[Carousel] Recalculate keyline state if it doesn't match the current container size

PiperOrigin-RevId: 718578581

Author: imhappi

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

@@ -121,8 +121,8 @@ public class CarouselLayoutManager extends LayoutManager
 
   private final OnLayoutChangeListener recyclerViewSizeChangeListener =
       (v, left, top, right, bottom, oldLeft, oldTop, oldRight, oldBottom) -> {
-        // If RV dimen values have changed, refresh the keyline state.
-        if (left != oldLeft || top != oldTop || right != oldRight || bottom != oldBottom) {
+        // If RV width or height values have changed, refresh the keyline state.
+        if ((right - left != oldRight - oldLeft) || (bottom - top != oldBottom - oldTop)) {
           v.post(this::refreshKeylineState);
         }
       };
@@ -297,9 +297,11 @@ public void onLayoutChildren(Recycler recycler, State state) {
     boolean isRtl = isLayoutRtl();
 
     boolean isInitialLoad = keylineStateList == null;
-    // If a keyline state hasn't been created, use the first child as a representative of how each
-    // child would like to be measured and allow the strategy to create a keyline state.
-    if (isInitialLoad) {
+    // If a keyline state hasn't been created or is the wrong size, use the first child as a
+    // representative of how each child would like to be measured and allow the strategy to create
+    // a keyline state.
+    if (isInitialLoad
+        || keylineStateList.getDefaultState().getCarouselSize() != getContainerSize()) {
       recalculateKeylineStateList(recycler);
     }
 

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

@@ -47,7 +47,7 @@ static float getSmallSizeMax(@NonNull Context context) {
   static KeylineState createKeylineState(
       @NonNull Context context,
       float childMargins,
-      float availableSpace,
+      int availableSpace,
       @NonNull Arrangement arrangement,
       @Alignment int alignment) {
     if (alignment == CarouselLayoutManager.ALIGNMENT_CENTER) {
@@ -69,7 +69,7 @@ static KeylineState createKeylineState(
   static KeylineState createLeftAlignedKeylineState(
       @NonNull Context context,
       float childHorizontalMargins,
-      float availableSpace,
+      int availableSpace,
       @NonNull Arrangement arrangement) {
 
     float extraSmallChildWidth =
@@ -132,7 +132,7 @@ static KeylineState createLeftAlignedKeylineState(
   static KeylineState createCenterAlignedKeylineState(
       @NonNull Context context,
       float childHorizontalMargins,
-      float availableSpace,
+      int availableSpace,
       @NonNull Arrangement arrangement) {
 
     float extraSmallChildWidth =

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

@@ -45,7 +45,7 @@ public class FullScreenCarouselStrategy extends CarouselStrategy {
   @NonNull
   public KeylineState onFirstChildMeasuredWithMargins(
       @NonNull Carousel carousel, @NonNull View child) {
-    float availableSpace;
+    int availableSpace;
     LayoutParams childLayoutParams = (LayoutParams) child.getLayoutParams();
     float childMargins;
     if (carousel.isHorizontal()) {

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

@@ -60,11 +60,14 @@ public final class KeylineState {
   private final int firstFocalKeylineIndex;
   private final int lastFocalKeylineIndex;
 
+  private final int carouselSize;
+
   private KeylineState(
       float itemSize,
       List<Keyline> keylines,
       int firstFocalKeylineIndex,
-      int lastFocalKeylineIndex) {
+      int lastFocalKeylineIndex,
+      int carouselSize) {
     this.itemSize = itemSize;
     this.keylines = Collections.unmodifiableList(keylines);
     this.firstFocalKeylineIndex = firstFocalKeylineIndex;
@@ -74,6 +77,7 @@ private KeylineState(
         this.totalVisibleFocalItems += 1;
       }
     }
+    this.carouselSize = carouselSize;
   }
 
   /**
@@ -165,6 +169,11 @@ int getNumberOfNonAnchorKeylines() {
     return keylines.size() - anchorKeylines;
   }
 
+  /** Returns the size of the carousel used to build this keyline state. */
+  int getCarouselSize() {
+    return carouselSize;
+  }
+
   /**
    * Linearly interpolate between two {@link KeylineState}s.
    *
@@ -198,7 +207,11 @@ static KeylineState lerp(KeylineState from, KeylineState to, float progress) {
             from.getLastFocalKeylineIndex(), to.getLastFocalKeylineIndex(), progress);
 
     return new KeylineState(
-        from.getItemSize(), keylines, focalKeylineFirstIndex, focalKeylineLastIndex);
+        from.getItemSize(),
+        keylines,
+        focalKeylineFirstIndex,
+        focalKeylineLastIndex,
+        from.carouselSize);
   }
 
   /**
@@ -207,19 +220,18 @@ static KeylineState lerp(KeylineState from, KeylineState to, float progress) {
    * <p>This is used to reverse a keyline state for RTL layouts.
    *
    * @param keylineState the {@link KeylineState} to reverse
-   * @param availableSpace the space in which the keylines calculate whether or not they are cut
-   *     off.
+   * @param carouselSize the size of the carousel used to build this keyline state
    * @return a new {@link KeylineState} that has all keylines reversed.
    */
-  static KeylineState reverse(KeylineState keylineState, float availableSpace) {
+  static KeylineState reverse(KeylineState keylineState, int carouselSize) {
 
     KeylineState.Builder builder =
-        new KeylineState.Builder(keylineState.getItemSize(), availableSpace);
+        new KeylineState.Builder(keylineState.getItemSize(), carouselSize);
 
     // The new start offset should now be the same distance from the left of the carousel container
     // as the last item's right was from the right of the container.
     float start =
-        availableSpace
+        carouselSize
             - keylineState.getLastKeyline().locOffset
             - (keylineState.getLastKeyline().maskedItemSize / 2F);
     for (int i = keylineState.getKeylines().size() - 1; i >= 0; i--) {
@@ -262,7 +274,7 @@ public static final class Builder {
 
     private final float itemSize;
 
-    private final float availableSpace;
+    private final int carouselSize;
 
     // A list of keylines that hold all values except the Keyline#loc which needs to be calculated
     // in the build method.
@@ -281,11 +293,11 @@ public static final class Builder {
      *
      * @param itemSize The size of a fully unmasked item. This is the size that will be used by the
      *     carousel to measure and lay out all children, overriding each child's desired size.
-     * @param availableSpace The available space of the carousel the keylines calculate cutoffs by.
+     * @param carouselSize the size of the carousel used to build this keyline state.
      */
-    public Builder(float itemSize, float availableSpace) {
+    public Builder(float itemSize, int carouselSize) {
       this.itemSize = itemSize;
-      this.availableSpace = availableSpace;
+      this.carouselSize = carouselSize;
     }
 
     /**
@@ -493,8 +505,8 @@ public Builder addKeyline(
       // sides, only the end cutoff will be included in the cutoff.
       float keylineStart = offsetLoc - maskedItemSize / 2F;
       float keylineEnd = offsetLoc + maskedItemSize / 2F;
-      if (keylineEnd > availableSpace) {
-        cutoff = Math.abs(keylineEnd - max(keylineEnd - maskedItemSize, availableSpace));
+      if (keylineEnd > carouselSize) {
+        cutoff = Math.abs(keylineEnd - max(keylineEnd - maskedItemSize, carouselSize));
       } else if (keylineStart < 0) {
         cutoff = Math.abs(keylineStart - min(keylineStart + maskedItemSize, 0));
       }
@@ -609,7 +621,12 @@ public KeylineState build() {
         keylines.add(keyline);
       }
 
-      return new KeylineState(itemSize, keylines, firstFocalKeylineIndex, lastFocalKeylineIndex);
+      return new KeylineState(
+          itemSize,
+          keylines,
+          firstFocalKeylineIndex,
+          lastFocalKeylineIndex,
+          carouselSize);
     }
 
     /**

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

@@ -380,7 +380,7 @@ private static boolean isLastFocalItemVisibleAtRightOfContainer(
 
   @NonNull
   private static KeylineState shiftKeylineStateForPadding(
-      @NonNull KeylineState keylineState, float padding, float carouselSize, boolean leftShift,
+      @NonNull KeylineState keylineState, float padding, int carouselSize, boolean leftShift,
       float childMargins, CarouselStrategy.StrategyType strategyType) {
     switch (strategyType) {
       case CONTAINED:
@@ -394,7 +394,7 @@ private static KeylineState shiftKeylineStateForPadding(
 
   @NonNull
   private static KeylineState shiftKeylineStateForPaddingUncontained(
-      @NonNull KeylineState keylineState, float padding, float carouselSize, boolean leftShift) {
+      @NonNull KeylineState keylineState, float padding, int carouselSize, boolean leftShift) {
     List<Keyline> tmpKeylines = new ArrayList<>(keylineState.getKeylines());
     KeylineState.Builder builder =
         new KeylineState.Builder(keylineState.getItemSize(), carouselSize);
@@ -428,7 +428,7 @@ private static KeylineState shiftKeylineStateForPaddingUncontained(
   }
 
   private static KeylineState shiftKeylineStateForPaddingContained(
-      KeylineState keylineState, float padding, float carouselSize, boolean leftShift,
+      KeylineState keylineState, float padding, int carouselSize, boolean leftShift,
       float childMargins) {
 
     List<Keyline> tmpKeylines = new ArrayList<>(keylineState.getKeylines());
@@ -503,7 +503,7 @@ private static List<KeylineState> getStateStepsStart(
     List<KeylineState> steps = new ArrayList<>();
     steps.add(defaultState);
     int firstNonAnchorKeylineIndex = findFirstNonAnchorKeylineIndex(defaultState);
-    float carouselSize =
+    int carouselSize =
         carousel.isHorizontal() ? carousel.getContainerWidth() : carousel.getContainerHeight();
 
     // If the first focal item is already at the left of the container or there are no in bounds
@@ -610,7 +610,7 @@ private static List<KeylineState> getStateStepsEnd(Carousel carousel, KeylineSta
     List<KeylineState> steps = new ArrayList<>();
     steps.add(defaultState);
     int lastNonAnchorKeylineIndex = findLastNonAnchorKeylineIndex(defaultState);
-    float carouselSize =
+    int carouselSize =
         carousel.isHorizontal() ? carousel.getContainerWidth() : carousel.getContainerHeight();
 
     // If the focal end item is already at the end of the container and is fully visible or there
@@ -704,7 +704,7 @@ private static List<KeylineState> getStateStepsEnd(Carousel carousel, KeylineSta
    * @return a new {@link KeylineState} with the shifted keylines
    */
   private static KeylineState shiftKeylinesAndCreateKeylineState(
-      KeylineState state, float startOffset, float carouselSize) {
+      KeylineState state, float startOffset, int carouselSize) {
     return moveKeylineAndCreateKeylineState(
         state,
         0,
@@ -735,7 +735,7 @@ private static KeylineState moveKeylineAndCreateKeylineState(
       float startOffset,
       int newFirstFocalIndex,
       int newLastFocalIndex,
-      float carouselSize) {
+      int carouselSize) {
 
     List<Keyline> tmpKeylines = new ArrayList<>(state.getKeylines());
     Keyline item = tmpKeylines.remove(keylineSrcIndex);

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

@@ -59,9 +59,9 @@ public final class MultiBrowseCarouselStrategy extends CarouselStrategy {
   @NonNull
   public KeylineState onFirstChildMeasuredWithMargins(
       @NonNull Carousel carousel, @NonNull View child) {
-    float availableSpace = carousel.getContainerHeight();
+    int carouselSize = carousel.getContainerHeight();
     if (carousel.isHorizontal()) {
-      availableSpace = carousel.getContainerWidth();
+      carouselSize = carousel.getContainerWidth();
     }
 
     LayoutParams childLayoutParams = (LayoutParams) child.getLayoutParams();
@@ -77,7 +77,7 @@ public KeylineState onFirstChildMeasuredWithMargins(
     float smallChildSizeMax = getSmallItemSizeMax() + childMargins;
     smallChildSizeMax = max(smallChildSizeMax, smallChildSizeMin);
 
-    float targetLargeChildSize = min(measuredChildSize + childMargins, availableSpace);
+    float targetLargeChildSize = min(measuredChildSize + childMargins, carouselSize);
     // Ideally we would like to create a balanced arrangement where a small item is 1/3 the size of
     // the large item and medium items are sized between large and small items. Clamp the small
     // target size within our min-max range and as close to 1/3 of the target large item size as
@@ -95,7 +95,7 @@ public KeylineState onFirstChildMeasuredWithMargins(
     // then finally 1.
 
     int[] smallCounts = SMALL_COUNTS;
-    if (availableSpace < smallChildSizeMin * 2) {
+    if (carouselSize < smallChildSizeMin * 2) {
       // If the available space is too small to fit a large item and small item and a large item
       // (large items must be at least as big as a small item), allow arrangements with no small
       // items.
@@ -111,18 +111,18 @@ public KeylineState onFirstChildMeasuredWithMargins(
     // Find the minimum space left for large items after filling the carousel with the most
     // permissible medium and small items to determine a plausible minimum large count.
     float minAvailableLargeSpace =
-        availableSpace
+        carouselSize
             - (targetMediumChildSize * maxValue(mediumCounts))
             - (smallChildSizeMax * maxValue(smallCounts));
     int largeCountMin = (int) max(1, floor(minAvailableLargeSpace / targetLargeChildSize));
-    int largeCountMax = (int) ceil(availableSpace / targetLargeChildSize);
+    int largeCountMax = (int) ceil(carouselSize / targetLargeChildSize);
     int[] largeCounts = new int[largeCountMax - largeCountMin + 1];
     for (int i = 0; i < largeCounts.length; i++) {
       largeCounts[i] = largeCountMax - i;
     }
 
     Arrangement arrangement = Arrangement.findLowestCostArrangement(
-        availableSpace,
+        carouselSize,
         targetSmallChildSize,
         smallChildSizeMin,
         smallChildSizeMax,
@@ -139,7 +139,7 @@ public KeylineState onFirstChildMeasuredWithMargins(
       // counts, we call `findLowestCostArrangement` again with the item counts set.
       arrangement =
           Arrangement.findLowestCostArrangement(
-              availableSpace,
+              carouselSize,
               targetSmallChildSize,
               smallChildSizeMin,
               smallChildSizeMax,
@@ -153,7 +153,7 @@ public KeylineState onFirstChildMeasuredWithMargins(
     return createKeylineState(
         child.getContext(),
         childMargins,
-        availableSpace,
+        carouselSize,
         arrangement,
         carousel.getCarouselAlignment());
   }

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

@@ -49,7 +49,7 @@ public final class UncontainedCarouselStrategy extends CarouselStrategy {
   @NonNull
   public KeylineState onFirstChildMeasuredWithMargins(
       @NonNull Carousel carousel, @NonNull View child) {
-    float availableSpace =
+    int availableSpace =
         carousel.isHorizontal() ? carousel.getContainerWidth() : carousel.getContainerHeight();
 
     LayoutParams childLayoutParams = (LayoutParams) child.getLayoutParams();
@@ -143,7 +143,7 @@ private float calculateMediumChildSize(
   }
 
   private KeylineState createCenterAlignedKeylineState(
-      float availableSpace,
+      int availableSpace,
       float childMargins,
       float largeSize,
       int largeCount,
@@ -184,7 +184,7 @@ private KeylineState createCenterAlignedKeylineState(
   private KeylineState createLeftAlignedKeylineState(
       Context context,
       float childMargins,
-      float availableSpace,
+      int availableSpace,
       float largeSize,
       int largeCount,
       float mediumSize,

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

@@ -457,7 +457,7 @@ static KeylineState getTestCenteredKeylineState() {
     float smallMask = getKeylineMaskPercentage(smallSize, largeSize);
     float mediumMask = getKeylineMaskPercentage(mediumSize, largeSize);
 
-    return new KeylineState.Builder(450F, 1320F)
+    return new KeylineState.Builder(450F, 1320)
         .addKeyline(5F, extraSmallMask, extraSmallSize)
         .addKeylineRange(38F, smallMask, smallSize, 2)
         .addKeyline(166F, mediumMask, mediumSize)
@@ -478,7 +478,7 @@ static KeylineState getTestCenteredVerticalKeylineState() {
     float smallMask = getKeylineMaskPercentage(smallSize, largeSize);
     float mediumMask = getKeylineMaskPercentage(mediumSize, largeSize);
 
-    return new KeylineState.Builder(100F, 200F)
+    return new KeylineState.Builder(100F, 200)
         .addKeyline(9F, smallMask, smallSize)
         .addKeyline(25F, mediumMask, mediumSize)
         .addKeyline(66F, 0F, largeSize, true)

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

@@ -238,7 +238,7 @@ public void testStartArrangementWithOutOfBoundsKeyline_shouldShiftEnd() {
         };
 
     KeylineState state =
-        new KeylineState.Builder(40F, 100F)
+        new KeylineState.Builder(40F, 100)
             .addAnchorKeyline(-10F, getKeylineMaskPercentage(20F, 40F), 20F)
             .addKeyline(10F, getKeylineMaskPercentage(20F, 40F), 20F, false)
             .addKeyline(40F, 0F, 40F, true)