[Catalog][Carousel] Update slider position when carousel is scrolled in catalog demos

Resolves #3521
Resolves #3520

GIT_ORIGIN_REV_ID=f26a8b55c9026a3418024a2e51ba3570a017c59d
PiperOrigin-RevId: 558934224

Author: manabu-nakamura

catalog/java/io/material/catalog/carousel/FullScreenStrategyDemoFragment.java

@@ -68,10 +68,8 @@ public void onViewCreated(@NonNull View view, @Nullable Bundle bundle) {
 
     new WindowPreferencesManager(requireContext())
         .applyEdgeToEdgePreference(bottomSheetDialog.getWindow());
-
     verticalDivider =
-        new MaterialDividerItemDecoration(
-            requireContext(), MaterialDividerItemDecoration.VERTICAL);
+        new MaterialDividerItemDecoration(requireContext(), MaterialDividerItemDecoration.VERTICAL);
 
     Button showBottomSheetButton = view.findViewById(R.id.show_bottomsheet_button);
     showBottomSheetButton.setOnClickListener(new OnClickListener() {
@@ -121,6 +119,26 @@ public void onClick(View v) {
         new CarouselAdapter(
             (item, position) -> fullscreenRecyclerView.scrollToPosition(position),
             R.layout.cat_carousel_item_vertical);
+    fullscreenRecyclerView.addOnScrollListener(
+        new RecyclerView.OnScrollListener() {
+          private boolean dragged = false;
+
+          @Override
+          public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {
+            if (newState == RecyclerView.SCROLL_STATE_DRAGGING) {
+              dragged = true;
+            } else if (dragged && newState == RecyclerView.SCROLL_STATE_IDLE) {
+              if (recyclerView.computeVerticalScrollRange() != 0) {
+                positionSlider.setValue(
+                    (adapter.getItemCount() - 1)
+                            * recyclerView.computeVerticalScrollOffset()
+                            / recyclerView.computeVerticalScrollRange()
+                        + 1);
+              }
+              dragged = false;
+            }
+          }
+        });
 
     SnapHelper flingDisabledSnapHelper = new CarouselSnapHelper();
     SnapHelper flingEnabledSnapHelper = new CarouselSnapHelper(false);
@@ -151,7 +169,7 @@ public void onStartTrackingTouch(@NonNull Slider slider) {}
 
           @Override
           public void onStopTrackingTouch(@NonNull Slider slider) {
-            fullscreenRecyclerView.smoothScrollToPosition((int) slider.getValue() - 1);
+            fullscreenRecyclerView.smoothScrollToPosition(((int) slider.getValue()) - 1);
           }
         });
 

catalog/java/io/material/catalog/carousel/HeroCarouselDemoFragment.java

@@ -101,8 +101,31 @@ public void onViewCreated(@NonNull View view, @Nullable Bundle bundle) {
 
     CarouselAdapter adapter =
         new CarouselAdapter(
-            (item, position) -> heroStartRecyclerView.scrollToPosition(position),
+            (item, position) -> {
+              heroStartRecyclerView.scrollToPosition(position);
+              positionSlider.setValue(position + 1);
+            },
             R.layout.cat_carousel_item);
+    heroStartRecyclerView.addOnScrollListener(
+        new RecyclerView.OnScrollListener() {
+          private boolean dragged = false;
+
+          @Override
+          public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {
+            if (newState == RecyclerView.SCROLL_STATE_DRAGGING) {
+              dragged = true;
+            } else if (dragged && newState == RecyclerView.SCROLL_STATE_IDLE) {
+              if (recyclerView.computeHorizontalScrollRange() != 0) {
+                positionSlider.setValue(
+                    (adapter.getItemCount() - 1)
+                            * recyclerView.computeHorizontalScrollOffset()
+                            / recyclerView.computeHorizontalScrollRange()
+                        + 1);
+              }
+              dragged = false;
+            }
+          }
+        });
 
     SnapHelper disableFlingSnapHelper = new CarouselSnapHelper();
     SnapHelper enableFlingSnapHelper = new CarouselSnapHelper(false);
@@ -137,7 +160,7 @@ public void onStartTrackingTouch(@NonNull Slider slider) {}
 
           @Override
           public void onStopTrackingTouch(@NonNull Slider slider) {
-            heroStartRecyclerView.smoothScrollToPosition((int) slider.getValue() - 1);
+            heroStartRecyclerView.smoothScrollToPosition(((int) slider.getValue()) - 1);
           }
         });
 

catalog/java/io/material/catalog/carousel/MultiBrowseCarouselDemoFragment.java

@@ -109,8 +109,31 @@ public void onViewCreated(@NonNull View view, @Nullable Bundle bundle) {
 
     CarouselAdapter adapter =
         new CarouselAdapter(
-            (item, position) -> multiBrowseStartRecyclerView.scrollToPosition(position),
+            (item, position) -> {
+              multiBrowseStartRecyclerView.scrollToPosition(position);
+              positionSlider.setValue(position + 1);
+            },
             R.layout.cat_carousel_item_narrow);
+    multiBrowseStartRecyclerView.addOnScrollListener(
+        new RecyclerView.OnScrollListener() {
+          private boolean dragged = false;
+
+          @Override
+          public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {
+            if (newState == RecyclerView.SCROLL_STATE_DRAGGING) {
+              dragged = true;
+            } else if (dragged && newState == RecyclerView.SCROLL_STATE_IDLE) {
+              if (recyclerView.computeHorizontalScrollRange() != 0) {
+                positionSlider.setValue(
+                    (adapter.getItemCount() - 1)
+                            * recyclerView.computeHorizontalScrollOffset()
+                            / recyclerView.computeHorizontalScrollRange()
+                        + 1);
+              }
+              dragged = false;
+            }
+          }
+        });
 
     itemCountDropdown.setOnItemClickListener(
         (parent, view1, position, id) -> {
@@ -126,7 +149,7 @@ public void onStartTrackingTouch(@NonNull Slider slider) {}
 
           @Override
           public void onStopTrackingTouch(@NonNull Slider slider) {
-            multiBrowseStartRecyclerView.smoothScrollToPosition((int) slider.getValue() - 1);
+            multiBrowseStartRecyclerView.smoothScrollToPosition(((int) slider.getValue()) - 1);
           }
         });