ui: implemented gui abstraction and dummy view

- added abstract class tree for gui elements.
- implemented concrete gui classes that wrap the qt specific content.
- implemented first DummyView which plays nice with the ViewManager.

review id = 12

src/lib/component/view/View.cpp

@@ -1,5 +1,35 @@
 #include "component/view/View.h"
+#include "component/view/ViewManager.h"
+
+View::View(std::shared_ptr<ViewManager> viewManager, std::shared_ptr<GuiElement> rootElement, const Vec2i& minSize)
+	: m_viewManager(viewManager)
+	, m_rootElement(rootElement)
+	, m_minSize(minSize)
+{
+	m_viewManager->addView(this);
+}
 
 View::~View()
 {
+	m_viewManager->removeView(this);
+}
+
+std::shared_ptr<GuiElement> View::getRootElement()
+{
+	return m_rootElement;
+}
+
+int View::getMinWidth() const
+{
+	return m_minSize.x;
+}
+
+int View::getMinHeight() const
+{
+	return m_minSize.y;
+}
+
+Vec2i View::getMinSize() const
+{
+	return m_minSize;
 }