Create draggable functions

app-compose/src/main/kotlin/com/pitchedapps/frost/compose/Draggable.kt

@@ -0,0 +1,138 @@
+/*
+ * Copyright 2023 Allan Wang
+ *
+ * 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 <http://www.gnu.org/licenses/>.
+ */
+package com.pitchedapps.frost.compose
+
+import androidx.compose.foundation.gestures.detectDragGesturesAfterLongPress
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.BoxScope
+import androidx.compose.foundation.layout.LayoutScopeMarker
+import androidx.compose.foundation.layout.offset
+import androidx.compose.foundation.layout.size
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.Immutable
+import androidx.compose.runtime.compositionLocalOf
+import androidx.compose.runtime.derivedStateOf
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.input.pointer.pointerInput
+import androidx.compose.ui.layout.onGloballyPositioned
+import androidx.compose.ui.layout.positionInWindow
+import androidx.compose.ui.platform.LocalDensity
+import androidx.compose.ui.unit.Density
+import androidx.compose.ui.unit.DpSize
+import androidx.compose.ui.unit.IntOffset
+import androidx.compose.ui.unit.IntSize
+import kotlin.math.roundToInt
+
+/*
+ * Resources:
+ *
+ * https://blog.canopas.com/android-drag-and-drop-ui-element-in-jetpack-compose-14922073b3f1
+ */
+
+@Composable
+fun DragContainer(modifier: Modifier = Modifier, content: @Composable DragScope.() -> Unit) {
+  val draggable = remember { Draggable() }
+  val dragScope = remember(draggable) { DragScopeImpl(draggable) }
+  Box(modifier = modifier) {
+    dragScope.content()
+
+    DraggingContent(draggable = draggable)
+  }
+}
+
+private class DragScopeImpl(private val draggable: Draggable) : DragScope {
+  @Composable
+  override fun DragTarget(
+    key: String,
+    content: @Composable BoxScope.(isDragging: Boolean) -> Unit
+  ) {
+
+    var isDragging by remember { mutableStateOf(false) }
+
+    var positionInWindow by remember { mutableStateOf(Offset.Zero) }
+
+    var size by remember { mutableStateOf(IntSize.Zero) }
+
+    Box(
+      modifier =
+        Modifier.onGloballyPositioned {
+            positionInWindow = it.positionInWindow()
+            size = it.size
+          }
+          .pointerInput(Unit) {
+            detectDragGesturesAfterLongPress(
+              onDragStart = {
+                isDragging = true
+                draggable.composable = content
+                draggable.composableSize = size
+                draggable.dragPosition = positionInWindow
+              },
+              onDrag = { _, offset -> draggable.dragPosition += offset },
+              onDragEnd = {
+                isDragging = false
+                draggable.composable = null
+              },
+            )
+          },
+    ) {
+      if (!isDragging) {
+        content(false)
+      }
+    }
+  }
+}
+
+private fun IntSize.toDpSize(density: Density): DpSize {
+  return with(density) { DpSize(width.toDp(), height.toDp()) }
+}
+
+@Composable
+private fun DraggingContent(draggable: Draggable) {
+  val composable = draggable.composable ?: return
+
+  val density = LocalDensity.current
+  val sizeDp =
+    remember { derivedStateOf { draggable.composableSize?.toDpSize(density) } }.value ?: return
+
+  Box(
+    modifier = Modifier.size(sizeDp).offset { draggable.dragPosition.toIntOffset() },
+  ) {
+    composable(true)
+  }
+}
+
+private fun Offset.toIntOffset() = IntOffset(x.roundToInt(), y.roundToInt())
+
+@LayoutScopeMarker
+@Immutable
+interface DragScope {
+  @Composable
+  fun DragTarget(key: String, content: @Composable BoxScope.(isDragging: Boolean) -> Unit)
+}
+
+class Draggable {
+  var composable by mutableStateOf<(@Composable BoxScope.(isDragging: Boolean) -> Unit)?>(null)
+  var composableSize by mutableStateOf<IntSize?>(null)
+  var dragPosition by mutableStateOf(Offset.Zero)
+}
+
+internal val LocalDraggable = compositionLocalOf {}

app-compose/src/main/kotlin/com/pitchedapps/frost/ext/Modifier.kt

@@ -0,0 +1,22 @@
+/*
+ * Copyright 2023 Allan Wang
+ *
+ * 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 <http://www.gnu.org/licenses/>.
+ */
+package com.pitchedapps.frost.ext
+
+import androidx.compose.ui.Modifier
+
+fun Modifier.thenIf(condition: Boolean, action: () -> Modifier): Modifier =
+  if (condition) then(action()) else this

app-compose/src/main/kotlin/com/pitchedapps/frost/main/MainScreenWebView.kt

@@ -19,6 +19,7 @@ package com.pitchedapps.frost.main
 import androidx.compose.foundation.ExperimentalFoundationApi
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.pager.HorizontalPager
 import androidx.compose.foundation.pager.rememberPagerState
 import androidx.compose.material.ExperimentalMaterialApi
@@ -42,6 +43,7 @@ import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.unit.dp
 import androidx.lifecycle.viewmodel.compose.viewModel
 import com.pitchedapps.frost.compose.webview.FrostWebCompose
 import com.pitchedapps.frost.ext.WebTargetId
@@ -98,7 +100,13 @@ fun MainBottomBar(
   NavigationBar(modifier = modifier) {
     items.forEach { item ->
       NavigationBarItem(
-        icon = { Icon(item.icon, contentDescription = item.title) },
+        icon = {
+          Icon(
+            modifier = Modifier.size(24.dp),
+            imageVector = item.icon,
+            contentDescription = item.title,
+          )
+        },
         selected = selectedTab == item.id,
         onClick = { onSelect(item.id) },
       )

app-compose/src/main/kotlin/com/pitchedapps/frost/tabselector/TabSelectorScreen.kt

@@ -20,6 +20,7 @@ import androidx.compose.foundation.ExperimentalFoundationApi
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.navigationBarsPadding
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.layout.statusBarsPadding
@@ -28,6 +29,8 @@ import androidx.compose.foundation.lazy.grid.LazyVerticalGrid
 import androidx.compose.foundation.lazy.grid.items
 import androidx.compose.material3.Icon
 import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.NavigationBar
+import androidx.compose.material3.NavigationBarItem
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.getValue
@@ -40,8 +43,10 @@ import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.unit.dp
+import com.pitchedapps.frost.compose.DragContainer
 import com.pitchedapps.frost.compose.effects.rememberShakeState
 import com.pitchedapps.frost.compose.effects.shake
+import com.pitchedapps.frost.ext.thenIf
 import com.pitchedapps.frost.facebook.FbItem
 import com.pitchedapps.frost.facebook.tab
 
@@ -61,7 +66,7 @@ fun TabSelectorScreen(modifier: Modifier = Modifier) {
   val unselected = remember(selected) { options.values - selected.toSet() }
 
   TabSelector(
-    modifier = modifier.statusBarsPadding(),
+    modifier = modifier,
     selected = selected,
     unselected = unselected,
     onSelect = { selected = it },
@@ -76,15 +81,21 @@ fun TabSelector(
   unselected: List<TabData>,
   onSelect: (List<TabData>) -> Unit
 ) {
+  DragContainer(modifier = modifier) {
+    Column(modifier = Modifier.statusBarsPadding()) {
       LazyVerticalGrid(
-    modifier = modifier,
+        modifier = Modifier.weight(1f),
         columns = GridCells.Fixed(4),
       ) {
         items(unselected, key = { it.key }) {
+          this@DragContainer.DragTarget(key = it.key) { isDragging ->
             val shakeState = rememberShakeState()
+
             TabItem(
               modifier =
-          Modifier.animateItemPlacement().shake(shakeState).clickable {
+                Modifier.thenIf(!isDragging) { Modifier.animateItemPlacement() }
+                  .shake(shakeState)
+                  .clickable {
                     shakeState.shake()
                     //            onSelect(listOf(it))
                   },
@@ -94,6 +105,30 @@ fun TabSelector(
         }
       }
 
+      TabBottomBar(modifier = Modifier.navigationBarsPadding(), items = selected)
+    }
+  }
+}
+
+@Composable
+fun TabBottomBar(modifier: Modifier = Modifier, items: List<TabData>) {
+  NavigationBar(modifier = modifier) {
+    items.forEach { item ->
+      NavigationBarItem(
+        icon = {
+          Icon(
+            modifier = Modifier.size(24.dp),
+            imageVector = item.icon,
+            contentDescription = item.title,
+          )
+        },
+        selected = false,
+        onClick = {},
+      )
+    }
+  }
+}
+
 @Composable
 fun TabItem(
   data: TabData,