ganfra
2 months ago
4 changed files with 67 additions and 5 deletions
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/* |
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* Copyright (c) 2024 New Vector Ltd |
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* |
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* Licensed under the Apache License, Version 2.0 (the "License"); |
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* you may not use this file except in compliance with the License. |
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* You may obtain a copy of the License at |
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* |
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* https://www.apache.org/licenses/LICENSE-2.0 |
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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*/ |
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package io.element.android.libraries.designsystem.utils |
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import androidx.compose.foundation.lazy.LazyListState |
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import androidx.compose.runtime.Composable |
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import androidx.compose.runtime.derivedStateOf |
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import androidx.compose.runtime.getValue |
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import androidx.compose.runtime.mutableIntStateOf |
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import androidx.compose.runtime.remember |
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import androidx.compose.runtime.setValue |
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/** |
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* Returns whether the lazy list is currently scrolling up. |
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*/ |
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@Composable |
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fun LazyListState.isScrollingUp(): Boolean { |
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var previousIndex by remember(this) { mutableIntStateOf(firstVisibleItemIndex) } |
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var previousScrollOffset by remember(this) { mutableIntStateOf(firstVisibleItemScrollOffset) } |
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return remember(this) { |
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derivedStateOf { |
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if (previousIndex != firstVisibleItemIndex) { |
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previousIndex > firstVisibleItemIndex |
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} else { |
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previousScrollOffset >= firstVisibleItemScrollOffset |
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}.also { |
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previousIndex = firstVisibleItemIndex |
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previousScrollOffset = firstVisibleItemScrollOffset |
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} |
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} |
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}.value |
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} |
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