Fix FileDialog::selectedNameFilter review findings

FileDialog::nameFilters contains an array of name filter strings that
combine the name and extensions. For example:
 - "Text files (*.txt)"
 - "HTML files (*.html *.htm)"

When dealing with multiple name filters, it is quite clumsy to use
a string type of 'selectedNameFilter' which is one of the above full
file name filter string values. Make it possible to read/write the
index of the selected name filter, and provide the filter's name and
extensions separately.

Change-Id: Ie416cc4ab3dcde93c10769b6f7ac44915307f194
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

6 files changed, 242 insertions, 21 deletions

diff --git a/src/imports/platform/plugins.qmltypes b/src/imports/platform/plugins.qmltypes
index 2bee7276..01d8eb94 100644
--- a/src/imports/platform/plugins.qmltypes
+++ b/src/imports/platform/plugins.qmltypes
@@ -130,12 +130,36 @@ Module {
         Property { name: "folder"; type: "QUrl" }
         Property { name: "options"; type: "QFileDialogOptions::FileDialogOptions" }
         Property { name: "nameFilters"; type: "QStringList" }
-        Property { name: "selectedNameFilter"; type: "string" }
+        Property {
+            name: "selectedNameFilter"
+            type: "QQuickPlatformFileNameFilter"
+            isReadonly: true
+            isPointer: true
+        }
         Property { name: "defaultSuffix"; type: "string" }
         Property { name: "acceptLabel"; type: "string" }
         Property { name: "rejectLabel"; type: "string" }
     }
     Component {
+        name: "QQuickPlatformFileNameFilter"
+        prototype: "QObject"
+        Property { name: "index"; type: "int" }
+        Property { name: "name"; type: "string"; isReadonly: true }
+        Property { name: "extensions"; type: "QStringList"; isReadonly: true }
+        Signal {
+            name: "indexChanged"
+            Parameter { name: "index"; type: "int" }
+        }
+        Signal {
+            name: "nameChanged"
+            Parameter { name: "name"; type: "string" }
+        }
+        Signal {
+            name: "extensionsChanged"
+            Parameter { name: "extensions"; type: "QStringList" }
+        }
+    }
+    Component {
         name: "QQuickPlatformFolderDialog"
         defaultProperty: "data"
         prototype: "QQuickPlatformDialog"
diff --git a/src/imports/platform/qquickplatformdialog.cpp b/src/imports/platform/qquickplatformdialog.cpp
index dee4335d..95bc6426 100644
--- a/src/imports/platform/qquickplatformdialog.cpp
+++ b/src/imports/platform/qquickplatformdialog.cpp
@@ -283,6 +283,7 @@ void QQuickPlatformDialog::close()
     if (!m_handle || !m_visible)
         return;
 
+    onHide(m_handle);
     m_handle->hide();
     m_visible = false;
     emit visibleChanged();
@@ -385,6 +386,11 @@ void QQuickPlatformDialog::onShow(QPlatformDialogHelper *dialog)
     Q_UNUSED(dialog);
 }
 
+void QQuickPlatformDialog::onHide(QPlatformDialogHelper *dialog)
+{
+    Q_UNUSED(dialog);
+}
+
 QWindow *QQuickPlatformDialog::findParentWindow() const
 {
     QObject *obj = parent();
diff --git a/src/imports/platform/qquickplatformdialog_p.h b/src/imports/platform/qquickplatformdialog_p.h
index 2a5caee7..a9797c1d 100644
--- a/src/imports/platform/qquickplatformdialog_p.h
+++ b/src/imports/platform/qquickplatformdialog_p.h
@@ -129,6 +129,7 @@ protected:
     virtual bool useNativeDialog() const;
     virtual void onCreate(QPlatformDialogHelper *dialog);
     virtual void onShow(QPlatformDialogHelper *dialog);
+    virtual void onHide(QPlatformDialogHelper *dialog);
 
     QWindow *findParentWindow() const;
 
diff --git a/src/imports/platform/qquickplatformfiledialog.cpp b/src/imports/platform/qquickplatformfiledialog.cpp
index 9da774d4..6a0f4e13 100644
--- a/src/imports/platform/qquickplatformfiledialog.cpp
+++ b/src/imports/platform/qquickplatformfiledialog.cpp
@@ -36,6 +36,8 @@
 
 #include "qquickplatformfiledialog_p.h"
 
+#include <QtCore/qvector.h>
+
 QT_BEGIN_NAMESPACE
 
 /*!
@@ -97,7 +99,8 @@ QT_BEGIN_NAMESPACE
 QQuickPlatformFileDialog::QQuickPlatformFileDialog(QObject *parent)
     : QQuickPlatformDialog(QPlatformTheme::FileDialog, parent),
       m_fileMode(OpenFile),
-      m_options(QFileDialogOptions::create())
+      m_options(QFileDialogOptions::create()),
+      m_selectedNameFilter(nullptr)
 {
     m_options->setFileMode(QFileDialogOptions::ExistingFile);
     m_options->setAcceptMode(QFileDialogOptions::AcceptOpen);
@@ -335,6 +338,12 @@ void QQuickPlatformFileDialog::setNameFilters(const QStringList &filters)
         return;
 
     m_options->setNameFilters(filters);
+    if (m_selectedNameFilter) {
+        int index = m_selectedNameFilter->index();
+        if (index < 0 || index >= filters.count())
+            index = 0;
+        m_selectedNameFilter->update(filters.value(index));
+    }
     emit nameFiltersChanged();
 }
 
@@ -344,24 +353,57 @@ void QQuickPlatformFileDialog::resetNameFilters()
 }
 
 /*!
-    \qmlproperty string Qt.labs.platform::FileDialog::selectedNameFilter
+    \qmlpropertygroup Qt.labs.platform::FileDialog::selectedNameFilter
+    \qmlproperty int Qt.labs.platform::FileDialog::selectedNameFilter.index
+    \qmlproperty string Qt.labs.platform::FileDialog::selectedNameFilter.name
+    \qmlproperty list<string> Qt.labs.platform::FileDialog::selectedNameFilter.extensions
+
+    These properties hold the currently selected name filter.
+
+    \table
+    \header
+        \li Name
+        \li Description
+    \row
+        \li \b index : int
+        \li This property determines which \l {nameFilters}{name filter} is selected.
+            The specified filter is selected when the dialog is opened. The value is
+            updated when the user selects another filter.
+    \row
+        \li [read-only] \b name : string
+        \li This property holds the name of the selected filter. In the
+            example below, the name of the first filter is \c {"Text files"}
+            and the second is \c {"HTML files"}.
+    \row
+        \li [read-only] \b extensions : list<string>
+        \li This property holds the list of extensions of the selected filter.
+            In the example below, the list of extensions of the first filter is
+            \c {["txt"]} and the second is \c {["html", "htm"]}.
+    \endtable
 
-    This property holds the currently selected name filter.
+    \code
+    FileDialog {
+        id: fileDialog
+        selectedNameFilter.index: 1
+        nameFilters: ["Text files (*.txt)", "HTML files (*.html *.htm)"]
+    }
+
+    MyDocument {
+        id: document
+        fileType: fileDialog.selectedNameFilter.extensions[0]
+    }
+    \endcode
 
     \sa nameFilters
 */
-QString QQuickPlatformFileDialog::selectedNameFilter() const
+QQuickPlatformFileNameFilter *QQuickPlatformFileDialog::selectedNameFilter() const
 {
-    if (QPlatformFileDialogHelper *fileDialog = qobject_cast<QPlatformFileDialogHelper *>(handle()))
-        return fileDialog->selectedNameFilter();
-    return m_options->initiallySelectedNameFilter();
-}
-
-void QQuickPlatformFileDialog::setSelectedNameFilter(const QString &filter)
-{
-    if (QPlatformFileDialogHelper *fileDialog = qobject_cast<QPlatformFileDialogHelper *>(handle()))
-        fileDialog->selectNameFilter(filter);
-    m_options->setInitiallySelectedNameFilter(filter);
+    if (!m_selectedNameFilter) {
+        QQuickPlatformFileDialog *that = const_cast<QQuickPlatformFileDialog *>(this);
+        m_selectedNameFilter = new QQuickPlatformFileNameFilter(that);
+        m_selectedNameFilter->setOptions(m_options);
+    }
+    return m_selectedNameFilter;
 }
 
 /*!
@@ -468,7 +510,6 @@ void QQuickPlatformFileDialog::onCreate(QPlatformDialogHelper *dialog)
         connect(fileDialog, &QPlatformFileDialogHelper::currentChanged, this, &QQuickPlatformFileDialog::currentFileChanged);
         connect(fileDialog, &QPlatformFileDialogHelper::currentChanged, this, &QQuickPlatformFileDialog::currentFilesChanged);
         connect(fileDialog, &QPlatformFileDialogHelper::directoryEntered, this, &QQuickPlatformFileDialog::folderChanged);
-        connect(fileDialog, &QPlatformFileDialogHelper::filterSelected, this, &QQuickPlatformFileDialog::selectedNameFilterChanged);
         fileDialog->setOptions(m_options);
     }
 }
@@ -476,8 +517,24 @@ void QQuickPlatformFileDialog::onCreate(QPlatformDialogHelper *dialog)
 void QQuickPlatformFileDialog::onShow(QPlatformDialogHelper *dialog)
 {
     m_options->setWindowTitle(title());
-    if (QPlatformFileDialogHelper *fileDialog = qobject_cast<QPlatformFileDialogHelper *>(dialog))
+    if (QPlatformFileDialogHelper *fileDialog = qobject_cast<QPlatformFileDialogHelper *>(dialog)) {
         fileDialog->setOptions(m_options);
+        if (m_selectedNameFilter) {
+            const int index = m_selectedNameFilter->index();
+            const QString filter = m_options->nameFilters().value(index);
+            m_options->setInitiallySelectedNameFilter(filter);
+            fileDialog->selectNameFilter(filter);
+            connect(fileDialog, &QPlatformFileDialogHelper::filterSelected, m_selectedNameFilter, &QQuickPlatformFileNameFilter::update);
+        }
+    }
+}
+
+void QQuickPlatformFileDialog::onHide(QPlatformDialogHelper *dialog)
+{
+    if (QPlatformFileDialogHelper *fileDialog = qobject_cast<QPlatformFileDialogHelper *>(dialog)) {
+        if (m_selectedNameFilter)
+            disconnect(fileDialog, &QPlatformFileDialogHelper::filterSelected, m_selectedNameFilter, &QQuickPlatformFileNameFilter::update);
+    }
 }
 
 void QQuickPlatformFileDialog::accept()
@@ -506,4 +563,98 @@ QList<QUrl> QQuickPlatformFileDialog::addDefaultSuffixes(const QList<QUrl> &file
     return urls;
 }
 
+QQuickPlatformFileNameFilter::QQuickPlatformFileNameFilter(QObject *parent)
+    : QObject(parent), m_index(-1)
+{
+}
+
+int QQuickPlatformFileNameFilter::index() const
+{
+    return m_index;
+}
+
+void QQuickPlatformFileNameFilter::setIndex(int index)
+{
+    if (m_index == index)
+        return;
+
+    m_index = index;
+    emit indexChanged(index);
+}
+
+QString QQuickPlatformFileNameFilter::name() const
+{
+    return m_name;
+}
+
+QStringList QQuickPlatformFileNameFilter::extensions() const
+{
+    return m_extensions;
+}
+
+QSharedPointer<QFileDialogOptions> QQuickPlatformFileNameFilter::options() const
+{
+    return m_options;
+}
+
+void QQuickPlatformFileNameFilter::setOptions(const QSharedPointer<QFileDialogOptions> &options)
+{
+    m_options = options;
+}
+
+static QString extractName(const QString &filter)
+{
+    return filter.left(filter.indexOf(QLatin1Char('(')) - 1);
+}
+
+static QString extractExtension(const QString &filter)
+{
+    return filter.mid(filter.indexOf(QLatin1Char('.')) + 1);
+}
+
+static QStringList extractExtensions(const QString &filter)
+{
+    QStringList extensions;
+    const int from = filter.indexOf(QLatin1Char('('));
+    const int to = filter.lastIndexOf(QLatin1Char(')')) - 1;
+    if (from >= 0 && from < to) {
+        const QStringRef ref = filter.midRef(from + 1, to - from);
+        const QVector<QStringRef> exts = ref.split(QLatin1Char(' '), QString::SkipEmptyParts);
+        for (const QStringRef &ref : exts)
+            extensions += extractExtension(ref.toString());
+    }
+
+    return extensions;
+}
+
+void QQuickPlatformFileNameFilter::update(const QString &filter)
+{
+    const QStringList filters = nameFilters();
+
+    const int oldIndex = m_index;
+    const QString oldName = m_name;
+    const QStringList oldExtensions = m_extensions;
+
+    m_index = filters.indexOf(filter);
+    m_name = extractName(filter);
+    m_extensions = extractExtensions(filter);
+
+    if (oldIndex != m_index)
+        emit indexChanged(m_index);
+    if (oldName != m_name)
+        emit nameChanged(m_name);
+    if (oldExtensions != m_extensions)
+        emit extensionsChanged(m_extensions);
+}
+
+QStringList QQuickPlatformFileNameFilter::nameFilters() const
+{
+    return m_options ? m_options->nameFilters() : QStringList();
+}
+
+QString QQuickPlatformFileNameFilter::nameFilter(int index) const
+{
+    return m_options ? m_options->nameFilters().value(index) : QString();
+}
+
 QT_END_NAMESPACE
diff --git a/src/imports/platform/qquickplatformfiledialog_p.h b/src/imports/platform/qquickplatformfiledialog_p.h
index a4c61c54..51f88d46 100644
--- a/src/imports/platform/qquickplatformfiledialog_p.h
+++ b/src/imports/platform/qquickplatformfiledialog_p.h
@@ -54,6 +54,8 @@
 
 QT_BEGIN_NAMESPACE
 
+class QQuickPlatformFileNameFilter;
+
 class QQuickPlatformFileDialog : public QQuickPlatformDialog
 {
     Q_OBJECT
@@ -65,7 +67,7 @@ class QQuickPlatformFileDialog : public QQuickPlatformDialog
     Q_PROPERTY(QUrl folder READ folder WRITE setFolder NOTIFY folderChanged FINAL)
     Q_PROPERTY(QFileDialogOptions::FileDialogOptions options READ options WRITE setOptions RESET resetOptions NOTIFY optionsChanged FINAL)
     Q_PROPERTY(QStringList nameFilters READ nameFilters WRITE setNameFilters RESET resetNameFilters NOTIFY nameFiltersChanged FINAL)
-    Q_PROPERTY(QString selectedNameFilter READ selectedNameFilter WRITE setSelectedNameFilter NOTIFY selectedNameFilterChanged FINAL)
+    Q_PROPERTY(QQuickPlatformFileNameFilter *selectedNameFilter READ selectedNameFilter CONSTANT)
     Q_PROPERTY(QString defaultSuffix READ defaultSuffix WRITE setDefaultSuffix RESET resetDefaultSuffix NOTIFY defaultSuffixChanged FINAL)
     Q_PROPERTY(QString acceptLabel READ acceptLabel WRITE setAcceptLabel RESET resetAcceptLabel NOTIFY acceptLabelChanged FINAL)
     Q_PROPERTY(QString rejectLabel READ rejectLabel WRITE setRejectLabel RESET resetRejectLabel NOTIFY rejectLabelChanged FINAL)
@@ -107,8 +109,7 @@ public:
     void setNameFilters(const QStringList &filters);
     void resetNameFilters();
 
-    QString selectedNameFilter() const;
-    void setSelectedNameFilter(const QString &filter);
+    QQuickPlatformFileNameFilter *selectedNameFilter() const;
 
     QString defaultSuffix() const;
     void setDefaultSuffix(const QString &suffix);
@@ -131,7 +132,6 @@ Q_SIGNALS:
     void folderChanged();
     void optionsChanged();
     void nameFiltersChanged();
-    void selectedNameFilterChanged();
     void defaultSuffixChanged();
     void acceptLabelChanged();
     void rejectLabelChanged();
@@ -140,6 +140,7 @@ protected:
     bool useNativeDialog() const override;
     void onCreate(QPlatformDialogHelper *dialog) override;
     void onShow(QPlatformDialogHelper *dialog) override;
+    void onHide(QPlatformDialogHelper *dialog) override;
     void accept() override;
 
 private:
@@ -149,6 +150,43 @@ private:
     FileMode m_fileMode;
     QList<QUrl> m_files;
     QSharedPointer<QFileDialogOptions> m_options;
+    mutable QQuickPlatformFileNameFilter *m_selectedNameFilter;
+};
+
+class QQuickPlatformFileNameFilter : public QObject
+{
+    Q_OBJECT
+    Q_PROPERTY(int index READ index WRITE setIndex NOTIFY indexChanged FINAL)
+    Q_PROPERTY(QString name READ name NOTIFY nameChanged FINAL)
+    Q_PROPERTY(QStringList extensions READ extensions NOTIFY extensionsChanged FINAL)
+
+public:
+    explicit QQuickPlatformFileNameFilter(QObject *parent = nullptr);
+
+    int index() const;
+    void setIndex(int index);
+
+    QString name() const;
+    QStringList extensions() const;
+
+    QSharedPointer<QFileDialogOptions> options() const;
+    void setOptions(const QSharedPointer<QFileDialogOptions> &options);
+
+    void update(const QString &filter);
+
+Q_SIGNALS:
+    void indexChanged(int index);
+    void nameChanged(const QString &name);
+    void extensionsChanged(const QStringList &extensions);
+
+private:
+    QStringList nameFilters() const;
+    QString nameFilter(int index) const;
+
+    int m_index;
+    QString m_name;
+    QStringList m_extensions;
+    QSharedPointer<QFileDialogOptions> m_options;
 };
 
 QT_END_NAMESPACE
diff --git a/src/imports/platform/qtlabsplatformplugin.cpp b/src/imports/platform/qtlabsplatformplugin.cpp
index 1762e267..f73b04e8 100644
--- a/src/imports/platform/qtlabsplatformplugin.cpp
+++ b/src/imports/platform/qtlabsplatformplugin.cpp
@@ -91,6 +91,7 @@ void QtLabsPlatformPlugin::registerTypes(const char *uri)
     qmlRegisterUncreatableType<QQuickPlatformDialog>(uri, 1, 0, "Dialog", QQuickPlatformDialog::tr("Dialog is an abstract base class"));
     qmlRegisterType<QQuickPlatformColorDialog>(uri, 1, 0, "ColorDialog");
     qmlRegisterType<QQuickPlatformFileDialog>(uri, 1, 0, "FileDialog");
+    qmlRegisterType<QQuickPlatformFileNameFilter>();
     qmlRegisterType<QQuickPlatformFolderDialog>(uri, 1, 0, "FolderDialog");
     qmlRegisterType<QQuickPlatformFontDialog>(uri, 1, 0, "FontDialog");
     qmlRegisterType<QQuickPlatformMessageDialog>(uri, 1, 0, "MessageDialog");