[TabLayout] Fix bug with setScrollPosition not updating indicator due…

… to onLayout call drawing the indicator below the selected tab.

Resolves #3101

PiperOrigin-RevId: 492562100
(cherry picked from commit 3194671)

lib/java/com/google/android/material/tabs/TabLayout.java

@@ -1030,9 +1030,17 @@ public void removeTabAt(int position) {
  }
 
  final int newTabCount = tabs.size();
+ int newIndicatorPosition = -1;
  for (int i = position; i < newTabCount; i++) {
+ // If the current tab position is the indicator position, mark its new position as the new
+ // indicator position.
+ if (tabs.get(i).getPosition() == indicatorPosition) {
+ newIndicatorPosition = i;
+ }
  tabs.get(i).setPosition(i);
  }
+ // Update the indicator position to the correct selected tab after refreshing tab positions.
+ indicatorPosition = newIndicatorPosition;
 
  if (selectedTabPosition == position) {
  selectTab(tabs.isEmpty() ? null : tabs.get(Math.max(0, position - 1)));
@@ -1678,9 +1686,16 @@ private void configureTab(@NonNull Tab tab, int position) {
  tabs.add(position, tab);
 
  final int count = tabs.size();
+ int newIndicatorPosition = -1;
  for (int i = position + 1; i < count; i++) {
+ // If the current tab position is the indicator position, mark its new position as the new
+ // indicator position.
+ if (tabs.get(i).getPosition() == indicatorPosition) {
+ newIndicatorPosition = i;
+ }
  tabs.get(i).setPosition(i);
  }
+ indicatorPosition = newIndicatorPosition;
  }
 
  private void addTabView(@NonNull Tab tab) {
@@ -3138,7 +3153,9 @@ boolean childrenNeedLayout() {
  * @param positionOffset Value from [0, 1) indicating the offset from the tab at position.
  */
  void setIndicatorPositionFromTabPosition(int position, float positionOffset) {
- indicatorPosition = position;
+ // Since we are tweening the indicator in between the position and position+positionOffset,
+ // we set the indicator position to whichever is closer.
+ indicatorPosition = Math.round(position + positionOffset);
  if (indicatorAnimator != null && indicatorAnimator.isRunning()) {
  indicatorAnimator.cancel();
  }
@@ -3238,20 +3255,37 @@ protected void onLayout(boolean changed, int l, int t, int r, int b) {
  /* recreateAnimation= */ false, getSelectedTabPosition(), /* duration= */ -1);
  } else {
  // If we've been laid out, update the indicator position
- jumpIndicatorToSelectedPosition();
+ jumpIndicatorToIndicatorPosition();
  }
  }
 
- /** Immediately update the indicator position to the currently selected position. */
- private void jumpIndicatorToSelectedPosition() {
+ /**
+ * Immediately update the indicator position to the specified position, unless we are mid-scroll
+ * in a viewpager.
+ */
+ private void jumpIndicatorToPosition(int position) {
  // Don't update the indicator position if the scroll state is not idle.
  if (viewPagerScrollState != SCROLL_STATE_IDLE) {
  return;
  }
- final View currentView = getChildAt(getSelectedTabPosition());
+ final View currentView = getChildAt(position);
  tabIndicatorInterpolator.setIndicatorBoundsForTab(
  TabLayout.this, currentView, tabSelectedIndicator);
- indicatorPosition = getSelectedTabPosition();
+ indicatorPosition = position;
+ }
+
+ /** Immediately update the indicator position to the currently selected position. */
+ private void jumpIndicatorToSelectedPosition() {
+ jumpIndicatorToPosition(getSelectedTabPosition());
+ }
+
+ /** Immediately update the indicator position to the current indicator position. */
+ private void jumpIndicatorToIndicatorPosition() {
+ // If indicator position has not yet been set, set indicator to the selected tab position.
+ if (indicatorPosition == -1) {
+ indicatorPosition = getSelectedTabPosition();
+ }
+ jumpIndicatorToPosition(indicatorPosition);
  }
 
  /**