QmlDesigner: Integrate drag and drop into the model/views system

so that any view can easily gets notified when a drag in another view
is started/ended.
This allows a view to show a highlight when a valid drag is started in
another view without coupling the 2 views.

Change-Id: I030d3dfe23ee06e2afdc0e4bbffc0b8d0c59f2f8
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>
Reviewed-by: Samuel Ghinet <samuel.ghinet@qt.io>

src/plugins/qmldesigner/components/itemlibrary/itemlibrarywidget.cpp

@@ -40,7 +40,6 @@
 #include "modelnodeoperations.h"
 #include <metainfo.h>
 #include <model.h>
-#include <navigatorwidget.h>
 #include <rewritingexception.h>
 #include <qmldesignerconstants.h>
 #include <qmldesignerplugin.h>
@@ -89,6 +88,9 @@ static QString propertyEditorResourcesPath()
 
 bool ItemLibraryWidget::eventFilter(QObject *obj, QEvent *event)
 {
+    auto document = QmlDesignerPlugin::instance()->currentDesignDocument();
+    Model *model = document ? document->documentModel() : nullptr;
+
     if (event->type() == QEvent::FocusOut) {
         if (obj == m_itemsWidget.data())
             QMetaObject::invokeMethod(m_itemsWidget->rootObject(), "closeContextMenu");
@@ -115,33 +117,19 @@ bool ItemLibraryWidget::eventFilter(QObject *obj, QEvent *event)
                         }
                     }
                 }
-                QWidget *view = QmlDesignerPlugin::instance()->viewManager().widget("Navigator");
-                if (view) {
-                    NavigatorWidget *navView = qobject_cast<NavigatorWidget *>(view);
-                    if (navView) {
-                        navView->setDragType(entry.typeName());
-                        navView->update();
+
+                if (model) {
+                    model->startDrag(m_itemLibraryModel->getMimeData(entry),
+                                     Utils::StyleHelper::dpiSpecificImageFile(entry.libraryEntryIconPath()));
                 }
-                }
-                auto drag = new QDrag(this);
-                drag->setPixmap(Utils::StyleHelper::dpiSpecificImageFile(entry.libraryEntryIconPath()));
-                drag->setMimeData(m_itemLibraryModel->getMimeData(entry));
-                drag->exec();
-                drag->deleteLater();
 
                 m_itemToDrag = {};
             }
         }
     } else if (event->type() == QMouseEvent::MouseButtonRelease) {
         m_itemToDrag = {};
-        QWidget *view = QmlDesignerPlugin::instance()->viewManager().widget("Navigator");
-        if (view) {
-            NavigatorWidget *navView = qobject_cast<NavigatorWidget *>(view);
-            if (navView) {
-                navView->setDragType("");
-                navView->update();
-            }
-        }
+        if (model)
+            model->endDrag();
     }
 
     return QObject::eventFilter(obj, event);

src/plugins/qmldesigner/components/navigator/navigatorview.cpp

@@ -36,6 +36,7 @@
 #include <bindingproperty.h>
 #include <designmodecontext.h>
 #include <designersettings.h>
+#include <itemlibraryinfo.h>
 #include <nodeproperty.h>
 #include <nodelistproperty.h>
 #include <variantproperty.h>
@@ -57,8 +58,9 @@
 #include <utils/stylehelper.h>
 
 #include <QHeaderView>
-#include <QTimer>
+#include <QMimeData>
 #include <QPixmap>
+#include <QTimer>
 
 static inline void setScenePos(const QmlDesigner::ModelNode &modelNode,const QPointF &pos)
 {
@@ -264,6 +266,25 @@ void NavigatorView::bindingPropertiesChanged(const QList<BindingProperty> & prop
     }
 }
 
+void NavigatorView::dragStarted(QMimeData *mimeData)
+{
+    if (mimeData->hasFormat("application/vnd.bauhaus.itemlibraryinfo")) {
+        QByteArray data = mimeData->data("application/vnd.bauhaus.itemlibraryinfo");
+        QDataStream stream(data);
+        ItemLibraryEntry itemLibraryEntry;
+        stream >> itemLibraryEntry;
+
+        m_widget->setDragType(itemLibraryEntry.typeName());
+        m_widget->update();
+    }
+}
+
+void NavigatorView::dragEnded()
+{
+    m_widget->setDragType("");
+    m_widget->update();
+}
+
 void NavigatorView::customNotification(const AbstractView *view, const QString &identifier,
                                        const QList<ModelNode> &nodeList, const QList<QVariant> &data)
 {

src/plugins/qmldesigner/components/navigator/navigatorview.h

@@ -92,6 +92,9 @@ public:
 
     void bindingPropertiesChanged(const QList<BindingProperty> &propertyList, PropertyChangeFlags) override;
 
+    void dragStarted(QMimeData *mimeData) override;
+    void dragEnded() override;
+
     void customNotification(const AbstractView *view, const QString &identifier, const QList<ModelNode> &nodeList, const QList<QVariant> &data) override;
 
     void handleChangedExport(const ModelNode &modelNode, bool exported);

src/plugins/qmldesigner/designercore/include/abstractview.h

@@ -254,6 +254,9 @@ public:
     virtual void updateImport3DSupport(const QVariantMap &supportMap);
     virtual void modelNodePreviewPixmapChanged(const ModelNode &node, const QPixmap &pixmap);
 
+    virtual void dragStarted(QMimeData *mimeData);
+    virtual void dragEnded();
+
     void changeRootNodeType(const TypeName &type, int majorVersion, int minorVersion);
 
     NodeInstanceView *nodeInstanceView() const;

src/plugins/qmldesigner/designercore/include/model.h

@@ -129,6 +129,9 @@ public:
     QString generateNewId(const QString &prefixName) const;
     QString generateNewId(const QString &prefixName, const QString &fallbackPrefix) const;
 
+    void startDrag(QMimeData *mimeData, const QString iconPath = {});
+    void endDrag();
+
 protected:
     Model();
 

src/plugins/qmldesigner/designercore/model/abstractview.cpp

@@ -398,6 +398,9 @@ void AbstractView::modelNodePreviewPixmapChanged(const ModelNode & /*node*/, con
 {
 }
 
+void AbstractView::dragStarted(QMimeData *mimeData) {}
+void AbstractView::dragEnded() {}
+
 QList<ModelNode> AbstractView::toModelNodeList(const QList<Internal::InternalNode::Pointer> &nodeList) const
 {
     return QmlDesigner::toModelNodeList(nodeList, const_cast<AbstractView*>(this));

src/plugins/qmldesigner/designercore/model/model.cpp

@@ -67,6 +67,7 @@
 
 #include <utils/algorithm.h>
 
+#include <QDrag>
 #include <QRegularExpression>
 
 /*!
@@ -588,6 +589,16 @@ void ModelPrivate::notifyImport3DSupportChanged(const QVariantMap &supportMap)
     notifyInstanceChanges([&](AbstractView *view) { view->updateImport3DSupport(supportMap); });
 }
 
+void ModelPrivate::notifyDragStarted(QMimeData *mimeData)
+{
+    notifyInstanceChanges([&](AbstractView *view) { view->dragStarted(mimeData); });
+}
+
+void ModelPrivate::notifyDragEnded()
+{
+    notifyInstanceChanges([&](AbstractView *view) { view->dragEnded(); });
+}
+
 void ModelPrivate::notifyRewriterBeginTransaction()
 {
     notifyNodeInstanceViewLast([&](AbstractView *view) { view->rewriterBeginTransaction(); });
@@ -1492,6 +1503,22 @@ QString Model::generateNewId(const QString &prefixName, const QString &fallbackP
     return newId;
 }
 
+void Model::startDrag(QMimeData *mimeData, const QString iconPath)
+{
+    d->notifyDragStarted(mimeData);
+
+    auto drag = new QDrag(this);
+    drag->setPixmap(iconPath);
+    drag->setMimeData(mimeData);
+    drag->exec();
+    drag->deleteLater();
+}
+
+void Model::endDrag()
+{
+    d->notifyDragEnded();
+}
+
 QString Model::generateNewId(const QString &prefixName) const
 {
     return generateNewId(prefixName, QStringLiteral("element"));

src/plugins/qmldesigner/designercore/model/model_p.h

@@ -183,6 +183,9 @@ public:
     void notifyModelNodePreviewPixmapChanged(const ModelNode &node, const QPixmap &pixmap);
     void notifyImport3DSupportChanged(const QVariantMap &supportMap);
 
+    void notifyDragStarted(QMimeData *mimeData);
+    void notifyDragEnded();
+
     void setDocumentMessages(const QList<DocumentMessage> &errors, const QList<DocumentMessage> &warnings);
 
     void notifyRewriterBeginTransaction();