SDLPP: add option to specify render object alignment

sdlpp/sdlpp_renderobject.cpp

@@ -242,4 +242,39 @@ void RenderObject::setAnimationSpeed( const double fps ) {
 void RenderObject::visit( Visitor &visitor ) {
     visitor.visit( *this );
 }
+void RenderObject::setAlignment( ObjectAlignment horizontal,
+                                 ObjectAlignment vertical ) {
+    _horizontal = horizontal;
+    _vertical = vertical;
+}
+Vec2D< double > RenderObject::computeAlignmentAdditions() {
+    double x_addition = 0, y_addition = 0;
+    auto dimensions = renderer->getDoubleDimensions();
+    auto width_diff = dimensions.getX() - 1;
+    auto height_diff = dimensions.getY() - 1;
+    switch ( _horizontal ) {
+    case OBJ_CENTER:
+        x_addition = width_diff / 2;
+        break;
+    case OBJ_END:
+        x_addition = width_diff;
+    default:
+        break;
+    }
+    switch ( _vertical ) {
+    case OBJ_CENTER:
+        y_addition = height_diff / 2;
+        break;
+    case OBJ_END:
+        y_addition = height_diff;
+    default:
+        break;
+    }
+    return { x_addition, y_addition };
+}
+void RenderObject::updateXY() {
+    auto additions = computeAlignmentAdditions();
+    current = { original.getX() + additions.getX(),
+                original.getY() + additions.getY() };
+}
 } // namespace SDLPP