三个实现透明效果的方法（我还没有试过，不保证质量）

方法一：

void CChessBoard::FillMarkedChess(CDC *pDC,CRect rect, COLORREF color)
{
//color为半透明的底色
COLORREF bkcolor;
int R1,G1,B1,R2,G2,B2;
R1=color&255;
G1=(color>>8)&255;
B1=(color>>16)&255;
//标记块的左边与右边各多显示一点
for(int x=rect.left-1;x<=rect.right;x++)
{
for(int y=rect.top-1;y<=rect.bottom;y++)
{
//nRatio为透光率
bkcolor=pDC->GetPixel(x,y);
R2=bkcolor&255;
G2=(bkcolor>>8)&255;
B2=(bkcolor>>16)&255;
R2=R1+(R2-R1)*m_nRatio/100;
G2=G1+(G2-G1)*m_nRatio/100;
B2=B1+(B2-B1)*m_nRatio/100;
pDC->SetPixel(x,y,RGB(R2,G2,B2));
}
}
}

方法二：

/*
这是一个用来填充透明位图的函数
CDC *pDC 需要画位图的CDC指针
HBITMAP hBitmap 位图's m_hObject
CRect &rect 指定位图在pDC中的位置
COLORREF rgbMask 位图的透明色
*/
void FillTransparentHBitmap(CDC *pDC, HBITMAP hBitmap,CRect &rect, COLORREF rgbMask)
{
CDC ImageDC,MaskDC;
CBitmap Image,*pOldImage=NULL;
CBrush *oldBrush=NULL;
CBitmap maskBitmap,*pOldMaskDCBitmap ;

//Image.LoadBitmap(IDImage);
Image.Attach(hBitmap);

ImageDC.CreateCompatibleDC(pDC);
//CBrush br(&Image);
pOldImage=ImageDC.SelectObject(&Image);
//ImageDC.FillRect(rect,&br);
BITMAP bm;
Image.GetBitmap(&bm);

MaskDC.CreateCompatibleDC(pDC);
maskBitmap.CreateBitmap( rect.Width(), rect.Height(), 1, 1, NULL );
pOldMaskDCBitmap = MaskDC.SelectObject( &maskBitmap );

ImageDC.SetBkColor(rgbMask);
int ix=0,iy=0;
for(iy=0;iy<rect.Height();iy+=bm.bmHeight)
{
for(ix=0;ix<rect.Width();ix+=bm.bmWidth)
{
MaskDC.BitBlt( ix, iy, bm.bmWidth, bm.bmHeight, &ImageDC, 0, 0, SRCCOPY );
}
}

ImageDC.SetBkColor(RGB(0,0,0));
ImageDC.SetTextColor(RGB(255,255,255));
ImageDC.BitBlt(0, 0, rect.Width(), rect.Height(), &MaskDC, 0, 0, SRCAND);

pDC->BitBlt(rect.left,rect.top,rect.Width(), rect.Height(), &MaskDC, 0, 0, SRCAND);
for(iy=rect.top;iy<rect.Height();iy+=bm.bmHeight)
{
for(ix=rect.left;ix<rect.Width();ix+=bm.bmWidth)
{
//MaskDC.BitBlt( ix, iy, bm.bmWidth, bm.bmHeight, &ImageDC, 0, 0, SRCCOPY );
pDC->BitBlt(ix,iy,bm.bmWidth, bm.bmHeight, &ImageDC, 0, 0,SRCPAINT);
}
}
//pDC->BitBlt(rect.left,rect.top,rect.Width(), rect.Height(), &ImageDC, 0, 0,SRCPAINT);

MaskDC.SelectObject(pOldMaskDCBitmap);
ImageDC.SelectObject(pOldImage);
//ImageDC.SelectObject(oldBrush);

Image.Detach();
}

方法三：

BOOL BitBlt_HT(
HDC hdc,//目標DC
RECT rect,//目標區域
COLORREF maskColor,//半透明前景
UINT maskRatio//半透明前景比重 ( 0 - 100 )
)
{
int x,y;
COLORREF bColor;
BYTE b_R,b_G,b_B,f_R,f_G,f_B;

maskRatio = maskRatio % 100;
f_R = GetRvalues(maskColor);f_G = GetGvalues(maskColor);f_B = GetBvalues(maskColor);

HDC hMemDC = ::CreateCompatibleDC(hdc);
if (hMemDC == NULL) return 0;
HBITMAP hOldBmp,hNewBmp = ::CreateCompatibleBitmap(hdc,rect.right - rect.left ,rect.bottom - rect.top );
if (hNewBmp == NULL)
{
::DeleteDC (hMemDC);
return 0;
}
hOldBmp = (HBITMAP)::SelectObject(hMemDC,hNewBmp);
::BitBlt (hMemDC,0,0 ,rect.right-rect.left ,rect.bottom - rect.top ,hdc,rect.left ,rect.top,SRCCOPY);

for (y = 0 ; y <rect.bottom - rect.top ; y ++)
{
for (x = 0 ; x <= rect.right - rect.top; x++)
{
bColor = GetPixel(hMemDC,x,y);
b_R = GetRvalues(bColor);b_G = GetGvalues(bColor);b_B = GetBvalues(bColor);
bColor = RGB(f_R*maskRatio/100+b_R*(100-maskRatio)/100,f_G*maskRatio/100+b_G*(100-maskRatio)/100,f_B*maskRatio/100+b_B*(100-maskRatio)/100);
SetPixel(hMemDC,x,y,bColor);
}
}
::BitBlt (hdc,rect.left ,rect.top ,rect.right-rect.left ,rect.bottom - rect.top ,hMemDC,0,0,SRCCOPY);
::SelectObject(hMemDC,hOldBmp);
::DeleteObject (hNewBmp);
::DeleteDC (hMemDC);
return 1;
}