refactor: simplify event transition of UnrollButtonStateMachine

Author: WhiredPlanck

app/src/main/java/com/osfans/trime/ime/bar/InputBarDelegate.kt

@@ -174,14 +174,10 @@ class InputBarDelegate : InputBroadcastReceiver {
     val unrollButtonStateMachine =
         UnrollButtonStateMachine.new {
             when (it) {
-                UnrollButtonStateMachine.State.AboutToAttachWindow -> {
-                    setUnrollButtonToDetach()
-                    setUnrollButtonEnabled(true)
-                    windowManager.attachWindow(FlexboxUnrolledCandidateWindow())
-                }
                 UnrollButtonStateMachine.State.ClickToAttachWindow -> {
                     setUnrollButtonToAttach()
                     setUnrollButtonEnabled(true)
+                    setUnrollWindowToAttach()
                 }
                 UnrollButtonStateMachine.State.ClickToDetachWindow -> {
                     setUnrollButtonToDetach()
@@ -211,6 +207,14 @@ class InputBarDelegate : InputBroadcastReceiver {
         candidateUi.unrollButton.visibility = if (enabled) View.VISIBLE else View.INVISIBLE
     }
 
+    private fun setUnrollWindowToAttach() {
+        unrollButtonStateMachine.getBooleanState(
+            UnrollButtonStateMachine.BooleanKey.UnrolledCandidatesHighlighted,
+        )?.let {
+            windowManager.attachWindow(FlexboxUnrolledCandidateWindow())
+        }
+    }
+
     override fun onCandidateListUpdate(data: RimeMessage.CandidateListMessage.Data) {
         barStateMachine.push(
             QuickBarStateMachine.TransitionEvent.CandidatesUpdated,

app/src/main/java/com/osfans/trime/ime/bar/UnrollButtonStateMachine.kt

@@ -1,12 +1,12 @@
-// SPDX-FileCopyrightText: 2015 - 2024 Rime community
-//
-// SPDX-License-Identifier: GPL-3.0-or-later
+/*
+ * SPDX-FileCopyrightText: 2015 - 2026 Rime community
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
 
 package com.osfans.trime.ime.bar
 
 import com.osfans.trime.ime.bar.UnrollButtonStateMachine.BooleanKey.UnrolledCandidatesEmpty
 import com.osfans.trime.ime.bar.UnrollButtonStateMachine.BooleanKey.UnrolledCandidatesHighlighted
-import com.osfans.trime.ime.bar.UnrollButtonStateMachine.State.AboutToAttachWindow
 import com.osfans.trime.ime.bar.UnrollButtonStateMachine.State.ClickToAttachWindow
 import com.osfans.trime.ime.bar.UnrollButtonStateMachine.State.ClickToDetachWindow
 import com.osfans.trime.ime.bar.UnrollButtonStateMachine.State.Hidden
@@ -16,7 +16,6 @@ import com.osfans.trime.util.TransitionBuildBlock
 
 object UnrollButtonStateMachine {
     enum class State {
-        AboutToAttachWindow,
         ClickToAttachWindow,
         ClickToDetachWindow,
         Hidden,
@@ -33,11 +32,10 @@ object UnrollButtonStateMachine {
         UnrolledCandidatesUpdated({
             from(Hidden) transitTo ClickToAttachWindow on (UnrolledCandidatesEmpty to false)
             from(ClickToAttachWindow) transitTo Hidden on (UnrolledCandidatesEmpty to true)
-            from(ClickToAttachWindow) transitTo AboutToAttachWindow on (UnrolledCandidatesHighlighted to true)
+            from(ClickToAttachWindow) transitTo ClickToDetachWindow on (UnrolledCandidatesHighlighted to true)
         }),
         UnrolledCandidatesAttached({
             from(ClickToAttachWindow) transitTo ClickToDetachWindow
-            from(AboutToAttachWindow) transitTo ClickToDetachWindow
         }),
         UnrolledCandidatesDetached({
             from(ClickToDetachWindow) transitTo Hidden on (UnrolledCandidatesEmpty to true)