使用GetDIBits直接读取位图数据

下面的代码演示了使用GetDIBits直接读取位图数据。

#include <math.h> void CDibtestDlg::OnOK() { // TODO: Add extra validation here HDC hDesktopDC = ::GetDC(NULL); HDC hTmpDC = CreateCompatibleDC(hDesktopDC); HBITMAP hBmp = CreateCompatibleBitmap(hDesktopDC, 351, 250); //351x250, 示例数据 SelectObject(hTmpDC, hBmp); BitBlt(hTmpDC, 0, 0, 351, 250, hDesktopDC, 0, 0, SRCCOPY); DeleteObject(hTmpDC); BITMAP bm; PBITMAPINFO bmpInf; if(GetObject(hBmp,sizeof(bm),&bm)==0) { ::ReleaseDC(NULL,hDesktopDC); return ; } int nPaletteSize=0; if(bm.bmBitsPixel<16) nPaletteSize=(int)pow(2,bm.bmBitsPixel); bmpInf=(PBITMAPINFO)LocalAlloc(LPTR,sizeof(BITMAPINFOHEADER)+ sizeof(RGBQUAD)*nPaletteSize+(bm.bmWidth+7)/8*bm.bmHeight*bm.bmBitsPixel); BYTE* buf=((BYTE*)bmpInf) + sizeof(BITMAPINFOHEADER)+ sizeof(RGBQUAD)*nPaletteSize; //----------------------------------------------- bmpInf->bmiHeader.biSize = sizeof(BITMAPINFOHEADER); bmpInf->bmiHeader.biWidth = bm.bmWidth; bmpInf->bmiHeader.biHeight = bm.bmHeight; bmpInf->bmiHeader.biPlanes = bm.bmPlanes; bmpInf->bmiHeader.biBitCount = bm.bmBitsPixel; bmpInf->bmiHeader.biCompression = BI_RGB; bmpInf->bmiHeader.biSizeImage = (bm.bmWidth+7)/8*bm.bmHeight*bm.bmBitsPixel; //----------------------------------------------- if(!::GetDIBits(hDesktopDC,hBmp,0,(UINT)bm.bmHeight,buf,bmpInf,DIB_RGB_COLORS)) { ::ReleaseDC(NULL,hDesktopDC); LocalFree(bmpInf); return ; } ::ReleaseDC(NULL,hDesktopDC); CString sMsg; sMsg.Format("BitsPixel:%d,width:%d,height:%d", bm.bmBitsPixel,bm.bmWidth,bm.bmHeight); AfxMessageBox(sMsg); CClientDC dc(this); int nOffset; BYTE r,g,b; int nWidth = bm.bmWidth*bm.bmBitsPixel/8; nWidth = ((nWidth+3)/4)*4; //4字节对齐 if(bmpInf->bmiHeader.biBitCount == 8) { for(int i=0; i<bm.bmHeight; i++) { for(int j=0; j<bm.bmWidth; j++) { RGBQUAD rgbQ; rgbQ = bmpInf->bmiColors[buf[i*nWidth+j]]; dc.SetPixel(j,bm.bmHeight-i,RGB(rgbQ.rgbRed,rgbQ.rgbGreen,rgbQ.rgbBlue)); //测试显示 } } } else if(bmpInf->bmiHeader.biBitCount == 16) { for(int i=0; i<bm.bmHeight; i++) { nOffset = i*nWidth; for(int j=0; j<bm.bmWidth; j++) { b = buf[nOffset+j*2]&0x1F; g = buf[nOffset+j*2]>>5; g |= (buf[nOffset+j*2+1]&0x03)<<3; r = (buf[nOffset+j*2+1]>>2)&0x1F; r *= 8; b *= 8; g *= 8; dc.SetPixel(j, bm.bmHeight-i, RGB(r,g,b)); //测试显示 } } } else if(bmpInf->bmiHeader.biBitCount == 24) { for(int i=0; i<bm.bmHeight; i++) { nOffset = i*nWidth; for(int j=0; j<bm.bmWidth; j++) { b = buf[nOffset+j*3]; g = buf[nOffset+j*3+1]; r = buf[nOffset+j*3+2]; dc.SetPixel(j, bm.bmHeight-i, RGB(r,g,b)); //测试显示 } } } else if(bmpInf->bmiHeader.biBitCount == 32) { for(int i=0; i<bm.bmHeight; i++) { nOffset = i*nWidth; for(int j=0; j<bm.bmWidth; j++) { b = buf[nOffset+j*4]; g = buf[nOffset+j*4+1]; r = buf[nOffset+j*4+2]; dc.SetPixel(j, bm.bmHeight-i, RGB(r,g,b)); //测试显示 } } } DeleteObject(hBmp); LocalFree(bmpInf); //CDialog::OnOK(); }