Gui: allow SelectionSingleton::hasSubSelection() check for sub-element

This is used by relative link command activation for sub-element
selection

src/Gui/CommandLink.cpp

@@ -197,7 +197,7 @@ void StdCmdLinkMakeGroup::activated(int option) {
 
 ////////////////////////////////////////////////////////////////////////////////////////////
 
-DEF_STD_CMD(StdCmdLinkMake)
+DEF_STD_CMD_A(StdCmdLinkMake)
 
 StdCmdLinkMake::StdCmdLinkMake()
   : Command("Std_LinkMake")
@@ -211,6 +211,10 @@ StdCmdLinkMake::StdCmdLinkMake()
     sPixmap       = "Link";
 }
 
+bool StdCmdLinkMake::isActive() {
+    return !!App::GetApplication().getActiveDocument();
+}
+
 void StdCmdLinkMake::activated(int) {
     auto doc = App::GetApplication().getActiveDocument();
     if(!doc) {
@@ -263,7 +267,7 @@ StdCmdLinkMakeRelative::StdCmdLinkMakeRelative()
 {
     sGroup        = QT_TR_NOOP("Link");
     sMenuText     = QT_TR_NOOP("Make relative link");
-    sToolTipText  = QT_TR_NOOP("Create a relative link of two selected objects");
+    sToolTipText  = QT_TR_NOOP("Create a sub-object or sub-element link");
     sWhatsThis    = "Std_LinkMakeRelative";
     sStatusTip    = sToolTipText;
     eType         = AlterDoc;
@@ -271,7 +275,7 @@ StdCmdLinkMakeRelative::StdCmdLinkMakeRelative()
 }
 
 bool StdCmdLinkMakeRelative::isActive() {
-    return Selection().hasSubSelection();
+    return Selection().hasSubSelection(0,true);
 }
 
 void StdCmdLinkMakeRelative::activated(int) {

src/Gui/Selection.cpp

@@ -437,7 +437,7 @@ bool SelectionSingleton::hasSelection(const char* doc, bool resolve) const
     return false;
 }
 
-bool SelectionSingleton::hasSubSelection(const char* doc) const
+bool SelectionSingleton::hasSubSelection(const char* doc, bool subElement) const
 {
     App::Document *pcDoc = 0;
     if(!doc || strcmp(doc,"*")!=0) {
@@ -446,11 +446,14 @@ bool SelectionSingleton::hasSubSelection(const char* doc) const
             return false;
     }
     for(auto &sel : _SelList) {
-        if((!pcDoc || pcDoc == sel.pDoc)
-                && sel.pObject != sel.pResolvedObject)
-        {
+        if(pcDoc && pcDoc != sel.pDoc)
+            continue;
+        if(sel.SubName.empty())
+            continue;
+        if(subElement && sel.SubName.back()!='.')
+            return true;
+        if(sel.pObject != sel.pResolvedObject)
             return true;
-        }
     }
 
     return false;
@@ -1794,7 +1797,7 @@ PyMethodDef SelectionSingleton::Methods[] = {
     {"hasSelection",      (PyCFunction) SelectionSingleton::sHasSelection, METH_VARARGS,
      "hasSelection(docName=None, resolve=False) -- check if there is any selection\n"},
     {"hasSubSelection",   (PyCFunction) SelectionSingleton::sHasSubSelection, METH_VARARGS,
-     "hasSubSelection(docName=None) -- check if there is any selection with subname\n"},
+     "hasSubSelection(docName=None,subElement=False) -- check if there is any selection with subname\n"},
     {"getSelectionFromStack",(PyCFunction) SelectionSingleton::sGetSelectionFromStack, METH_VARARGS,
      "getSelectionFromStack(docName=None,resolve=1,index=0) -- Return a list of SelectionObjects from selection stack\n"
      "\ndocName - document name. None means the active document, and '*' means all document"
@@ -2271,11 +2274,13 @@ PyObject *SelectionSingleton::sHasSelection(PyObject * /*self*/, PyObject *args)
 PyObject *SelectionSingleton::sHasSubSelection(PyObject * /*self*/, PyObject *args)
 {
     const char *doc = 0;
-    if (!PyArg_ParseTuple(args, "|s",&doc))
+    PyObject *subElement = Py_False;
+    if (!PyArg_ParseTuple(args, "|sO!",&doc,&PyBool_Type,&subElement))
         return NULL;                             // NULL triggers exception 
 
     PY_TRY {
-        return Py::new_reference_to(Py::Boolean(Selection().hasSubSelection(doc)));
+        return Py::new_reference_to(
+                Py::Boolean(Selection().hasSubSelection(doc,PyObject_IsTrue(subElement))));
     } PY_CATCH;
 }
 

src/Gui/Selection.h

@@ -506,7 +506,19 @@ public:
     std::vector<SelObj> getCompleteSelection(int resolve=1) const;
     bool hasSelection() const;
     bool hasSelection(const char* doc, bool resolve=true) const;
-    bool hasSubSelection(const char *doc=0) const;
+
+    /** Check if there is any sub-element selection
+     *
+     * @param doc: optional document to check for selection
+     * @param subElement: whether to count sub-element only selection
+     *
+     * Example sub selections are face, edge or vertex. If \c resolve is false,
+     * then sub-object (i.e. a group child object) selection is also counted
+     * even if it selects the whole sub-object.
+     */
+    bool hasSubSelection(const char *doc=0, bool subElement=false) const;
+
+    /// Check if there is any pre-selection
     bool hasPreselection() const;
 
     /// Size of selected entities for all documents