glance/glance-appwidget/src/main/java/androidx/glance/appwidget/translators/LazyVerticalGridTranslator.kt

/*
 * Copyright 2022 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 androidx.glance.appwidget.translators

import android.app.PendingIntent
import android.app.PendingIntent.FLAG_ALLOW_UNSAFE_IMPLICIT_INTENT
import android.app.PendingIntent.FLAG_MUTABLE
import android.app.PendingIntent.FLAG_UPDATE_CURRENT
import android.content.Intent
import android.content.Intent.FILL_IN_COMPONENT
import android.os.Build
import android.widget.RemoteViews
import androidx.core.widget.RemoteViewsCompat.setGridViewColumnWidth
import androidx.glance.appwidget.InsertedViewInfo
import androidx.glance.appwidget.LayoutType
import androidx.glance.appwidget.RemoteCollectionItems
import androidx.glance.appwidget.TopLevelLayoutsCount
import androidx.glance.appwidget.TranslationContext
import androidx.glance.appwidget.applyModifiers
import androidx.glance.appwidget.insertView
import androidx.glance.appwidget.lazy.EmittableLazyVerticalGrid
import androidx.glance.appwidget.lazy.EmittableLazyVerticalGridListItem
import androidx.glance.appwidget.lazy.GridCells
import androidx.glance.appwidget.lazy.ReservedItemIdRangeEnd
import androidx.glance.appwidget.setRemoteAdapter
import androidx.glance.appwidget.toSizeString
import androidx.glance.appwidget.translateChild
import androidx.glance.appwidget.translateComposition
import androidx.glance.layout.Alignment

/**
 * Translates an EmittableLazyVerticalGrid and its children to a EmittableLazyList.
 */
internal fun RemoteViews.translateEmittableLazyVerticalGrid(
    translationContext: TranslationContext,
    element: EmittableLazyVerticalGrid,
) {

    val viewDef = insertView(translationContext, element.gridCells.toLayout(), element.modifier)
    translateEmittableLazyVerticalGrid(
        translationContext,
        element,
        viewDef,
    )
}

private fun RemoteViews.translateEmittableLazyVerticalGrid(
    translationContext: TranslationContext,
    element: EmittableLazyVerticalGrid,
    viewDef: InsertedViewInfo,
) {
    check(!translationContext.isLazyCollectionDescendant) {
        "Glance does not support nested list views."
    }

    val gridCells = element.gridCells
    if (gridCells is GridCells.Fixed) {
      require(gridCells.count in 1..5) {
          "Only counts from 1 to 5 are supported."
      }
    }
    setPendingIntentTemplate(
        viewDef.mainViewId,
        PendingIntent.getActivity(
            translationContext.context,
            0,
            Intent(),
            FILL_IN_COMPONENT
                or FLAG_MUTABLE
                or FLAG_UPDATE_CURRENT
                or FLAG_ALLOW_UNSAFE_IMPLICIT_INTENT,
            element.activityOptions,
        )
    )
    val items = RemoteCollectionItems.Builder().apply {
        val childContext = translationContext.forLazyCollection(viewDef.mainViewId)
        element.children.foldIndexed(false) { position, previous, itemEmittable ->
            itemEmittable as EmittableLazyVerticalGridListItem
            val itemId = itemEmittable.itemId
            addItem(
                itemId,
                translateComposition(
                    childContext.forLazyViewItem(position, LazyVerticalGridItemStartingViewId),
                    listOf(itemEmittable),
                    translationContext.layoutConfiguration?.addLayout(itemEmittable) ?: -1,
                )
            )
            // If the user specifies any explicit ids, we assume the list to be stable
            previous || (itemId > ReservedItemIdRangeEnd)
        }.let { setHasStableIds(it) }
        setViewTypeCount(TopLevelLayoutsCount)
    }.build()
    setRemoteAdapter(
        translationContext.context,
        translationContext.appWidgetId,
        viewDef.mainViewId,
        translationContext.layoutSize.toSizeString(),
        items
    )
    if (Build.VERSION.SDK_INT >= 31 && gridCells is GridCells.Adaptive) {
      setGridViewColumnWidth(viewId = viewDef.mainViewId,
                             value = gridCells.minSize.value,
                             unit = android.util.TypedValue.COMPLEX_UNIT_DIP)
    }
    applyModifiers(translationContext, this, element.modifier, viewDef)
}

/**
 * Translates a list item either to its immediate only child, or a column layout wrapping all its
 * children.
 */
internal fun RemoteViews.translateEmittableLazyVerticalGridListItem(
    translationContext: TranslationContext,
    element: EmittableLazyVerticalGridListItem
) {
    require(element.children.size == 1 && element.alignment == Alignment.CenterStart) {
        "Lazy vertical grid items can only have a single child align at the center start of the " +
        "view. The normalization of the composition tree failed."
    }
    translateChild(translationContext, element.children.first())
}

// All the lazy list items should use the same ids, to ensure the layouts can be re-used.
// Using a very high number to avoid collision with the main app widget ids.
private const val LazyVerticalGridItemStartingViewId: Int = 0x00100000

private fun GridCells.toLayout(): LayoutType =
  when (this) {
    GridCells.Fixed(1) -> LayoutType.VerticalGridOneColumn
    GridCells.Fixed(2) -> LayoutType.VerticalGridTwoColumns
    GridCells.Fixed(3) -> LayoutType.VerticalGridThreeColumns
    GridCells.Fixed(4) -> LayoutType.VerticalGridFourColumns
    GridCells.Fixed(5) -> LayoutType.VerticalGridFiveColumns
    else -> LayoutType.VerticalGridAutoFit
  }