/** 
 * @file llscrollbar.h
 * @brief Scrollbar UI widget
 *
 * $LicenseInfo:firstyear=2001&license=viewerlgpl$
 * Second Life Viewer Source Code
 * Copyright (C) 2010, Linden Research, Inc.
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 of the License only.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
 * $/LicenseInfo$
 */

#ifndef LL_SCROLLBAR_H
#define LL_SCROLLBAR_H

#include "stdtypes.h"
#include "lluictrl.h"
#include "v4color.h"
#include "llbutton.h"

//
// Constants
//
const S32 SCROLLBAR_SIZE = 16;


//
// Classes
//
class LLScrollbar
: public LLUICtrl
{
public:
	enum ORIENTATION { HORIZONTAL, VERTICAL };

	typedef boost::function<void (S32, LLScrollbar*)> callback_t;
	LLScrollbar(const std::string& name, LLRect rect,
		ORIENTATION orientation,
		S32 doc_size, S32 doc_pos, S32 page_size,
		callback_t change_callback,
		S32 step_size = 1);

public:
	virtual ~LLScrollbar();

	virtual void setValue(const LLSD& value);

	// Overrides from LLView
	virtual BOOL	handleKeyHere(KEY key, MASK mask);
	virtual BOOL	handleMouseDown(S32 x, S32 y, MASK mask);
	virtual BOOL	handleMouseUp(S32 x, S32 y, MASK mask);
	virtual BOOL	handleDoubleClick(S32 x, S32 y, MASK mask);
	virtual BOOL	handleHover(S32 x, S32 y, MASK mask);
	virtual BOOL	handleScrollWheel(S32 x, S32 y, S32 clicks);
	virtual BOOL	handleDragAndDrop(S32 x, S32 y, MASK mask, BOOL drop, 
		EDragAndDropType cargo_type, void *cargo_data, EAcceptance *accept, std::string &tooltip_msg);

	virtual void	reshape(S32 width, S32 height, BOOL called_from_parent = TRUE);

	virtual void	draw();

	// How long the "document" is.
	void				setDocSize( S32 size );
	S32					getDocSize() const		{ return mDocSize; }

	// How many "lines" the "document" has scrolled.
	// 0 <= DocPos <= DocSize - DocVisibile
	bool				setDocPos( S32 pos, BOOL update_thumb = TRUE );
	S32					getDocPos() const		{ return mDocPos; }

	BOOL				isAtBeginning();
	BOOL				isAtEnd();

	// Setting both at once.
	void				setDocParams( S32 size, S32 pos );

	// How many "lines" of the "document" is can appear on a page.
	void				setPageSize( S32 page_size );
	S32					getPageSize() const		{ return mPageSize; }
	
	// The farthest the document can be scrolled (top of the last page).
	S32					getDocPosMax() const	{ return llmax( 0, mDocSize - mPageSize); }

	void				pageUp(S32 overlap);
	void				pageDown(S32 overlap);

	void				onLineUpBtnPressed(const LLSD& data);
	void				onLineDownBtnPressed(const LLSD& data);

	S32					getThickness() const { return mThickness; }
	void				setThickness(S32 thickness);

	void setTrackColor( const LLColor4& color ) { mTrackColor = color; }
	void setThumbColor( const LLColor4& color ) { mThumbColor = color; }
	void setHighlightColor( const LLColor4& color ) { mHighlightColor = color; }
	void setShadowColor( const LLColor4& color ) { mShadowColor = color; }

	void setOnScrollEndCallback(void (*callback)(void*), void* userdata) { mOnScrollEndCallback = callback; mOnScrollEndData = userdata;}

private:
	void				updateThumbRect();
	bool				changeLine(S32 delta, BOOL update_thumb );

	callback_t			mChangeCallback;

	const ORIENTATION	mOrientation;	
	S32					mDocSize;		// Size of the document that the scrollbar is modeling.  Units depend on the user.  0 <= mDocSize.
	S32					mDocPos;		// Position within the doc that the scrollbar is modeling, in "lines" (user size)
	S32					mPageSize;		// Maximum number of lines that can be seen at one time.
	S32					mStepSize;
	BOOL				mDocChanged;

	LLRect				mThumbRect;
	S32					mDragStartX;
	S32					mDragStartY;
	F32					mHoverGlowStrength;
	F32					mCurGlowStrength;

	LLRect				mOrigRect;
	S32					mLastDelta;

	LLColor4			mTrackColor;
	LLColor4			mThumbColor;
	LLColor4			mFocusColor;
	LLColor4			mHighlightColor;
	LLColor4			mShadowColor;

	void			(*mOnScrollEndCallback)(void*);
	void			*mOnScrollEndData;
	S32					mThickness;
};


#endif  // LL_SCROLLBAR_H