[Carousel] Support unclipped padding for uncontained variant of carousel

PiperOrigin-RevId: 625101250

catalog/java/io/material/catalog/carousel/res/layout/cat_carousel_uncontained_fragment.xml

@@ -112,7 +112,8 @@
  android:id="@+id/uncontained_carousel_recycler_view"
  android:layout_width="match_parent"
  android:layout_height="196dp"
- android:layout_marginHorizontal="16dp"
+ android:paddingStart="16dp"
+ android:paddingEnd="16dp"
  android:layout_marginVertical="16dp"
  android:clipChildren="false"
  android:clipToPadding="false" />

lib/java/com/google/android/material/carousel/CarouselLayoutManager.java

@@ -55,6 +55,7 @@
 import androidx.core.math.MathUtils;
 import androidx.core.util.Preconditions;
 import androidx.core.view.ViewCompat;
+import com.google.android.material.carousel.CarouselStrategy.StrategyType;
 import com.google.android.material.carousel.KeylineState.Keyline;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
@@ -98,6 +99,7 @@ public class CarouselLayoutManager extends LayoutManager
  private boolean isDebuggingEnabled = false;
  private final DebugItemDecoration debugItemDecoration = new DebugItemDecoration();
  @NonNull private CarouselStrategy carouselStrategy;
+
  @Nullable private KeylineStateList keylineStateList;
  // A KeylineState shifted for any current scroll offset.
  @Nullable private KeylineState currentKeylineState;
@@ -227,8 +229,7 @@ public int getCarouselAlignment() {
  private int getLeftOrTopPaddingForKeylineShift() {
  // TODO(b/316969331): Fix keyline shifting by decreasing carousel size when carousel is clipped
  // to padding.
- // TODO(b/316968490): Fix keyline shifting by adjusting cutoffs if strategy is not contained.
- if (getClipToPadding() || !carouselStrategy.isContained()) {
+ if (getClipToPadding()) {
  return 0;
  }
  if (getOrientation() == VERTICAL) {
@@ -240,8 +241,7 @@ private int getLeftOrTopPaddingForKeylineShift() {
  private int getRightOrBottomPaddingForKeylineShift() {
  // TODO(b/316969331): Fix keyline shifting by decreasing carousel size when carousel is clipped
  // to padding.
- // TODO(b/316968490): Fix keyline shifting by adjusting cutoffs if strategy is not contained.
- if (getClipToPadding() || !carouselStrategy.isContained()) {
+ if (getClipToPadding()) {
  return 0;
  }
  if (getOrientation() == VERTICAL) {
@@ -348,7 +348,8 @@ private void recalculateKeylineStateList(Recycler recycler) {
  isLayoutRtl() ? KeylineState.reverse(keylineState, getContainerSize()) : keylineState,
  getItemMargins(),
  getLeftOrTopPaddingForKeylineShift(),
- getRightOrBottomPaddingForKeylineShift());
+ getRightOrBottomPaddingForKeylineShift(),
+ carouselStrategy.getStrategyType());
  }
 
  private int getItemMargins() {
@@ -853,10 +854,7 @@ private int calculateEndScroll(State state, KeylineStateList stateList) {
  float lastItemDistanceFromFirstItem =
  ((state.getItemCount() - 1) * endState.getItemSize()) * (isRtl ? -1F : 1F);
 
- float endPadding =
- isRtl ? -endFocalKeyline.leftOrTopPaddingShift : endFocalKeyline.rightOrBottomPaddingShift;
  float endFocalLocDistanceFromStart = endFocalKeyline.loc - getParentStart();
- float endFocalLocDistanceFromEnd = getParentEnd() - endFocalKeyline.loc;
 
  // We want the last item in the list to only be able to scroll to the end of the list. Subtract
  // the distance to the end focal keyline and then add the distance needed to let the last
@@ -865,11 +863,7 @@ private int calculateEndScroll(State state, KeylineStateList stateList) {
  (int)
  (lastItemDistanceFromFirstItem
  - endFocalLocDistanceFromStart
- + endFocalLocDistanceFromEnd
- // If there is padding, adjust for the extra padding offset since offset is
- // implicitly added from both endFocalLocDistance calculations.
- + endPadding);
-
+ + (isRtl ? -1 : 1) * endFocalKeyline.maskedItemSize / 2F);
  return isRtl ? min(0, endScroll) : max(0, endScroll);
  }
 
@@ -994,7 +988,7 @@ private void updateChildMaskForLocation(
  // container instead of bleeding and being clipped by the RecyclerView's bounds.
  // Only do this if there is only one side of the mask that is out of bounds; if
  // both sides are out of bounds on the same side, then the whole mask is out of view.
- if (carouselStrategy.isContained()) {
+ if (carouselStrategy.getStrategyType() == StrategyType.CONTAINED) {
  orientationHelper.containMaskWithinBounds(maskRect, offsetMaskRect, parentBoundsRect);
  }
 
@@ -1060,10 +1054,6 @@ private int getParentRight() {
  return orientationHelper.getParentRight();
  }
 
- private int getParentEnd() {
- return orientationHelper.getParentEnd();
- }
-
  private int getParentTop() {
  return orientationHelper.getParentTop();
  }

lib/java/com/google/android/material/carousel/CarouselStrategy.java

@@ -31,6 +31,15 @@ public abstract class CarouselStrategy {
 
  private float smallSizeMax;
 
+ /**
+ * Enum that defines whether or not the strategy is contained or uncontained. Contained strategies
+ * will always have all of its items within bounds of the carousel width.
+ */
+ enum StrategyType {
+ CONTAINED,
+ UNCONTAINED
+ }
+
  void initialize(Context context) {
  smallSizeMin =
  smallSizeMin > 0 ? smallSizeMin : CarouselStrategyHelper.getSmallSizeMin(context);
@@ -130,14 +139,16 @@ static int[] doubleCounts(int[] count) {
  }
 
  /**
- * Gets whether this carousel should mask items against the edges of the carousel container.
+ * Gets the strategy type of this strategy. Contained strategies should mask items against the
+ * edges of the carousel container.
  *
- * @return true if items in the carousel should mask/squash against the edges of the carousel
- * container. false if the carousel should allow items to bleed past the edges of the
- * container and be clipped.
+ * @return the {@link StrategyType} of this strategy. A value of {@link StrategyType#CONTAINED}
+ * means items in the carousel should mask/squash against the edges of the carousel container.
+ * {@link StrategyType#UNCONTAINED} means the carousel should allow items to bleed past the edges
+ * of the container and be clipped.
  */
- boolean isContained() {
- return true;
+ StrategyType getStrategyType() {
+ return StrategyType.CONTAINED;
  }
 
  /**

lib/java/com/google/android/material/carousel/KeylineStateList.java

@@ -16,6 +16,9 @@
 
 package com.google.android.material.carousel;
 
+import static java.lang.Math.max;
+import static java.lang.Math.min;
+
 import androidx.annotation.NonNull;
 import androidx.core.math.MathUtils;
 import com.google.android.material.animation.AnimationUtils;
@@ -82,11 +85,17 @@ private KeylineStateList(
  }
 
  /** Creates a new {@link KeylineStateList} from a {@link KeylineState}. */
- static KeylineStateList from(Carousel carousel, KeylineState state, float itemMargins,
- float leftOrTopPadding, float rightOrBottomPadding) {
+ static KeylineStateList from(
+ Carousel carousel,
+ KeylineState state,
+ float itemMargins,
+ float leftOrTopPadding,
+ float rightOrBottomPadding,
+ CarouselStrategy.StrategyType strategyType) {
  return new KeylineStateList(
- state, getStateStepsStart(carousel, state, itemMargins, leftOrTopPadding),
- getStateStepsEnd(carousel, state, itemMargins, rightOrBottomPadding));
+ state,
+ getStateStepsStart(carousel, state, itemMargins, leftOrTopPadding, strategyType),
+ getStateStepsEnd(carousel, state, itemMargins, rightOrBottomPadding, strategyType));
  }
 
  /** Returns the default state for this state list. */
@@ -155,14 +164,17 @@ KeylineState getShiftedState(
  float startShiftOffset = minScrollOffset + startShiftRange;
  float endShiftOffset = maxScrollOffset - endShiftRange;
  float startPaddingShift = getStartState().getFirstFocalKeyline().leftOrTopPaddingShift;
- float endPaddingShift = getEndState().getLastFocalKeyline().rightOrBottomPaddingShift;
+ float endPaddingShift = getEndState().getFirstFocalKeyline().rightOrBottomPaddingShift;
 
  // Normally we calculate the interpolation such that by scrollShiftOffset, we are always at the
- // default state but in this case, we want to start shifting earlier/increase startShiftOffset
- // so that the interpolation will choose the start state instead of the default state when the
- // scroll offset is equal to startPaddingShift. This is so we are always at the start state
- // at the beginning of the carousel, instead of getting to a state where the start state is only
+ // default state. In the case where the start state is equal to the default state but with
+ // padding, we want to start shifting earlier/increase startShiftOffset so that the
+ // interpolation will choose the start state instead of the default state when the scroll offset
+ // is equal to startPaddingShift. This is so we are always at the start state with padding at
+ // the beginning of the carousel, instead of getting to a state where the start state is only
  // when scrollOffset <= startPaddingShift.
+ // We know that the start state is equal to the default state with padding if the start shift
+ // range is equal to the padding.
  if (startShiftRange == startPaddingShift) {
  startShiftOffset += startPaddingShift;
  }
@@ -362,7 +374,56 @@ private static boolean isLastFocalItemVisibleAtRightOfContainer(
  && state.getLastFocalKeyline() == state.getLastNonAnchorKeyline();
  }
 
+ @NonNull
  private static KeylineState shiftKeylineStateForPadding(
+ @NonNull KeylineState keylineState, float padding, float carouselSize, boolean leftShift,
+ float childMargins, CarouselStrategy.StrategyType strategyType) {
+ switch (strategyType) {
+ case CONTAINED:
+ return shiftKeylineStateForPaddingContained(
+ keylineState, padding, carouselSize, leftShift, childMargins);
+ default:
+ return shiftKeylineStateForPaddingUncontained(
+ keylineState, padding, carouselSize, leftShift);
+ }
+ }
+
+ @NonNull
+ private static KeylineState shiftKeylineStateForPaddingUncontained(
+ @NonNull KeylineState keylineState, float padding, float carouselSize, boolean leftShift) {
+ List<Keyline> tmpKeylines = new ArrayList<>(keylineState.getKeylines());
+ KeylineState.Builder builder =
+ new KeylineState.Builder(keylineState.getItemSize(), carouselSize);
+ int unchangingAnchorPosition = leftShift ? 0 : tmpKeylines.size() - 1;
+ for (int j = 0; j < tmpKeylines.size(); j++) {
+ Keyline k = tmpKeylines.get(j);
+ if (k.isAnchor && j == unchangingAnchorPosition) {
+ builder.addKeyline(k.locOffset, k.mask, k.maskedItemSize, false, true, k.cutoff);
+ continue;
+ }
+ float newOffset = leftShift ? k.locOffset + padding : k.locOffset - padding;
+ float leftOrTopPadding = leftShift ? padding : 0;
+ float rightOrBottomPadding = leftShift ? 0 : padding;
+ boolean isFocal =
+ j >= keylineState.getFirstFocalKeylineIndex()
+ && j <= keylineState.getLastFocalKeylineIndex();
+ builder.addKeyline(
+ newOffset,
+ k.mask,
+ k.maskedItemSize,
+ isFocal,
+ k.isAnchor,
+ Math.abs(
+ leftShift
+ ? max(0, newOffset + k.maskedItemSize / 2 - carouselSize)
+ : min(0, newOffset - k.maskedItemSize / 2)),
+ leftOrTopPadding,
+ rightOrBottomPadding);
+ }
+ return builder.build();
+ }
+
+ private static KeylineState shiftKeylineStateForPaddingContained(
  KeylineState keylineState, float padding, float carouselSize, boolean leftShift,
  float childMargins) {
 
@@ -400,7 +461,7 @@ private static KeylineState shiftKeylineStateForPadding(
  maskedItemSize, keylineState.getItemSize(), childMargins);
  float locOffset = nextOffset + maskedItemSize / 2F;
 
- float actualPaddingShift = locOffset - k.locOffset;
+ float actualPaddingShift = Math.abs(locOffset - k.locOffset);
 
  builder.addKeyline(
  locOffset,
@@ -434,7 +495,7 @@ private static KeylineState shiftKeylineStateForPadding(
  */
  private static List<KeylineState> getStateStepsStart(
  Carousel carousel, KeylineState defaultState, float itemMargins,
- float leftOrTopPaddingForKeylineShift) {
+ float leftOrTopPaddingForKeylineShift, CarouselStrategy.StrategyType strategyType) {
  List<KeylineState> steps = new ArrayList<>();
  steps.add(defaultState);
  int firstNonAnchorKeylineIndex = findFirstNonAnchorKeylineIndex(defaultState);
@@ -453,7 +514,8 @@ private static List<KeylineState> getStateStepsStart(
  leftOrTopPaddingForKeylineShift,
  carouselSize,
  true,
- itemMargins));
+ itemMargins,
+ strategyType));
  }
  return steps;
  }
@@ -471,8 +533,10 @@ private static List<KeylineState> getStateStepsStart(
  // view.
  float cutoffs = defaultState.getFirstFocalKeyline().cutoff;
  steps.add(
- shiftKeylinesAndCreateKeylineState(defaultState, originalStart + cutoffs, carouselSize));
- // TODO(b/316968490): If there is padding, this should affect keylines and the cutoffs
+ shiftKeylinesAndCreateKeylineState(
+ defaultState,
+ originalStart + cutoffs + leftOrTopPaddingForKeylineShift,
+ carouselSize));
  return steps;
  }
 
@@ -512,7 +576,8 @@ private static List<KeylineState> getStateStepsStart(
  leftOrTopPaddingForKeylineShift,
  carouselSize,
  true,
- itemMargins);
+ itemMargins,
+ strategyType);
  }
  steps.add(shifted);
  }
@@ -536,7 +601,8 @@ private static List<KeylineState> getStateStepsStart(
  * carousel.
  */
  private static List<KeylineState> getStateStepsEnd(Carousel carousel, KeylineState defaultState,
- float itemMargins, float rightOrBottomPaddingForKeylineShift) {
+ float itemMargins, float rightOrBottomPaddingForKeylineShift,
+ CarouselStrategy.StrategyType strategyType) {
  List<KeylineState> steps = new ArrayList<>();
  steps.add(defaultState);
  int lastNonAnchorKeylineIndex = findLastNonAnchorKeylineIndex(defaultState);
@@ -556,7 +622,8 @@ private static List<KeylineState> getStateStepsEnd(Carousel carousel, KeylineSta
  rightOrBottomPaddingForKeylineShift,
  carouselSize,
  false,
- itemMargins));
+ itemMargins,
+ strategyType));
  }
  return steps;
  }
@@ -573,9 +640,8 @@ private static List<KeylineState> getStateStepsEnd(Carousel carousel, KeylineSta
  // view. Add a step that shifts all the keylines over to bring the last focal item into full
  // view.
  float cutoffs = defaultState.getLastFocalKeyline().cutoff;
- steps.add(
- shiftKeylinesAndCreateKeylineState(defaultState, originalStart - cutoffs, carouselSize));
- // TODO(b/316968490): If there is padding, this should affect keylines and the cutoffs
+ steps.add(shiftKeylinesAndCreateKeylineState(defaultState,
+ originalStart - cutoffs - rightOrBottomPaddingForKeylineShift, carouselSize));
  return steps;
  }
 
@@ -614,7 +680,8 @@ private static List<KeylineState> getStateStepsEnd(Carousel carousel, KeylineSta
  rightOrBottomPaddingForKeylineShift,
  carouselSize,
  false,
- itemMargins);
+ itemMargins,
+ strategyType);
  }
  steps.add(shifted);
  }

lib/java/com/google/android/material/carousel/UncontainedCarouselStrategy.java

@@ -237,7 +237,7 @@ private KeylineState createLeftAlignedKeylineState(
  }
 
  @Override
- boolean isContained() {
- return false;
+ StrategyType getStrategyType() {
+ return StrategyType.UNCONTAINED;
  }
 }

lib/javatests/com/google/android/material/carousel/CarouselLayoutManagerRtlTest.java

@@ -40,6 +40,7 @@
 import androidx.test.core.app.ApplicationProvider;
 import com.google.android.material.carousel.CarouselHelper.CarouselTestAdapter;
 import com.google.android.material.carousel.CarouselHelper.WrappedCarouselLayoutManager;
+import com.google.android.material.carousel.CarouselStrategy.StrategyType;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -100,7 +101,7 @@ public void testScrollBeyondMaxHorizontalScroll_shouldLimitToMaxScrollOffset() t
  KeylineState leftState =
  KeylineStateList.from(
  layoutManager, KeylineState.reverse(keylineState, DEFAULT_RECYCLER_VIEW_WIDTH),
- 0, 0, 0)
+ 0, 0, 0, StrategyType.CONTAINED)
  .getStartState();
 
  MaskableFrameLayout child =