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src/Source/FreeImage/PluginDDS.cpp  view on Meta::CPAN

		colors[i].r = (BYTE)((block.colors[i].r << 3U) | (block.colors[i].r >> 2U));
		colors[i].g = (BYTE)((block.colors[i].g << 2U) | (block.colors[i].g >> 4U));
		colors[i].b = (BYTE)((block.colors[i].b << 3U) | (block.colors[i].b >> 2U));
	}

	WORD *wCol = (WORD *)block.colors;
	if (wCol[0] > wCol[1] || !isDXT1) {
		// 4 color block
		for (i = 0; i < 2; i++)	{
			colors[i + 2].a = 0xff;
			colors[i + 2].r = (BYTE)((WORD (colors[0].r) * (2 - i) + WORD (colors[1].r) * (1 + i)) / 3);
			colors[i + 2].g = (BYTE)((WORD (colors[0].g) * (2 - i) + WORD (colors[1].g) * (1 + i)) / 3);
			colors[i + 2].b = (BYTE)((WORD (colors[0].b) * (2 - i) + WORD (colors[1].b) * (1 + i)) / 3);
		}
	}
	else {
		// 3 color block, number 4 is transparent
		colors[2].a = 0xff;
		colors[2].r = (BYTE)((WORD (colors[0].r) + WORD (colors[1].r)) / 2);
		colors[2].g = (BYTE)((WORD (colors[0].g) + WORD (colors[1].g)) / 2);
		colors[2].b = (BYTE)((WORD (colors[0].b) + WORD (colors[1].b)) / 2);

		colors[3].a = 0x00;
		colors[3].g = 0x00;
		colors[3].b = 0x00;
		colors[3].r = 0x00;
	}
}

struct DXT_INFO_1 {
	typedef DXT1Block Block;
	enum {
		isDXT1 = 1,
		bytesPerBlock = 8
	};
};

struct DXT_INFO_3 {
	typedef DXT3Block Block;
	enum {
		isDXT1 = 1,
		bytesPerBlock = 16
	};
};

struct DXT_INFO_5 {
	typedef DXT5Block Block;
	enum
	{
		isDXT1 = 1,
		bytesPerBlock = 16
	};
};

template <class INFO> class DXT_BLOCKDECODER_BASE {
protected:
	Color8888 m_colors[4];
	const typename INFO::Block *m_pBlock;
	unsigned m_colorRow;

public:
	void Setup (const BYTE *pBlock) {
		m_pBlock = (const typename INFO::Block *)pBlock;
		GetBlockColors (m_pBlock->color, m_colors, INFO::isDXT1);
	}

	void SetY (int y) {
		m_colorRow = m_pBlock->color.row[y];
	}

	void GetColor (int x, int y, Color8888 &color) {
		unsigned bits = (m_colorRow >> (x * 2)) & 3;
		color = m_colors[bits];
	}
};

class DXT_BLOCKDECODER_1 : public DXT_BLOCKDECODER_BASE <DXT_INFO_1> {
public:
	typedef DXT_INFO_1 INFO;
};

class DXT_BLOCKDECODER_3 : public DXT_BLOCKDECODER_BASE <DXT_INFO_3> {
public:
	typedef DXT_BLOCKDECODER_BASE <DXT_INFO_3> base;
	typedef DXT_INFO_3 INFO;

protected:
	unsigned m_alphaRow;

public:
	void SetY (int y) {
		base::SetY (y);
		m_alphaRow = m_pBlock->alpha.row[y];
	}

	void GetColor (int x, int y, Color8888 &color) {
		base::GetColor (x, y, color);
		const unsigned bits = (m_alphaRow >> (x * 4)) & 0xF;
		color.a = (BYTE)((bits * 0xFF) / 0xF);
	}
};

class DXT_BLOCKDECODER_5 : public DXT_BLOCKDECODER_BASE <DXT_INFO_5> {
public:
	typedef DXT_BLOCKDECODER_BASE <DXT_INFO_5> base;
	typedef DXT_INFO_5 INFO;

protected:
	unsigned m_alphas[8];
	unsigned m_alphaBits;
	int m_offset;

public:
	void Setup (const BYTE *pBlock) {
		base::Setup (pBlock);

		const DXTAlphaBlock3BitLinear &block = m_pBlock->alpha;
		m_alphas[0] = block.alpha[0];
		m_alphas[1] = block.alpha[1];
		if (m_alphas[0] > m_alphas[1]) {
			// 8 alpha block
			for (int i = 0; i < 6; i++) {
				m_alphas[i + 2] = ((6 - i) * m_alphas[0] + (1 + i) * m_alphas[1] + 3) / 7;
			}
		}
		else {
			// 6 alpha block
			for (int i = 0; i < 4; i++) {
				m_alphas[i + 2] = ((4 - i) * m_alphas[0] + (1 + i) * m_alphas[1] + 2) / 5;
			}
			m_alphas[6] = 0;
			m_alphas[7] = 0xFF;
		}

	}

	void SetY (int y) {
		base::SetY (y);
		int i = y / 2;
		const DXTAlphaBlock3BitLinear &block = m_pBlock->alpha;
		m_alphaBits = unsigned(block.data[0 + i * 3]) | (unsigned(block.data[1 + i * 3]) << 8)
			| (unsigned(block.data[2 + i * 3]) << 16);
		m_offset = (y & 1) * 12;
	}

	void GetColor (int x, int y, Color8888 &color) {
		base::GetColor (x, y, color);
		unsigned bits = (m_alphaBits >> (x * 3 + m_offset)) & 7;
		color.a = (BYTE)m_alphas[bits];
	}
};

template <class DECODER> void DecodeDXTBlock (BYTE *dstData, const BYTE *srcBlock, long dstPitch, int bw, int bh) {
	DECODER decoder;
	decoder.Setup (srcBlock);
	for (int y = 0; y < bh; y++) {
		BYTE *dst = dstData - y * dstPitch;
		decoder.SetY (y);
		for (int x = 0; x < bw; x++) {
			decoder.GetColor (x, y, (Color8888 &)*dst);

#if FREEIMAGE_COLORORDER == FREEIMAGE_COLORORDER_RGB 
			INPLACESWAP(dst[FI_RGBA_RED], dst[FI_RGBA_BLUE]);
#endif 
			dst += 4;
		}
	}
}

// ==========================================================
// Plugin Interface
// ==========================================================