src/com/android/wallpaper/picker/preview/ui/binder/PreviewSelectorBinder.kt

/*
 * Copyright (C) 2023 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.android.wallpaper.picker.preview.ui.binder

import android.content.Context
import android.graphics.Point
import androidx.lifecycle.LifecycleOwner
import androidx.viewpager.widget.ViewPager
import androidx.viewpager2.widget.ViewPager2
import com.android.wallpaper.picker.preview.ui.viewmodel.WallpaperPreviewViewModel
import com.android.wallpaper.util.PreviewUtils
import kotlinx.coroutines.CoroutineScope

/** Binds and synchronizes the tab and preview view pagers. */
object PreviewSelectorBinder {

    fun bind(
        tabsViewPager: ViewPager,
        previewsViewPager: ViewPager2,
        previewDisplaySize: Point,
        wallpaperPreviewViewModel: WallpaperPreviewViewModel,
        applicationContext: Context,
        viewLifecycleOwner: LifecycleOwner,
        mainScope: CoroutineScope,
        homePreviewUtils: PreviewUtils,
        lockPreviewUtils: PreviewUtils,
        navigate: (() -> Unit)? = null,
    ) {
        // set up tabs view pager
        TabPagerBinder.bind(tabsViewPager)

        // set up previews view pager
        PreviewPagerBinder.bind(
            applicationContext,
            viewLifecycleOwner,
            mainScope,
            previewsViewPager,
            wallpaperPreviewViewModel,
            previewDisplaySize,
            homePreviewUtils,
            lockPreviewUtils,
            navigate,
        )

        // synchronize the two pagers
        synchronizePreviewAndTabsPager(tabsViewPager, previewsViewPager)
    }

    private fun synchronizePreviewAndTabsPager(
        tabsViewPager: ViewPager,
        previewsViewPager: ViewPager2,
    ) {
        val onPageChangeListener =
            object : ViewPager.OnPageChangeListener {
                override fun onPageSelected(position: Int) {
                    previewsViewPager.setCurrentItem(position, true)
                }

                override fun onPageScrolled(
                    position: Int,
                    positionOffset: Float,
                    positionOffsetPixels: Int
                ) {}

                override fun onPageScrollStateChanged(state: Int) {}
            }

        tabsViewPager.addOnPageChangeListener(onPageChangeListener)

        previewsViewPager.registerOnPageChangeCallback(
            object : ViewPager2.OnPageChangeCallback() {
                override fun onPageSelected(position: Int) {
                    super.onPageSelected(position)
                    tabsViewPager.setCurrentItem(position, true)
                }
            }
        )
    }
}