Ease a released long press into the selection (#141)

app/src/main/java/de/jeanlucmakiola/calendula/ui/common/HourGutter.kt

@@ -19,6 +19,8 @@ import androidx.compose.runtime.Composable
 import androidx.compose.runtime.derivedStateOf
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.remember
+import androidx.compose.ui.graphics.graphicsLayer
+import androidx.compose.runtime.mutableStateOf
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalDensity
@@ -107,12 +109,25 @@ fun HourGutter(
                 }
             }
         }
-        dragStartMin?.let { startMin ->
+        // Held while it fades, so it goes out where it was rather than blinking off.
+        val badgeMin = remember { mutableStateOf<Int?>(null) }
+        dragStartMin?.let { badgeMin.value = it }
+        val badgeIn by animateFloatAsState(
+            targetValue = if (dragStartMin != null) 1f else 0f,
+            animationSpec = MaterialTheme.motionScheme.fastEffectsSpec(),
+            label = "gutterBadge",
+        )
+        badgeMin.value?.takeIf { badgeIn > 0f }?.let { startMin ->
             val top = (hourHeight * (startMin / 60f) - BADGE_HEIGHT / 2).coerceAtLeast(0.dp)
             Box(
                 modifier = Modifier
                     .align(Alignment.TopCenter)
                     .offset(y = top)
+                    .graphicsLayer {
+                        alpha = badgeIn
+                        scaleX = 0.8f + 0.2f * badgeIn
+                        scaleY = 0.8f + 0.2f * badgeIn
+                    }
                     .height(BADGE_HEIGHT)
                     .background(MaterialTheme.colorScheme.primary, CircleShape)
                     .padding(horizontal = 4.dp)

app/src/main/java/de/jeanlucmakiola/calendula/ui/common/TimelineDrag.kt

@@ -1,7 +1,7 @@
 package de.jeanlucmakiola.calendula.ui.common
 
 import androidx.compose.animation.core.animateFloatAsState
-import androidx.compose.animation.core.snap
+import androidx.compose.animation.core.Animatable
 import androidx.compose.animation.core.tween
 import androidx.compose.foundation.ScrollState
 import androidx.compose.foundation.MutatePriority
@@ -117,7 +117,13 @@ data class TimelineDrag(
  * action bar up. [date] is the column the press landed in. [moved] holds from a
  * move or resize of it until the grid shows where it landed.
  */
-data class TimelineSelection(val event: EventInstance, val date: LocalDate, val moved: Boolean = false)
+data class TimelineSelection(
+    val event: EventInstance,
+    val date: LocalDate,
+    val moved: Boolean = false,
+    /** Selected by letting go of a lifted block: the block takes the lift over as it is. */
+    val fromLift: Boolean = false,
+)
 
 /**
  * One day column's share of a dragged event, ready to draw. Both halves of an
@@ -407,8 +413,8 @@ class TimelineDragController {
     var selection: TimelineSelection? by mutableStateOf(null)
         private set
 
-    fun select(event: EventInstance, date: LocalDate, moved: Boolean = false) {
-        selection = TimelineSelection(event, date, moved)
+    fun select(event: EventInstance, date: LocalDate, moved: Boolean = false, fromLift: Boolean = false) {
+        selection = TimelineSelection(event, date, moved, fromLift)
     }
 
     fun deselect() {
@@ -1190,15 +1196,21 @@ private fun DragCopy(
     }
 }
 
-/** How far a selected block is lifted, animated between 0 and 1 (#141). */
+/**
+ * How far a selected block is lifted, between 0 and 1 (#141). [snap] takes the
+ * lift over at once — from the floating copy it replaces — rather than raising
+ * the block a second time.
+ */
 @Composable
-fun selectionLift(selected: Boolean): Float {
+fun selectionLift(selected: Boolean, snap: Boolean = false): Float {
     val reduceMotion = rememberReduceMotion()
-    return animateFloatAsState(
-        targetValue = if (selected) 1f else 0f,
-        animationSpec = if (reduceMotion) snap() else MaterialTheme.motionScheme.fastSpatialSpec(),
-        label = "selection-lift",
-    ).value
+    val spec = MaterialTheme.motionScheme.fastSpatialSpec<Float>()
+    val raise = remember { Animatable(if (selected) 1f else 0f) }
+    LaunchedEffect(selected) {
+        val target = if (selected) 1f else 0f
+        if (reduceMotion || (selected && snap)) raise.snapTo(target) else raise.animateTo(target, spec)
+    }
+    return raise.value
 }
 
 /**

app/src/main/java/de/jeanlucmakiola/calendula/ui/week/WeekScreen.kt

@@ -95,6 +95,7 @@ import androidx.compose.ui.draw.alpha
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.draw.clipToBounds
 import androidx.compose.ui.graphics.graphicsLayer
+import androidx.compose.animation.core.animateFloatAsState
 import androidx.compose.ui.layout.layout
 import androidx.compose.ui.graphics.RectangleShape
 import androidx.compose.ui.input.pointer.pointerInput
@@ -1583,11 +1584,15 @@ private fun EventBlock(
         onMove = dragController::move,
         onDrop = { dragController.finish()?.let(onDrop) },
         onCancel = dragController::cancel,
-        onRelease = { dragController.select(block.event, date) },
+        onRelease = { dragController.select(block.event, date, fromLift = draggable) },
     )
     val lifted = draggable && dragController.ghosts(block)
-    val ghost = ghostAlpha(lifted)
-    val raise = selectionLift(selected)
+    // Let go of without moving, the block takes the floating copy's place as it
+    // stands: whole and lifted at once, not faded back up and raised again.
+    val takesOverLift = selected && dragController.selection?.fromLift == true
+    val ghostFade = ghostAlpha(lifted)
+    val ghost = if (takesOverLift && !lifted) 1f else ghostFade
+    val raise = selectionLift(selected, snap = takesOverLift)
     // Where the selected event's bottom handle sits against the action bar, which
     // compacts itself rather than cover it. Read off the piece that ends the event.
     val revealExtraPx = with(density) { (ResizeHandleTarget / 2).toPx() }
@@ -1661,7 +1666,16 @@ private fun EventBlock(
                 }
             }
             val end = { dragController.finishResize(zone)?.let(dragController.onResize) }
-            val handleAlpha = if (handlesShown) Modifier else Modifier.alpha(0f)
+            val handleIn by animateFloatAsState(
+                targetValue = if (handlesShown) 1f else 0f,
+                animationSpec = MaterialTheme.motionScheme.fastSpatialSpec(),
+                label = "handles",
+            )
+            val handleAlpha = Modifier.graphicsLayer {
+                alpha = handleIn.coerceIn(0f, 1f)
+                scaleX = 0.5f + 0.5f * handleIn
+                scaleY = 0.5f + 0.5f * handleIn
+            }
             if (!cuts.top) {
                 ResizeHandle(
                     color = accent,