/** 
 * @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"

//
// Classes
//
class LLScrollbar
: public LLUICtrl
{
public:

	typedef boost::function<void (S32, LLScrollbar*)> callback_t;
	struct Params 
	:	public LLInitParam::Block<Params, LLUICtrl::Params>
	{
		Mandatory<EOrientation>			orientation;
		Mandatory<S32>					doc_size;
		Mandatory<S32>					doc_pos;
		Mandatory<S32>					page_size;

		Optional<callback_t> 			change_callback;
		Optional<S32>					step_size;
		Optional<S32>					thickness;

		Optional<LLUIImage*>			thumb_image_vertical,
										thumb_image_horizontal,
										track_image_horizontal,
										track_image_vertical;

		Optional<bool>					bg_visible;

		Optional<LLUIColor>				track_color,
										thumb_color,
										bg_color;

		Optional<LLButton::Params>		up_button;
		Optional<LLButton::Params>		down_button;
		Optional<LLButton::Params>		left_button;
		Optional<LLButton::Params>		right_button;

		Params();
	};

protected:
	LLScrollbar (const Params & p);
	friend class LLUICtrlFactory;

public:
	virtual ~LLScrollbar();

	void setValue(const LLSD& value) override;

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

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

	void	draw() override;

	// 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);

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

	callback_t			mChangeCallback;

	const EOrientation	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;

	LLUIColor			mTrackColor;
	LLUIColor			mThumbColor;
	LLUIColor			mBGColor;

	bool				mBGVisible;

	LLUIImagePtr		mThumbImageV;
	LLUIImagePtr		mThumbImageH;
	LLUIImagePtr		mTrackImageV;
	LLUIImagePtr		mTrackImageH;

	S32					mThickness;

	LLButton*			mBtnScrollUp;
	LLButton*			mBtnScrollDown;
};


#endif  // LL_SCROLLBAR_H
