QFileDialog: add MIME Type filters

Currently just a convenience method for setNameFilters(), it uses
QMimeType to create a name filter from the glob patterns and
description defined in each MIME type.

In the longer term, this API could be used to do proper mimetype-based
filtering using QMimeDatabase::mimeTypeForFile() in the builtin
QFileDialog (aka "not native"), instead of only looking at globs via the
name filters.

Change-Id: I0edccf5f30c514481b47cd100d743d1ed7a24024
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@digia.com>

src/gui/kernel/qplatformdialoghelper.cpp

@@ -359,6 +359,7 @@ public:
     QDir::Filters filters;
     QList<QUrl> sidebarUrls;
     QStringList nameFilters;
+    QStringList mimeTypeFilters;
     QString defaultSuffix;
     QStringList history;
     QUrl initialDirectory;
@@ -477,6 +478,16 @@ QStringList QFileDialogOptions::nameFilters() const
     return d->nameFilters;
 }
 
+void QFileDialogOptions::setMimeTypeFilters(const QStringList &filters)
+{
+    d->mimeTypeFilters = filters;
+}
+
+QStringList QFileDialogOptions::mimeTypeFilters() const
+{
+    return d->mimeTypeFilters;
+}
+
 void QFileDialogOptions::setDefaultSuffix(const QString &suffix)
 {
     d->defaultSuffix = suffix;

src/gui/kernel/qplatformdialoghelper.h

@@ -265,6 +265,9 @@ public:
     void setNameFilters(const QStringList &filters);
     QStringList nameFilters() const;
 
+    void setMimeTypeFilters(const QStringList &filters);
+    QStringList mimeTypeFilters() const;
+
     void setDefaultSuffix(const QString &suffix);
     QString defaultSuffix() const;
 

src/widgets/dialogs/qfiledialog.cpp

@@ -57,6 +57,7 @@
 #include <stdlib.h>
 #include <qsettings.h>
 #include <qdebug.h>
+#include <qmimedatabase.h>
 #include <qapplication.h>
 #include <qstylepainter.h>
 #if !defined(Q_OS_WINCE)
@@ -1441,6 +1442,75 @@ void QFileDialog::setFilter(QDir::Filters filters)
     d->showHiddenAction->setChecked((filters & QDir::Hidden));
 }
 
+static QString nameFilterForMime(const QString &mimeType)
+{
+    QMimeDatabase db;
+    QMimeType mime(db.mimeTypeForName(mimeType));
+    if (mime.isValid()) {
+        if (mime.isDefault()) {
+            return QFileDialog::tr("All files (*)");
+        } else {
+            const QString patterns = mime.globPatterns().join(QLatin1Char(' '));
+            return mime.comment() + QStringLiteral(" (") + patterns + QLatin1Char(')');
+        }
+    }
+    return QString();
+}
+
+/*!
+    \since 5.2
+
+    Sets the \a filters used in the file dialog, from a list of MIME types.
+
+    Convenience method for setNameFilters().
+    Uses QMimeType to create a name filter from the glob patterns and description
+    defined in each MIME type.
+
+    Use application/octet-stream for the "All files (*)" filter, since that
+    is the base MIME type for all files.
+
+    Calling setMimeTypeFilters overrides any previously set name filters,
+    and changes the return value of nameFilters().
+
+    \snippet code/src_gui_dialogs_qfiledialog.cpp 13
+*/
+void QFileDialog::setMimeTypeFilters(const QStringList &filters)
+{
+    Q_D(QFileDialog);
+    QStringList nameFilters;
+    foreach (const QString &mimeType, filters) {
+        const QString text = nameFilterForMime(mimeType);
+        if (!text.isEmpty())
+            nameFilters.append(text);
+    }
+    setNameFilters(nameFilters);
+    d->options->setMimeTypeFilters(filters);
+}
+
+/*!
+    \since 5.2
+
+    Returns the MIME type filters that are in operation on this file
+    dialog.
+*/
+QStringList QFileDialog::mimeTypeFilters() const
+{
+    return d_func()->options->mimeTypeFilters();
+}
+
+/*!
+    \since 5.2
+
+    Sets the current MIME type \a filter.
+
+*/
+void QFileDialog::selectMimeTypeFilter(const QString &filter)
+{
+    const QString text = nameFilterForMime(filter);
+    if (!text.isEmpty())
+        selectNameFilter(text);
+}
+
 /*!
     \property QFileDialog::viewMode
     \brief the way files and directories are displayed in the dialog

src/widgets/dialogs/qfiledialog.h

@@ -124,6 +124,10 @@ public:
     void selectNameFilter(const QString &filter);
     QString selectedNameFilter() const;
 
+    void setMimeTypeFilters(const QStringList &filters);
+    QStringList mimeTypeFilters() const;
+    void selectMimeTypeFilter(const QString &filter);
+
     QDir::Filters filter() const;
     void setFilter(QDir::Filters filters);
 

src/widgets/doc/snippets/code/src_gui_dialogs_qfiledialog.cpp

@@ -129,3 +129,14 @@ QString dir = QFileDialog::getExistingDirectory(this, tr("Open Directory"),
                                                 QFileDialog::ShowDirsOnly
                                                 | QFileDialog::DontResolveSymlinks);
 //! [12]
+
+//! [13]
+QStringList mimeTypeFilters;
+mimeTypeFilters << "image/jpeg" // will show "JPEG image (*.jpeg *.jpg *.jpe)
+            << "image/png"  // will show "PNG image (*.png)"
+            << "application/octet-stream"; // will show "All files (*)"
+
+QFileDialog dialog(this);
+dialog.setMimeTypeFilters(mimeTypeFilters);
+dialog.exec();
+//! [13]

tests/manual/dialogs/filedialogpanel.cpp

@@ -162,6 +162,7 @@ FileDialogPanel::FileDialogPanel(QWidget *parent)
     , m_defaultSuffix(new QLineEdit(this))
     , m_directory(new QLineEdit(this))
     , m_selectedFileName(new QLineEdit(this))
+    , m_useMimeTypeFilters(new QCheckBox(this))
     , m_nameFilters(new QPlainTextEdit)
     , m_selectedNameFilter(new QLineEdit(this))
     , m_deleteNonModalDialogButton(0)
@@ -183,10 +184,11 @@ FileDialogPanel::FileDialogPanel(QWidget *parent)
 
     // Files
     QGroupBox *filesGroupBox = new QGroupBox(tr("Files / Filters"));
-    QFormLayout *filesLayout = new QFormLayout(filesGroupBox);
+    filesLayout = new QFormLayout(filesGroupBox);
     filesLayout->addRow(tr("Default Suffix:"), m_defaultSuffix);
     filesLayout->addRow(tr("Directory:"), m_directory);
     filesLayout->addRow(tr("Selected file:"), m_selectedFileName);
+    filesLayout->addRow(tr("Use mime type filters:"), m_useMimeTypeFilters);
     m_nameFilters->setMaximumHeight(80);
     filesLayout->addRow(tr("Name filters:"), m_nameFilters);
     filesLayout->addRow(tr("Selected name filter:"), m_selectedNameFilter);
@@ -236,6 +238,8 @@ FileDialogPanel::FileDialogPanel(QWidget *parent)
     gridLayout->addWidget(labelsGroupBox, 1, 0);
     gridLayout->addWidget(buttonsGroupBox, 1, 1);
 
+    connect(m_useMimeTypeFilters, SIGNAL(toggled(bool)), this, SLOT(useMimeTypeFilters(bool)));
+
     enableDeleteModalDialogButton();
     enableDeleteNonModalDialogButton();
     restoreDefaults();
@@ -461,7 +465,8 @@ void FileDialogPanel::restoreDefaults()
     m_customDirIcons->setChecked(d.testOption(QFileDialog::DontUseCustomDirectoryIcons));
     m_directory->setText(QDir::homePath());
     m_defaultSuffix->setText(QLatin1String("txt"));
-    m_nameFilters->setPlainText(QLatin1String("Any files (*)\nImage files (*.png *.xpm *.jpg)\nText files (*.txt)"));
+    m_useMimeTypeFilters->setChecked(false);
+    useMimeTypeFilters(false);
     m_selectedFileName->setText(QString());
     m_selectedNameFilter->setText(QString());
     foreach (LabelLineEdit *l, m_labelLineEdits)
@@ -481,14 +486,36 @@ void FileDialogPanel::applySettings(QFileDialog *d) const
     const QString file = m_selectedFileName->text().trimmed();
     if (!file.isEmpty())
        d->selectFile(file);
-    d->setNameFilters(m_nameFilters->toPlainText().trimmed().split(QLatin1Char('\n'), QString::SkipEmptyParts));
     const QString filter = m_selectedNameFilter->text().trimmed();
-    if (!filter.isEmpty())
+    const QStringList filters = m_nameFilters->toPlainText().trimmed().split(QLatin1Char('\n'), QString::SkipEmptyParts);
-        d->selectNameFilter(filter);
+    if (!m_useMimeTypeFilters->isChecked()) {
+        d->setNameFilters(filters);
+        if (!filter.isEmpty())
+            d->selectNameFilter(filter);
+    } else {
+        d->setMimeTypeFilters(filters);
+        if (!filter.isEmpty())
+            d->selectMimeTypeFilter(filter);
+    }
     foreach (LabelLineEdit *l, m_labelLineEdits)
         l->apply(d);
 }
 
+void FileDialogPanel::useMimeTypeFilters(bool b)
+{
+    QWidget *textEdit = filesLayout->labelForField(m_nameFilters);
+    if (QLabel *label = qobject_cast<QLabel *>(textEdit))
+        label->setText(b ? tr("Mime type filters:") : tr("Name filters:"));
+    QWidget *w = filesLayout->labelForField(m_selectedNameFilter);
+    if (QLabel *label = qobject_cast<QLabel *>(w))
+        label->setText(b ? tr("Selected mime type filter:") : tr("Selected name filter:"));
+
+    if (b)
+        m_nameFilters->setPlainText(QLatin1String("image/jpeg\nimage/png\ntext/plain\napplication/octet-stream"));
+    else
+        m_nameFilters->setPlainText(QLatin1String("Any files (*)\nImage files (*.png *.xpm *.jpg)\nText files (*.txt)"));
+}
+
 void FileDialogPanel::accepted()
 {
     const QFileDialog *d = qobject_cast<const QFileDialog *>(sender());

tests/manual/dialogs/filedialogpanel.h

@@ -52,6 +52,7 @@ class QCheckBox;
 class QComboBox;
 class QLineEdit;
 class QPlainTextEdit;
+class QFormLayout;
 QT_END_NAMESPACE
 class LabelLineEdit;
 
@@ -82,6 +83,7 @@ public slots:
 private slots:
     void enableDeleteNonModalDialogButton();
     void enableDeleteModalDialogButton();
+    void useMimeTypeFilters(bool);
 
 private:
     QString filterString() const;
@@ -89,6 +91,7 @@ private:
     QStringList allowedSchemes() const;
     void applySettings(QFileDialog *d) const;
 
+    QFormLayout *filesLayout;
     QCheckBox *m_readOnly;
     QCheckBox *m_confirmOverWrite;
     QCheckBox *m_nameFilterDetailsVisible;
@@ -103,6 +106,7 @@ private:
     QLineEdit *m_directory;
     QLineEdit *m_selectedFileName;
     QList<LabelLineEdit *> m_labelLineEdits;
+    QCheckBox *m_useMimeTypeFilters;
     QPlainTextEdit *m_nameFilters;
     QLineEdit *m_selectedNameFilter;
     QPushButton *m_deleteNonModalDialogButton;