请问怎么用drectdraw从内存中加载一幅图片到屏幕上？

[swimcamel]

如题，，能否提供代码参考。

[zhao1zhong6]

基本上就是锁定页面，然后根据模式一行一行的复制过去

//将图片和掩膜直接绘制到后备缓冲
void CGraphics::DrawAlpha(CDoubleSurface* pSurface, int nDesX,int nDesY)
{
	DDSURFACEDESC2 ddba,ddsp,ddma;
	DDRAW_INIT_STRUCT(ddba);
	DDRAW_INIT_STRUCT(ddsp);
	DDRAW_INIT_STRUCT(ddma);
	m_pddsBackBuffer->Lock(     NULL, &ddba, DDLOCK_WAIT, NULL );
	pSurface->m_pMask->Lock( NULL, &ddma, DDLOCK_WAIT, NULL );
	pSurface->m_pSprite->Lock( NULL, &ddsp, DDLOCK_WAIT, NULL );

	int nEndX=ddsp.dwWidth;
	int nEndY=ddsp.dwHeight;
	int	 nStartX=0;
	int nStartY=0;
	int nCurrent;
	int y;
	//裁剪图片如果超出了边界
	if( nDesX < 0 )
	{
		nStartX=-nDesX;
		nDesX = 0;		
	}
	if( nDesY < 0 )
	{
		nStartY= -nDesY;
		nDesY = 0;		
	}
	if (nDesY>=FRONT_WINDOW_HEIGHT-nEndY)
	{
		nEndY=FRONT_WINDOW_HEIGHT-nDesY;
	}
	if (nDesX>=FRONT_WINDOW_WIDTH-nEndX)
	{
		nEndX=FRONT_WINDOW_WIDTH-nDesX;
	}

	if( ddba.ddpfPixelFormat.dwRGBBitCount == 32 )
	{
		const DWORD dwBackPatch=ddba.lPitch;
		const DWORD dwSrcPatch  =ddsp.lPitch;

		BYTE* pbB = (BYTE*)(ddba.lpSurface)+nDesY*dwBackPatch+(nDesX<<2);
		BYTE* pbS = (BYTE*)(ddsp.lpSurface)+nStartY*dwSrcPatch+(nStartX<<2) ;
		BYTE* pbM= (BYTE*)(ddma.lpSurface)+nStartY*dwSrcPatch+(nStartX<<2) ;

		for(y=nStartY; y<nEndY; y++ )
		{
			nCurrent=nStartX;
			while( nCurrent<nEndX )
			{
				if(0== pbM[0])//colorkey
				{
					if (nCurrent+pbM[1]<nEndX)
					{
						nCurrent+= pbM[1];
						pbB += pbM[1]<<2;					
						pbS += pbM[1]<<2;
						pbM += pbM[1]<<2;
					}
					else
					{
						pbB += (nEndX-nCurrent)<<2;					
						pbS += (nEndX-nCurrent)<<2;
						pbM +=(nEndX-nCurrent)<<2;
						nCurrent=nEndX;
					}
				}
				else if( 255==pbM[0])
				{	
					if (nCurrent+pbM[1]<nEndX)
					{
						::memcpy((void*)pbB,(void*)pbS,pbM[1]<<2);
						nCurrent+=pbM[1];
						pbB += pbM[1]<<2;					
						pbS += pbM[1]<<2;
						pbM += pbM[1]<<2;
					}
					else
					{
						::memcpy((void*)pbB,(void*)pbS,(nEndX-nCurrent)<<2);
						pbB += (nEndX-nCurrent)<<2;					
						pbS += (nEndX-nCurrent)<<2;
						pbM += (nEndX-nCurrent)<<2;
						nCurrent=nEndX;
					}
				}
				else//Alpha
				{
					pbB[0]  = (pbB[0]*pbM[1]>>8) +pbS[0];
					pbB[1]  = (pbB[1]*pbM[1]>>8) +pbS[1];
					pbB[2]  = (pbB[2]*pbM[1]>>8) +pbS[2];
					pbB+=4;
					pbM+=4;
					pbS+=4;
					nCurrent++;	
				}
			}//end while
			pbB+=dwBackPatch-((nEndX-nStartX)<<2);
			pbS+=dwSrcPatch-((nEndX-nStartX)<<2);
			pbM+=dwSrcPatch-((nEndX-nStartX)<<2);

		}//end for
	}
	else
		if( ddba.ddpfPixelFormat.dwRGBBitCount == 16 )
		{	
			const DWORD dwBackPatch16=ddba.lPitch>>1;
			const DWORD dwSrcPatch16  =ddsp.lPitch>>1;
			WORD* pwB =(WORD*)(ddba.lpSurface)+(nDesY*dwBackPatch16)+nDesX;
			WORD* pwS =(WORD*)(ddsp.lpSurface)+(nStartY*dwSrcPatch16)+nStartX;
			WORD* pwM =(WORD*)(ddma.lpSurface)+(nStartY*dwSrcPatch16)+nStartX;
			DWORD R,G,B,_R,_G,/*_B,*/RR,GG,BB;
			int  nLow;
			for( y=nStartY; y<nEndY; y++ )
			{
				nCurrent=nStartX;
				while( nCurrent<nEndX )
				{
					if(*pwM<32)
					{

						if (nCurrent+*pwM<nEndX)
						{
							nCurrent+= *pwM;
							pwB +=*pwM;					
							pwS +=*pwM;
							pwM +=*pwM;
						}
						else
						{
							pwB += (nEndX-nCurrent);					
							pwS += (nEndX-nCurrent);
							pwM +=(nEndX-nCurrent);
							nCurrent=nEndX;
						}
					}
					else if (*pwM>=63488)//31<<11
					{
						nLow=*pwM-63488;
						if (nCurrent+nLow<nEndX)
						{
							::memcpy((void*)pwB,(void*)pwS,nLow<<1);
							pwB += nLow;					
							pwS += nLow;
							pwM += nLow;
							nCurrent+=nLow;
						}
						else
						{
							::memcpy((void*)pwB,(void*)pwS,(nEndX-nCurrent)<<1);
							pwB += nEndX-nCurrent;					
							pwS += nEndX-nCurrent;
							pwM +=nEndX-nCurrent;
							nCurrent=nEndX;
						}
					}
					else
					{						
						_R=*pwM>>11;//只保留最高位
						_G=_R<<1;//(*pwM-(_R<<11))>>5;
						//_B=(*pwM-(_R<<11)-(_G<<5));

						R=*pwS>>11;
						G=(*pwS-(R<<11))>>5;
						B=(*pwS-(R<<11)-(G<<5));

						RR=*pwB>>11;
						GG=(*pwB-(RR<<11))>>5;
						BB=(*pwB-(RR<<11)-(GG<<5));

						RR=(R*_R+RR*(32-_R))>>5;
						GG=(G*_G+GG*(64-_G))>>6;
						BB=(B*_R+BB*(32-_R))>>5;

						*pwB = (WORD)((RR<<11)+(GG<<5)+BB);
						pwB++;
						pwS++;
						pwM++;
						nCurrent++;
					}
				}
				pwB+=dwBackPatch16-(nEndX-nStartX);
				pwS+=dwSrcPatch16-(nEndX-nStartX);
				pwM+=dwSrcPatch16-(nEndX-nStartX);

			} 
		}

		pSurface->m_pSprite->Unlock( NULL );
		pSurface->m_pMask->Unlock( NULL );
		m_pddsBackBuffer->Unlock( NULL );

}

[zzz822163]

你装了directx8的话就有例子程序的啊,看D:\DXSDK\samples\Multimedia\DirectDraw\WindowedMode

[swimcamel]

是在内存创建一个位图，然后直接加载到屏幕上，相当于操作一个内存阵列，是否需要用到换页操作。。请高手指点？