请问怎么用drectdraw从内存中加载一幅图片到屏幕上？

Question

如题，，能否提供代码参考。

Answer 1

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

Answer 2

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 );}