imageresample.cpp

这个是symbian下的一个蛮庞大的3D游戏源代码！对于学习3D开发的人有很大的帮助！

#include "ImageResample.h"


ImageResample::ImageResample() :
	m_buffer( 0 )
{
}

ImageResample::~ImageResample()
{
	deinit();
}

void ImageResample::init( int bufferSize )
{
	m_buffer.resize( bufferSize );
}

void ImageResample::deinit()
{
	m_buffer.clear();
}

uint8_t* ImageResample::getBuffer()
{
	return m_buffer.begin();
}

uint8_t* ImageResample::getBuffer( int size )
{
	if ( m_buffer.size() < size )
	{
		m_buffer.resize( size );
	}
	return m_buffer.begin();
}

void ImageResample::resampleHalf(	uint8_t* dst,
									const int width, const int height, const int pitch,
									const int /*sourceWidth*/, const int sourceHeight, const int sourcePitch,
									const uint16_t* palette, const int paletteEntryCount,
									int sourceFrameHeight )
{
	assert( ( sourcePitch * sourceHeight ) <= m_buffer.size() );
	resampleHalf(	dst, m_buffer.begin(),
					width, height, pitch,
					-1, sourceHeight, sourcePitch,
					palette, paletteEntryCount,
					sourceFrameHeight );
}

void ImageResample::resampleHalf(	uint8_t* dst, const uint8_t* src,
									const int width, const int height, const int pitch,
									const int /*sourceWidth*/, const int sourceHeight, const int sourcePitch,
									const uint16_t* palette, const int paletteEntryCount,
									int sourceFrameHeight )
{
	// Resample half x half
	//- Assumes A4R4G4B4 format
	//- If the data is palettized, the palette must be 8-bit
	//- The source data size must be 200% of the destination data size

	int sd00, sd01, sd10, sd11;
	int alpha, red, green, blue;
	int a, f;
	int pAlpha, pRed, pGreen, pBlue;
	int alphaDist, redDist, greenDist, blueDist;
	int colorDistSqr, minColorDistSqr;
	int si = 0, di = 0;
	int nearestEntry;
	int sourceLineWidth = sourcePitch;
	int lineWidth = pitch;
	if ( !palette )
	{
		//2 bytes per pixel
		sourceLineWidth >>= 1;
		lineWidth >>= 1;
	}

	bool cropFrames = ( ( sourceFrameHeight > 0 ) && ( ( sourceFrameHeight & 1 ) != 0 ) ); //Odd frame height in source => crop
	if ( sourceFrameHeight < 1 ) sourceFrameHeight = sourceHeight;
	int frameHeight = sourceFrameHeight >> 1;

	for ( int dsty = 0; dsty < height; dsty++ )
	{
		for ( int dstx = 0; dstx < width; dstx++ )
		{
			//Get the average color of the resampling area
			//-------
			if ( palette )
			{
				sd00 = palette[ src[ si ] ];
				sd10 = palette[ src[ si + 1 ] ];
				sd01 = palette[ src[ si + sourceLineWidth ] ];
				sd11 = palette[ src[ si + sourceLineWidth + 1 ] ];

			}
			else
			{
				sd00 = ((uint16_t*) src)[ si ];
				sd10 = ((uint16_t*) src)[ si + 1 ];
				sd01 = ((uint16_t*) src)[ si + sourceLineWidth ];
				sd11 = ((uint16_t*) src)[ si + sourceLineWidth + 1 ];
			}
			//-------

			a = ( sd00 >> 12 ) & 0xF;
			red = ( ( sd00 >> 8 ) & 0xF ) * a;
			green = ( ( sd00 >> 4 ) & 0xF ) * a;
			blue = ( sd00 & 0xF ) * a;
			alpha = a;
			a = ( sd10 >> 12 ) & 0xF;
			red += ( ( sd10 >> 8 ) & 0xF ) * a;
			green += ( ( sd10 >> 4 ) & 0xF ) * a;
			blue += ( sd10 & 0xF ) * a;
			alpha += a;
			a = ( sd01 >> 12 ) & 0xF;
			red += ( ( sd01 >> 8 ) & 0xF ) * a;
			green += ( ( sd01 >> 4 ) & 0xF ) * a;
			blue += ( sd01 & 0xF ) * a;
			alpha += a;
			a = ( sd11 >> 12 ) & 0xF;
			red += ( ( sd11 >> 8 ) & 0xF ) * a;
			green += ( ( sd11 >> 4 ) & 0xF ) * a;
			blue += ( sd11 & 0xF ) * a;
			alpha += a;
			if ( alpha > 0 )
			{
				//Fixed point multiplication by 1 / x (with rounding)
				f = ( 1 << 16 ) / alpha;
				red = ( red * f + ( 1 << 15 ) + 64 ) >> 16;
				green = ( green * f + ( 1 << 15 ) + 64 ) >> 16;
				blue = ( blue * f + ( 1 << 15 ) + 64 ) >> 16;
			}
			else
			{
				red = 0;
				green = 0;
				blue = 0;
			}
			alpha >>= 2;

			if ( palette )
			{
				//Find the nearest color in the palette
				minColorDistSqr = -1;
				nearestEntry = -1;
				for ( int entry = 0; entry < paletteEntryCount; entry++ )
				{
					pAlpha = ( palette[ entry ] >> 12 ) & 0xF;
					if ( pAlpha > 0 )
					{
						pRed = ( palette[ entry ] >> 8 ) & 0xF;
						pGreen = ( palette[ entry ] >> 4 ) & 0xF;
						pBlue = palette[ entry ] & 0xF;
					}
					else
					{
						//Full transparency: remove the significance of color
						pAlpha = 0;
						pRed = 0;
						pGreen = 0;
						pBlue = 0;
					}
					alphaDist = pAlpha - alpha;
					redDist = pRed - red;
					greenDist = pGreen - green;
					blueDist = pBlue - blue;
					colorDistSqr = alphaDist * alphaDist;
					colorDistSqr += redDist * redDist + greenDist * greenDist + blueDist * blueDist;
					if ( ( minColorDistSqr < 0 ) || ( colorDistSqr < minColorDistSqr ) )
					{
						minColorDistSqr = colorDistSqr;
						nearestEntry = entry;
					}
				}

				//Store
				dst[ di ] = (uint8_t) nearestEntry;
			}
			else
			{
				//Store
				((uint16_t*) dst)[ di ] = (uint16_t) ( ( ( alpha & 0xF ) << 12 ) + ( ( red & 0xF ) << 8 ) + ( ( green & 0xF ) << 4 ) + ( blue & 0xF ) );
			}

			//Advance
			si += 2;
			di++;
		}

		//Next scan line
		si += ( sourceLineWidth << 1 ) - ( width << 1 );
		di += lineWidth - width;

		if ( cropFrames && ( ( ( dsty + 1 ) % frameHeight ) == 0 ) )
		{
			//The last odd line of a source frame must be cropped to maintain frames in resize
			si += sourceLineWidth;
		}
	}
}

// End of file