Allow displaying and editing diameter constraints as radius.

The savefile format is not changed; the display option is
stored in Constraint::other.

src/describescreen.cpp

@@ -41,6 +41,16 @@ void TextWindow::ScreenSetTtfFont(int link, uint32_t v) {
     SS.ScheduleShowTW();
 }
 
+void TextWindow::ScreenConstraintShowAsRadius(int link, uint32_t v) {
+    hConstraint hc = { v };
+    Constraint *c = SK.GetConstraint(hc);
+
+    SS.UndoRemember();
+    c->other = !c->other;
+
+    SS.ScheduleShowTW();
+}
+
 void TextWindow::DescribeSelection(void) {
     Entity *e;
     Vector p;
@@ -291,8 +301,18 @@ void TextWindow::DescribeSelection(void) {
     } else if(gs.n == 0 && gs.stylables > 0) {
         Printf(false, "%FtSELECTED:%E comment text");
     } else if(gs.n == 0 && gs.constraints == 1) {
+        Constraint *c = SK.GetConstraint(gs.constraint[0]);
+
+        if(c->type == Constraint::DIAMETER) {
+            Printf(false, "%FtDIAMETER CONSTRAINT");
+
+            Printf(true, "  %Fd%f%D%Ll%c  show as radius",
+                   &ScreenConstraintShowAsRadius, gs.constraint[0],
+                   c->other ? CHECK_TRUE : CHECK_FALSE);
+        } else {
             Printf(false, "%FtSELECTED:%E %s",
-            SK.GetConstraint(gs.constraint[0])->DescriptionString());
+                c->DescriptionString());
+        }
     } else {
         int n = SS.GW.selection.n;
         Printf(false, "%FtSELECTED:%E %d item%s", n, n == 1 ? "" : "s");

src/drawconstraint.cpp

@@ -66,8 +66,12 @@ char *Constraint::Label(void) {
     } else if(type == COMMENT) {
         strcpy(Ret, comment.str);
     } else if(type == DIAMETER) {
+        if(!other) {
             // leading spaces for diameter symbol
             sprintf(Ret, "  %s", SS.MmToString(valA));
+        } else {
+            sprintf(Ret, "R%s", SS.MmToString(valA / 2));
+        }
     } else {
         // valA has units of distance
         strcpy(Ret, SS.MmToString(fabs(valA)));
@@ -521,6 +525,8 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
             DoLabel(ref, &topLeft, gr, gu);
             if(labelPos) *labelPos = topLeft;
 
+            // Show this as diameter or radius?
+            if(!other) {
                 // Draw the diameter symbol
                 Vector dc = topLeft;
                 dc = dc.Plus(gu.WithMagnitude(5/SS.GW.scale));
@@ -542,6 +548,7 @@ void Constraint::DrawOrGetDistance(Vector *labelPos) {
                             gr.WithMagnitude(sin(theta)*dr)),
                     dc.Plus(gu.WithMagnitude(cos(theta+dtheta)*dr)).Plus(
                             gr.WithMagnitude(sin(theta+dtheta)*dr)));
+            }
             break;
         }
 

src/mouse.cpp

@@ -1157,6 +1157,11 @@ void GraphicsWindow::MouseLeftDoubleClick(double mx, double my) {
 
             default: {
                 double v = fabs(c->valA);
+
+                // If displayed as radius, also edit as radius.
+                if(c->type == Constraint::DIAMETER && c->other)
+                    v /= 2;
+
                 char *def = SS.MmToString(v);
                 double eps = 1e-12;
                 if(fabs(SS.StringToMm(def) - v) < eps) {
@@ -1217,6 +1222,15 @@ void GraphicsWindow::EditControlDone(const char *s) {
                 c->valA = fabs(e->Eval());
                 break;
 
+            case Constraint::DIAMETER:
+                c->valA = fabs(SS.ExprToMm(e));
+
+                // If displayed and edited as radius, convert back
+                // to diameter
+                if(c->other)
+                    c->valA *= 2;
+                break;
+
             default:
                 // These are always positive, and they get the units conversion.
                 c->valA = fabs(SS.ExprToMm(e));

src/ui.h

@@ -236,6 +236,9 @@ public:
     static void ScreenSetTtfFont(int link, uint32_t v);
     static void ScreenUnselectAll(int link, uint32_t v);
 
+    // when we're describing a constraint
+    static void ScreenConstraintShowAsRadius(int link, uint32_t v);
+
     // and the rest from the stuff in textscreens.cpp
     static void ScreenSelectGroup(int link, uint32_t v);
     static void ScreenActivateGroup(int link, uint32_t v);