From 15878ac37792aae56065cf878c97710469d15a42 Mon Sep 17 00:00:00 2001
From: David Schulz <david.schulz@qt.io>
Date: Fri, 28 Feb 2025 15:04:35 +0100
Subject: [PATCH] Editor: optimize clearing layouts after edit width change

Change-Id: Ic3f700c48f05e2d231021379a5e154b23c2d1858
Reviewed-by: Christian Stenger <christian.stenger@qt.io>
---
 src/libs/utils/plaintextedit/plaintextedit.cpp | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/libs/utils/plaintextedit/plaintextedit.cpp b/src/libs/utils/plaintextedit/plaintextedit.cpp
index a4e21243299..e7b8e510df4 100644
--- a/src/libs/utils/plaintextedit/plaintextedit.cpp
+++ b/src/libs/utils/plaintextedit/plaintextedit.cpp
@@ -337,7 +337,17 @@ void PlainTextDocumentLayout::requestUpdate()
 void PlainTextDocumentLayout::setTextWidth(qreal newWidth)
 {
     d->width = d->maximumWidth = newWidth;
-    d->relayout();
+    bool layoutChanged = false;
+    for (QTextBlock block = document()->firstBlock(); block.isValid(); block = block.next()) {
+        QTextLayout *tl = block.layout();
+        if (tl->lineCount() == 0 || (tl->lineCount() == 1 && tl->lineAt(0).naturalTextWidth() < newWidth))
+            continue;
+        layoutChanged = true;
+        tl->clearLayout();
+        block.setLineCount(block.isVisible() ? 1 : 0);
+    }
+    if (layoutChanged)
+        emit update();
 }
 
 qreal PlainTextDocumentLayout::textWidth() const