Fix issue161 and 174. Use the same logic for selction and dragging, but ignore entites that are inherently undraggable.

This allows the selection to reach through entities to their corresponding ones on the underlying sketch which can be dragged if they are not fully constrained. This is decided in a new function Entity::CanBeDragged().

src/draw.cpp

@@ -353,18 +353,34 @@ GraphicsWindow::Selection GraphicsWindow::ChooseFromHoverToSelect() {
     return sel;
 }
 
+// This uses the same logic as hovering and static entity selection
+// but ignores points known not to be draggable
 GraphicsWindow::Selection GraphicsWindow::ChooseFromHoverToDrag() {
     Selection sel = {};
-    for(const Hover &hov : hoverList) {
-        if(hov.selection.entity.v == 0) continue;
-        if(!hov.selection.entity.isFromRequest()) continue;
-        sel = hov.selection;
-        break;
-    }
-    if(!sel.IsEmpty()) {
+    if(hoverList.IsEmpty())
         return sel;
+
+    Group *activeGroup = SK.GetGroup(SS.GW.activeGroup);
+    int bestOrder = -1;
+    int bestZIndex = 0;
+    for(const Hover &hov : hoverList) {
+        hGroup hg = {};
+        if(hov.selection.entity.v != 0) {
+            Entity *e = SK.GetEntity(hov.selection.entity);
+            if (!e->CanBeDragged()) continue;
+            hg = e->group;
+        } else if(hov.selection.constraint.v != 0) {
+            hg = SK.GetConstraint(hov.selection.constraint)->group;
+        }
+
+        Group *g = SK.GetGroup(hg);
+        if(g->order > activeGroup->order) continue;
+        if(bestOrder != -1 && (bestOrder >= g->order || bestZIndex > hov.zIndex)) continue;
+        bestOrder  = g->order;
+        bestZIndex = hov.zIndex;
+        sel = hov.selection;
     }
-    return ChooseFromHoverToSelect();
+    return sel;
 }
 
 void GraphicsWindow::HitTestMakeSelection(Point2d mp) {

src/drawentity.cpp

@@ -180,6 +180,25 @@ bool Entity::IsVisible() const {
     return true;
 }
 
+// entities that were created via some copy types will not be
+// draggable with the mouse. We identify the undraggables here
+bool Entity::CanBeDragged() const {
+    // a numeric copy can not move
+    if(type == Entity::Type::POINT_N_COPY) return false;
+    // these transforms applied zero times can not be moved
+    if(((type == Entity::Type::POINT_N_TRANS) ||
+       (type == Entity::Type::POINT_N_ROT_AA) ||
+       (type == Entity::Type::POINT_N_ROT_TRANS) ||
+       (type == Entity::Type::POINT_N_ROT_AXIS_TRANS))
+        && (timesApplied == 0)) return false;
+    // for these types of entities the first point will indicate draggability
+    if(HasEndpoints() || type == Entity::Type::CIRCLE) {
+        return SK.GetEntity(point[0])->CanBeDragged();
+    }
+    // if we're not certain it can't be dragged then default to true
+    return true;
+}
+
 void Entity::CalculateNumerical(bool forExport) {
     if(IsPoint()) actPoint = PointGetNum();
     if(IsNormal()) actNormal = NormalGetNum();

src/sketch.h

@@ -566,6 +566,7 @@ public:
 
     bool IsStylable() const;
     bool IsVisible() const;
+    bool CanBeDragged() const;
 
     enum class DrawAs { DEFAULT, OVERLAY, HIDDEN, HOVERED, SELECTED };
     void Draw(DrawAs how, Canvas *canvas);