From fa52aab149ad074ecc66d1a9c7a5066779bea259 Mon Sep 17 00:00:00 2001
From: Kellermorph <thomas.heynk@web.de>
Date: Fri, 18 Sep 2026 11:13:26 +0200
Subject: [PATCH] Persist QColorDialog custom colors across application
 restarts

Qt's QColorDialog loads custom colors from QSettings on startup but
never writes them back, so user-defined colors in the color picker
are lost when the application exits.

Save and load the 16 custom color slots explicitly via QSettings
in QETApp's constructor (after initStyle) and destructor (before
other settings are flushed). This covers every QColorDialog usage
in the application transparently.

Also fixes a QColorDialog memory leak in DiagramView.
---
 sources/diagramview.cpp |  5 +++-
 sources/qet.cpp         | 55 +++++++++++++++++++++++++++++++++++++++++
 sources/qet.h           |  3 +++
 sources/qetapp.cpp      |  3 +++
 4 files changed, 65 insertions(+), 1 deletion(-)

diff --git a/sources/diagramview.cpp b/sources/diagramview.cpp
index 9e89be6cb..a0e662306 100644
--- a/sources/diagramview.cpp
+++ b/sources/diagramview.cpp
@@ -40,6 +40,7 @@
 #include "NameList/nameslist.h"
 #include "elementdialog.h"
 #include <QDropEvent>
+#include <QPointer>
 
 /**
 	Constructeur
@@ -122,7 +123,7 @@ DiagramView::DiagramView(Diagram *diagram, QWidget *parent) :
 		ConductorProperties initial_properties = edited_conductor->properties();
 
 			// prepare a color dialog showing the initial conductor color
-		QColorDialog *color_dialog = new QColorDialog(this);
+		QPointer<QColorDialog> color_dialog = new QColorDialog(this);
 		color_dialog->setWindowTitle(tr("Choisir la nouvelle couleur de ce conducteur"));
 #ifdef Q_OS_MACOS
 		color_dialog -> setWindowFlags(Qt::Sheet);
@@ -150,6 +151,8 @@ DiagramView::DiagramView(Diagram *diagram, QWidget *parent) :
 				LastUsedStyle::setConductorColor(new_color);
 			}
 		}
+		if (color_dialog)
+			delete color_dialog;
 	});
 }
 
diff --git a/sources/qet.cpp b/sources/qet.cpp
index bf4415e94..f253fc114 100644
--- a/sources/qet.cpp
+++ b/sources/qet.cpp
@@ -20,10 +20,13 @@
 #include "shortcutmanager.h"
 
 #include <limits>
+#include <QBuffer>
+#include <QColorDialog>
 #include <QGraphicsSceneContextMenuEvent>
 #include <QAction>
 #include <QFileInfo>
 #include <QSaveFile>
+#include <QSettings>
 #include <QTextStream>
 #include <QRegularExpression>
 #include <QActionGroup>
@@ -845,3 +848,55 @@ bool QET::writeToFile(QDomDocument &xml_doc, QFile *file, QString *error_message
 
 	return(true);
 }
+
+/**
+	@brief QET::saveCustomColors
+	Save the 16 QColorDialog custom colors to QSettings so they persist
+	across application restarts.
+*/
+void QET::saveCustomColors()
+{
+	QByteArray ba;
+	QBuffer buf(&ba);
+	buf.open(QIODevice::WriteOnly);
+	QDataStream s(&buf);
+	s.setVersion(QDataStream::Qt_6_0);
+	for (int i = 0; i < 16; i++)
+		s << QColorDialog::customColor(i);
+	QSettings settings;
+	settings.setValue(QStringLiteral("color/customColors"), ba);
+}
+
+/**
+	@brief QET::loadCustomColors
+	Load the 16 QColorDialog custom colors from QSettings into Qt's
+	internal custom color array.  A short or corrupt buffer is ignored
+	so that unread slots keep their default rather than turning black.
+*/
+void QET::loadCustomColors()
+{
+	QSettings settings;
+	QByteArray ba = settings.value(QStringLiteral("color/customColors")).toByteArray();
+
+	// Fall back to the legacy ungrouped key used by earlier versions.
+	if (ba.isEmpty())
+		ba = settings.value(QStringLiteral("customColors")).toByteArray();
+
+	if (ba.isEmpty())
+		return;
+
+	QBuffer buf(&ba);
+	buf.open(QIODevice::ReadOnly);
+	QDataStream s(&buf);
+	s.setVersion(QDataStream::Qt_6_0);
+
+	QColor colors[16];
+	for (int i = 0; i < 16; i++)
+		s >> colors[i];
+
+	if (s.status() != QDataStream::Ok)
+		return;
+
+	for (int i = 0; i < 16; i++)
+		QColorDialog::setCustomColor(i, colors[i]);
+}
diff --git a/sources/qet.h b/sources/qet.h
index 51e951d0f..da544ac13 100644
--- a/sources/qet.h
+++ b/sources/qet.h
@@ -18,6 +18,7 @@
 #ifndef _QET_H
 #define _QET_H
 
+#include <QColor>
 #include <QDomElement>
 #include <QFile>
 #include <QObject>
@@ -185,6 +186,8 @@ namespace QET {
 	bool writeToFile (QDomDocument &xml_doc, QFile *file, QString *error_message = nullptr);
 	bool eachStrIsEqual (const QStringList &qsl);
 	QActionGroup *depthActionGroup(QObject *parent = nullptr);
+	void saveCustomColors();
+	void loadCustomColors();
 }
 
 Q_DECLARE_METATYPE(QET::DepthOption)
diff --git a/sources/qetapp.cpp b/sources/qetapp.cpp
index 76c1203fc..02aff3a19 100644
--- a/sources/qetapp.cpp
+++ b/sources/qetapp.cpp
@@ -18,6 +18,7 @@
 #include "qetapp.h"
 
 #include "configdialog.h"
+#include "qet.h"
 #include "ui/configpage/configpages.h"
 #include "editor/ui/qetelementeditor.h"
 #include "elementscollectioncache.h"
@@ -124,6 +125,7 @@ QETApp::QETApp() :
 	QET::Icons::initIcons();
 	initFonts();
 	initStyle();
+	QET::loadCustomColors();
 	initSplashScreen();
 	initSystemTray();
 
@@ -168,6 +170,7 @@ QETApp::QETApp() :
 */
 QETApp::~QETApp()
 {
+	QET::saveCustomColors();
 	m_elements_recent_files->save();
 	m_projects_recent_files->save();