Drag a selected event straight away and keep it selected (#141)

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

@@ -116,14 +116,18 @@ private fun rememberPickUpSurface(
     val currentDrop by rememberUpdatedState(onDrop)
     val currentCancel by rememberUpdatedState(onCancel)
     val currentRelease by rememberUpdatedState(onRelease)
+    // Read per gesture rather than keyed on: the pickup itself can change it,
+    // and a restart would cancel the drag it just began.
+    val currentImmediate by rememberUpdatedState(immediate)
 
     return Modifier
         .onGloballyPositioned { coordinates[0] = it }
-        .pointerInput(key, immediate) {
+        .pointerInput(key) {
             val slop = viewConfiguration.touchSlop
             awaitEachGesture {
                 val down = awaitFirstDown(requireUnconsumed = false)
                 val origin = down.position
+                val immediate = currentImmediate
                 // Null on the timeout — held still — true once an [immediate]
                 // block has been moved past slop, false when the press is
                 // abandoned.

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

@@ -401,9 +401,9 @@ class TimelineDragController {
         pointerInRoot: Offset,
         blockInRoot: Offset,
     ) {
-        // A pickup ends any selection: a drop moves the event out from under
-        // it, and a release without moving selects again.
-        selection = null
+        // Picking up another event ends the selection; the selected one keeps
+        // it through the drag, and the screen moves it along with the drop.
+        if (!isSelected(block)) selection = null
         source = block
         this.clipOffsetMin = clipOffsetMin
         this.titleLines = titleLines

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

@@ -519,6 +519,14 @@ private fun WeekContent(
     val move = LocalEventMove.current
     val zone = remember { TimeZone.currentSystemDefault() }
     val onDrop: (TimelineDrop) -> Unit = { drop ->
+        // A selected event stays selected where it landed (#141).
+        if (dragController.selection?.event?.instanceId == drop.event.instanceId) {
+            val start = drop.startInstant(zone)
+            dragController.select(
+                drop.event.copy(start = start, end = start + (drop.event.end - drop.event.start)),
+                start.toLocalDateTime(zone).date,
+            )
+        }
         move?.move(
             MoveRequest(
                 eventId = drop.event.eventId,