/** 
 * @file llimagedxt.h
 *
 * $LicenseInfo:firstyear=2001&license=viewergpl$
 * 
 * Copyright (c) 2001-2009, 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://secondlifegrid.net/programs/open_source/licensing/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://secondlifegrid.net/programs/open_source/licensing/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.
 * $/LicenseInfo$
 */

#ifndef LL_LLIMAGEDXT_H
#define LL_LLIMAGEDXT_H

#include "llimage.h"

// This class decodes and encodes LL DXT files (which may unclude uncompressed RGB or RGBA mipped data)

class LLImageDXT : public LLImageFormatted
{
public:
	enum EFileFormat
	{ 
		FORMAT_UNKNOWN = 0,
		FORMAT_I8 = 1,
		FORMAT_A8,
		FORMAT_RGB8,
		FORMAT_RGBA8,
		FORMAT_DXT1,
		FORMAT_DXT2,
		FORMAT_DXT3,
		FORMAT_DXT4,
		FORMAT_DXT5,
		FORMAT_DXR1,
		FORMAT_DXR2,
		FORMAT_DXR3,
		FORMAT_DXR4,
		FORMAT_DXR5,
		FORMAT_NOFILE = 0xff,
	};
	
	struct dxtfile_header_old_t
	{
		S32 format;
		S32 maxlevel;
		S32 maxwidth;
		S32 maxheight;
	};

	struct dxtfile_header_t
	{
		S32 fourcc;
		// begin DDSURFACEDESC2 struct
		S32 header_size; // size of the header
		S32 flags; // flags - unused
		S32 maxheight;
		S32 maxwidth;
		S32 image_size; // size of the compressed image
		S32 depth;
		S32 num_mips;
		S32 reserved[11];
		struct pixel_format
		{
			S32 struct_size; // size of this structure
			S32 flags;
			S32 fourcc;
			S32 bit_count;
			S32 r_mask;
			S32 g_mask;
			S32 b_mask;
			S32 a_mask;
		} pixel_fmt;
		S32 caps[4];
		S32 reserved2;
	};

protected:
	/*virtual*/ ~LLImageDXT();

private:
	BOOL encodeDXT(const LLImageRaw* raw_image, F32 decode_time, bool explicit_mips);
	
public:
	LLImageDXT();

	/*virtual*/ std::string getExtension() { return std::string("dxt"); }
	/*virtual*/ BOOL updateData();

	/*virtual*/ BOOL decode(LLImageRaw* raw_image, F32 decode_time);
	/*virtual*/ BOOL encode(const LLImageRaw* raw_image, F32 encode_time);

	/*virtual*/ S32 calcHeaderSize();
	/*virtual*/ S32 calcDataSize(S32 discard_level = 0);

	BOOL getMipData(LLPointer<LLImageRaw>& raw, S32 discard=-1);
	
	void setFormat();
	S32 getMipOffset(S32 discard);
	
	EFileFormat getFileFormat() { return mFileFormat; }
	bool isCompressed() { return (mFileFormat >= FORMAT_DXT1 && mFileFormat <= FORMAT_DXR5); }

	bool convertToDXR(); // convert from DXT to DXR
	
	static void checkMinWidthHeight(EFileFormat format, S32& width, S32& height);
	static S32 formatBits(EFileFormat format);
	static S32 formatBytes(EFileFormat format, S32 width, S32 height);
	static S32 formatOffset(EFileFormat format, S32 width, S32 height, S32 max_width, S32 max_height);
	static S32 formatComponents(EFileFormat format);
	
	static EFileFormat getFormat(S32 fourcc);
	static S32 getFourCC(EFileFormat format);

	static void calcDiscardWidthHeight(S32 discard_level, EFileFormat format, S32& width, S32& height);
	static S32 calcNumMips(S32 width, S32 height);

private:
	static void extractMip(const U8 *indata, U8* mipdata, int width, int height,
						   int mip_width, int mip_height, EFileFormat format);
	
private:
	EFileFormat mFileFormat;
	S32 mHeaderSize;
};

#endif