Improve mime type filters in QFileDialog

This patch improves the handling of mime type filters in QFileDialog.

The main change is in selectMimeTypeFilter(), which was just falling back
unconditionally on selectNameFilter(). Instead, mime type filters should
have an higher priority than name filters.

This patch also adds a new selectedMimeTypeFilter() method, which is used in the unit test.

Change-Id: Ice8bb08f5ff46e4a942d539f6001424eca878f74
Reviewed-by: David Faure <david.faure@kdab.com>

5 files changed, 69 insertions, 3 deletions

diff --git a/src/gui/kernel/qplatformdialoghelper.cpp b/src/gui/kernel/qplatformdialoghelper.cpp
index c36186b815..16f31db50d 100644
--- a/src/gui/kernel/qplatformdialoghelper.cpp
+++ b/src/gui/kernel/qplatformdialoghelper.cpp
@@ -451,6 +451,7 @@ public:
     QString defaultSuffix;
     QStringList history;
     QUrl initialDirectory;
+    QString initiallySelectedMimeTypeFilter;
     QString initiallySelectedNameFilter;
     QList<QUrl> initiallySelectedFiles;
     QStringList supportedSchemes;
@@ -668,6 +669,16 @@ void QFileDialogOptions::setInitialDirectory(const QUrl &directory)
     d->initialDirectory = directory;
 }
 
+QString QFileDialogOptions::initiallySelectedMimeTypeFilter() const
+{
+    return d->initiallySelectedMimeTypeFilter;
+}
+
+void QFileDialogOptions::setInitiallySelectedMimeTypeFilter(const QString &filter)
+{
+    d->initiallySelectedMimeTypeFilter = filter;
+}
+
 QString QFileDialogOptions::initiallySelectedNameFilter() const
 {
     return d->initiallySelectedNameFilter;
@@ -699,6 +710,16 @@ QStringList QFileDialogOptions::supportedSchemes() const
     return d->supportedSchemes;
 }
 
+void QPlatformFileDialogHelper::selectMimeTypeFilter(const QString &filter)
+{
+    Q_UNUSED(filter)
+}
+
+QString QPlatformFileDialogHelper::selectedMimeTypeFilter() const
+{
+    return QString();
+}
+
 // Return true if the URL is supported by the filedialog implementation *and* by the application.
 bool QPlatformFileDialogHelper::isSupportedUrl(const QUrl &url) const
 {
diff --git a/src/gui/kernel/qplatformdialoghelper.h b/src/gui/kernel/qplatformdialoghelper.h
index 6caef070e2..ed88c19c84 100644
--- a/src/gui/kernel/qplatformdialoghelper.h
+++ b/src/gui/kernel/qplatformdialoghelper.h
@@ -372,6 +372,9 @@ public:
     QUrl initialDirectory() const;
     void setInitialDirectory(const QUrl &);
 
+    QString initiallySelectedMimeTypeFilter() const;
+    void setInitiallySelectedMimeTypeFilter(const QString &);
+
     QString initiallySelectedNameFilter() const;
     void setInitiallySelectedNameFilter(const QString &);
 
@@ -397,7 +400,9 @@ public:
     virtual void selectFile(const QUrl &filename) = 0;
     virtual QList<QUrl> selectedFiles() const = 0;
     virtual void setFilter() = 0;
+    virtual void selectMimeTypeFilter(const QString &filter);
     virtual void selectNameFilter(const QString &filter) = 0;
+    virtual QString selectedMimeTypeFilter() const;
     virtual QString selectedNameFilter() const = 0;
 
     virtual bool isSupportedUrl(const QUrl &url) const;
diff --git a/src/widgets/dialogs/qfiledialog.cpp b/src/widgets/dialogs/qfiledialog.cpp
index 8058dee567..5bfb7553a5 100644
--- a/src/widgets/dialogs/qfiledialog.cpp
+++ b/src/widgets/dialogs/qfiledialog.cpp
@@ -1461,6 +1461,19 @@ void QFileDialog::selectNameFilter(const QString &filter)
 }
 
 /*!
+ * \since 5.9
+ * \return The mimetype of the file that the user selected in the file dialog.
+ */
+QString QFileDialog::selectedMimeTypeFilter() const
+{
+    Q_D(const QFileDialog);
+    if (!d->usingWidgets())
+        return d->selectedMimeTypeFilter_sys();
+
+    return d->options->initiallySelectedMimeTypeFilter();
+}
+
+/*!
     \since 4.4
 
     Returns the filter that the user selected in the file dialog.
@@ -1579,9 +1592,19 @@ QStringList QFileDialog::mimeTypeFilters() const
 */
 void QFileDialog::selectMimeTypeFilter(const QString &filter)
 {
-    const QString text = nameFilterForMime(filter);
-    if (!text.isEmpty())
-        selectNameFilter(text);
+    Q_D(QFileDialog);
+    d->options->setInitiallySelectedMimeTypeFilter(filter);
+
+    const QString filterForMime = nameFilterForMime(filter);
+
+    if (!d->usingWidgets()) {
+        d->selectMimeTypeFilter_sys(filter);
+        if (d->selectedMimeTypeFilter_sys().isEmpty() && !filterForMime.isEmpty()) {
+            selectNameFilter(filterForMime);
+        }
+    } else if (!filterForMime.isEmpty()) {
+        selectNameFilter(filterForMime);
+    }
 }
 
 #endif // QT_NO_MIMETYPE
diff --git a/src/widgets/dialogs/qfiledialog.h b/src/widgets/dialogs/qfiledialog.h
index c2ab0b3918..7959eebd7b 100644
--- a/src/widgets/dialogs/qfiledialog.h
+++ b/src/widgets/dialogs/qfiledialog.h
@@ -125,6 +125,7 @@ public:
     void setNameFilters(const QStringList &filters);
     QStringList nameFilters() const;
     void selectNameFilter(const QString &filter);
+    QString selectedMimeTypeFilter() const;
     QString selectedNameFilter() const;
 
 #ifndef QT_NO_MIMETYPE
diff --git a/src/widgets/dialogs/qfiledialog_p.h b/src/widgets/dialogs/qfiledialog_p.h
index afebad4457..b665b54a9b 100644
--- a/src/widgets/dialogs/qfiledialog_p.h
+++ b/src/widgets/dialogs/qfiledialog_p.h
@@ -258,6 +258,8 @@ public:
     void selectFile_sys(const QUrl &filename);
     QList<QUrl> selectedFiles_sys() const;
     void setFilter_sys();
+    void selectMimeTypeFilter_sys(const QString &filter);
+    QString selectedMimeTypeFilter_sys() const;
     void selectNameFilter_sys(const QString &filter);
     QString selectedNameFilter_sys() const;
     //////////////////////////////////////////////
@@ -400,6 +402,20 @@ inline void QFileDialogPrivate::setFilter_sys()
         helper->setFilter();
 }
 
+inline void QFileDialogPrivate::selectMimeTypeFilter_sys(const QString &filter)
+{
+    if (QPlatformFileDialogHelper *helper = platformFileDialogHelper())
+        helper->selectMimeTypeFilter(filter);
+}
+
+QString QFileDialogPrivate::selectedMimeTypeFilter_sys() const
+{
+    if (QPlatformFileDialogHelper *helper = platformFileDialogHelper())
+        return helper->selectedMimeTypeFilter();
+
+    return QString();
+}
+
 inline void QFileDialogPrivate::selectNameFilter_sys(const QString &filter)
 {
     if (QPlatformFileDialogHelper *helper = platformFileDialogHelper())