From 67ed2ef4783427db5ed312c4ba0d8a5dd30d22fe Mon Sep 17 00:00:00 2001
From: Hojun-Cho <ghwns6743@gmail.com>
Date: Sat, 15 Aug 2026 15:07:13 +0900
Subject: [PATCH] fix(engine): redraw only for visible caret changes

---
 strans.c            | 15 ++++++++++++---
 tests/engine_test.c | 32 ++++++++++++++++++++++++++++----
 2 files changed, 40 insertions(+), 7 deletions(-)

diff --git a/strans.c b/strans.c
index 222f8cd..872c3e9 100644
--- a/strans.c
+++ b/strans.c
@@ -925,6 +925,13 @@ setactivecap(int cap)
 	return old != (activecap & Cclientpreedit);
 }
 
+static int
+careteq(Caret *a, Caret *b)
+{
+	return a->valid == b->valid && a->x == b->x && a->y == b->y &&
+		a->h == b->h;
+}
+
 static void
 imhandlekey(Keyreq *kr)
 {
@@ -952,9 +959,10 @@ imhandlekey(Keyreq *kr)
 		}
 		break;
 	case Keycaret:
-		if(kr->owner == activeowner){
+		if(kr->owner == activeowner && !careteq(&caret, &kr->caret)){
 			caret = kr->caret;
-			redraw();
+			if(visible)
+				redraw();
 		}
 		break;
 	case Keycap:
@@ -978,7 +986,8 @@ imhandlekey(Keyreq *kr)
 				activecap = kr->cap & Cclientpreedit;
 				caret = kr->caret;
 				changed = 1;
-			}else if(kr->caret.valid){
+			}else if(kr->caret.valid &&
+			   !careteq(&caret, &kr->caret)){
 				caret = kr->caret;
 				changed = 1;
 			}
diff --git a/tests/engine_test.c b/tests/engine_test.c
index aacc0d9..25f878e 100644
--- a/tests/engine_test.c
+++ b/tests/engine_test.c
@@ -370,6 +370,7 @@ void
 engine_active_owner_caret(struct ct *t)
 {
 	Caret a, moved;
+	Drawcmd dc;
 	char one, two;
 
 	memset(&a, 0, sizeof a);
@@ -380,14 +381,37 @@ engine_active_owner_caret(struct ct *t)
 	moved = a;
 	moved.x = 80;
 	init();
-	im.l = getlang(LangJP);
-	ownerrequestat(&one, Keypress, 'k', 0, &a);
+	draindraw(nil);
+	im.l = getlang(LangEN);
+	ownerrequestat(&one, Keypress, 'x', 0, &a);
 	CT_CHECK(t, caret.valid);
 	CT_EQ_INT(t, 10, caret.x);
-	ownerrequestat(&two, Keycaret, 0, 0, &moved);
-	CT_EQ_INT(t, 10, caret.x);
 	ownerrequestat(&one, Keycaret, 0, 0, &moved);
 	CT_EQ_INT(t, 80, caret.x);
+	CT_EQ_INT(t, 0, draindraw(nil));
+	im.kouho[0] = mkstr("candidate");
+	im.nkouho = 1;
+	im.sel = 0;
+	redraw();
+	if(CT_CHECK(t, draindraw(&dc) > 0))
+		CT_EQ_INT(t, 80, dc.caret.x);
+	moved.x = 90;
+	ownerrequestat(&two, Keycaret, 0, 0, &moved);
+	CT_EQ_INT(t, 80, caret.x);
+	CT_EQ_INT(t, 0, draindraw(nil));
+	ownerrequestat(&one, Keycaret, 0, 0, &moved);
+	CT_EQ_INT(t, 90, caret.x);
+	if(CT_CHECK(t, draindraw(&dc) > 0))
+		CT_EQ_INT(t, 90, dc.caret.x);
+	ownerrequestat(&one, Keycaret, 0, 0, &moved);
+	CT_EQ_INT(t, 0, draindraw(nil));
+	ownerrequestat(&one, Keypress, 'x', 0, &moved);
+	CT_EQ_INT(t, 0, draindraw(nil));
+	moved.x = 100;
+	ownerrequestat(&one, Keypress, 'x', 0, &moved);
+	CT_EQ_INT(t, 100, caret.x);
+	if(CT_CHECK(t, draindraw(&dc) > 0))
+		CT_EQ_INT(t, 100, dc.caret.x);
 	ownerrequest(&two, Keypress, 'n', 0);
 	CT_EQ_PTR(t, &two, activeowner);
 	CT_CHECK(t, !caret.valid);