SDLPP: add option to specify render object alignment

sdlpp/sdlpp_renderobject.hpp

@@ -12,7 +12,14 @@
 #include <vector>
 
 namespace SDLPP {
-class SDLPPSCOPE Scene;
+
+enum ObjectAlignment {
+    OBJ_START,
+    OBJ_CENTER,
+    OBJ_END,
+};
+
+class Scene;
 
 class SDLPPSCOPE RenderObject {
 public:
@@ -82,10 +89,10 @@ public:
     virtual void move( int ticks );
     virtual void custom_move( int ticks ) = 0;
     virtual void updateSizeAndPosition() = 0;
+    virtual void updateXY();
     virtual SDL_Rect getRect() = 0;
     void setPermanent( bool perm = true );
     bool getPermanent() const;
-    virtual void centerX() = 0;
     virtual std::shared_ptr< RenderObject > copySelf() = 0;
     bool isStatic();
     void setStatic( bool stat = true );
@@ -103,6 +110,7 @@ public:
     void removeAnimation();
     void animate( int ticks );
     void visit( Visitor &visitor );
+    void setAlignment( ObjectAlignment horizontal, ObjectAlignment vertical );
 
 protected:
     virtual void copyTo( std::shared_ptr< RenderObject > other );
@@ -115,6 +123,7 @@ protected:
     double movementSpeed = 0;
     Vec2D< double > movementDirection = { 0, 0 };
     std::vector< std::shared_ptr< RenderObject > > colidedWith;
+    virtual Vec2D< double > computeAlignmentAdditions();
     uint64_t id = -1;
     bool hidden = false;
     bool kill = false;
@@ -133,12 +142,14 @@ protected:
     bool animating = true;
 
 private:
-    void setSceneID( int id );
     friend Scene;
+    void setSceneID( int id );
 
 protected:
     Vec2D< double > original;
     Vec2D< double > current;
+    ObjectAlignment _horizontal = OBJ_START;
+    ObjectAlignment _vertical = OBJ_START;
 };
 } // end of namespace SDLPP