Change signature and usage

Schematic::sizeOfSelection returns values back to the client
via four reference variables passed to it as arguments. This
is not very elegant and most important it doesn't convey return
values semantics.

This commit makes 'sizeOfSelection' return QRect as usual return
value of function.

qucs/schematic.cpp

@@ -934,14 +934,10 @@ void Schematic::zoomToSelection() {
                     return;
                 }
 
-    // Coordinates of top-left and bottom-right corners of the selected
-    // elements bounding rectangle
-    int selectedX1, selectedX2, selectedY1, selectedY2 = 0;
-    sizeOfSelection(selectedX1, selectedY1, selectedX2, selectedY2);
+    const QRect selectedBoundingRect{ sizeOfSelection() };
 
     // Working with raw coordinates is clumsy, abstract them out
     const QRect usedBoundingRect{UsedX1, UsedY1, UsedX2 - UsedX1, UsedY2 - UsedY1};
-    const QRect selectedBoundingRect{selectedX1, selectedY1, selectedX2 - selectedX1, selectedY2 - selectedY1};
 
     if (selectedBoundingRect.width() == 0 || selectedBoundingRect.height() == 0) {
         // If nothing is selected, then what should be shown? Probably it's best
@@ -1284,22 +1280,20 @@ void Schematic::sizeOfAll(int &xmin, int &ymin, int &xmax, int &ymax)
     }
 }
 
-void Schematic::sizeOfSelection(int &xmin, int &ymin, int &xmax, int &ymax)
+QRect Schematic::sizeOfSelection() const
 {
-    xmin = INT_MAX;
-    ymin = INT_MAX;
-    xmax = INT_MIN;
-    ymax = INT_MIN;
+    int xmin = INT_MAX;
+    int ymin = INT_MAX;
+    int xmax = INT_MIN;
+    int ymax = INT_MIN;
 
     bool isAnySelected = false;
 
     if (Components->isEmpty())
         if (Wires->isEmpty())
             if (Diagrams->isEmpty())
                 if (Paintings->isEmpty()) {
-                    xmin = xmax = 0;
-                    ymin = ymax = 0;
-                    return;
+                    return QRect{};
                 }
 
     int x1, y1, x2, y2;
@@ -1417,9 +1411,10 @@ void Schematic::sizeOfSelection(int &xmin, int &ymin, int &xmax, int &ymax)
     }
 
     if (!isAnySelected) {
-        xmin = xmax = 0;
-        ymin = ymax = 0;
+        return QRect{};
     }
+
+    return QRect{xmin, ymin, xmax - xmin, ymax - ymin};
 }
 
 // ---------------------------------------------------

qucs/schematic.h

@@ -93,7 +93,7 @@ class Schematic : public Q3ScrollView, public QucsDoc {
   float textCorr();
   bool sizeOfFrame(int&, int&);
   void  sizeOfAll(int&, int&, int&, int&);
-  void  sizeOfSelection(int&, int&, int&, int&);
+  QRect  sizeOfSelection() const;
   bool  rotateElements();
   bool  mirrorXComponents();
   bool  mirrorYComponents();