1 /* 2 * Copyright (C) 2025 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.wallpaper.picker.customization.ui.view.listener 18 19 import androidx.recyclerview.widget.RecyclerView 20 import com.android.wallpaper.picker.category.ui.view.adapter.CuratedPhotosAdapter 21 import com.google.android.material.carousel.CarouselLayoutManager 22 23 /** 24 * This scroll listener implementation finds the positions of the first visible carousel item, and 25 * updates the [CuratedPhotosAdapter] with that position 26 */ 27 class WallpaperCarouselScrollListener : RecyclerView.OnScrollListener() { 28 private var lastScrollState = RecyclerView.NO_POSITION 29 onScrollStateChangednull30 override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) { 31 super.onScrollStateChanged(recyclerView, newState) 32 33 if ( 34 newState == RecyclerView.SCROLL_STATE_IDLE && 35 lastScrollState != RecyclerView.SCROLL_STATE_IDLE 36 ) { 37 updateCarouselTitle(recyclerView) 38 } 39 lastScrollState = newState 40 } 41 onScrollednull42 override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) { 43 super.onScrolled(recyclerView, dx, dy) 44 if (lastScrollState == RecyclerView.NO_POSITION) { 45 updateCarouselTitle(recyclerView) 46 } 47 } 48 updateCarouselTitlenull49 private fun updateCarouselTitle(recyclerView: RecyclerView) { 50 // Get the LayoutManager 51 val layoutManager = recyclerView.layoutManager as CarouselLayoutManager 52 53 // Find the first completely visible item position 54 var firstVisiblePosition = RecyclerView.NO_POSITION 55 56 for (i in 0 until layoutManager.childCount) { 57 val child = layoutManager.getChildAt(i) 58 if (child != null) { 59 val position = recyclerView.getChildAdapterPosition(child) 60 if ( 61 position != RecyclerView.NO_POSITION && 62 layoutManager.isViewPartiallyVisible(child, true, true) 63 ) { 64 if ( 65 firstVisiblePosition == RecyclerView.NO_POSITION || 66 position < firstVisiblePosition 67 ) { 68 firstVisiblePosition = position 69 } 70 } 71 } 72 } 73 74 // Update the adapter with the new visible position 75 if (firstVisiblePosition != RecyclerView.NO_POSITION) { 76 recyclerView.post { 77 (recyclerView.adapter as CuratedPhotosAdapter).setVisiblePosition( 78 firstVisiblePosition 79 ) 80 } 81 } 82 } 83 } 84