Polish the SimpleTextViewer example

- Port to Qt 5 connection syntax, fixing error in Qt 6
QObject::connect: No such signal QComboBox::currentIndexChanged(QString) in findfiledialog.cpp:194
- Remove unused functions and parameters to avoid QOverload
- Add process error handling

Change-Id: I923f44ce0eb27b7f73f9a0e16c11f48a80a0c03a
Reviewed-by: Kai Koehne <kai.koehne@qt.io>
(cherry picked from commit 153b75db83ca4d3db26829bd85271e7fa88b402c)

6 files changed, 57 insertions, 45 deletions

diff --git a/examples/assistant/simpletextviewer/assistant.cpp b/examples/assistant/simpletextviewer/assistant.cpp
index da29cea9e..ceda2c384 100644
--- a/examples/assistant/simpletextviewer/assistant.cpp
+++ b/examples/assistant/simpletextviewer/assistant.cpp
@@ -55,22 +55,20 @@
 #include <QDir>
 #include <QLibraryInfo>
 #include <QMessageBox>
-#include <QProcess>
 #include <QStandardPaths>
 
-Assistant::Assistant()
-    : proc(0)
-{
-}
+Assistant::Assistant() = default;
 
 //! [0]
 Assistant::~Assistant()
 {
-    if (proc && proc->state() == QProcess::Running) {
-        proc->terminate();
-        proc->waitForFinished(3000);
+    if (!m_process.isNull() && m_process->state() == QProcess::Running) {
+        QObject::disconnect(m_process.data(),
+                            QOverload<int, QProcess::ExitStatus>::of(&QProcess::finished),
+                            nullptr, nullptr);
+        m_process->terminate();
+        m_process->waitForFinished(3000);
     }
-    delete proc;
 }
 //! [0]
 
@@ -83,7 +81,7 @@ void Assistant::showDocumentation(const QString &page)
     QByteArray ba("SetSource ");
     ba.append("qthelp://org.qt-project.examples.simpletextviewer/doc/");
 
-    proc->write(ba + page.toLocal8Bit() + '\n');
+    m_process->write(ba + page.toLocal8Bit() + '\n');
 }
 //! [1]
 
@@ -107,12 +105,18 @@ QString documentationDirectory()
 //! [2]
 bool Assistant::startAssistant()
 {
-    if (!proc)
-        proc = new QProcess();
+    if (m_process.isNull()) {
+        m_process.reset(new QProcess());
+        QObject::connect(m_process.data(),
+                         QOverload<int, QProcess::ExitStatus>::of(&QProcess::finished),
+                         m_process.data(), [this](int exitCode, QProcess::ExitStatus status) {
+                             this->finished(exitCode, status);
+                         });
+    }
 
-    if (proc->state() != QProcess::Running) {
+    if (m_process->state() != QProcess::Running) {
         QString app = QLibraryInfo::location(QLibraryInfo::BinariesPath) + QDir::separator();
-#if !defined(Q_OS_MAC)
+#ifndef Q_OS_DARWIN
         app += QLatin1String("assistant");
 #else
         app += QLatin1String("Assistant.app/Contents/MacOS/Assistant");
@@ -128,10 +132,10 @@ bool Assistant::startAssistant()
                          collectionDirectory + QLatin1String("/simpletextviewer.qhc"),
                          QLatin1String("-enableRemoteControl")};
 
-        proc->start(app, args);
+        m_process->start(app, args);
 
-        if (!proc->waitForStarted()) {
-            showError(tr("Unable to launch Qt Assistant (%1): %2").arg(app, proc->errorString()));
+        if (!m_process->waitForStarted()) {
+            showError(tr("Unable to launch Qt Assistant (%1): %2").arg(app, m_process->errorString()));
             return false;
         }
     }
@@ -144,3 +148,13 @@ void Assistant::showError(const QString &message)
     QMessageBox::critical(QApplication::activeWindow(),
                           tr("Simple Text Viewer"), message);
 }
+
+void Assistant::finished(int exitCode, QProcess::ExitStatus status)
+{
+    const QString stdErr = QString::fromLocal8Bit(m_process->readAllStandardError());
+    if (status != QProcess::NormalExit) {
+        showError(tr("Assistant crashed: ").arg(stdErr));
+    } else if (exitCode != 0) {
+        showError(tr("Assistant exited with %1: %2").arg(exitCode).arg(stdErr));
+    }
+}
diff --git a/examples/assistant/simpletextviewer/assistant.h b/examples/assistant/simpletextviewer/assistant.h
index c9b8f382c..c513c3428 100644
--- a/examples/assistant/simpletextviewer/assistant.h
+++ b/examples/assistant/simpletextviewer/assistant.h
@@ -52,11 +52,10 @@
 #define ASSISTANT_H
 
 #include <QCoreApplication>
+#include <QProcess>
+#include <QScopedPointer>
 #include <QString>
 
-QT_BEGIN_NAMESPACE
-class QProcess;
-QT_END_NAMESPACE
 
 class Assistant
 {
@@ -70,7 +69,9 @@ public:
 private:
     bool startAssistant();
     void showError(const QString &message);
-    QProcess *proc;
+    void finished(int exitCode, QProcess::ExitStatus status);
+
+    QScopedPointer<QProcess> m_process;
 };
 
 #endif
diff --git a/examples/assistant/simpletextviewer/findfiledialog.cpp b/examples/assistant/simpletextviewer/findfiledialog.cpp
index bb47ae4fd..1eab5ad7f 100644
--- a/examples/assistant/simpletextviewer/findfiledialog.cpp
+++ b/examples/assistant/simpletextviewer/findfiledialog.cpp
@@ -105,13 +105,11 @@ void FindFileDialog::help()
 }
 //! [2]
 
-void FindFileDialog::openFile(QTreeWidgetItem *item)
+void FindFileDialog::openFile()
 {
-    if (!item) {
-        item = foundFilesTree->currentItem();
-        if (!item)
-            return;
-    }
+    auto item  = foundFilesTree->currentItem();
+    if (!item)
+        return;
 
     QString fileName = item->text(0);
     QString path = directoryComboBox->currentText() + QDir::separator();
@@ -161,14 +159,14 @@ void FindFileDialog::createButtons()
 {
     browseButton = new QToolButton;
     browseButton->setText(tr("..."));
-    connect(browseButton, SIGNAL(clicked()), this, SLOT(browse()));
+    connect(browseButton, &QAbstractButton::clicked, this, &FindFileDialog::browse);
 
     buttonBox = new QDialogButtonBox(QDialogButtonBox::Open
                                      | QDialogButtonBox::Cancel
                                      | QDialogButtonBox::Help);
-    connect(buttonBox, SIGNAL(accepted()), this, SLOT(openFile()));
-    connect(buttonBox, SIGNAL(rejected()), this, SLOT(reject()));
-    connect(buttonBox, SIGNAL(helpRequested()), this, SLOT(help()));
+    connect(buttonBox, &QDialogButtonBox::accepted, this, &FindFileDialog::openFile);
+    connect(buttonBox, &QDialogButtonBox::rejected, this, &QDialog::reject);
+    connect(buttonBox, &QDialogButtonBox::helpRequested, this, &FindFileDialog::help);
 }
 
 void FindFileDialog::createComboBoxes()
@@ -186,10 +184,10 @@ void FindFileDialog::createComboBoxes()
     directoryComboBox->setSizePolicy(QSizePolicy::Expanding,
                                      QSizePolicy::Preferred);
 
-    connect(fileNameComboBox, SIGNAL(editTextChanged(QString)),
-            this, SLOT(update()));
-    connect(directoryComboBox, SIGNAL(currentIndexChanged(QString)),
-            this, SLOT(update()));
+    connect(fileNameComboBox, &QComboBox::editTextChanged,
+            this, &FindFileDialog::update);
+    connect(directoryComboBox, &QComboBox::currentTextChanged,
+            this, &FindFileDialog::update);
 }
 
 void FindFileDialog::createFilesTree()
@@ -200,8 +198,8 @@ void FindFileDialog::createFilesTree()
     foundFilesTree->setRootIsDecorated(false);
     foundFilesTree->setSelectionMode(QAbstractItemView::SingleSelection);
 
-    connect(foundFilesTree, SIGNAL(itemActivated(QTreeWidgetItem*,int)),
-            this, SLOT(openFile(QTreeWidgetItem*)));
+    connect(foundFilesTree, &QTreeWidget::itemActivated,
+            this, &FindFileDialog::openFile);
 }
 
 void FindFileDialog::createLabels()
diff --git a/examples/assistant/simpletextviewer/findfiledialog.h b/examples/assistant/simpletextviewer/findfiledialog.h
index 6ca57b061..605da0954 100644
--- a/examples/assistant/simpletextviewer/findfiledialog.h
+++ b/examples/assistant/simpletextviewer/findfiledialog.h
@@ -76,7 +76,7 @@ public:
 private slots:
     void browse();
     void help();
-    void openFile(QTreeWidgetItem *item = nullptr);
+    void openFile();
     void update();
 
 private:
diff --git a/examples/assistant/simpletextviewer/mainwindow.cpp b/examples/assistant/simpletextviewer/mainwindow.cpp
index 5b0564ca1..f70162c21 100644
--- a/examples/assistant/simpletextviewer/mainwindow.cpp
+++ b/examples/assistant/simpletextviewer/mainwindow.cpp
@@ -112,26 +112,26 @@ void MainWindow::createActions()
 {
     assistantAct = new QAction(tr("Help Contents"), this);
     assistantAct->setShortcut(QKeySequence::HelpContents);
-    connect(assistantAct, SIGNAL(triggered()), this, SLOT(showDocumentation()));
+    connect(assistantAct, &QAction::triggered, this, &MainWindow::showDocumentation);
 //! [4]
 
     openAct = new QAction(tr("&Open..."), this);
     openAct->setShortcut(QKeySequence::Open);
-    connect(openAct, SIGNAL(triggered()), this, SLOT(open()));
+    connect(openAct, &QAction::triggered, this, &MainWindow::open);
 
     clearAct = new QAction(tr("&Clear"), this);
     clearAct->setShortcut(tr("Ctrl+C"));
-    connect(clearAct, SIGNAL(triggered()), textViewer, SLOT(clear()));
+    connect(clearAct, &QAction::triggered, textViewer, &QTextEdit::clear);
 
     exitAct = new QAction(tr("E&xit"), this);
     exitAct->setShortcuts(QKeySequence::Quit);
-    connect(exitAct, SIGNAL(triggered()), this, SLOT(close()));
+    connect(exitAct, &QAction::triggered, this, &QWidget::close);
 
     aboutAct = new QAction(tr("&About"), this);
-    connect(aboutAct, SIGNAL(triggered()), this, SLOT(about()));
+    connect(aboutAct, &QAction::triggered, this, &MainWindow::about);
 
     aboutQtAct = new QAction(tr("About &Qt"), this);
-    connect(aboutQtAct, SIGNAL(triggered()), qApp, SLOT(aboutQt()));
+    connect(aboutQtAct, &QAction::triggered, QApplication::aboutQt);
 //! [5]
 }
 //! [5]
diff --git a/examples/assistant/simpletextviewer/mainwindow.h b/examples/assistant/simpletextviewer/mainwindow.h
index e8e917ea3..1c7f21761 100644
--- a/examples/assistant/simpletextviewer/mainwindow.h
+++ b/examples/assistant/simpletextviewer/mainwindow.h
@@ -67,7 +67,6 @@ class MainWindow : public QMainWindow
 
 public:
     MainWindow();
-    void showDocumentation(const QString &file);
 
 private slots:
     void about();