Enable pan and zoom gestures for the formeditor

Use continuous zoom for mouse-wheel zoom
Directly apply zoom and not by detouring through custom notification
Moved logic related to zooming from the zoom-action into the view

Change-Id: Ib56779f3ea686736cc419aec94d7b5566091fb96
Reviewed-by: Henning Gründl <henning.gruendl@qt.io>
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

7 files changed, 375 insertions, 113 deletions

diff --git a/src/plugins/qmldesigner/components/componentcore/componentcore.pri b/src/plugins/qmldesigner/components/componentcore/componentcore.pri
index decf24a5a8..ef97a93343 100644
--- a/src/plugins/qmldesigner/components/componentcore/componentcore.pri
+++ b/src/plugins/qmldesigner/components/componentcore/componentcore.pri
@@ -5,6 +5,7 @@ SOURCES += addimagesdialog.cpp
 SOURCES += changestyleaction.cpp
 SOURCES += theme.cpp
 SOURCES += findimplementation.cpp
+SOURCES += gestures.cpp
 SOURCES += addsignalhandlerdialog.cpp
 SOURCES += layoutingridlayout.cpp
 SOURCES += abstractactiongroup.cpp
@@ -24,6 +25,7 @@ HEADERS += addimagesdialog.h
 HEADERS += changestyleaction.h
 HEADERS += theme.h
 HEADERS += findimplementation.h
+HEADERS += gestures.h
 HEADERS += addsignalhandlerdialog.h
 HEADERS += layoutingridlayout.h
 HEADERS += abstractactiongroup.h
diff --git a/src/plugins/qmldesigner/components/componentcore/gestures.cpp b/src/plugins/qmldesigner/components/componentcore/gestures.cpp
new file mode 100644
index 0000000000..29ff23c243
--- /dev/null
+++ b/src/plugins/qmldesigner/components/componentcore/gestures.cpp
@@ -0,0 +1,156 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the Qt Design Tooling
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+****************************************************************************/
+
+#include "gestures.h"
+
+#include <QWidget>
+
+namespace QmlDesigner {
+
+Qt::GestureType TwoFingerSwipe::m_type = static_cast<Qt::GestureType>(0);
+
+TwoFingerSwipe::TwoFingerSwipe() {}
+
+Qt::GestureType TwoFingerSwipe::type()
+{
+    return m_type;
+}
+
+void TwoFingerSwipe::registerRecognizer()
+{
+    m_type = QGestureRecognizer::registerRecognizer(new TwoFingerSwipeRecognizer());
+}
+
+QPointF TwoFingerSwipe::direction() const
+{
+    return m_current.center() - m_last.center();
+}
+
+void TwoFingerSwipe::reset()
+{
+    m_start = QLineF();
+    m_current = QLineF();
+    m_last = QLineF();
+}
+
+QGestureRecognizer::Result TwoFingerSwipe::begin(QTouchEvent *event)
+{
+    Q_UNUSED(event);
+    return QGestureRecognizer::MayBeGesture;
+}
+
+QGestureRecognizer::Result TwoFingerSwipe::update(QTouchEvent *event)
+{
+    if (event->touchPoints().size() != 2) {
+        if (state() == Qt::NoGesture)
+            return QGestureRecognizer::Ignore;
+        else
+            return QGestureRecognizer::FinishGesture;
+    }
+
+    QTouchEvent::TouchPoint p0 = event->touchPoints().at(0);
+    QTouchEvent::TouchPoint p1 = event->touchPoints().at(1);
+
+    QLineF line(p0.scenePos(), p1.screenPos());
+
+    if (m_start.isNull()) {
+        m_start = line;
+        m_current = line;
+        m_last = line;
+    } else {
+        auto deltaLength = line.length() - m_current.length();
+        auto deltaCenter = QLineF(line.center(), m_current.center()).length();
+        if (deltaLength > deltaCenter)
+            return QGestureRecognizer::CancelGesture;
+
+        m_last = m_current;
+        m_current = line;
+    }
+
+    setHotSpot(m_current.center());
+
+    return QGestureRecognizer::TriggerGesture;
+}
+
+QGestureRecognizer::Result TwoFingerSwipe::end(QTouchEvent *event)
+{
+    Q_UNUSED(event);
+    bool finish = state() != Qt::NoGesture;
+
+    reset();
+
+    if (finish)
+        return QGestureRecognizer::FinishGesture;
+    else
+        return QGestureRecognizer::CancelGesture;
+}
+
+TwoFingerSwipeRecognizer::TwoFingerSwipeRecognizer()
+    : QGestureRecognizer()
+{}
+
+QGesture *TwoFingerSwipeRecognizer::create(QObject *target)
+{
+    if (target && target->isWidgetType())
+        qobject_cast<QWidget *>(target)->setAttribute(Qt::WA_AcceptTouchEvents);
+
+    return new TwoFingerSwipe;
+}
+
+QGestureRecognizer::Result TwoFingerSwipeRecognizer::recognize(QGesture *gesture,
+                                                               QObject *,
+                                                               QEvent *event)
+{
+    if (gesture->gestureType() != TwoFingerSwipe::type())
+        return QGestureRecognizer::Ignore;
+
+    TwoFingerSwipe *swipe = static_cast<TwoFingerSwipe *>(gesture);
+    QTouchEvent *touch = static_cast<QTouchEvent *>(event);
+
+    switch (event->type()) {
+    case QEvent::TouchBegin:
+        return swipe->begin(touch);
+
+    case QEvent::TouchUpdate:
+        return swipe->update(touch);
+
+    case QEvent::TouchEnd:
+        return swipe->end(touch);
+
+    default:
+        return QGestureRecognizer::Ignore;
+    }
+}
+
+void TwoFingerSwipeRecognizer::reset(QGesture *gesture)
+{
+    if (gesture->gestureType() == TwoFingerSwipe::type()) {
+        TwoFingerSwipe *swipe = static_cast<TwoFingerSwipe *>(gesture);
+        swipe->reset();
+    }
+    QGestureRecognizer::reset(gesture);
+}
+
+} // End namespace QmlDesigner.
diff --git a/src/plugins/qmldesigner/components/componentcore/gestures.h b/src/plugins/qmldesigner/components/componentcore/gestures.h
new file mode 100644
index 0000000000..3100560904
--- /dev/null
+++ b/src/plugins/qmldesigner/components/componentcore/gestures.h
@@ -0,0 +1,72 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the Qt Design Tooling
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+****************************************************************************/
+#pragma once
+
+#include <QGesture>
+#include <QGestureRecognizer>
+#include <QLineF>
+
+QT_FORWARD_DECLARE_CLASS(QTouchEvent)
+
+namespace QmlDesigner {
+
+class TwoFingerSwipe : public QGesture
+{
+    Q_OBJECT
+
+public:
+    TwoFingerSwipe();
+
+    static Qt::GestureType type();
+    static void registerRecognizer();
+
+    QPointF direction() const;
+
+    void reset();
+    QGestureRecognizer::Result begin(QTouchEvent *event);
+    QGestureRecognizer::Result update(QTouchEvent *event);
+    QGestureRecognizer::Result end(QTouchEvent *event);
+
+private:
+    static Qt::GestureType m_type;
+
+    QLineF m_start;
+    QLineF m_current;
+    QLineF m_last;
+};
+
+class TwoFingerSwipeRecognizer : public QGestureRecognizer
+{
+public:
+    TwoFingerSwipeRecognizer();
+
+    QGesture *create(QObject *target) override;
+
+    QGestureRecognizer::Result recognize(QGesture *gesture, QObject *watched, QEvent *event) override;
+
+    void reset(QGesture *gesture) override;
+};
+
+} // namespace QmlDesigner
diff --git a/src/plugins/qmldesigner/components/componentcore/navigation2d.cpp b/src/plugins/qmldesigner/components/componentcore/navigation2d.cpp
index 94d6b5ad38..eccd8a517e 100644
--- a/src/plugins/qmldesigner/components/componentcore/navigation2d.cpp
+++ b/src/plugins/qmldesigner/components/componentcore/navigation2d.cpp
@@ -23,10 +23,13 @@
 **
 ****************************************************************************/
 #include "navigation2d.h"
+#include "gestures.h"
 
 #include <QGestureEvent>
 #include <QWheelEvent>
 
+#include <cmath>
+
 namespace QmlDesigner {
 
 Navigation2dScrollBar::Navigation2dScrollBar(QWidget *parent)
@@ -53,39 +56,60 @@ Navigation2dFilter::Navigation2dFilter(QWidget *parent, Navigation2dScrollBar *s
     : QObject(parent)
     , m_scrollbar(scrollbar)
 {
-    if (parent)
+    if (parent) {
         parent->grabGesture(Qt::PinchGesture);
+        if (!scrollbar)
+            parent->grabGesture(TwoFingerSwipe::type());
+    }
 }
 
-bool Navigation2dFilter::eventFilter(QObject *, QEvent *event)
+bool Navigation2dFilter::eventFilter(QObject *object, QEvent *event)
 {
     if (event->type() == QEvent::Gesture)
         return gestureEvent(static_cast<QGestureEvent *>(event));
-    else if (event->type() == QEvent::Wheel && m_scrollbar)
+    else if (event->type() == QEvent::Wheel)
         return wheelEvent(static_cast<QWheelEvent *>(event));
 
-    return QObject::event(event);
+    return QObject::eventFilter(object, event);
 }
 
 bool Navigation2dFilter::gestureEvent(QGestureEvent *event)
 {
     if (QPinchGesture *pinch = static_cast<QPinchGesture *>(event->gesture(Qt::PinchGesture))) {
         QPinchGesture::ChangeFlags changeFlags = pinch->changeFlags();
-        if (changeFlags & QPinchGesture::ScaleFactorChanged) {
+        if (changeFlags.testFlag(QPinchGesture::ScaleFactorChanged)) {
             emit zoomChanged(-(1.0 - pinch->scaleFactor()), pinch->startCenterPoint());
             event->accept();
             return true;
         }
+    } else if (TwoFingerSwipe *swipe = static_cast<TwoFingerSwipe *>(
+                   event->gesture(TwoFingerSwipe::type()))) {
+        emit panChanged(swipe->direction());
+        event->accept();
+        return true;
     }
     return false;
 }
 
 bool Navigation2dFilter::wheelEvent(QWheelEvent *event)
 {
-    if (m_scrollbar->postEvent(event))
-        event->ignore();
-
-    return false;
+    if (m_scrollbar) {
+        if (m_scrollbar->postEvent(event))
+            event->ignore();
+    } else if (event->source() == Qt::MouseEventNotSynthesized) {
+        if (event->modifiers().testFlag(Qt::ControlModifier)) {
+            if (QPointF angle = event->angleDelta(); !angle.isNull()) {
+                double delta = std::abs(angle.x()) > std::abs(angle.y()) ? angle.x() : angle.y();
+                if (delta > 0)
+                    emit zoomIn();
+                else
+                    emit zoomOut();
+                event->accept();
+                return true;
+            }
+        }
+    }
+    return true;
 }
 
 } // End namespace QmlDesigner.
diff --git a/src/plugins/qmldesigner/components/componentcore/navigation2d.h b/src/plugins/qmldesigner/components/componentcore/navigation2d.h
index 434b59055c..fe432b4a6b 100644
--- a/src/plugins/qmldesigner/components/componentcore/navigation2d.h
+++ b/src/plugins/qmldesigner/components/componentcore/navigation2d.h
@@ -51,6 +51,10 @@ class Navigation2dFilter : public QObject
 
 signals:
     void zoomChanged(double scale, const QPointF &pos);
+    void panChanged(const QPointF &direction);
+
+    void zoomIn();
+    void zoomOut();
 
 public:
     Navigation2dFilter(QWidget *parent = nullptr, Navigation2dScrollBar *scrollbar = nullptr);
diff --git a/src/plugins/qmldesigner/components/componentcore/zoomaction.cpp b/src/plugins/qmldesigner/components/componentcore/zoomaction.cpp
index c59c1ffe83..024dd60502 100644
--- a/src/plugins/qmldesigner/components/componentcore/zoomaction.cpp
+++ b/src/plugins/qmldesigner/components/componentcore/zoomaction.cpp
@@ -24,130 +24,135 @@
 ****************************************************************************/
 
 #include "zoomaction.h"
+#include "formeditorwidget.h"
+#include <algorithm>
+#include <iterator>
+#include <utility>
 
-#include <QComboBox>
 #include <QAbstractItemView>
+#include <QComboBox>
+#include <QToolBar>
+
+#include <cmath>
 
 namespace QmlDesigner {
 
-const int defaultZoomIndex = 13;
+// Order matters!
+std::array<double, 27> ZoomAction::m_zooms = {
+    0.01, 0.02, 0.05, 0.0625, 0.1, 0.125, 0.2, 0.25, 0.33, 0.5,  0.66, 0.75, 0.9,
+    1.0, 1.1, 1.25, 1.33, 1.5, 1.66, 1.75, 2.0, 3.0, 4.0, 6.0, 8.0, 10.0, 16.0
+};
 
-ZoomAction::ZoomAction(QObject *parent)
-    :  QWidgetAction(parent),
-    m_zoomLevel(1.0),
-    m_currentComboBoxIndex(defaultZoomIndex)
+bool isValidIndex(int index)
 {
+    if (index >= 0 && index < static_cast<int>(ZoomAction::zoomLevels().size()))
+        return true;
 
+    return false;
 }
 
-float ZoomAction::zoomLevel() const
-{
-    return m_zoomLevel;
-}
+ZoomAction::ZoomAction(QObject *parent)
+    : QWidgetAction(parent)
+    , m_combo(nullptr)
+{}
 
-void ZoomAction::zoomIn()
+std::array<double, 27> ZoomAction::zoomLevels()
 {
-    if (m_currentComboBoxIndex < (m_comboBoxModel->rowCount() - 1))
-        emit indexChanged(m_currentComboBoxIndex + 1);
+    return m_zooms;
 }
 
-void ZoomAction::zoomOut()
+int ZoomAction::indexOf(double zoom)
 {
-    if (m_currentComboBoxIndex > 0)
-        emit indexChanged(m_currentComboBoxIndex - 1);
-}
+    auto finder = [zoom](double val) { return qFuzzyCompare(val, zoom); };
+    if (auto iter = std::find_if(m_zooms.begin(), m_zooms.end(), finder); iter != m_zooms.end())
+        return static_cast<int>(std::distance(m_zooms.begin(), iter));
 
-void ZoomAction::resetZoomLevel()
-{
-    m_zoomLevel = 1.0;
-    m_currentComboBoxIndex = defaultZoomIndex;
-    emit reseted();
+    return -1;
 }
 
-void ZoomAction::setZoomLevel(float zoomLevel)
+void ZoomAction::setZoomFactor(double zoom)
 {
-    if (qFuzzyCompare(m_zoomLevel, zoomLevel))
+    if (int index = indexOf(zoom); index >= 0) {
+        m_combo->setCurrentIndex(index);
+        m_combo->setToolTip(m_combo->currentText());
         return;
-
-    forceZoomLevel(zoomLevel);
+    }
+    int rounded = static_cast<int>(std::round(zoom * 100));
+    m_combo->setEditable(true);
+    m_combo->setEditText(QString::number(rounded) + " %");
+    m_combo->setToolTip(m_combo->currentText());
 }
 
-void ZoomAction::forceZoomLevel(float zoomLevel)
+double ZoomAction::setNextZoomFactor(double zoom)
 {
-    m_zoomLevel = qBound(0.01f, zoomLevel, 16.0f);
-    emit zoomLevelChanged(m_zoomLevel);
+    if (zoom >= m_zooms.back())
+        return zoom;
+
+    auto greater = [zoom](double val) { return val > zoom; };
+    if (auto iter = std::find_if(m_zooms.begin(), m_zooms.end(), greater); iter != m_zooms.end()) {
+        auto index = std::distance(m_zooms.begin(), iter);
+        m_combo->setCurrentIndex(static_cast<int>(index));
+        m_combo->setToolTip(m_combo->currentText());
+        return *iter;
+    }
+    return zoom;
 }
 
-//initial m_zoomLevel and m_currentComboBoxIndex
-const QVector<float> s_zoomFactors = {0.01f, 0.02f, 0.05f, 0.0625f, 0.1f, 0.125f, 0.2f, 0.25f,
-                                      0.33f, 0.5f, 0.66f, 0.75f, 0.9f, 1.0f, 1.1f, 1.25f, 1.33f,
-                                      1.5f, 1.66f, 1.75f, 2.0f, 3.0f, 4.0f, 6.0f, 8.0f, 10.0f, 16.0f };
-
-int getZoomIndex(float zoom)
+double ZoomAction::setPreviousZoomFactor(double zoom)
 {
-    for (int i = 0; i < s_zoomFactors.length(); i++) {
-        if (qFuzzyCompare(s_zoomFactors.at(i), zoom))
-            return i;
+    if (zoom <= m_zooms.front())
+        return zoom;
+
+    auto smaller = [zoom](double val) { return val < zoom; };
+    if (auto iter = std::find_if(m_zooms.rbegin(), m_zooms.rend(), smaller); iter != m_zooms.rend()) {
+        auto index = std::distance(iter, m_zooms.rend() - 1);
+        m_combo->setCurrentIndex(static_cast<int>(index));
+        m_combo->setToolTip(m_combo->currentText());
+        return *iter;
     }
-    return -1;
+    return zoom;
 }
 
-float ZoomAction::getClosestZoomLevel(float zoomLevel)
+bool parentIsFormEditor(QWidget *parent)
 {
-    int i = 0;
-    while (i < s_zoomFactors.size() && s_zoomFactors[i] < zoomLevel)
-        ++i;
+    while (parent) {
+        if (qobject_cast<FormEditorWidget *>(parent))
+            return true;
+        parent = qobject_cast<QWidget *>(parent->parent());
+    }
+    return false;
+}
 
-    return s_zoomFactors[qBound(0, i - 1, s_zoomFactors.size() - 1)];
+QComboBox *createZoomComboBox(QWidget *parent)
+{
+    auto *combo = new QComboBox(parent);
+    for (double z : ZoomAction::zoomLevels()) {
+        const QString name = QString::number(z * 100., 'g', 4) + " %";
+        combo->addItem(name, z);
+    }
+    return combo;
 }
 
 QWidget *ZoomAction::createWidget(QWidget *parent)
 {
-    auto comboBox = new QComboBox(parent);
-
-    /*
-     * When add zoom levels do not forget to update defaultZoomIndex
-     */
-    if (m_comboBoxModel.isNull()) {
-        m_comboBoxModel = comboBox->model();
-        for (float z : s_zoomFactors) {
-            const QString name = QString::number(z * 100, 'g', 4) + " %";
-            comboBox->addItem(name, z);
-        }
-    } else {
-        comboBox->setModel(m_comboBoxModel.data());
+    if (!m_combo && parentIsFormEditor(parent)) {
+        m_combo = createZoomComboBox(parent);
+        m_combo->setProperty("hideborder", true);
+        m_combo->setCurrentIndex(indexOf(1.0));
+        m_combo->setToolTip(m_combo->currentText());
+
+        auto currentChanged = QOverload<int>::of(&QComboBox::currentIndexChanged);
+        connect(m_combo, currentChanged, this, &ZoomAction::emitZoomLevelChanged);
+
+        return m_combo.data();
     }
+    return nullptr;
+}
 
-    comboBox->setCurrentIndex(m_currentComboBoxIndex);
-    comboBox->setToolTip(comboBox->currentText());
-    connect(this, &ZoomAction::reseted, comboBox, [this, comboBox]() {
-        blockSignals(true);
-        comboBox->setCurrentIndex(m_currentComboBoxIndex);
-        blockSignals(false);
-    });
-    connect(comboBox, QOverload<int>::of(&QComboBox::currentIndexChanged),
-            [this, comboBox](int index) {
-        m_currentComboBoxIndex = index;
-
-        if (index == -1)
-            return;
-
-        const QModelIndex modelIndex(m_comboBoxModel.data()->index(index, 0));
-        setZoomLevel(m_comboBoxModel.data()->data(modelIndex, Qt::UserRole).toFloat());
-        comboBox->setToolTip(modelIndex.data().toString());
-    });
-
-    connect(this, &ZoomAction::indexChanged, comboBox, &QComboBox::setCurrentIndex);
-
-    connect(this, &ZoomAction::zoomLevelChanged, comboBox, [comboBox](double zoom){
-        const int index = getZoomIndex(zoom);
-        if (comboBox->currentIndex() != index)
-            comboBox->setCurrentIndex(index);
-    });
-
-    comboBox->setProperty("hideborder", true);
-    comboBox->setMaximumWidth(qMax(comboBox->view()->sizeHintForColumn(0) / 2, 16));
-    return comboBox;
+void ZoomAction::emitZoomLevelChanged(int index)
+{
+    if (index >= 0 && index < static_cast<int>(m_zooms.size()))
+        emit zoomLevelChanged(m_zooms[static_cast<size_t>(index)]);
 }
 
 } // namespace QmlDesigner
diff --git a/src/plugins/qmldesigner/components/componentcore/zoomaction.h b/src/plugins/qmldesigner/components/componentcore/zoomaction.h
index bd46f915d9..85d855c1d1 100644
--- a/src/plugins/qmldesigner/components/componentcore/zoomaction.h
+++ b/src/plugins/qmldesigner/components/componentcore/zoomaction.h
@@ -26,11 +26,13 @@
 
 #include <qmldesignercorelib_global.h>
 
-#include <QWidgetAction>
 #include <QPointer>
+#include <QWidgetAction>
+
+#include <array>
 
 QT_BEGIN_NAMESPACE
-class QAbstractItemModel;
+class QComboBox;
 QT_END_NAMESPACE
 
 namespace QmlDesigner {
@@ -39,30 +41,27 @@ class QMLDESIGNERCORE_EXPORT ZoomAction : public QWidgetAction
 {
     Q_OBJECT
 
+signals:
+    void zoomLevelChanged(double zoom);
+
 public:
     ZoomAction(QObject *parent);
 
-    float zoomLevel() const;
-
-    void zoomIn();
-    void zoomOut();
-    void resetZoomLevel();
-    void setZoomLevel(float zoomLevel);
-    void forceZoomLevel(float zoomLevel);
+    static std::array<double, 27> zoomLevels();
+    static int indexOf(double zoom);
 
-    static float getClosestZoomLevel(float zoomLevel);
+    void setZoomFactor(double zoom);
+    double setNextZoomFactor(double zoom);
+    double setPreviousZoomFactor(double zoom);
 
 protected:
     QWidget *createWidget(QWidget *parent) override;
-signals:
-    void zoomLevelChanged(float zoom);
-    void indexChanged(int);
-    void reseted();
 
 private:
-    QPointer<QAbstractItemModel> m_comboBoxModel;
-    float m_zoomLevel;
-    int m_currentComboBoxIndex;
+    void emitZoomLevelChanged(int index);
+
+    static std::array<double, 27> m_zooms;
+    QPointer<QComboBox> m_combo;
 };
 
 } // namespace QmlDesigner