两张bmp叠加

//创建24位bmp区域

HBITMAP CreateBitmapSection(HDC hdc,int cx,int cy,BYTE** ppbit)

{

BITMAPINFO bmi ;

memset(&bmi.bmiHeader, 0, sizeof(BITMAPINFOHEADER));

bmi.bmiHeader.biSize = sizeof (BITMAPINFOHEADER) ;

bmi.bmiHeader.biPlanes = 1;

bmi.bmiHeader.biBitCount = 24;

bmi.bmiHeader.biCompression = BI_RGB;

bmi.bmiHeader.biWidth = cx;

bmi.bmiHeader.biHeight = cy;

return CreateDIBSection(hdc,&bmi,DIB_RGB_COLORS,(void**)ppbit,NULL,0);

}

//叠加两张bmp图片并输出到制定DC，Alpha取值范围 0~255(0为全透明，255为不透明)

void TransParentPicture(CDC *pDC, HBITMAP hOneBitmap, HBITMAP hTwoBitmap, CRect ClientRect,int Alpha)

{

BITMAP OneBitmap;

BITMAP TwoBitmap;

GetObject(hOneBitmap, sizeof(BITMAP), &OneBitmap);

GetObject(hTwoBitmap, sizeof(BITMAP), &TwoBitmap);

int nOneImageWidth = OneBitmap.bmWidth;

int nOneImageHeight = OneBitmap.bmHeight;

int nTwoImageWidth = TwoBitmap.bmWidth;

int nTwoImageHeight = TwoBitmap.bmHeight;

if (nOneImageWidth < nTwoImageWidth)

{

nOneImageWidth = nTwoImageWidth;

}  

else

{

nTwoImageWidth = nOneImageWidth;

}

if (nOneImageHeight < nTwoImageHeight)

{

nOneImageHeight = nTwoImageHeight;

}

else

{

nTwoImageHeight = nOneImageHeight;

}

int nImageWidth = nOneImageWidth;

int nImageHeight = nOneImageHeight;

CDC MemDC1, MemDC2;

HBITMAP hOldBitmap1 = NULL, hOldBitmap2 = NULL;

BYTE *pOneBits = NULL;

MemDC1.CreateCompatibleDC(pDC);

MemDC2.CreateCompatibleDC(pDC);

HBITMAP hOneBmp = NULL;

hOneBmp = CreateBitmapSection(pDC->m_hDC, nImageWidth, nImageHeight, &pOneBits);

hOldBitmap1 = (HBITMAP)SelectObject(MemDC1.m_hDC, hOneBmp);

hOldBitmap2 = (HBITMAP)SelectObject(MemDC2.m_hDC, hOneBitmap);

//BitBlt(MemDC1.m_hDC, 0, 0, m_nTwoImage_w, m_nTwoImage_h, MemDC2.m_hDC, 0, 0, SRCCOPY);

StretchBlt(MemDC1.m_hDC, 0, 0, nImageWidth, nImageHeight,

MemDC2.m_hDC, 0, 0, OneBitmap.bmWidth, OneBitmap.bmHeight, SRCCOPY);

CDC MemDC3, MemDC4;

HBITMAP hOldBitmap3 = NULL, hOldBitmap4 = NULL;

BYTE *pTwoBits = NULL;

MemDC3.CreateCompatibleDC(pDC);

MemDC4.CreateCompatibleDC(pDC);

HBITMAP hTwoBmp = NULL;

hTwoBmp = CreateBitmapSection(pDC->m_hDC, nImageWidth, nImageHeight, &pTwoBits);

hOldBitmap3 = (HBITMAP)SelectObject(MemDC3.m_hDC, hTwoBmp);

hOldBitmap4 = (HBITMAP)SelectObject(MemDC4.m_hDC, hTwoBitmap);

//BitBlt(MemDC3.m_hDC, 0, 0, m_nTwoImage_w, m_nTwoImage_h, MemDC4.m_hDC, 0, 0, SRCCOPY);

StretchBlt(MemDC3.m_hDC, 0, 0, nImageWidth, nImageHeight,

MemDC4.m_hDC, 0, 0, TwoBitmap.bmWidth, TwoBitmap.bmHeight, SRCCOPY);

CDC MemDC5;

HBITMAP hOldBitmap5 = NULL;

BYTE* pNewBits=NULL;

MemDC5.CreateCompatibleDC(pDC);

HBITMAP hNewBitmap = NULL;

hNewBitmap = CreateBitmapSection(pDC->m_hDC, nImageWidth, nImageHeight, &pNewBits);

hOldBitmap5 = (HBITMAP)SelectObject(MemDC5.m_hDC, hNewBitmap);

int linebytes=0;

int col=0;

int line=(((nImageWidth*24)+31)>>5)<<2;

linebytes = line;

col = nImageHeight;

for(int j=0;j<col;j++)

{

for(int i=0;i<linebytes;i++)

{

*(pNewBits + j*line + i)=(*(pOneBits + j*line + i)*Alpha +

*(pTwoBits+j*line+i)*(255-Alpha))/255;

}

}

BitBlt(pDC->m_hDC, 0, 0, ClientRect.Width(), ClientRect.Height(), MemDC5.m_hDC, 0, 0, SRCCOPY);

//StretchBlt(pDC->m_hDC, 0, 0, m_ClientRect.Width(), m_ClientRect.Height(),

// MemDC5.m_hDC, 0, 0, m_nOneImage_w, m_nOneImage_h, SRCCOPY);

SelectObject(MemDC5.m_hDC,hOldBitmap5);

MemDC5.DeleteDC();

SelectObject(MemDC4.m_hDC,hOldBitmap4);

MemDC4.DeleteDC();

SelectObject(MemDC3.m_hDC,hOldBitmap3);

MemDC3.DeleteDC();

SelectObject(MemDC2.m_hDC,hOldBitmap2);

MemDC2.DeleteDC();

SelectObject(MemDC1.m_hDC,hOldBitmap1);

MemDC1.DeleteDC();

}