/** 
 * @file llui.h
 * @brief GL function declarations and other general static UI services.
 *
 * $LicenseInfo:firstyear=2001&license=viewergpl$
 * 
 * Copyright (c) 2001-2007, Linden Research, Inc.
 * 
 * Second Life Viewer Source Code
 * The source code in this file ("Source Code") is provided by Linden Lab
 * to you under the terms of the GNU General Public License, version 2.0
 * ("GPL"), unless you have obtained a separate licensing agreement
 * ("Other License"), formally executed by you and Linden Lab.  Terms of
 * the GPL can be found in doc/GPL-license.txt in this distribution, or
 * online at http://secondlife.com/developers/opensource/gplv2
 * 
 * There are special exceptions to the terms and conditions of the GPL as
 * it is applied to this Source Code. View the full text of the exception
 * in the file doc/FLOSS-exception.txt in this software distribution, or
 * online at http://secondlife.com/developers/opensource/flossexception
 * 
 * By copying, modifying or distributing this software, you acknowledge
 * that you have read and understood your obligations described above,
 * and agree to abide by those obligations.
 * 
 * ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
 * WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
 * COMPLETENESS OR PERFORMANCE.
 * $/LicenseInfo$
 */

// All immediate-mode gl drawing should happen here.

#ifndef LL_LLUI_H
#define LL_LLUI_H

#include "llrect.h"
#include "llcontrol.h"
#include "llrect.h"
#include "llcoord.h"
#include "llhtmlhelp.h"
#include "llgl.h"
#include <stack>
#include "llimagegl.h"

// LLUIFactory
#include "llsd.h"

class LLColor4; 
class LLVector3;
class LLVector2;
class LLUUID;
class LLWindow;
class LLView;
class LLUIImage;

// UI colors
extern const LLColor4 UI_VERTEX_COLOR;
void make_ui_sound(const LLString& name);

BOOL ui_point_in_rect(S32 x, S32 y, S32 left, S32 top, S32 right, S32 bottom);
void gl_state_for_2d(S32 width, S32 height);

void gl_line_2d(S32 x1, S32 y1, S32 x2, S32 y2);
void gl_line_2d(S32 x1, S32 y1, S32 x2, S32 y2, const LLColor4 &color );
void gl_triangle_2d(S32 x1, S32 y1, S32 x2, S32 y2, S32 x3, S32 y3, const LLColor4& color, BOOL filled);
void gl_rect_2d_simple( S32 width, S32 height );

void gl_draw_x(const LLRect& rect, const LLColor4& color);

void gl_rect_2d(S32 left, S32 top, S32 right, S32 bottom, BOOL filled = TRUE );
void gl_rect_2d(S32 left, S32 top, S32 right, S32 bottom, const LLColor4 &color, BOOL filled = TRUE );
void gl_rect_2d_offset_local( S32 left, S32 top, S32 right, S32 bottom, const LLColor4 &color, S32 pixel_offset = 0, BOOL filled = TRUE );
void gl_rect_2d_offset_local( S32 left, S32 top, S32 right, S32 bottom, S32 pixel_offset = 0, BOOL filled = TRUE );
void gl_rect_2d(const LLRect& rect, BOOL filled = TRUE );
void gl_rect_2d(const LLRect& rect, const LLColor4& color, BOOL filled = TRUE );
void gl_rect_2d_checkerboard(const LLRect& rect);

void gl_drop_shadow(S32 left, S32 top, S32 right, S32 bottom, const LLColor4 &start_color, S32 lines);

void gl_circle_2d(F32 x, F32 y, F32 radius, S32 steps, BOOL filled);
void gl_arc_2d(F32 center_x, F32 center_y, F32 radius, S32 steps, BOOL filled, F32 start_angle, F32 end_angle);
void gl_deep_circle( F32 radius, F32 depth );
void gl_ring( F32 radius, F32 width, const LLColor4& center_color, const LLColor4& side_color, S32 steps, BOOL render_center );
void gl_corners_2d(S32 left, S32 top, S32 right, S32 bottom, S32 length, F32 max_frac);
void gl_washer_2d(F32 outer_radius, F32 inner_radius, S32 steps, const LLColor4& inner_color, const LLColor4& outer_color);
void gl_washer_segment_2d(F32 outer_radius, F32 inner_radius, F32 start_radians, F32 end_radians, S32 steps, const LLColor4& inner_color, const LLColor4& outer_color);
void gl_washer_spokes_2d(F32 outer_radius, F32 inner_radius, S32 count, const LLColor4& inner_color, const LLColor4& outer_color);

void gl_draw_image(S32 x, S32 y, LLImageGL* image, const LLColor4& color = UI_VERTEX_COLOR, const LLRectf& uv_rect = LLRectf(0.f, 1.f, 1.f, 0.f));
void gl_draw_scaled_image(S32 x, S32 y, S32 width, S32 height, LLImageGL* image, const LLColor4& color = UI_VERTEX_COLOR, const LLRectf& uv_rect = LLRectf(0.f, 1.f, 1.f, 0.f));
void gl_draw_rotated_image(S32 x, S32 y, F32 degrees, LLImageGL* image, const LLColor4& color = UI_VERTEX_COLOR, const LLRectf& uv_rect = LLRectf(0.f, 1.f, 1.f, 0.f));
void gl_draw_scaled_rotated_image(S32 x, S32 y, S32 width, S32 height, F32 degrees,LLImageGL* image, const LLColor4& color = UI_VERTEX_COLOR, const LLRectf& uv_rect = LLRectf(0.f, 1.f, 1.f, 0.f));
void gl_draw_scaled_image_with_border(S32 x, S32 y, S32 border_width, S32 border_height, S32 width, S32 height, LLImageGL* image, const LLColor4 &color, BOOL solid_color = FALSE, const LLRectf& uv_rect = LLRectf(0.f, 1.f, 1.f, 0.f));
void gl_draw_scaled_image_with_border(S32 x, S32 y, S32 width, S32 height, LLImageGL* image, const LLColor4 &color, BOOL solid_color = FALSE, const LLRectf& uv_rect = LLRectf(0.f, 1.f, 1.f, 0.f), const LLRectf& scale_rect = LLRectf(0.f, 1.f, 1.f, 0.f));
// Flip vertical, used for LLFloaterHTML
void gl_draw_scaled_image_inverted(S32 x, S32 y, S32 width, S32 height, LLImageGL* image, const LLColor4& color = UI_VERTEX_COLOR, const LLRectf& uv_rect = LLRectf(0.f, 1.f, 1.f, 0.f));

void gl_rect_2d_xor(S32 left, S32 top, S32 right, S32 bottom);
void gl_stippled_line_3d( const LLVector3& start, const LLVector3& end, const LLColor4& color, F32 phase = 0.f ); 

void gl_rect_2d_simple_tex( S32 width, S32 height );

// segmented rectangles

/*
   TL |______TOP_________| TR 
     /|                  |\  
   _/_|__________________|_\_
   L| |    MIDDLE        | |R
   _|_|__________________|_|_
    \ |    BOTTOM        | /  
   BL\|__________________|/ BR
      |                  |    
*/

typedef enum e_rounded_edge
{
	ROUNDED_RECT_LEFT	= 0x1, 
	ROUNDED_RECT_TOP	= 0x2, 
	ROUNDED_RECT_RIGHT	= 0x4, 
	ROUNDED_RECT_BOTTOM	= 0x8,
	ROUNDED_RECT_ALL	= 0xf
}ERoundedEdge;


void gl_segmented_rect_2d_tex(const S32 left, const S32 top, const S32 right, const S32 bottom, const S32 texture_width, const S32 texture_height, const S32 border_size, const U32 edges = ROUNDED_RECT_ALL);
void gl_segmented_rect_2d_fragment_tex(const S32 left, const S32 top, const S32 right, const S32 bottom, const S32 texture_width, const S32 texture_height, const S32 border_size, const F32 start_fragment, const F32 end_fragment, const U32 edges = ROUNDED_RECT_ALL);
void gl_segmented_rect_3d_tex(const LLVector2& border_scale, const LLVector3& border_width, const LLVector3& border_height, const LLVector3& width_vec, const LLVector3& height_vec, U32 edges = ROUNDED_RECT_ALL);
void gl_segmented_rect_3d_tex_top(const LLVector2& border_scale, const LLVector3& border_width, const LLVector3& border_height, const LLVector3& width_vec, const LLVector3& height_vec);

inline void gl_rect_2d( const LLRect& rect, BOOL filled )
{
	gl_rect_2d( rect.mLeft, rect.mTop, rect.mRight, rect.mBottom, filled );
}

inline void gl_rect_2d_offset_local( const LLRect& rect, S32 pixel_offset, BOOL filled)
{
	gl_rect_2d_offset_local( rect.mLeft, rect.mTop, rect.mRight, rect.mBottom, pixel_offset, filled );
}

// No longer used
// Initializes translation table
// void init_tr();

// Returns a string from the string table in the correct language
// LLString tr(const LLString& english_chars);

// Used to hide the flashing text cursor when window doesn't have focus.
extern BOOL gShowTextEditCursor;

class LLImageProviderInterface;

typedef	void (*LLUIAudioCallback)(const LLUUID& uuid);

class LLUI
{
public:
	//
	// Methods
	//
	static void initClass(LLControlGroup* config, 
						  LLControlGroup* colors, 
						  LLControlGroup* assets, 
						  LLImageProviderInterface* image_provider,
						  LLUIAudioCallback audio_callback = NULL,
						  const LLVector2 *scale_factor = NULL,
						  const LLString& language = LLString::null);
	static void cleanupClass();

	static void pushMatrix();
	static void popMatrix();
	static void loadIdentity();
	static void translate(F32 x, F32 y, F32 z = 0.0f);

	//helper functions (should probably move free standing rendering helper functions here)
	static LLString locateSkin(const LLString& filename);
	static void setCursorPositionScreen(S32 x, S32 y);
	static void setCursorPositionLocal(const LLView* viewp, S32 x, S32 y);
	static void setScaleFactor(const LLVector2& scale_factor);
	static void setLineWidth(F32 width);
	static LLUUID findAssetUUIDByName(const LLString& name);
	static LLUIImage* getUIImageByName(const LLString& name);
	static LLVector2 getWindowSize();
	static void screenPointToGL(S32 screen_x, S32 screen_y, S32 *gl_x, S32 *gl_y);
	static void glPointToScreen(S32 gl_x, S32 gl_y, S32 *screen_x, S32 *screen_y);
	static void screenRectToGL(const LLRect& screen, LLRect *gl);
	static void glRectToScreen(const LLRect& gl, LLRect *screen);
	static void setHtmlHelp(LLHtmlHelp* html_help);

	//
	// Data
	//
	static LLControlGroup* sConfigGroup;
	static LLControlGroup* sColorsGroup;
	static LLControlGroup* sAssetsGroup;
	static LLImageProviderInterface* sImageProvider;
	static LLUIAudioCallback sAudioCallback;
	static LLVector2		sGLScaleFactor;
	static LLWindow*		sWindow;
	static BOOL             sShowXUINames;
	static LLHtmlHelp*		sHtmlHelp;

};

// UI widgets
// This MUST match UICtrlNames in lluictrlfactory.cpp
typedef enum e_widget_type
{
	WIDGET_TYPE_VIEW = 0,
	WIDGET_TYPE_ROOT_VIEW,
	WIDGET_TYPE_FLOATER_VIEW,
	WIDGET_TYPE_BUTTON,
	WIDGET_TYPE_JOYSTICK_TURN,
	WIDGET_TYPE_JOYSTICK_SLIDE,
	WIDGET_TYPE_CHECKBOX,
	WIDGET_TYPE_COLOR_SWATCH,
	WIDGET_TYPE_COMBO_BOX,
	WIDGET_TYPE_LINE_EDITOR,
	WIDGET_TYPE_SEARCH_EDITOR,
	WIDGET_TYPE_SCROLL_LIST,
	WIDGET_TYPE_NAME_LIST,
	WIDGET_TYPE_WEBBROWSER,
	WIDGET_TYPE_SLIDER,	// actually LLSliderCtrl
	WIDGET_TYPE_SLIDER_BAR, // actually LLSlider
	WIDGET_TYPE_VOLUME_SLIDER,//actually LLVolumeSliderCtrl
	WIDGET_TYPE_SPINNER,
	WIDGET_TYPE_TEXT_EDITOR,
	WIDGET_TYPE_TEXTURE_PICKER,
	WIDGET_TYPE_TEXT_BOX,
	WIDGET_TYPE_PAD,	// used in XML for positioning, not a real widget
	WIDGET_TYPE_RADIO_GROUP,
	WIDGET_TYPE_ICON,
	WIDGET_TYPE_LANDMARK_PICKER,
	WIDGET_TYPE_LOCATE,	// used in XML for positioning, not a real widget
	WIDGET_TYPE_VIEW_BORDER,	// decorative border
	WIDGET_TYPE_PANEL,
	WIDGET_TYPE_MENU,
	WIDGET_TYPE_PIE_MENU,
	WIDGET_TYPE_PIE_MENU_BRANCH,
	WIDGET_TYPE_MENU_ITEM,
	WIDGET_TYPE_MENU_ITEM_SEPARATOR,
	WIDGET_TYPE_MENU_SEPARATOR_VERTICAL,
	WIDGET_TYPE_MENU_ITEM_CALL,
	WIDGET_TYPE_MENU_ITEM_CHECK,
	WIDGET_TYPE_MENU_ITEM_BRANCH,
	WIDGET_TYPE_MENU_ITEM_BRANCH_DOWN,
	WIDGET_TYPE_MENU_ITEM_BLANK,
	WIDGET_TYPE_TEAROFF_MENU,
	WIDGET_TYPE_MENU_BAR,
	WIDGET_TYPE_TAB_CONTAINER,
	WIDGET_TYPE_SCROLL_CONTAINER, // LLScrollableContainerView
	WIDGET_TYPE_SCROLLBAR,
	WIDGET_TYPE_INVENTORY_PANEL, // LLInventoryPanel
	WIDGET_TYPE_FLOATER,
	WIDGET_TYPE_DRAG_HANDLE_TOP,
	WIDGET_TYPE_DRAG_HANDLE_LEFT,
	WIDGET_TYPE_RESIZE_HANDLE,
	WIDGET_TYPE_RESIZE_BAR,
	WIDGET_TYPE_NAME_EDITOR,
	WIDGET_TYPE_MULTI_FLOATER,
	WIDGET_TYPE_MEDIA_REMOTE,
	WIDGET_TYPE_FOLDER_VIEW,
	WIDGET_TYPE_FOLDER_ITEM,
	WIDGET_TYPE_FOLDER,
	WIDGET_TYPE_STAT_GRAPH,
	WIDGET_TYPE_STAT_VIEW,
	WIDGET_TYPE_STAT_BAR,
	WIDGET_TYPE_DROP_TARGET,
	WIDGET_TYPE_TEXTURE_BAR,
	WIDGET_TYPE_TEX_MEM_BAR,
	WIDGET_TYPE_SNAPSHOT_LIVE_PREVIEW,
	WIDGET_TYPE_STATUS_BAR,
	WIDGET_TYPE_PROGRESS_VIEW,
	WIDGET_TYPE_TALK_VIEW,
	WIDGET_TYPE_OVERLAY_BAR,
	WIDGET_TYPE_HUD_VIEW,
	WIDGET_TYPE_HOVER_VIEW,
	WIDGET_TYPE_MORPH_VIEW,
	WIDGET_TYPE_NET_MAP,
	WIDGET_TYPE_PERMISSIONS_VIEW,
	WIDGET_TYPE_MENU_HOLDER,
	WIDGET_TYPE_DEBUG_VIEW,
	WIDGET_TYPE_SCROLLING_PANEL_LIST,
	WIDGET_TYPE_AUDIO_STATUS,
	WIDGET_TYPE_CONTAINER_VIEW,
	WIDGET_TYPE_CONSOLE,
	WIDGET_TYPE_FAST_TIMER_VIEW,
	WIDGET_TYPE_VELOCITY_BAR,
	WIDGET_TYPE_TEXTURE_VIEW,
	WIDGET_TYPE_MEMORY_VIEW,
	WIDGET_TYPE_FRAME_STAT_VIEW,
	WIDGET_TYPE_LAYOUT_STACK,
	WIDGET_TYPE_FLYOUT_BUTTON,
	WIDGET_TYPE_DONTCARE,
	WIDGET_TYPE_COUNT
} EWidgetType;

//	FactoryPolicy is a static class that controls the creation and lookup of UI elements, 
//	such as floaters.
//	The key parameter is used to provide a unique identifier and/or associated construction 
//	parameters for a given UI instance
//
//	Specialize this traits for different types, or provide a class with an identical interface 
//	in the place of the traits parameter
//
//	For example:
//
//	template <>
//	class FactoryPolicy<MyClass> /* FactoryPolicy specialized for MyClass */
//	{
//	public:
//		static MyClass* findInstance(const LLSD& key = LLSD())
//		{
//			/* return instance of MyClass associated with key */
//		}
//	
//		static MyClass* createInstance(const LLSD& key = LLSD())
//		{
//			/* create new instance of MyClass using key for construction parameters */
//		}
//	}
//	
//	class MyClass : public LLUIFactory<MyClass>
//	{
//		/* uses FactoryPolicy<MyClass> by default */
//	}

template <class T>
class FactoryPolicy
{
public:
	// basic factory methods
	static T* findInstance(const LLSD& key); // unimplemented, provide specialiation
	static T* createInstance(const LLSD& key); // unimplemented, provide specialiation
};

//	VisibilityPolicy controls the visibility of UI elements, such as floaters.
//	The key parameter is used to store the unique identifier of a given UI instance
//
//	Specialize this traits for different types, or duplicate this interface for specific instances
//	(see above)

template <class T>
class VisibilityPolicy
{
public:
	// visibility methods
	static bool visible(T* instance, const LLSD& key); // unimplemented, provide specialiation
	static void show(T* instance, const LLSD& key); // unimplemented, provide specialiation
	static void hide(T* instance, const LLSD& key); // unimplemented, provide specialiation
};

//	Manages generation of UI elements by LLSD, such that (generally) there is
//	a unique instance per distinct LLSD parameter
//	Class T is the instance type being managed, and the FACTORY_POLICY and VISIBILITY_POLICY 
//	classes provide static methods for creating, accessing, showing and hiding the associated 
//	element T
template <class T, class FACTORY_POLICY = FactoryPolicy<T>, class VISIBILITY_POLICY = VisibilityPolicy<T> >
class LLUIFactory
{
public:
	// give names to the template parameters so derived classes can refer to them
	// except this doesn't work in gcc
	typedef FACTORY_POLICY factory_policy_t;
	typedef VISIBILITY_POLICY visibility_policy_t;

	LLUIFactory()
	{
	}

 	virtual ~LLUIFactory() 
	{ 
	}

	// default show and hide methods
	static T* showInstance(const LLSD& key = LLSD()) 
	{ 
		T* instance = getInstance(key); 
		if (instance != NULL)
		{
			VISIBILITY_POLICY::show(instance, key);
		}
		return instance;
	}

	static void hideInstance(const LLSD& key = LLSD()) 
	{ 
		T* instance = getInstance(key); 
		if (instance != NULL)
		{
			VISIBILITY_POLICY::hide(instance, key);
		}
	}

	static void toggleInstance(const LLSD& key = LLSD())
	{
		if (instanceVisible(key))
		{
			hideInstance(key);
		}
		else
		{
			showInstance(key);
		}
	}

	static bool instanceVisible(const LLSD& key = LLSD())
	{
		T* instance = FACTORY_POLICY::findInstance(key);
		return instance != NULL && VISIBILITY_POLICY::visible(instance, key);
	}

	static T* getInstance(const LLSD& key = LLSD()) 
	{
		T* instance = FACTORY_POLICY::findInstance(key);
		if (instance == NULL)
		{
			instance = FACTORY_POLICY::createInstance(key);
		}
		return instance;
	}

};


//	Creates a UI singleton by ignoring the identifying parameter
//	and always generating the same instance via the LLUIFactory interface.
//	Note that since UI elements can be destroyed by their hierarchy, this singleton
//	pattern uses a static pointer to an instance that will be re-created as needed.
//	
//	Usage Pattern:
//	
//	class LLFloaterFoo : public LLFloater, public LLUISingleton<LLFloaterFoo>
//	{
//		friend class LLUISingleton<LLFloaterFoo>;
//		private:
//			LLFloaterFoo(const LLSD& key);
//	};
//	
//	Note that LLUISingleton takes an option VisibilityPolicy parameter that defines
//	how showInstance(), hideInstance(), etc. work.
// 
//  https://wiki.lindenlab.com/mediawiki/index.php?title=LLUISingleton&oldid=79352

template <class T, class VISIBILITY_POLICY = VisibilityPolicy<T> >
class LLUISingleton: public LLUIFactory<T, LLUISingleton<T, VISIBILITY_POLICY>, VISIBILITY_POLICY>
{
protected:

	// T must derive from LLUISingleton<T>
	LLUISingleton() { sInstance = static_cast<T*>(this); }

	~LLUISingleton() { sInstance = NULL; }

public:
	static T* findInstance(const LLSD& key = LLSD())
	{
		return sInstance;
	}
	
	static T* createInstance(const LLSD& key = LLSD())
	{
		if (sInstance == NULL)
		{
			sInstance = new T(key);
		}
		return sInstance;
	}

private:
	static T*	sInstance;
};

template <class T, class U> T* LLUISingleton<T,U>::sInstance = NULL;

class LLScreenClipRect
{
public:
	LLScreenClipRect(const LLRect& rect, BOOL enabled = TRUE);
	virtual ~LLScreenClipRect();

private:
	static void pushClipRect(const LLRect& rect);
	static void popClipRect();
	static void updateScissorRegion();

private:
	LLGLState		mScissorState;
	BOOL			mEnabled;

	static std::stack<LLRect> sClipRectStack;
};

class LLLocalClipRect : public LLScreenClipRect
{
public:
	LLLocalClipRect(const LLRect& rect, BOOL enabled = TRUE);
};

class LLUIImage : public LLRefCount
{
public:
	LLUIImage(LLPointer<LLImageGL> image);

	void setClipRegion(const LLRectf& region);
	void setScaleRegion(const LLRectf& region);

	LLPointer<LLImageGL> getImage() { return mImage; }
	const LLPointer<LLImageGL>& getImage() const { return mImage; }

	void draw(S32 x, S32 y, const LLColor4& color = UI_VERTEX_COLOR) const;
	void draw(S32 x, S32 y, S32 width, S32 height, const LLColor4& color = UI_VERTEX_COLOR) const;
	void drawSolid(S32 x, S32 y, S32 width, S32 height, const LLColor4& color) const;
	void drawSolid(S32 x, S32 y, const LLColor4& color) const;

	S32 getWidth() const;
	S32 getHeight() const;

protected:
	LLRectf				mScaleRegion;
	LLRectf				mClipRegion;
	LLPointer<LLImageGL> mImage;
	BOOL				mUniformScaling;
	BOOL				mNoClip;
};


template <typename T>
class LLTombStone : public LLRefCount
{
public:
	LLTombStone(T* target = NULL) : mTarget(target) {}
	
	void setTarget(T* target) { mTarget = target; }
	T* getTarget() const { return mTarget; }
private:
	T* mTarget;
};

//	LLHandles are used to refer to objects whose lifetime you do not control or influence.  
//	Calling get() on a handle will return a pointer to the referenced object or NULL, 
//	if the object no longer exists.  Note that during the lifetime of the returned pointer, 
//	you are assuming that the object will not be deleted by any action you perform, 
//	or any other thread, as normal when using pointers, so avoid using that pointer outside of
//	the local code block.
// 
//  https://wiki.lindenlab.com/mediawiki/index.php?title=LLHandle&oldid=79669

template <typename T>
class LLHandle
{
public:
	LLHandle() : mTombStone(sDefaultTombStone) {}
	const LLHandle<T>& operator =(const LLHandle<T>& other)  
	{ 
		mTombStone = other.mTombStone;
		return *this; 
	}

	bool isDead() const 
	{ 
		return mTombStone->getTarget() == NULL; 
	}

	void markDead() 
	{ 
		mTombStone = sDefaultTombStone; 
	}

	T* get() const
	{
		return mTombStone->getTarget();
	}

	friend bool operator== (const LLHandle<T>& lhs, const LLHandle<T>& rhs)
	{
		return lhs.mTombStone == rhs.mTombStone;
	}
	friend bool operator!= (const LLHandle<T>& lhs, const LLHandle<T>& rhs)
	{
		return !(lhs == rhs);
	}
	friend bool	operator< (const LLHandle<T>& lhs, const LLHandle<T>& rhs)
	{
		return lhs.mTombStone < rhs.mTombStone;
	}
	friend bool	operator> (const LLHandle<T>& lhs, const LLHandle<T>& rhs)
	{
		return lhs.mTombStone > rhs.mTombStone;
	}
protected:

protected:
	LLPointer<LLTombStone<T> > mTombStone;

private:
	static LLPointer<LLTombStone<T> > sDefaultTombStone;
};

// initialize static "empty" tombstone pointer
template <typename T> LLPointer<LLTombStone<T> > LLHandle<T>::sDefaultTombStone = new LLTombStone<T>();


template <typename T>
class LLRootHandle : public LLHandle<T>
{
public:
	LLRootHandle(T* object) { bind(object); }
	LLRootHandle() {};
	~LLRootHandle() { unbind(); }

	// this is redundant, since a LLRootHandle *is* an LLHandle
	LLHandle<T> getHandle() { return LLHandle<T>(*this); }

	void bind(T* object) 
	{ 
		// unbind existing tombstone
		if (LLHandle<T>::mTombStone.notNull())
		{
			if (LLHandle<T>::mTombStone->getTarget() == object) return;
			LLHandle<T>::mTombStone->setTarget(NULL);
		}
		// tombstone reference counted, so no paired delete
		LLHandle<T>::mTombStone = new LLTombStone<T>(object);
	}

	void unbind() 
	{
		LLHandle<T>::mTombStone->setTarget(NULL);
	}

	//don't allow copying of root handles, since there should only be one
private:
	LLRootHandle(const LLRootHandle& other) {};
};

// Use this as a mixin for simple classes that need handles and when you don't
// want handles at multiple points of the inheritance hierarchy
template <typename T>
class LLHandleProvider
{
protected:
	typedef LLHandle<T> handle_type_t;
	LLHandleProvider() 
	{
		// provided here to enforce T deriving from LLHandleProvider<T>
	} 

	LLHandle<T> getHandle() 
	{ 
		// perform lazy binding to avoid small tombstone allocations for handle
		// providers whose handles are never referenced
		mHandle.bind(static_cast<T*>(this)); 
		return mHandle; 
	}

private:
	LLRootHandle<T> mHandle;
};

//RN: maybe this needs to moved elsewhere?
class LLImageProviderInterface
{
public:
	LLImageProviderInterface() {};
	virtual ~LLImageProviderInterface() {};

	virtual LLUIImage* getUIImageByID(const LLUUID& id, BOOL clamped = TRUE) = 0;
	virtual LLImageGL* getImageByID(const LLUUID& id, BOOL clamped = TRUE) = 0;
};

#endif