/** 
 * @file llimagedxt.h
 *
 * $LicenseInfo:firstyear=2001&license=viewerlgpl$
 * 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_LLIMAGEDXT_H
#define LL_LLIMAGEDXT_H

#include "llimage.h"
#include "llpointer.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() override { return std::string("dxt"); }
	/*virtual*/ bool updateData() override;

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

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

	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
