QFileSystemModel: Add options

Add Options flags similar to QFileDialog:

- DontWatch: Do not use file system watchers for simple
  use cases like line edit completion. This brings it
  closer to QDirModel, which then can be deprecated.

- DontResolveSymlinks: Similar to
  QFileDialog::DontResolveSymlinks.

- DontUseCustomDirectoryIcons: matching
  QFileIconProvider::DontUseCustomDirectoryIcons for
  convenience.

Task-number: QTBUG-76493
Change-Id: I09d3cb73ef902a700e6ebfba427e2d990fce4b4c
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

examples/widgets/itemviews/dirview/main.cpp

@@ -65,8 +65,10 @@ int main(int argc, char *argv[])
     parser.setApplicationDescription("Qt Dir View Example");
     parser.addHelpOption();
     parser.addVersionOption();
-    QCommandLineOption dontUseCustomDirectoryIconsOption("c", "Set QFileIconProvider::DontUseCustomDirectoryIcons");
+    QCommandLineOption dontUseCustomDirectoryIconsOption("c", "Set QFileSystemModel::DontUseCustomDirectoryIcons");
     parser.addOption(dontUseCustomDirectoryIconsOption);
+    QCommandLineOption dontWatchOption("w", "Set QFileSystemModel::DontWatch");
+    parser.addOption(dontWatchOption);
     parser.addPositionalArgument("directory", "The directory to start in.");
     parser.process(app);
     const QString rootPath = parser.positionalArguments().isEmpty()
@@ -75,7 +77,9 @@ int main(int argc, char *argv[])
     QFileSystemModel model;
     model.setRootPath("");
     if (parser.isSet(dontUseCustomDirectoryIconsOption))
-        model.iconProvider()->setOptions(QFileIconProvider::DontUseCustomDirectoryIcons);
+        model.setOption(QFileSystemModel::DontUseCustomDirectoryIcons);
+    if (parser.isSet(dontWatchOption))
+        model.setOption(QFileSystemModel::DontWatch);
     QTreeView tree;
     tree.setModel(&model);
     if (!rootPath.isEmpty()) {

src/widgets/dialogs/qfilesystemmodel.cpp

@@ -1263,6 +1263,107 @@ Qt::DropActions QFileSystemModel::supportedDropActions() const
     return Qt::CopyAction | Qt::MoveAction | Qt::LinkAction;
 }
 
+/*!
+    \enum QFileSystemModel::Option
+    \since 5.14
+
+    \value DontWatch Do not add file watchers to the paths.
+    This reduces overhead when using the model for simple tasks
+    like line edit completion.
+
+    \value DontResolveSymlinks Don't resolve symlinks in the file
+    system model. By default, symlinks are resolved.
+
+    \value DontUseCustomDirectoryIcons Always use the default directory icon.
+    Some platforms allow the user to set a different icon. Custom icon lookup
+    causes a big performance impact over network or removable drives.
+    This sets the QFileIconProvider::DontUseCustomDirectoryIcons
+    option in the icon provider accordingly.
+
+    \sa resolveSymlinks
+*/
+
+/*!
+    \since 5.14
+    Sets the given \a option to be enabled if \a on is true; otherwise,
+    clears the given \a option.
+
+    Options should be set before changing properties.
+
+    \sa options, testOption()
+*/
+void QFileSystemModel::setOption(Option option, bool on)
+{
+    QFileSystemModel::Options previousOptions = options();
+    setOptions(previousOptions.setFlag(option, on));
+}
+
+/*!
+    \since 5.14
+
+    Returns \c true if the given \a option is enabled; otherwise, returns
+    false.
+
+    \sa options, setOption()
+*/
+bool QFileSystemModel::testOption(Option option) const
+{
+    return options().testFlag(option);
+}
+
+/*!
+    \property QFileSystemModel::options
+    \brief the various options that affect the model
+    \since 5.14
+
+    By default, all options are disabled.
+
+    Options should be set before changing properties.
+
+    \sa setOption(), testOption()
+*/
+void QFileSystemModel::setOptions(Options options)
+{
+    const Options changed = (options ^ QFileSystemModel::options());
+
+    if (changed.testFlag(DontResolveSymlinks))
+        setResolveSymlinks(!options.testFlag(DontResolveSymlinks));
+
+#if QT_CONFIG(filesystemwatcher)
+    Q_D(QFileSystemModel);
+    if (changed.testFlag(DontWatch))
+        d->fileInfoGatherer.setWatching(!options.testFlag(DontWatch));
+#endif
+
+    if (changed.testFlag(DontUseCustomDirectoryIcons)) {
+        if (auto provider = iconProvider()) {
+            QFileIconProvider::Options providerOptions = provider->options();
+            providerOptions.setFlag(QFileIconProvider::DontUseCustomDirectoryIcons,
+                                    options.testFlag(QFileSystemModel::DontUseCustomDirectoryIcons));
+            provider->setOptions(providerOptions);
+        } else {
+            qWarning("Setting QFileSystemModel::DontUseCustomDirectoryIcons has no effect when no provider is used");
+        }
+    }
+}
+
+QFileSystemModel::Options QFileSystemModel::options() const
+{
+    QFileSystemModel::Options result;
+    result.setFlag(DontResolveSymlinks, !resolveSymlinks());
+#if QT_CONFIG(filesystemwatcher)
+    Q_D(const QFileSystemModel);
+    result.setFlag(DontWatch, !d->fileInfoGatherer.isWatching());
+#else
+    result.setFlag(DontWatch);
+#endif
+    if (auto provider = iconProvider()) {
+        result.setFlag(DontUseCustomDirectoryIcons,
+                       provider->options().testFlag(QFileIconProvider::DontUseCustomDirectoryIcons));
+    }
+    return result;
+}
+
 /*!
     Returns the path of the item stored in the model under the
     \a index given.
@@ -1509,6 +1610,8 @@ QDir::Filters QFileSystemModel::filter() const
     This is only relevant on Windows.
 
     By default, this property is \c true.
+
+    \sa QFileSystemModel::Options
 */
 void QFileSystemModel::setResolveSymlinks(bool enable)
 {

src/widgets/dialogs/qfilesystemmodel.h

@@ -61,6 +61,7 @@ class Q_WIDGETS_EXPORT QFileSystemModel : public QAbstractItemModel
     Q_PROPERTY(bool resolveSymlinks READ resolveSymlinks WRITE setResolveSymlinks)
     Q_PROPERTY(bool readOnly READ isReadOnly WRITE setReadOnly)
     Q_PROPERTY(bool nameFilterDisables READ nameFilterDisables WRITE setNameFilterDisables)
+    Q_PROPERTY(Options options READ options WRITE setOptions)
 
 Q_SIGNALS:
     void rootPathChanged(const QString &newPath);
@@ -75,6 +76,15 @@ public:
         FilePermissions = Qt::UserRole + 3
     };
 
+    enum Option
+    {
+        DontWatch                   = 0x00000001,
+        DontResolveSymlinks         = 0x00000002,
+        DontUseCustomDirectoryIcons = 0x00000004
+    };
+    Q_ENUM(Option)
+    Q_DECLARE_FLAGS(Options, Option)
+
     explicit QFileSystemModel(QObject *parent = nullptr);
     ~QFileSystemModel();
 
@@ -129,6 +139,11 @@ public:
     void setNameFilters(const QStringList &filters);
     QStringList nameFilters() const;
 
+    void setOption(Option option, bool on = true);
+    bool testOption(Option option) const;
+    void setOptions(Options options);
+    Options options() const;
+
     QString filePath(const QModelIndex &index) const;
     bool isDir(const QModelIndex &index) const;
     qint64 size(const QModelIndex &index) const;
@@ -165,6 +180,8 @@ inline QString QFileSystemModel::fileName(const QModelIndex &aindex) const
 inline QIcon QFileSystemModel::fileIcon(const QModelIndex &aindex) const
 { return qvariant_cast<QIcon>(aindex.data(Qt::DecorationRole)); }
 
+Q_DECLARE_OPERATORS_FOR_FLAGS(QFileSystemModel::Options)
+
 QT_END_NAMESPACE
 
 #endif // QFILESYSTEMMODEL_H