[TD]add extensions for drag and drop

src/Mod/TechDraw/Gui/ViewProviderPageExtension.cpp

@@ -0,0 +1,134 @@
+/***************************************************************************
+ *   Copyright (c) 2022 WandererFan <wandererfan@gmail.com>                *
+ *                                                                         *
+ *   This file is part of the FreeCAD CAx development system.              *
+ *                                                                         *
+ *   This library is free software; you can redistribute it and/or         *
+ *   modify it under the terms of the GNU Library General Public           *
+ *   License as published by the Free Software Foundation; either          *
+ *   version 2 of the License, or (at your option) any later version.      *
+ *                                                                         *
+ *   This library  is distributed in the hope that it will be useful,      *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
+ *   GNU Library General Public License for more details.                  *
+ *                                                                         *
+ *   You should have received a copy of the GNU Library General Public     *
+ *   License along with this library; see the file COPYING.LIB. If not,    *
+ *   write to the Free Software Foundation, Inc., 59 Temple Place,         *
+ *   Suite 330, Boston, MA  02111-1307, USA                                *
+ *                                                                         *
+ ***************************************************************************/
+
+#include "PreCompiled.h"
+
+#ifndef _PreComp_
+# include <QMessageBox>
+#endif
+
+#include <App/Document.h>
+#include <App/DocumentObject.h>
+#include <Base/Console.h>
+#include <Base/Tools.h>
+
+#include <Mod/TechDraw/App/DrawPage.h>
+#include <Mod/TechDraw/App/DrawTemplate.h>
+#include <Mod/TechDraw/App/DrawProjGroupItem.h>
+
+#include "ViewProviderPageExtension.h"
+#include "ViewProviderPage.h"
+
+using namespace TechDrawGui;
+
+EXTENSION_PROPERTY_SOURCE(TechDrawGui::ViewProviderPageExtension, Gui::ViewProviderExtension)
+
+ViewProviderPageExtension::ViewProviderPageExtension()
+{
+    initExtensionType(ViewProviderPageExtension::getExtensionClassTypeId());
+}
+
+ViewProviderPageExtension::~ViewProviderPageExtension()
+{
+}
+
+bool ViewProviderPageExtension::extensionCanDragObjects() const {
+    return true;
+}
+
+//we don't want another extension to drag our objects, so we say that we can handle this object
+bool ViewProviderPageExtension::extensionCanDragObject(App::DocumentObject* docObj) const {
+    (void) docObj;
+    return true;
+}
+
+//we don't take any action on drags.  everything is handling in drop
+void ViewProviderPageExtension::extensionDragObject(App::DocumentObject* obj) {
+    (void) obj;
+}
+
+//we handle our own drops
+bool ViewProviderPageExtension::extensionCanDropObjects() const {
+    return true;
+}
+
+bool ViewProviderPageExtension::extensionCanDropObject(App::DocumentObject* obj) const {
+    //only DrawView objects can live on pages (except special case Template)
+    if ( obj->isDerivedFrom(TechDraw::DrawView::getClassTypeId()) ) {
+        return true;
+    }
+    if ( obj->isDerivedFrom(TechDraw::DrawTemplate::getClassTypeId()) ) {
+        //don't let another extension try to drop templates
+        return true;
+    }
+
+    return false;
+}
+
+void ViewProviderPageExtension::extensionDropObject(App::DocumentObject* obj) {
+    if ( obj->isDerivedFrom(TechDraw::DrawView::getClassTypeId()) ) {
+        dropObject(obj);
+        return;
+    }
+}
+
+//this code used to live in ViewProviderPage
+void ViewProviderPageExtension::dropObject(App::DocumentObject* docObj)
+{
+    if (docObj->isDerivedFrom(TechDraw::DrawProjGroupItem::getClassTypeId())) {
+        //DPGI can not be dropped onto the Page as it belongs to DPG, not Page
+        return;
+    }
+    if (docObj->isDerivedFrom(TechDraw::DrawView::getClassTypeId()) ) {
+        auto dv = static_cast<TechDraw::DrawView*>(docObj);
+        if (dv->findParentPage()) {
+            dv->findParentPage()->removeView(dv);
+        }
+        getViewProviderPage()->getDrawPage()->addView(dv);
+        //don't run ancestor's method as addView does everything we need
+        return;
+    }
+    //don't try to drop random objects
+}
+
+const ViewProviderPage* ViewProviderPageExtension::getViewProviderPage() const
+{
+    return dynamic_cast<const ViewProviderPage*>(getExtendedViewProvider());
+}
+
+
+const char*  ViewProviderPageExtension::whoAmI() const
+{
+    auto parent = getViewProviderPage();
+    if (parent) {
+        return parent->whoAmI();
+    }
+    return nullptr;
+}
+
+namespace Gui {
+EXTENSION_PROPERTY_SOURCE_TEMPLATE(ViewProviderPageExtensionPython, ViewProviderPageExtension)
+
+// explicit template instantiation
+template class GuiExport ViewProviderExtensionPythonT<ViewProviderPageExtension>;
+}
+