Open native file dialog inside sandbox when opening directories

Flatpak FileChooser portal doesn't support opening and exporting
directories to the sandbox as it's not technically possible. Files are
simply exported through document-portal, but directories are a different
story. We have to, in case we want to open a directory, use native file
dialog provided by platform theme we have loaded into flatpak platform
theme. Applications which need to open directories to be able to work,
like IDEs, music players, will have enabled access ho host's filesystem
anyway so it's fine to open a file dialog inside sandbox.

[ChangeLog][Linux] QFileDialog will use the native dialogs provided by
the platform theme instead of trying to use Flatpak portal to select
directories.

Change-Id: I0716193bb9878aa621b8ca88506f87c72f690887
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/plugins/platformthemes/flatpak/qflatpakfiledialog.cpp

@@ -101,6 +101,10 @@ const QDBusArgument &operator >>(const QDBusArgument &arg, QFlatpakFileDialog::F
 class QFlatpakFileDialogPrivate
 {
 public:
+    QFlatpakFileDialogPrivate(QPlatformFileDialogHelper *nativeFileDialog)
+        : nativeFileDialog(nativeFileDialog)
+    { }
+
     WId winId = 0;
     bool modal = false;
     bool multipleFiles = false;
@@ -111,12 +115,19 @@ public:
     QStringList nameFilters;
     QStringList mimeTypesFilters;
     QStringList selectedFiles;
+    QPlatformFileDialogHelper *nativeFileDialog = nullptr;
 };
 
-QFlatpakFileDialog::QFlatpakFileDialog()
+QFlatpakFileDialog::QFlatpakFileDialog(QPlatformFileDialogHelper *nativeFileDialog)
     : QPlatformFileDialogHelper()
-    , d_ptr(new QFlatpakFileDialogPrivate)
+    , d_ptr(new QFlatpakFileDialogPrivate(nativeFileDialog))
 {
+    Q_D(QFlatpakFileDialog);
+
+    if (d->nativeFileDialog) {
+        connect(d->nativeFileDialog, SIGNAL(accept()), this, SIGNAL(accept()));
+        connect(d->nativeFileDialog, SIGNAL(reject()), this, SIGNAL(reject()));
+    }
 }
 
 QFlatpakFileDialog::~QFlatpakFileDialog()
@@ -127,6 +138,9 @@ void QFlatpakFileDialog::initializeDialog()
 {
     Q_D(QFlatpakFileDialog);
 
+    if (d->nativeFileDialog)
+        d->nativeFileDialog->setOptions(options());
+
     if (options()->fileMode() == QFileDialogOptions::ExistingFiles)
         d->multipleFiles = true;
 
@@ -265,6 +279,9 @@ void QFlatpakFileDialog::setDirectory(const QUrl &directory)
 {
     Q_D(QFlatpakFileDialog);
 
+    if (d->nativeFileDialog)
+        d->nativeFileDialog->setDirectory(directory);
+
     d->directory = directory.path();
 }
 
@@ -272,6 +289,9 @@ QUrl QFlatpakFileDialog::directory() const
 {
     Q_D(const QFlatpakFileDialog);
 
+    if (d->nativeFileDialog && options()->fileMode() == QFileDialogOptions::Directory)
+        return d->nativeFileDialog->directory();
+
     return d->directory;
 }
 
@@ -279,6 +299,9 @@ void QFlatpakFileDialog::selectFile(const QUrl &filename)
 {
     Q_D(QFlatpakFileDialog);
 
+    if (d->nativeFileDialog)
+        d->nativeFileDialog->selectFile(filename);
+
     d->selectedFiles << filename.path();
 }
 
@@ -286,6 +309,9 @@ QList<QUrl> QFlatpakFileDialog::selectedFiles() const
 {
     Q_D(const QFlatpakFileDialog);
 
+    if (d->nativeFileDialog && options()->fileMode() == QFileDialogOptions::Directory)
+        return d->nativeFileDialog->selectedFiles();
+
     QList<QUrl> files;
     for (const QString &file : d->selectedFiles) {
         files << QUrl(file);
@@ -295,13 +321,18 @@ QList<QUrl> QFlatpakFileDialog::selectedFiles() const
 
 void QFlatpakFileDialog::setFilter()
 {
-    // TODO
+    Q_D(QFlatpakFileDialog);
+
+    if (d->nativeFileDialog)
+        d->nativeFileDialog->setFilter();
 }
 
 void QFlatpakFileDialog::selectNameFilter(const QString &filter)
 {
-    Q_UNUSED(filter);
-    // TODO
+    Q_D(QFlatpakFileDialog);
+
+    if (d->nativeFileDialog)
+        d->nativeFileDialog->selectNameFilter(filter);
 }
 
 QString QFlatpakFileDialog::selectedNameFilter() const
@@ -312,6 +343,13 @@ QString QFlatpakFileDialog::selectedNameFilter() const
 
 void QFlatpakFileDialog::exec()
 {
+    Q_D(QFlatpakFileDialog);
+
+    if (d->nativeFileDialog && options()->fileMode() == QFileDialogOptions::Directory) {
+        d->nativeFileDialog->exec();
+        return;
+    }
+
     // HACK we have to avoid returning until we emit that the dialog was accepted or rejected
     QEventLoop loop;
     loop.connect(this, SIGNAL(accept()), SLOT(quit()));
@@ -321,18 +359,24 @@ void QFlatpakFileDialog::exec()
 
 void QFlatpakFileDialog::hide()
 {
+    Q_D(QFlatpakFileDialog);
+
+    if (d->nativeFileDialog)
+        d->nativeFileDialog->hide();
 }
 
 bool QFlatpakFileDialog::show(Qt::WindowFlags windowFlags, Qt::WindowModality windowModality, QWindow *parent)
 {
     Q_D(QFlatpakFileDialog);
-    Q_UNUSED(windowFlags);
 
     initializeDialog();
 
     d->modal = windowModality != Qt::NonModal;
     d->winId = parent ? parent->winId() : 0;
 
+    if (d->nativeFileDialog && options()->fileMode() == QFileDialogOptions::Directory)
+        return d->nativeFileDialog->show(windowFlags, windowModality, parent);
+
     openPortal();
 
     return true;

src/plugins/platformthemes/flatpak/qflatpakfiledialog_p.h

@@ -69,7 +69,7 @@ public:
     };
     typedef QVector<Filter> FilterList;
 
-    QFlatpakFileDialog();
+    QFlatpakFileDialog(QPlatformFileDialogHelper *nativeFileDialog = nullptr);
     ~QFlatpakFileDialog();
 
     bool defaultNameFilterDisables() const override;

src/plugins/platformthemes/flatpak/qflatpaktheme.cpp

@@ -130,8 +130,12 @@ QPlatformDialogHelper* QFlatpakTheme::createPlatformDialogHelper(DialogType type
 {
     Q_D(const QFlatpakTheme);
 
-    if (type == FileDialog)
+    if (type == FileDialog) {
+        if (d->baseTheme->usePlatformNativeDialog(type))
+            return new QFlatpakFileDialog(static_cast<QPlatformFileDialogHelper*>(d->baseTheme->createPlatformDialogHelper(type)));
+
         return new QFlatpakFileDialog;
+    }
 
     return d->baseTheme->createPlatformDialogHelper(type);
 }