Reinventing the wheel, but better this time. Better approach for draggable history list in calculator:

- Using anchored draggable
- Remembering button sizes
- Additional buttons are not resizeable anymore

closes #75

feature/calculator/src/main/java/com/sadellie/unitto/feature/calculator/CalculatorScreen.kt

@@ -20,18 +20,16 @@ package com.sadellie.unitto.feature.calculator
 
 import android.content.res.Configuration
 import androidx.compose.animation.Crossfade
-import androidx.compose.animation.core.Animatable
-import androidx.compose.animation.rememberSplineBasedDecay
 import androidx.compose.foundation.background
 import androidx.compose.foundation.gestures.Orientation
-import androidx.compose.foundation.gestures.draggable
+import androidx.compose.foundation.gestures.anchoredDraggable
-import androidx.compose.foundation.gestures.rememberDraggableState
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.BoxWithConstraints
 import androidx.compose.foundation.layout.Column
-import androidx.compose.foundation.layout.fillMaxHeight
-import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.offset
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.sizeIn
 import androidx.compose.foundation.shape.RoundedCornerShape
@@ -45,18 +43,17 @@ import androidx.compose.material3.Text
 import androidx.compose.material3.TextButton
 import androidx.compose.material3.TopAppBarDefaults
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.derivedStateOf
 import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableIntStateOf
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
-import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.layout.onPlaced
 import androidx.compose.ui.platform.LocalConfiguration
+import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.platform.LocalFocusManager
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.text.TextRange
@@ -73,13 +70,9 @@ import com.sadellie.unitto.core.ui.common.textfield.ExpressionTextField
 import com.sadellie.unitto.core.ui.common.textfield.UnformattedTextField
 import com.sadellie.unitto.data.model.HistoryItem
 import com.sadellie.unitto.feature.calculator.components.CalculatorKeyboard
-import com.sadellie.unitto.feature.calculator.components.DragDownView
 import com.sadellie.unitto.feature.calculator.components.HistoryList
-import kotlinx.coroutines.launch
 import java.text.SimpleDateFormat
 import java.util.Locale
-import kotlin.math.abs
-import kotlin.math.roundToInt
 
 @Composable
 internal fun CalculatorRoute(
@@ -117,24 +110,15 @@ private fun CalculatorScreen(
     clearHistory: () -> Unit
 ) {
     val focusManager = LocalFocusManager.current
-    val dragAmount = remember { Animatable(0f) }
-    val dragCoroutineScope = rememberCoroutineScope()
-    val dragAnimSpec = rememberSplineBasedDecay<Float>()
-
-    var textThingyHeight by remember { mutableIntStateOf(0) }
-    var historyItemHeight by remember { mutableIntStateOf(0) }
-
     var showClearHistoryDialog by rememberSaveable { mutableStateOf(false) }
-    val showClearHistoryButton by remember(dragAmount.value, historyItemHeight) {
+    var showClearHistoryButton by rememberSaveable { mutableStateOf(false) }
-        derivedStateOf { dragAmount.value > historyItemHeight }
-    }
 
     UnittoScreenWithTopBar(
         title = { Text(stringResource(R.string.calculator)) },
         navigationIcon = { MenuButton { navigateToMenu() } },
         colors = TopAppBarDefaults.topAppBarColors(MaterialTheme.colorScheme.surfaceVariant),
         actions = {
-            Crossfade(showClearHistoryButton) {
+            Crossfade(showClearHistoryButton, label = "Clear button reveal") {
                 if (it) {
                     IconButton(
                         onClick = { showClearHistoryDialog = true },
@@ -151,26 +135,57 @@ private fun CalculatorScreen(
             }
         }
     ) { paddingValues ->
-        DragDownView(
+        BoxWithConstraints(
             modifier = Modifier.padding(paddingValues),
-            drag = dragAmount.value.roundToInt().coerceAtLeast(0),
+        ) {
-            historyItemHeight = historyItemHeight,
+            val density = LocalDensity.current
-            historyList = {
+            var historyItemHeight by remember { mutableStateOf(0.dp) }
+            val textBoxHeight = maxHeight * 0.25f
+            var dragStateCurrentValue by rememberSaveable { mutableStateOf(DragState.CLOSED) }
+
+            val dragState = rememberDragState(
+                historyItem = historyItemHeight,
+                max = maxHeight - textBoxHeight,
+                initialValue = dragStateCurrentValue
+            )
+            val dragDp by remember(dragState.requireOffset()) {
+                derivedStateOf {
+                    focusManager.clearFocus(true)
+                    with(density) { dragState.requireOffset().toDp() }
+                }
+            }
+            val keyboardHeight by remember(dragState.requireOffset()) {
+                derivedStateOf {
+                    if (dragDp > historyItemHeight) {
+                        maxHeight - textBoxHeight - historyItemHeight
+                    } else {
+                        maxHeight - textBoxHeight - dragDp
+                    }
+                }
+            }
+
+            LaunchedEffect(dragState.currentValue) {
+                dragStateCurrentValue = dragState.currentValue
+                showClearHistoryButton = dragState.currentValue == DragState.OPEN
+            }
+
+            // History
             HistoryList(
                 modifier = Modifier
                     .background(MaterialTheme.colorScheme.surfaceVariant.copy(alpha = 0.5f))
-                        .fillMaxSize(),
+                    .fillMaxWidth()
+                    .height(dragDp),
                 historyItems = uiState.history,
-                    historyItemHeightCallback = { historyItemHeight = it },
+                heightCallback = { historyItemHeight = it },
                 formatterSymbols = uiState.formatterSymbols,
                 addTokens = addSymbol,
             )
-            },
+
-            textFields = { maxDragAmount ->
+            // Input
             Column(
                 Modifier
-                        .fillMaxHeight(0.25f)
+                    .offset(y = dragDp)
-                        .onPlaced { textThingyHeight = it.size.height }
+                    .height(textBoxHeight)
                     .background(
                         MaterialTheme.colorScheme.surfaceVariant,
                         RoundedCornerShape(
@@ -178,29 +193,9 @@ private fun CalculatorScreen(
                             bottomStartPercent = 20, bottomEndPercent = 20
                         )
                     )
-                        .draggable(
+                    .anchoredDraggable(
-                            orientation = Orientation.Vertical,
+                        state = dragState,
-                            state = rememberDraggableState { delta ->
+                        orientation = Orientation.Vertical
-                                dragCoroutineScope.launch {
-                                    val draggedAmount = (dragAmount.value + delta).coerceAtLeast(0f)
-                                    dragAmount.snapTo(draggedAmount)
-                                }
-                            },
-                            onDragStarted = {
-                                // Moving composables with focus causes performance drop
-                                focusManager.clearFocus(true)
-                            },
-                            onDragStopped = { velocity ->
-                                dragCoroutineScope.launch {
-                                    dragAmount.animateDecay(velocity, dragAnimSpec)
-
-                                    // Snap to closest anchor (0, one history item, all history items)
-                                    val draggedAmount = listOf(0, historyItemHeight, maxDragAmount)
-                                        .minBy { abs(dragAmount.value.roundToInt() - it) }
-                                        .toFloat()
-                                    dragAmount.animateTo(draggedAmount)
-                                }
-                            }
                     )
                     .padding(top = 12.dp),
                 horizontalAlignment = Alignment.CenterHorizontally,
@@ -268,11 +263,13 @@ private fun CalculatorScreen(
                         .sizeIn(24.dp, 4.dp)
                 )
             }
-            },
+
-            numPad = {
+            // Keyboard
             CalculatorKeyboard(
                 modifier = Modifier
-                        .fillMaxSize()
+                    .offset(y = dragDp + textBoxHeight)
+                    .height(keyboardHeight)
+                    .fillMaxWidth()
                     .padding(horizontal = 8.dp, vertical = 4.dp),
                 radianMode = uiState.radianMode,
                 fractional = uiState.formatterSymbols.fractional,
@@ -284,7 +281,6 @@ private fun CalculatorScreen(
                 evaluate = evaluate
             )
         }
-        )
     }
 
     if (showClearHistoryDialog) {

feature/calculator/src/main/java/com/sadellie/unitto/feature/calculator/DragState.kt

@@ -0,0 +1,53 @@
+/*
+ * Unitto is a unit converter for Android
+ * Copyright (c) 2023 Elshan Agaev
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.sadellie.unitto.feature.calculator
+
+import androidx.compose.animation.core.tween
+import androidx.compose.foundation.gestures.AnchoredDraggableState
+import androidx.compose.foundation.gestures.DraggableAnchors
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
+import androidx.compose.ui.platform.LocalDensity
+import androidx.compose.ui.unit.Dp
+
+internal enum class DragState { CLOSED, HALF, OPEN }
+
+@Composable
+internal fun rememberDragState(
+    initialValue: DragState = DragState.CLOSED,
+    historyItem: Dp,
+    max: Dp,
+): AnchoredDraggableState<DragState> {
+    val historyItemHeight = with(LocalDensity.current) { historyItem.toPx() }
+    val maxHeight = with(LocalDensity.current) { max.toPx() }
+
+    return remember(key1 = historyItem) {
+        AnchoredDraggableState(
+            initialValue = initialValue,
+            anchors = DraggableAnchors {
+                DragState.CLOSED at 0f
+                DragState.HALF at historyItemHeight
+                DragState.OPEN at maxHeight
+            },
+            positionalThreshold = { 0f },
+            velocityThreshold = { 0f },
+            animationSpec = tween()
+        )
+    }
+}

feature/calculator/src/main/java/com/sadellie/unitto/feature/calculator/components/CalculatorKeyboard.kt

@@ -41,6 +41,7 @@ import androidx.compose.material3.IconButton
 import androidx.compose.material3.IconButtonDefaults
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.derivedStateOf
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
@@ -50,7 +51,6 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.rotate
 import androidx.compose.ui.platform.LocalConfiguration
 import androidx.compose.ui.tooling.preview.Preview
-import androidx.compose.ui.unit.Dp
 import com.sadellie.unitto.core.base.Token
 import com.sadellie.unitto.core.ui.common.ColumnWithConstraints
 import com.sadellie.unitto.core.ui.common.KeyboardButtonAdditional
@@ -160,23 +160,36 @@ private fun PortraitKeyboard(
     ColumnWithConstraints(
         modifier = modifier
     ) { constraints ->
-        fun verticalFraction(fraction: Float): Dp = constraints.maxHeight * fraction
+        val mainButtonHorizontalPadding by remember {
-        fun horizontalFraction(fraction: Float): Dp = constraints.maxWidth * fraction
+            derivedStateOf { (constraints.maxWidth * 0.01f) }
+        }
+
+        val additionalButtonHeight by remember {
+            mutableStateOf(constraints.maxHeight * 0.09f)
+        }
+
+        val spacerHeight by remember {
+            mutableStateOf(constraints.maxHeight * 0.025f)
+        }
+
+        val additionalRowSpacedBy by remember {
+            mutableStateOf(constraints.maxWidth * 0.03f)
+        }
 
         val weightModifier = Modifier.weight(1f)
         val mainButtonModifier = Modifier
             .fillMaxSize()
             .weight(1f)
-            .padding(horizontalFraction(0.015f), verticalFraction(0.009f))
+            .padding(mainButtonHorizontalPadding)
         val additionalButtonModifier = Modifier
             .weight(1f)
-            .height(verticalFraction(0.09f))
+            .height(additionalButtonHeight)
 
-        Spacer(modifier = Modifier.height(verticalFraction(0.025f)))
+        Spacer(modifier = Modifier.height(spacerHeight))
 
         Row(
             modifier = Modifier,
-            horizontalArrangement = Arrangement.spacedBy(horizontalFraction(0.03f))
+            horizontalArrangement = Arrangement.spacedBy(additionalRowSpacedBy)
         ) {
             // Additional buttons
             Crossfade(invMode, weightModifier) {
@@ -204,7 +217,7 @@ private fun PortraitKeyboard(
             }
 
             Box(
-                modifier = Modifier.size(verticalFraction(0.09f)),
+                modifier = Modifier.size(additionalButtonHeight),
                 contentAlignment = Alignment.Center
             ) {
                 // Expand/Collapse
@@ -217,7 +230,7 @@ private fun PortraitKeyboard(
             }
         }
 
-        Spacer(modifier = Modifier.height(verticalFraction(0.025f)))
+        Spacer(modifier = Modifier.height(spacerHeight))
 
         Row(weightModifier) {
             KeyboardButtonFilled(mainButtonModifier, UnittoIcons.LeftBracket, allowVibration) { addSymbol(Token.Operator.leftBracket) }
@@ -250,7 +263,7 @@ private fun PortraitKeyboard(
             KeyboardButtonFilled(mainButtonModifier, UnittoIcons.Equal, allowVibration) { evaluate() }
         }
 
-        Spacer(modifier = Modifier.height(verticalFraction(0.015f)))
+        Spacer(modifier = Modifier.height(spacerHeight))
     }
 }
 

feature/calculator/src/main/java/com/sadellie/unitto/feature/calculator/components/DragDownView.kt

@@ -1,92 +0,0 @@
-/*
- * Unitto is a unit converter for Android
- * Copyright (c) 2023 Elshan Agaev
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
-
-package com.sadellie.unitto.feature.calculator.components
-
-import androidx.compose.runtime.Composable
-import androidx.compose.ui.Modifier
-import androidx.compose.ui.layout.SubcomposeLayout
-import androidx.compose.ui.unit.offset
-
-/**
- * Screen layout where [historyList] can be seen only when you drag [textFields] down.
- *
- * @param modifier [Modifier] that will be applied to [SubcomposeLayout].
- * @param drag Drag amount. Update this when dragging [textFields].
- * @param historyItemHeight Height of one item in [historyList].
- * @param textFields This part of the UI should be used as a handle. Offsets when dragging.
- * @param numPad Composable with buttons. Offsets when drag amount is higher than [historyItemHeight]
- *  (otherwise will just shrink).
- */
-@Composable
-internal fun DragDownView(
-    modifier: Modifier,
-    drag: Int,
-    historyItemHeight: Int,
-    historyList: @Composable () -> Unit,
-    textFields: @Composable (maxDragAmount: Int) -> Unit,
-    numPad: @Composable () -> Unit
-) {
-    SubcomposeLayout(modifier = modifier) { constraints ->
-        val showHistory = drag < historyItemHeight
-        val offset = if (showHistory) (drag - historyItemHeight).coerceAtLeast(0) else 0
-
-        val textFieldPlaceables = subcompose(DragDownContent.TextFields) {
-            textFields(constraints.maxHeight)
-        }.map { it.measure(constraints.offset(offset)) }
-        val textFieldsHeight = textFieldPlaceables.maxByOrNull { it.height }?.height ?: 0
-
-        val historyListPlaceables = subcompose(DragDownContent.HistoryList) {
-            historyList()
-        }.map {
-            it.measure(
-                constraints.copy(
-                    maxHeight = drag.coerceAtMost(constraints.maxHeight - textFieldsHeight)
-                )
-            )
-        }
-
-        val padding = if (showHistory) drag.coerceAtLeast(0) else historyItemHeight
-        val numPadConstraints = constraints
-            .offset(offset)
-            .copy(maxHeight = constraints.maxHeight - textFieldsHeight - padding)
-        val numPadPlaceables = subcompose(DragDownContent.NumPad, numPad).map {
-            it.measure(numPadConstraints)
-        }
-
-        layout(constraints.maxWidth, constraints.maxHeight) {
-            var yPos = 0
-            historyListPlaceables.forEach {
-                it.place(0, yPos)
-                yPos += it.height
-            }
-
-            textFieldPlaceables.forEach {
-                it.place(0, yPos)
-                yPos += it.height
-            }
-
-            numPadPlaceables.forEach {
-                it.place(0, yPos)
-                yPos += it.height
-            }
-        }
-    }
-}
-
-private enum class DragDownContent { HistoryList, TextFields, NumPad }

feature/calculator/src/main/java/com/sadellie/unitto/feature/calculator/components/HistoryList.kt

@@ -49,6 +49,7 @@ import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.layout.onPlaced
 import androidx.compose.ui.platform.LocalClipboardManager
+import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.platform.LocalTextInputService
 import androidx.compose.ui.platform.LocalTextToolbar
 import androidx.compose.ui.platform.LocalView
@@ -57,6 +58,7 @@ import androidx.compose.ui.text.TextRange
 import androidx.compose.ui.text.input.TextFieldValue
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
 import com.sadellie.unitto.core.base.R
 import com.sadellie.unitto.core.ui.common.textfield.ExpressionTransformer
@@ -73,14 +75,14 @@ import java.util.Locale
 internal fun HistoryList(
     modifier: Modifier,
     historyItems: List<HistoryItem>,
-    historyItemHeightCallback: (Int) -> Unit,
+    heightCallback: (Dp) -> Unit,
     formatterSymbols: FormatterSymbols,
     addTokens: (String) -> Unit,
 ) {
     if (historyItems.isEmpty()) {
         HistoryListPlaceholder(
             modifier = modifier,
-            historyItemHeightCallback = historyItemHeightCallback
+            heightCallback = heightCallback
         )
     } else {
         HistoryListContent(
@@ -88,7 +90,7 @@ internal fun HistoryList(
             historyItems = historyItems,
             addTokens = addTokens,
             formatterSymbols = formatterSymbols,
-            historyItemHeightCallback = historyItemHeightCallback
+            heightCallback = heightCallback
         )
     }
 }
@@ -96,15 +98,17 @@ internal fun HistoryList(
 @Composable
 private fun HistoryListPlaceholder(
     modifier: Modifier,
-    historyItemHeightCallback: (Int) -> Unit
+    heightCallback: (Dp) -> Unit,
 ) {
+    val density = LocalDensity.current
+
     Column(
         modifier = modifier.wrapContentHeight(unbounded = true),
         verticalArrangement = Arrangement.Center
     ) {
         Column(
             modifier = Modifier
-                .onPlaced { historyItemHeightCallback(it.size.height) }
+                .onPlaced { heightCallback(with(density) { it.size.height.toDp() }) }
                 .fillMaxWidth()
                 .padding(vertical = 32.dp),
             verticalArrangement = Arrangement.Center,
@@ -122,8 +126,9 @@ private fun HistoryListContent(
     historyItems: List<HistoryItem>,
     addTokens: (String) -> Unit,
     formatterSymbols: FormatterSymbols,
-    historyItemHeightCallback: (Int) -> Unit
+    heightCallback: (Dp) -> Unit,
 ) {
+    val density = LocalDensity.current
     val state = rememberLazyListState()
     val firstItem by remember(historyItems) { mutableStateOf(historyItems.first()) }
     val restOfTheItems by remember(firstItem) { mutableStateOf(historyItems.drop(1)) }
@@ -139,7 +144,7 @@ private fun HistoryListContent(
         // We do this so that callback for items height is called only once
         item(firstItem.id) {
             HistoryListItem(
-                modifier = Modifier.onPlaced { historyItemHeightCallback(it.size.height) },
+                modifier = Modifier.onPlaced { heightCallback(with(density) { it.size.height.toDp() }) },
                 historyItem = historyItems.first(),
                 formatterSymbols = formatterSymbols,
                 addTokens = addTokens,
@@ -270,7 +275,7 @@ private fun PreviewHistoryList() {
             .fillMaxSize(),
         historyItems = historyItems,
         formatterSymbols = FormatterSymbols.Spaces,
-        historyItemHeightCallback = {},
+        heightCallback = {},
         addTokens = {}
     )
 }