From 9ecf47a8a8d11227ecf192246d7df7c2c4dc9105 Mon Sep 17 00:00:00 2001
From: Christian Ehrlicher <ch.ehrlicher@gmx.de>
Date: Tue, 19 Dec 2023 09:41:01 +0100
Subject: Add QPainterStateGuard

Add QPainterStateGuard as a small RAII helper class to avoid unbalanced
QPainter::save()/restore() calls.

Change-Id: I618a5d720b7bc9267a0fbac7dcc90e61f5d9cefd
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: David Faure <david.faure@kdab.com>
---
 .../code/src_gui_painting_qpainterstateguard.cpp   | 54 ++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 src/gui/doc/snippets/code/src_gui_painting_qpainterstateguard.cpp

(limited to 'src/gui/doc/snippets/code')

diff --git a/src/gui/doc/snippets/code/src_gui_painting_qpainterstateguard.cpp b/src/gui/doc/snippets/code/src_gui_painting_qpainterstateguard.cpp
new file mode 100644
index 00000000000..adcccd60aa1
--- /dev/null
+++ b/src/gui/doc/snippets/code/src_gui_painting_qpainterstateguard.cpp
@@ -0,0 +1,54 @@
+// Copyright (C) 2024 Christian Ehrlicher <ch.ehrlicher@gmx.de>
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
+#include <QPaintEvent>
+#include <QPainter>
+#include <QPainterStateGuard>
+#include <QWidget>
+
+
+namespace src_gui_painting_qpainterstateguard {
+struct MyWidget : public QWidget
+{
+    void paintEvent(QPaintEvent *) override;
+    bool drawText = true;
+    QLine line;
+};
+struct MyGuardWidget : public QWidget
+{
+    void paintEvent(QPaintEvent *) override;
+    bool drawText = true;
+    QLine line;
+};
+
+//! [0]
+void MyWidget::paintEvent(QPaintEvent *)
+{
+    QPainter painter(this);
+    painter.setPen(Qt::red);
+    if (drawText) {
+        painter.save();
+        painter.setPen(Qt::blue);
+        painter.setFont(QFont("Arial", 30));
+        painter.drawText(rect(), Qt::AlignCenter, "Qt");
+        painter.restore();  // don't forget to restore previous painter state
+    }
+    painter.drawLine(line);
+}
+//! [0]
+
+//! [1]
+void MyGuardWidget::paintEvent(QPaintEvent *)
+{
+    QPainter painter(this);
+    painter.setPen(Qt::red);
+    if (drawText) {
+        QPainterStateGuard guard(&painter)
+        painter.setPen(Qt::blue);
+        painter.setFont(QFont("Arial", 30));
+        painter.drawText(rect(), Qt::AlignCenter, "Qt");
+    }
+    painter.drawLine(line);
+}
+//! [1]
+
+} // src_gui_painting_qpainterstateguard
-- 
cgit v1.2.3