Platform: create platform dialog instances lazily on demand

Change-Id: Ie963cb5c082b49205f7b7244ace3b88254ec37c7
Reviewed-by: J-P Nurmi <jpnurmi@qt.io>

12 files changed, 131 insertions, 102 deletions

diff --git a/src/imports/platform/qquickplatformcolordialog.cpp b/src/imports/platform/qquickplatformcolordialog.cpp
index c86c0030..b71797f5 100644
--- a/src/imports/platform/qquickplatformcolordialog.cpp
+++ b/src/imports/platform/qquickplatformcolordialog.cpp
@@ -102,19 +102,6 @@ Q_DECLARE_LOGGING_CATEGORY(qtLabsPlatformDialogs)
 QQuickPlatformColorDialog::QQuickPlatformColorDialog(QObject *parent)
     : QQuickPlatformDialog(parent), m_options(QColorDialogOptions::create())
 {
-    QPlatformDialogHelper *dialog = QGuiApplicationPrivate::platformTheme()->createPlatformDialogHelper(QPlatformTheme::ColorDialog);
-#ifdef QT_WIDGETS_LIB
-    if (!dialog)
-        dialog = new QWidgetPlatformColorDialog(this);
-#endif
-    qCDebug(qtLabsPlatformDialogs) << "ColorDialog:" << dialog;
-
-    if (QPlatformColorDialogHelper *colorDialog = qobject_cast<QPlatformColorDialogHelper *>(dialog)) {
-        connect(colorDialog, &QPlatformColorDialogHelper::currentColorChanged, this, &QQuickPlatformColorDialog::currentColorChanged);
-        connect(colorDialog, &QPlatformColorDialogHelper::colorSelected, this, &QQuickPlatformColorDialog::colorSelected);
-        colorDialog->setOptions(m_options);
-    }
-    setHandle(dialog);
 }
 
 /*!
@@ -166,6 +153,23 @@ void QQuickPlatformColorDialog::setOptions(QColorDialogOptions::ColorDialogOptio
     emit optionsChanged();
 }
 
+QPlatformDialogHelper *QQuickPlatformColorDialog::createHelper()
+{
+    QPlatformDialogHelper *dialog = QGuiApplicationPrivate::platformTheme()->createPlatformDialogHelper(QPlatformTheme::ColorDialog);
+#ifdef QT_WIDGETS_LIB
+    if (!dialog)
+        dialog = new QWidgetPlatformColorDialog(this);
+#endif
+    qCDebug(qtLabsPlatformDialogs) << "ColorDialog:" << dialog;
+
+    if (QPlatformColorDialogHelper *colorDialog = qobject_cast<QPlatformColorDialogHelper *>(dialog)) {
+        connect(colorDialog, &QPlatformColorDialogHelper::currentColorChanged, this, &QQuickPlatformColorDialog::currentColorChanged);
+        connect(colorDialog, &QPlatformColorDialogHelper::colorSelected, this, &QQuickPlatformColorDialog::colorSelected);
+        colorDialog->setOptions(m_options);
+    }
+    return dialog;
+}
+
 void QQuickPlatformColorDialog::applyOptions()
 {
     m_options->setWindowTitle(title());
diff --git a/src/imports/platform/qquickplatformcolordialog_p.h b/src/imports/platform/qquickplatformcolordialog_p.h
index 48b4aac1..403582e4 100644
--- a/src/imports/platform/qquickplatformcolordialog_p.h
+++ b/src/imports/platform/qquickplatformcolordialog_p.h
@@ -76,6 +76,7 @@ Q_SIGNALS:
     void colorSelected(const QColor &color);
 
 protected:
+    QPlatformDialogHelper *createHelper() override;
     void applyOptions() override;
 
 private:
diff --git a/src/imports/platform/qquickplatformdialog.cpp b/src/imports/platform/qquickplatformdialog.cpp
index 5f28ca05..68321554 100644
--- a/src/imports/platform/qquickplatformdialog.cpp
+++ b/src/imports/platform/qquickplatformdialog.cpp
@@ -94,31 +94,16 @@ QQuickPlatformDialog::QQuickPlatformDialog(QObject *parent)
 
 QQuickPlatformDialog::~QQuickPlatformDialog()
 {
-    delete m_handle;
-    m_handle = nullptr;
+    destroy();
 }
 
 QPlatformDialogHelper *QQuickPlatformDialog::handle() const
 {
+    if (!m_handle)
+        const_cast<QQuickPlatformDialog *>(this)->create();
     return m_handle;
 }
 
-void QQuickPlatformDialog::setHandle(QPlatformDialogHelper *handle)
-{
-    if (m_handle == handle)
-        return;
-
-    if (m_handle) {
-        disconnect(m_handle, &QPlatformDialogHelper::accept, this, &QQuickPlatformDialog::accept);
-        disconnect(m_handle, &QPlatformDialogHelper::reject, this, &QQuickPlatformDialog::reject);
-    }
-    m_handle = handle;
-    if (handle) {
-        connect(handle, &QPlatformDialogHelper::accept, this, &QQuickPlatformDialog::accept);
-        connect(handle, &QPlatformDialogHelper::reject, this, &QQuickPlatformDialog::reject);
-    }
-}
-
 /*!
     \default
     \qmlproperty list<Object> Qt.labs.platform::Dialog::data
@@ -245,7 +230,7 @@ void QQuickPlatformDialog::setVisible(bool visible)
 */
 void QQuickPlatformDialog::open()
 {
-    if (!m_handle || m_visible)
+    if (m_visible || !create())
         return;
 
     applyOptions();
@@ -308,6 +293,24 @@ void QQuickPlatformDialog::componentComplete()
         setParentWindow(findParentWindow());
 }
 
+bool QQuickPlatformDialog::create()
+{
+    if (!m_handle) {
+        m_handle = createHelper();
+        if (m_handle) {
+            connect(m_handle, &QPlatformDialogHelper::accept, this, &QQuickPlatformDialog::accept);
+            connect(m_handle, &QPlatformDialogHelper::reject, this, &QQuickPlatformDialog::reject);
+        }
+    }
+    return m_handle;
+}
+
+void QQuickPlatformDialog::destroy()
+{
+    delete m_handle;
+    m_handle = nullptr;
+}
+
 void QQuickPlatformDialog::applyOptions()
 {
 }
diff --git a/src/imports/platform/qquickplatformdialog_p.h b/src/imports/platform/qquickplatformdialog_p.h
index b4ba62ec..577cec94 100644
--- a/src/imports/platform/qquickplatformdialog_p.h
+++ b/src/imports/platform/qquickplatformdialog_p.h
@@ -76,7 +76,6 @@ public:
     ~QQuickPlatformDialog();
 
     QPlatformDialogHelper *handle() const;
-    void setHandle(QPlatformDialogHelper *handle);
 
     QQmlListProperty<QObject> data();
 
@@ -114,6 +113,10 @@ protected:
     void classBegin() override;
     void componentComplete() override;
 
+    bool create();
+    void destroy();
+
+    virtual QPlatformDialogHelper *createHelper() = 0;
     virtual void applyOptions();
 
     QWindow *findParentWindow() const;
diff --git a/src/imports/platform/qquickplatformfiledialog.cpp b/src/imports/platform/qquickplatformfiledialog.cpp
index 8ff5c4ac..1900952c 100644
--- a/src/imports/platform/qquickplatformfiledialog.cpp
+++ b/src/imports/platform/qquickplatformfiledialog.cpp
@@ -118,30 +118,6 @@ QQuickPlatformFileDialog::QQuickPlatformFileDialog(QObject *parent)
 {
     m_options->setFileMode(QFileDialogOptions::ExistingFile);
     m_options->setAcceptMode(QFileDialogOptions::AcceptOpen);
-
-    QPlatformDialogHelper *dialog = QGuiApplicationPrivate::platformTheme()->createPlatformDialogHelper(QPlatformTheme::FileDialog);
-#ifdef QT_WIDGETS_LIB
-    if (!dialog)
-        dialog = new QWidgetPlatformFileDialog(this);
-#endif
-    qCDebug(qtLabsPlatformDialogs) << "FileDialog:" << dialog;
-
-    if (QPlatformFileDialogHelper *fileDialog = qobject_cast<QPlatformFileDialogHelper *>(dialog)) {
-        connect(fileDialog, &QPlatformFileDialogHelper::fileSelected, [this](const QUrl &file) {
-            emit fileSelected(addDefaultSuffix(file));
-        });
-        connect(fileDialog, &QPlatformFileDialogHelper::filesSelected, [this](const QList<QUrl> &files) {
-            emit filesSelected(addDefaultSuffixes(files));
-        });
-        connect(fileDialog, &QPlatformFileDialogHelper::currentChanged, [this](const QUrl &url) {
-            if (m_current == url)
-                return;
-            m_current = url;
-            emit currentFileChanged();
-        });
-        fileDialog->setOptions(m_options);
-    }
-    setHandle(dialog);
 }
 
 /*!
@@ -366,6 +342,33 @@ void QQuickPlatformFileDialog::resetRejectLabel()
     setRejectLabel(QString());
 }
 
+QPlatformDialogHelper *QQuickPlatformFileDialog::createHelper()
+{
+    QPlatformDialogHelper *dialog = QGuiApplicationPrivate::platformTheme()->createPlatformDialogHelper(QPlatformTheme::FileDialog);
+#ifdef QT_WIDGETS_LIB
+    if (!dialog)
+        dialog = new QWidgetPlatformFileDialog(this);
+#endif
+    qCDebug(qtLabsPlatformDialogs) << "FileDialog:" << dialog;
+
+    if (QPlatformFileDialogHelper *fileDialog = qobject_cast<QPlatformFileDialogHelper *>(dialog)) {
+        connect(fileDialog, &QPlatformFileDialogHelper::fileSelected, [this](const QUrl &file) {
+            emit fileSelected(addDefaultSuffix(file));
+        });
+        connect(fileDialog, &QPlatformFileDialogHelper::filesSelected, [this](const QList<QUrl> &files) {
+            emit filesSelected(addDefaultSuffixes(files));
+        });
+        connect(fileDialog, &QPlatformFileDialogHelper::currentChanged, [this](const QUrl &url) {
+            if (m_current == url)
+                return;
+            m_current = url;
+            emit currentFileChanged();
+        });
+        fileDialog->setOptions(m_options);
+    }
+    return dialog;
+}
+
 void QQuickPlatformFileDialog::applyOptions()
 {
     m_options->setWindowTitle(title());
diff --git a/src/imports/platform/qquickplatformfiledialog_p.h b/src/imports/platform/qquickplatformfiledialog_p.h
index 53e34731..c3c6a490 100644
--- a/src/imports/platform/qquickplatformfiledialog_p.h
+++ b/src/imports/platform/qquickplatformfiledialog_p.h
@@ -115,6 +115,7 @@ Q_SIGNALS:
     void filesSelected(const QList<QUrl> &files);
 
 protected:
+    QPlatformDialogHelper *createHelper() override;
     void applyOptions() override;
 
 private:
diff --git a/src/imports/platform/qquickplatformfolderdialog.cpp b/src/imports/platform/qquickplatformfolderdialog.cpp
index bf0ba09b..04c39f6f 100644
--- a/src/imports/platform/qquickplatformfolderdialog.cpp
+++ b/src/imports/platform/qquickplatformfolderdialog.cpp
@@ -118,26 +118,6 @@ QQuickPlatformFolderDialog::QQuickPlatformFolderDialog(QObject *parent)
 {
     m_options->setFileMode(QFileDialogOptions::Directory);
     m_options->setAcceptMode(QFileDialogOptions::AcceptOpen);
-
-    QPlatformDialogHelper *dialog = QGuiApplicationPrivate::platformTheme()->createPlatformDialogHelper(QPlatformTheme::FileDialog);
-#ifdef QT_WIDGETS_LIB
-    if (!dialog)
-        dialog = new QWidgetPlatformFileDialog(this);
-#endif
-    qCDebug(qtLabsPlatformDialogs) << "FolderDialog:" << dialog;
-
-    if (QPlatformFileDialogHelper *fileDialog = qobject_cast<QPlatformFileDialogHelper *>(dialog)) {
-        connect(fileDialog, &QPlatformFileDialogHelper::fileSelected, this, &QQuickPlatformFolderDialog::folderSelected);
-        connect(fileDialog, &QPlatformFileDialogHelper::filesSelected, this, &QQuickPlatformFolderDialog::foldersSelected);
-        connect(fileDialog, &QPlatformFileDialogHelper::currentChanged, [this](const QUrl &url) {
-            if (m_current == url)
-                return;
-            m_current = url;
-            emit currentFolderChanged();
-        });
-        fileDialog->setOptions(m_options);
-    }
-    setHandle(dialog);
 }
 
 /*!
@@ -259,6 +239,29 @@ void QQuickPlatformFolderDialog::resetRejectLabel()
     setRejectLabel(QString());
 }
 
+QPlatformDialogHelper *QQuickPlatformFolderDialog::createHelper()
+{
+    QPlatformDialogHelper *dialog = QGuiApplicationPrivate::platformTheme()->createPlatformDialogHelper(QPlatformTheme::FileDialog);
+#ifdef QT_WIDGETS_LIB
+    if (!dialog)
+        dialog = new QWidgetPlatformFileDialog(this);
+#endif
+    qCDebug(qtLabsPlatformDialogs) << "FolderDialog:" << dialog;
+
+    if (QPlatformFileDialogHelper *fileDialog = qobject_cast<QPlatformFileDialogHelper *>(dialog)) {
+        connect(fileDialog, &QPlatformFileDialogHelper::fileSelected, this, &QQuickPlatformFolderDialog::folderSelected);
+        connect(fileDialog, &QPlatformFileDialogHelper::filesSelected, this, &QQuickPlatformFolderDialog::foldersSelected);
+        connect(fileDialog, &QPlatformFileDialogHelper::currentChanged, [this](const QUrl &url) {
+            if (m_current == url)
+                return;
+            m_current = url;
+            emit currentFolderChanged();
+        });
+        fileDialog->setOptions(m_options);
+    }
+    return dialog;
+}
+
 void QQuickPlatformFolderDialog::applyOptions()
 {
     m_options->setWindowTitle(title());
diff --git a/src/imports/platform/qquickplatformfolderdialog_p.h b/src/imports/platform/qquickplatformfolderdialog_p.h
index 4b5f6a9b..39dc025f 100644
--- a/src/imports/platform/qquickplatformfolderdialog_p.h
+++ b/src/imports/platform/qquickplatformfolderdialog_p.h
@@ -91,6 +91,7 @@ Q_SIGNALS:
     void foldersSelected(const QList<QUrl> &folders);
 
 protected:
+    QPlatformDialogHelper *createHelper() override;
     void applyOptions() override;
 
 private:
diff --git a/src/imports/platform/qquickplatformfontdialog.cpp b/src/imports/platform/qquickplatformfontdialog.cpp
index bf778ff0..13e35389 100644
--- a/src/imports/platform/qquickplatformfontdialog.cpp
+++ b/src/imports/platform/qquickplatformfontdialog.cpp
@@ -102,19 +102,6 @@ Q_DECLARE_LOGGING_CATEGORY(qtLabsPlatformDialogs)
 QQuickPlatformFontDialog::QQuickPlatformFontDialog(QObject *parent)
     : QQuickPlatformDialog(parent), m_options(QFontDialogOptions::create())
 {
-    QPlatformDialogHelper *dialog = QGuiApplicationPrivate::platformTheme()->createPlatformDialogHelper(QPlatformTheme::FontDialog);
-#ifdef QT_WIDGETS_LIB
-    if (!dialog)
-        dialog = new QWidgetPlatformFontDialog(this);
-#endif
-    qCDebug(qtLabsPlatformDialogs) << "FontDialog:" << dialog;
-
-    if (QPlatformFontDialogHelper *fontDialog = qobject_cast<QPlatformFontDialogHelper *>(dialog)) {
-        connect(fontDialog, &QPlatformFontDialogHelper::currentFontChanged, this, &QQuickPlatformFontDialog::currentFontChanged);
-        connect(fontDialog, &QPlatformFontDialogHelper::fontSelected, this, &QQuickPlatformFontDialog::fontSelected);
-        fontDialog->setOptions(m_options);
-    }
-    setHandle(dialog);
 }
 
 /*!
@@ -169,6 +156,23 @@ void QQuickPlatformFontDialog::setOptions(QFontDialogOptions::FontDialogOptions
     emit optionsChanged();
 }
 
+QPlatformDialogHelper *QQuickPlatformFontDialog::createHelper()
+{
+    QPlatformDialogHelper *dialog = QGuiApplicationPrivate::platformTheme()->createPlatformDialogHelper(QPlatformTheme::FontDialog);
+#ifdef QT_WIDGETS_LIB
+    if (!dialog)
+        dialog = new QWidgetPlatformFontDialog(this);
+#endif
+    qCDebug(qtLabsPlatformDialogs) << "FontDialog:" << dialog;
+
+    if (QPlatformFontDialogHelper *fontDialog = qobject_cast<QPlatformFontDialogHelper *>(dialog)) {
+        connect(fontDialog, &QPlatformFontDialogHelper::currentFontChanged, this, &QQuickPlatformFontDialog::currentFontChanged);
+        connect(fontDialog, &QPlatformFontDialogHelper::fontSelected, this, &QQuickPlatformFontDialog::fontSelected);
+        fontDialog->setOptions(m_options);
+    }
+    return dialog;
+}
+
 void QQuickPlatformFontDialog::applyOptions()
 {
     m_options->setWindowTitle(title());
diff --git a/src/imports/platform/qquickplatformfontdialog_p.h b/src/imports/platform/qquickplatformfontdialog_p.h
index 91f9a31a..0c4f64ee 100644
--- a/src/imports/platform/qquickplatformfontdialog_p.h
+++ b/src/imports/platform/qquickplatformfontdialog_p.h
@@ -76,6 +76,7 @@ Q_SIGNALS:
     void fontSelected(const QFont &font);
 
 protected:
+    QPlatformDialogHelper *createHelper() override;
     void applyOptions() override;
 
 private:
diff --git a/src/imports/platform/qquickplatformmessagedialog.cpp b/src/imports/platform/qquickplatformmessagedialog.cpp
index 3e27e083..2fe4f88f 100644
--- a/src/imports/platform/qquickplatformmessagedialog.cpp
+++ b/src/imports/platform/qquickplatformmessagedialog.cpp
@@ -237,18 +237,6 @@ QQuickPlatformMessageDialog::QQuickPlatformMessageDialog(QObject *parent)
       m_options(QMessageDialogOptions::create()),
       m_clickedButton(QPlatformDialogHelper::NoButton)
 {
-    QPlatformDialogHelper *dialog = QGuiApplicationPrivate::platformTheme()->createPlatformDialogHelper(QPlatformTheme::MessageDialog);
-#ifdef QT_WIDGETS_LIB
-    if (!dialog)
-        dialog = new QWidgetPlatformMessageDialog(this);
-#endif
-    qCDebug(qtLabsPlatformDialogs) << "MessageDialog:" << dialog;
-
-    if (QPlatformMessageDialogHelper *messageDialog = qobject_cast<QPlatformMessageDialogHelper *>(dialog)) {
-        connect(messageDialog, &QPlatformMessageDialogHelper::clicked, this, &QQuickPlatformMessageDialog::handleClick);
-        messageDialog->setOptions(m_options);
-    }
-    setHandle(dialog);
 }
 
 /*!
@@ -371,6 +359,22 @@ QPlatformDialogHelper::StandardButton QQuickPlatformMessageDialog::clickedButton
     return m_clickedButton;
 }
 
+QPlatformDialogHelper *QQuickPlatformMessageDialog::createHelper()
+{
+    QPlatformDialogHelper *dialog = QGuiApplicationPrivate::platformTheme()->createPlatformDialogHelper(QPlatformTheme::MessageDialog);
+#ifdef QT_WIDGETS_LIB
+    if (!dialog)
+        dialog = new QWidgetPlatformMessageDialog(this);
+#endif
+    qCDebug(qtLabsPlatformDialogs) << "MessageDialog:" << dialog;
+
+    if (QPlatformMessageDialogHelper *messageDialog = qobject_cast<QPlatformMessageDialogHelper *>(dialog)) {
+        connect(messageDialog, &QPlatformMessageDialogHelper::clicked, this, &QQuickPlatformMessageDialog::handleClick);
+        messageDialog->setOptions(m_options);
+    }
+    return dialog;
+}
+
 void QQuickPlatformMessageDialog::applyOptions()
 {
     m_options->setWindowTitle(title());
diff --git a/src/imports/platform/qquickplatformmessagedialog_p.h b/src/imports/platform/qquickplatformmessagedialog_p.h
index bd44082e..e5548174 100644
--- a/src/imports/platform/qquickplatformmessagedialog_p.h
+++ b/src/imports/platform/qquickplatformmessagedialog_p.h
@@ -108,6 +108,7 @@ Q_SIGNALS:
     void restoreDefaultsClicked();
 
 protected:
+    QPlatformDialogHelper *createHelper() override;
     void applyOptions() override;
 
 private Q_SLOTS: