Qt Designer/calculatorbuilder example: Remove the form class and its autoconnected slots

The autoconnection feature is considered error-prone and is warned
about by clazy. As this removes the need for a class, remove it entirely
and use a lambda for the slot.

As a drive-by, fix the documentation of the project files.

Task-number: QTBUG-110447
Change-Id: Idf78b58445a3f89399f7ae09065f145428ef83fe
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>
(cherry picked from commit 0e5a54f96dda1ea72fdc43026e3d9bb74886c61e)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

1 files changed, 56 insertions, 3 deletions

diff --git a/examples/designer/calculatorbuilder/main.cpp b/examples/designer/calculatorbuilder/main.cpp
index 54f091438..cfc146091 100644
--- a/examples/designer/calculatorbuilder/main.cpp
+++ b/examples/designer/calculatorbuilder/main.cpp
@@ -1,16 +1,69 @@
 // Copyright (C) 2016 The Qt Company Ltd.
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
 
-#include "calculatorform.h"
+//! [0]
+#include <QtUiTools>
+//! [0]
 
 #include <QApplication>
+#include <QLabel>
+#include <QSpinBox>
+#include <QVBoxLayout>
+
+#include <QFile>
+
+#include <memory>
+
+using namespace Qt::StringLiterals;
+
+//! [1]
+static QWidget *loadCalculatorForm(QWidget *parent = nullptr)
+{
+    QUiLoader loader;
+
+    QFile file(u":/forms/calculatorform.ui"_s);
+    if (!file.open(QFile::ReadOnly))
+        return nullptr;
+    QWidget *formWidget = loader.load(&file, parent);
+    file.close();
+    if (formWidget == nullptr)
+        return nullptr;
+//! [1]
+
+//! [2]
+    auto *inputSpinBox1 = formWidget->findChild<QSpinBox*>(u"inputSpinBox1"_s);
+    auto *inputSpinBox2 = formWidget->findChild<QSpinBox*>(u"inputSpinBox2"_s);
+    auto *outputWidget = formWidget->findChild<QLabel*>(u"outputWidget"_s);
+//! [2]
+
+//! [3]
+    auto updateResult = [inputSpinBox1, inputSpinBox2, outputWidget]()
+    {
+        const int sum = inputSpinBox1->value() + inputSpinBox2->value();
+        outputWidget->setText(QString::number(sum));
+    };
+    QObject::connect(inputSpinBox1, &QSpinBox::valueChanged, formWidget, updateResult);
+    QObject::connect(inputSpinBox2, &QSpinBox::valueChanged, formWidget, updateResult);
+//! [3]
+
+    return formWidget;
+}
 
 int main(int argc, char *argv[])
 {
     Q_INIT_RESOURCE(calculatorbuilder);
 
     QApplication app(argc, argv);
-    CalculatorForm calculator;
-    calculator.show();
+    QWidget w;
+    auto *formWidget = loadCalculatorForm(&w);
+    if (formWidget == nullptr)
+        return -1;
+    //! [4]
+    auto *layout = new QVBoxLayout(&w);
+    layout->addWidget(formWidget);
+    w.setWindowTitle(QCoreApplication::translate("CalculatorForm",
+                                                 "Calculator Builder"));
+    //! [4]
+    w.show();
     return app.exec();
 }