Layout.h
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	#ifndef _ECHOLAYOUTELEMENT_H_
	#define _ECHOLAYOUTELEMENT_H_

	#include <echo/GUI/Container.h>

	namespace Echo
	{
	namespace GUI
	{
	/**
	* An element that positions its child elements either horizontally or vertically.
	* The space that the contents of a layout vary depending on the size mode used.
	*/
	class Layout : public Container
	{
	public:
	/**
	* Available Directions the layout can place elements in.
	* Typically the X axis is horizontal and the Y axis is vertical. There aren't any
	* situations at the moment where this is not true.
	*/
	struct Directions
	{
	enum _
	{
	HORIZONTAL_MIN_TO_MAX, /// Place elements horizontally from the minimum to maximum in the order they were added.
	HORIZONTAL_MAX_TO_MIN, /// Place elements horizontally from the maximum to minimum in the order they were added.
	VERTICAL_MIN_TO_MAX, /// Place elements vertically from the minimum to maximum in the order they were added.
	VERTICAL_MAX_TO_MIN /// Place elements vertically from the maximum to minimum in the order they were added.
	};
	};
	typedef Directions::_ Direction;

	struct PlacementModes
	{
	enum _
	{
	FIT_CONTENTS, /// Contents will be scaled to fit the layout size, some child size modes have unspecified* behaviour,
	/// For example: Horizontal directions do not support height first child element size modes as these
	/// modes expect to be able to determine the width but the horizontal placement needs to be able to
	/// scale by the width of the child element, which in doing so would break the height first rule.
	/// Children using the max fit size modes
	ALLOW_OVERFLOW, /// Contents will be positioned and are allowed to be positioned outside of the layout's bounds. All size
	/// modes are supported.
	};
	};
	typedef PlacementModes::_ PlacementMode;

	Layout(Direction direction = Directions::HORIZONTAL_MIN_TO_MAX, PlacementMode placementMode = PlacementModes::FIT_CONTENTS);
	virtual ~Layout();

	/**
	* Copying a layout only copies the layout settings and not the child elements.
	* See the base class documentation for more information on element copying.
	* If you want to copy the layout with contents consider the Clone() method.
	* @see Element::operator=() for documentation on Element copying.
	* @see Node::operator=() for documentation on copying.
	*/
	Layout(const Layout& other);
	Layout& operator=(const Layout& other);

	/**
	* Set the direction of the layout.
	* @param direction The direction.
	*/
	void SetDirection(Direction direction);

	/**
	* Set the placement mode of the layout.
	* @see PlacementModes.
	* @param palcementMode the placement mode.
	*/
	void SetPlacementMode(PlacementMode placementMode);

	/**
	* Get the direction of the layout.
	* @return the direction.
	*/
	Direction GetDirection() const {return mDirection;}

	/**
	* Get the placement mode of the layout.
	* @see PlacementModes.
	* @return the placement mode.
	*/
	PlacementMode GetPlacementMode() const {return mPlacementMode;}

	/**
	* Set whether to apply settings on child elements when the layout changes so they are positioned consistently.
	* When this is turned off child parameters are persistent when you modify layout settings. For example,
	* changing from a vertical layout to a horizontal layout will mean all child elements will still have the
	* vertical from the previous direction.
	* This setting was added so you could create a layout and modify the child element's parameters to get the
	* desired result and not worry about your changes being overwritten.
	* When this setting is enabled elements are aligned centre to the the layout and the size mode is modified
	* to the most appropriate for the layout's setting.
	* This setting is enabled by default.
	* @note Positions are always overwritten.
	* @note Sizes are always overwritten when using PlacementModes::FIT_CONTENTS.
	* @note Each placement mode and direction has will modify the alignment for the corresponding axis to lay the
	* items out adjacent to one another.
	*/
	void SetUseOptimalChildSettings(bool useOptimalChildSettings);

	/**
	* These methods are overridden from Element so we can manage our own ordered
	* list of elements.
	* Adding an element to a Layout will cause some of its parameters to be modified. For example, when
	* the layout is updated the alignment is set to best fit with positioning elements.
	*/
	virtual void AddElement(shared_ptr<Element> element) override;
	virtual void RemoveElement(shared_ptr<Element> element) override;
	virtual void RemoveElement(Element& element) override;

	/**
	* Update the position and size of the children as per the layout settings.
	* This method is usually automatically called within the class however because elements currently aren't
	* reporting size changes to their parent elements this method is public for classes that will need the
	* layout updated at specific times.
	*/
	void UpdateChildren();
	private:
	virtual shared_ptr<Element> _Clone() const override;

	void ChildrenHorizontalMinToMax();
	void ChildrenHorizontalMaxToMin();
	void ChildrenVerticalMinToMax();
	void ChildrenVerticalMaxToMin();
	void SetOptimalChildSettings();

	Direction mDirection;
	PlacementMode mPlacementMode;
	bool mUseOptimalChildSettings;
	typedef std::list< Element* > OrderedChildrenContainer;
	OrderedChildrenContainer mOrderedChildren;
	};
	}
	}
	#endif

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