From 392b9df2ebc0f344f487bc9e7f3e5b9affd19ca3 Mon Sep 17 00:00:00 2001
From: Dean Lee <deanlee3@gmail.com>
Date: Wed, 8 Mar 2023 02:08:33 +0800
Subject: [PATCH] cabana: improve the performance of updating TreeView in
 real-time. (#27517)

old-commit-hash: ddcafeb7dcac709dbd517e619fe3807cfc898198
---
 tools/cabana/signaledit.cc | 18 ++++++++++++------
 tools/cabana/signaledit.h  |  1 +
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/tools/cabana/signaledit.cc b/tools/cabana/signaledit.cc
index e425a13f82..5684edf95a 100644
--- a/tools/cabana/signaledit.cc
+++ b/tools/cabana/signaledit.cc
@@ -1,7 +1,7 @@
 #include "tools/cabana/signaledit.h"
 
+#include <QApplication>
 #include <QDialogButtonBox>
-#include <QGuiApplication>
 #include <QHBoxLayout>
 #include <QHeaderView>
 #include <QMessageBox>
@@ -304,11 +304,17 @@ SignalItemDelegate::SignalItemDelegate(QObject *parent) : QStyledItemDelegate(pa
 }
 
 QSize SignalItemDelegate::sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const {
-  QSize size = QStyledItemDelegate::sizeHint(option, index);
-  if (index.column() == 0 && !index.parent().isValid()) {
-    size.rwidth() = std::min(option.widget->size().width() / 2, size.width() + color_label_width + 8);
+  int width = option.widget->size().width() / 2;
+  if (index.column() == 0) {
+    auto text = index.data(Qt::DisplayRole).toString();
+    auto it = width_cache.find(text);
+    if (it == width_cache.end()) {
+      int spacing = option.widget->style()->pixelMetric(QStyle::PM_TreeViewIndentation) + color_label_width + 8;
+      it = width_cache.insert(text, option.fontMetrics.width(text) + spacing);
+    }
+    width = std::min(width, it.value());
   }
-  return size;
+  return {width, QApplication::fontMetrics().height()};
 }
 
 void SignalItemDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const {
@@ -508,7 +514,7 @@ void SignalView::signalHovered(const Signal *sig) {
   for (int i = 0; i < children.size(); ++i) {
     bool highlight = children[i]->sig == sig;
     if (std::exchange(children[i]->highlight, highlight) != highlight) {
-      emit model->dataChanged(model->index(i, 0), model->index(i, 0));
+      emit model->dataChanged(model->index(i, 0), model->index(i, 0), {Qt::DecorationRole});
     }
   }
 }
diff --git a/tools/cabana/signaledit.h b/tools/cabana/signaledit.h
index 73a107f5c9..da3bc36c62 100644
--- a/tools/cabana/signaledit.h
+++ b/tools/cabana/signaledit.h
@@ -85,6 +85,7 @@ public:
   QValidator *name_validator, *double_validator;
   QFont small_font;
   const int color_label_width = 18;
+  mutable QHash<QString, int> width_cache;
 };
 
 class SignalView : public QFrame {