commonMain.androidx.compose.foundation.lazy.grid.LazySemantics.kt Maven / Gradle / Ivy

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Higher level abstractions of the Compose UI primitives. This library is design system agnostic, providing the high-level building blocks for both application and design-system developers

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/*
 * Copyright 2021 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.compose.foundation.lazy.grid

import androidx.compose.foundation.gestures.Orientation
import androidx.compose.foundation.lazy.layout.LazyLayoutSemanticState
import androidx.compose.foundation.lazy.layout.estimatedLazyMaxScrollOffset
import androidx.compose.foundation.lazy.layout.estimatedLazyScrollOffset
import androidx.compose.runtime.Composable
import androidx.compose.runtime.remember
import androidx.compose.ui.semantics.CollectionInfo

@Composable
internal fun rememberLazyGridSemanticState(
    state: LazyGridState,
    reverseScrolling: Boolean
): LazyLayoutSemanticState =
    remember(state, reverseScrolling) {
        object : LazyLayoutSemanticState {
            override val scrollOffset: Float
                get() =
                    estimatedLazyScrollOffset(
                        state.firstVisibleItemIndex,
                        state.firstVisibleItemScrollOffset
                    )

            override val maxScrollOffset: Float
                get() =
                    estimatedLazyMaxScrollOffset(
                        state.firstVisibleItemIndex,
                        state.firstVisibleItemScrollOffset,
                        state.canScrollForward
                    )

            override suspend fun scrollToItem(index: Int) {
                state.scrollToItem(index)
            }

            // TODO(popam): check if this is correct - it would be nice to provide correct columns
            override fun collectionInfo(): CollectionInfo =
                CollectionInfo(rowCount = -1, columnCount = -1)

            override val viewport: Int
                get() =
                    if (state.layoutInfo.orientation == Orientation.Vertical) {
                        state.layoutInfo.viewportSize.height
                    } else {
                        state.layoutInfo.viewportSize.width
                    }

            override val contentPadding: Int
                get() = state.layoutInfo.beforeContentPadding + state.layoutInfo.afterContentPadding
        }
    }