterPadding() > 0) {
- // Child view top is entering screen. Align its top with parent top.
- scrollDistance = orientationHelper.getDecoratedStart(lastChild)
+
+ // Ignore the child if it's above the currentview, as scrolldown will only move down.
+ // Note that in case of gridview, child will not be the same as the currentview.
+ if (orientationHelper.getDecoratedStart(child)
+ <= orientationHelper.getDecoratedStart(currentPosView)) {
+ break;
+ }
+
+ // Ignore the child if the scroll distance is bigger than the max scroll size
+ if (orientationHelper.getDecoratedStart(child)
+ - orientationHelper.getStartAfterPadding() <= screenSize) {
+ // If the child is already fully visible we can scroll even further.
+ if (orientationHelper.getDecoratedEnd(child)
+ <= orientationHelper.getEndAfterPadding()) {
+ scrollDistance = orientationHelper.getDecoratedStart(child)
+ - orientationHelper.getEndAfterPadding();
+ } else {
+ scrollDistance = orientationHelper.getDecoratedStart(child)
- orientationHelper.getStartAfterPadding();
- } else if (screenSize < orientationHelper.getDecoratedEnd(child)
- && orientationHelper.getDecoratedEnd(child) < 2 * screenSize) {
- // Child view bottom is about to enter screen - its distance to parent bottom
- // is less than a full scroll. Align child bottom with parent bottom.
- scrollDistance = orientationHelper.getDecoratedEnd(child) - screenSize;
}
- // There can be two items that are longer than the screen. We stop at the first one.
- // This is affected by the iteration order.
break;
}
}
