From 290a19e7735dbfb6527d89b75a102b575083116a Mon Sep 17 00:00:00 2001
From: wandererfan <wandererfan@gmail.com>
Date: Thu, 3 Nov 2022 08:58:02 -0400
Subject: [PATCH] [TD]fix view drag and drop to page

---
 src/Mod/TechDraw/Gui/ViewProviderPage.cpp | 55 +++++++++++++++++++++++
 src/Mod/TechDraw/Gui/ViewProviderPage.h   |  6 +++
 2 files changed, 61 insertions(+)

diff --git a/src/Mod/TechDraw/Gui/ViewProviderPage.cpp b/src/Mod/TechDraw/Gui/ViewProviderPage.cpp
index a3c3281339..4a36526192 100644
--- a/src/Mod/TechDraw/Gui/ViewProviderPage.cpp
+++ b/src/Mod/TechDraw/Gui/ViewProviderPage.cpp
@@ -460,6 +460,61 @@ bool ViewProviderPage::canDelete(App::DocumentObject *obj) const
     return true;
 }
 
+bool ViewProviderPage::canDragObjects() const
+{
+//    Base::Console().Message("VPP:canDragObjects()\n");
+    return ViewProviderDocumentObject::canDragObjects();
+}
+
+bool ViewProviderPage::canDragObject(App::DocumentObject* docObj) const
+{
+//    Base::Console().Message("VPP:canDragObject()\n");
+    if (docObj->isDerivedFrom(TechDraw::DrawProjGroupItem::getClassTypeId())) {
+        //DPGI can not be dragged from the Page as it belongs to DPG, not Page
+        return false;
+    }
+
+    if (docObj->isDerivedFrom(TechDraw::DrawView::getClassTypeId()) ) {
+        return true;
+    }
+    return false;
+}
+
+
+bool ViewProviderPage::canDropObject(App::DocumentObject* docObj) const
+{
+//    Base::Console().Message("VPP:canDropObject()\n");
+    if (docObj->isDerivedFrom(TechDraw::DrawProjGroupItem::getClassTypeId())) {
+        //DPGI can not be dropped onto the Page as it belongs to DPG, not Page
+        return false;
+    }
+
+    if (docObj->isDerivedFrom(TechDraw::DrawView::getClassTypeId()) ) {
+        return true;
+    }
+    return false;
+}
+
+void ViewProviderPage::dropObject(App::DocumentObject* docObj)
+{
+//    Base::Console().Message("VPP:dropObject()\n");
+    if (docObj->isDerivedFrom(TechDraw::DrawProjGroupItem::getClassTypeId())) {
+        //DPGI can not be dropped onto the Page as it belongs to DPG, not Page
+        ViewProviderDocumentObject::dropObject(docObj);
+        return;
+    }
+    if (docObj->isDerivedFrom(TechDraw::DrawView::getClassTypeId()) ) {
+        auto dv = static_cast<TechDraw::DrawView*>(docObj);
+        if (dv->findParentPage()) {
+            dv->findParentPage()->removeView(dv);
+        }
+        getDrawPage()->addView(dv);
+        //don't run ancestor's method as addView does everything we need
+        return;
+    }
+    ViewProviderDocumentObject::dropObject(docObj);
+}
+
 //! Redo the whole visual page
 void ViewProviderPage::onGuiRepaint(const TechDraw::DrawPage* dp)
 {
diff --git a/src/Mod/TechDraw/Gui/ViewProviderPage.h b/src/Mod/TechDraw/Gui/ViewProviderPage.h
index 3ec2ac0829..04331bba3c 100644
--- a/src/Mod/TechDraw/Gui/ViewProviderPage.h
+++ b/src/Mod/TechDraw/Gui/ViewProviderPage.h
@@ -59,6 +59,12 @@ public:
 
     void attach(App::DocumentObject *) override;
     void setDisplayMode(const char* ModeName) override;
+
+    bool canDragObjects() const override;
+    bool canDragObject(App::DocumentObject* docObj) const override;
+    bool canDropObject(App::DocumentObject* docObj) const override;
+    void dropObject(App::DocumentObject* docObj) override;
+
     bool useNewSelectionModel() const override {return false;}
     /// returns a list of all possible modes
     std::vector<std::string> getDisplayModes() const override;