Let tangent arc modify the original entities.

Modifying the original entities instead of deleting them, retains the
original associated constraints. This makes creating rounded rectangles
a lot easier.

CHANGELOG.md

@@ -88,6 +88,8 @@ Bugs fixed:
   * A step rotate/translate group using a group forced to triangle mesh
     as a source group also gets forced to triangle mesh.
   * Paste Transformed with a negative scale does not invert arcs.
+  * The tangent arc now modifies the original entities instead of deleting
+    them, such that their constraints are retained.
 
 2.x
 ---

src/modify.cpp

@@ -161,19 +161,32 @@ Vector GraphicsWindow::ParametricCurve::TangentAt(double t) {
         return t;
     }
 }
-hRequest GraphicsWindow::ParametricCurve::CreateRequestTrimmedTo(double t,
+/** Changes or copies the given entity and connects it to the arc.
-    bool extraConstraints, hEntity orig, hEntity arc, bool arcFinish)
+ * \param t Where on this parametric curve does it connect to the arc.
+ * \param reuseOrig Should the original entity be modified
+ * \param orig The original entity.
+ * \param arc The arc that will be connected to.
+ * \param arcFinish Whether to connect to the end point of the arc.
+ * \param pointf When changing the original entity, whether the end point should be modified.
+ */
+void GraphicsWindow::ParametricCurve::CreateRequestTrimmedTo(double t,
+    bool reuseOrig, hEntity orig, hEntity arc, bool arcFinish, bool pointf)
 {
     hRequest hr;
     Entity *e;
     if(isLine) {
-        hr = SS.GW.AddRequest(Request::Type::LINE_SEGMENT, /*rememberForUndo=*/false),
+        if (reuseOrig) {
-        e = SK.GetEntity(hr.entity(0));
+            e = SK.GetEntity(orig);
-        SK.GetEntity(e->point[0])->PointForceTo(PointAt(t));
+            int i = pointf ? 1 : 0;
-        SK.GetEntity(e->point[1])->PointForceTo(PointAt(1));
+            SK.GetEntity(e->point[i])->PointForceTo(PointAt(t));
-        ConstrainPointIfCoincident(e->point[0]);
+            ConstrainPointIfCoincident(e->point[i]);
-        ConstrainPointIfCoincident(e->point[1]);
+        } else {
-        if(extraConstraints) {
+            hr = SS.GW.AddRequest(Request::Type::LINE_SEGMENT, /*rememberForUndo=*/false),
+            e = SK.GetEntity(hr.entity(0));
+            SK.GetEntity(e->point[0])->PointForceTo(PointAt(t));
+            SK.GetEntity(e->point[1])->PointForceTo(PointAt(1));
+            ConstrainPointIfCoincident(e->point[0]);
+            ConstrainPointIfCoincident(e->point[1]);
             Constraint::Constrain(Constraint::Type::PT_ON_LINE,
                 hr.entity(1), Entity::NO_ENTITY, orig);
         }
@@ -181,26 +194,32 @@ hRequest GraphicsWindow::ParametricCurve::CreateRequestTrimmedTo(double t,
             Entity::NO_ENTITY, Entity::NO_ENTITY,
             arc, e->h, /*other=*/arcFinish, /*other2=*/false);
     } else {
-        hr = SS.GW.AddRequest(Request::Type::ARC_OF_CIRCLE, /*rememberForUndo=*/false),
+        if (reuseOrig) {
-        e = SK.GetEntity(hr.entity(0));
+            e = SK.GetEntity(orig);
-        SK.GetEntity(e->point[0])->PointForceTo(p0);
+            int i = pointf ? 2 : 1;
-        if(dtheta > 0) {
+            SK.GetEntity(e->point[i])->PointForceTo(PointAt(t));
-            SK.GetEntity(e->point[1])->PointForceTo(PointAt(t));
+            ConstrainPointIfCoincident(e->point[i]);
-            SK.GetEntity(e->point[2])->PointForceTo(PointAt(1));
         } else {
-            SK.GetEntity(e->point[2])->PointForceTo(PointAt(t));
+            hr = SS.GW.AddRequest(Request::Type::ARC_OF_CIRCLE, /*rememberForUndo=*/false),
-            SK.GetEntity(e->point[1])->PointForceTo(PointAt(1));
+            e = SK.GetEntity(hr.entity(0));
+            SK.GetEntity(e->point[0])->PointForceTo(p0);
+            if(dtheta > 0) {
+                SK.GetEntity(e->point[1])->PointForceTo(PointAt(t));
+                SK.GetEntity(e->point[2])->PointForceTo(PointAt(1));
+            } else {
+                SK.GetEntity(e->point[2])->PointForceTo(PointAt(t));
+                SK.GetEntity(e->point[1])->PointForceTo(PointAt(1));
+            }
+            ConstrainPointIfCoincident(e->point[0]);
+            ConstrainPointIfCoincident(e->point[1]);
+            ConstrainPointIfCoincident(e->point[2]);
         }
-        ConstrainPointIfCoincident(e->point[0]);
-        ConstrainPointIfCoincident(e->point[1]);
-        ConstrainPointIfCoincident(e->point[2]);
         // The tangency constraint alone is enough to fully constrain it,
         // so there's no need for more.
         Constraint::Constrain(Constraint::Type::CURVE_CURVE_TANGENT,
             Entity::NO_ENTITY, Entity::NO_ENTITY,
             arc, e->h, /*other=*/arcFinish, /*other2=*/(dtheta < 0));
     }
-    return hr;
 }
 
 //-----------------------------------------------------------------------------
@@ -388,6 +407,27 @@ void GraphicsWindow::MakeTangentArc() {
 
     SS.UndoRemember();
 
+    if (SS.tangentArcModify) {
+        // Delete the coincident constraint for the removed point.
+        SK.constraint.ClearTags();
+        for(i = 0; i < SK.constraint.n; i++) {
+            Constraint *cs = &(SK.constraint.elem[i]);
+            if(cs->group.v != activeGroup.v) continue;
+            if(cs->workplane.v != ActiveWorkplane().v) continue;
+            if(cs->type != Constraint::Type::POINTS_COINCIDENT) continue;
+            if (SK.GetEntity(cs->ptA)->PointGetNum().Equals(pshared)) {
+            cs->tag = 1;
+            }
+        }
+        SK.constraint.RemoveTagged();
+    } else {
+        // Make the original entities construction, or delete them
+        // entirely, according to user preference.
+        SK.GetRequest(hreq[0])->construction = true;
+        SK.GetRequest(hreq[1])->construction = true;
+    }
+
+    // Create and position the new tangent arc.
     hRequest harc = AddRequest(Request::Type::ARC_OF_CIRCLE, /*rememberForUndo=*/false);
     Entity *earc = SK.GetEntity(harc.entity(0));
     hEntity hearc = earc->h;
@@ -398,27 +438,11 @@ void GraphicsWindow::MakeTangentArc() {
 
     earc = NULL;
 
-    pc[0].CreateRequestTrimmedTo(t[0], !SS.tangentArcDeleteOld,
+    // Modify or duplicate the original entities and connect them to the tangent arc.
-                hent[0], hearc, /*arcFinish=*/(b == 1));
+    pc[0].CreateRequestTrimmedTo(t[0], SS.tangentArcModify,
-    pc[1].CreateRequestTrimmedTo(t[1], !SS.tangentArcDeleteOld,
+                hent[0], hearc, /*arcFinish=*/(b == 1), pointf[0]);
-                hent[1], hearc, /*arcFinish=*/(a == 1));
+    pc[1].CreateRequestTrimmedTo(t[1], SS.tangentArcModify,
-
+                hent[1], hearc, /*arcFinish=*/(a == 1), pointf[1]);
-    // Now either make the original entities construction, or delete them
-    // entirely, according to user preference.
-    Request *re;
-    SK.request.ClearTags();
-    for(re = SK.request.First(); re; re = SK.request.NextAfter(re)) {
-        if(re->h.v == hreq[0].v || re->h.v == hreq[1].v) {
-            if(SS.tangentArcDeleteOld) {
-                re->tag = 1;
-            } else {
-                re->construction = true;
-            }
-        }
-    }
-    if(SS.tangentArcDeleteOld) {
-        DeleteTaggedRequests();
-    }
 }
 
 hEntity GraphicsWindow::SplitLine(hEntity he, Vector pinter) {

src/solvespace.h

@@ -638,7 +638,7 @@ public:
     // as special requests.
     double tangentArcRadius;
     bool tangentArcManual;
-    bool tangentArcDeleteOld;
+    bool tangentArcModify;
 
     // The platform-dependent code calls this before entering the msg loop
     void Init();

src/textscreens.cpp

@@ -643,7 +643,7 @@ void TextWindow::ScreenChangeTangentArc(int link, uint32_t v) {
         }
 
         case 'a': SS.tangentArcManual = !SS.tangentArcManual; break;
-        case 'd': SS.tangentArcDeleteOld = !SS.tangentArcDeleteOld; break;
+        case 'm': SS.tangentArcModify = !SS.tangentArcModify; break;
     }
 }
 void TextWindow::ShowTangentArc() {
@@ -662,9 +662,9 @@ void TextWindow::ShowTangentArc() {
     Printf(false, "  %Fd%f%La%s  choose radius automatically%E",
         &ScreenChangeTangentArc,
         !SS.tangentArcManual ? CHECK_TRUE : CHECK_FALSE);
-    Printf(false, "  %Fd%f%Ld%s  delete original entities afterward%E",
+    Printf(false, "  %Fd%f%Lm%s  modify original entities%E",
         &ScreenChangeTangentArc,
-        SS.tangentArcDeleteOld ? CHECK_TRUE : CHECK_FALSE);
+        SS.tangentArcModify ? CHECK_TRUE : CHECK_FALSE);
 
     Printf(false, "");
     Printf(false, "To create a tangent arc at a point,");

src/ui.h

@@ -668,8 +668,8 @@ public:
         Vector TangentAt(double t);
         double LengthForAuto();
 
-        hRequest CreateRequestTrimmedTo(double t, bool extraConstraints,
+        void CreateRequestTrimmedTo(double t, bool reuseOrig,
-            hEntity orig, hEntity arc, bool arcFinish);
+            hEntity orig, hEntity arc, bool arcFinish, bool pointf);
         void ConstrainPointIfCoincident(hEntity hpt);
     };
     void MakeTangentArc();
@@ -718,6 +718,7 @@ public:
     void HitTestMakeSelection(Point2d mp);
     void ClearSelection();
     void ClearNonexistentSelectionItems();
+    /// This structure is filled by a call to GroupSelection().
     struct {
         std::vector<hEntity>     point;
         std::vector<hEntity>     entity;
@@ -740,7 +741,7 @@ public:
         int         stylables;
         int         constraintLabels;
         int         withEndpoints;
-        int         n;
+        int         n;                 ///< Number of selected items
     } gs;
     void GroupSelection();
     bool IsSelected(Selection *s);