Lots of UI Component Updates

src/dawn/scene/components/ui/UICanvas.cpp

@@ -16,7 +16,6 @@ std::shared_ptr<UICanvas> UICanvas::createCanvas(std::shared_ptr<Scene> scene) {
 }
 
 UICanvas::UICanvas(SceneItem &item) : SceneItemComponent(item) {
-
 }
 
 float_t UICanvas::getWidth() {
@@ -27,6 +26,27 @@ float_t UICanvas::getHeight() {
   return this->getGame().renderManager.getBackBuffer().getHeight();
 }
 
-void UICanvas::start() {
+void UICanvas::onStart() {
+  std::cout << "Canvas event" << std::endl;
+  this->getGame().renderManager.getBackBuffer()
+    .eventRenderTargetResized.addListener(this, &UICanvas::onBackBufferResize)
+  ;
+}
 
+void UICanvas::onBackBufferResize(
+  RenderTarget &target,
+  float_t width,
+  float_t height
+) {
+  auto it = this->children.begin();
+  while(it != this->children.end()) {
+    (*it)->updatePositions();
+    ++it;
+  }
+}
+
+UICanvas::~UICanvas() {
+  this->getGame().renderManager.getBackBuffer()
+    .eventRenderTargetResized.removeListener(this, &UICanvas::onBackBufferResize)
+  ;
 }