Bitmap -> blob  
Author Message
DJO





PostPosted: Visual C++ General, Bitmap -> blob Top

I have an object of type Bitmap that I'd like to save in an SQL server (type blob), and then retrieve it. I can find a few examples of how to do this using MFC, but I'm not using MFC. :) I can't find anything in the documentation about this.



Visual C++10  
 
 
Harold Jimenez





PostPosted: Visual C++ General, Bitmap -> blob Top

Ok, I guess you have a handle (HBITMAP) with your image so the next step is make a call to GetDIBits to obtain raw bytes. Here is some code I extracted and prepared for you!

void SendBitmapToSQLServer(HDC hDC, HBITMAP hBmp)
{
BITMAP bmp;
LPBYTE lpBits; // memory pointer
PBITMAPINFO pbmi;
WORD cClrBits;

// Retrieve the bitmap color format, width, and height.
if (!GetObject(hBmp, sizeof(BITMAP), (LPSTR)&bmp))
return; //Send some message to your log about this issue!

// Convert the color format to a count of bits.
cClrBits = (WORD)(bmp.bmPlanes * bmp.bmBitsPixel);
if (cClrBits == 1)
cClrBits = 1;
else if (cClrBits <= 4)
cClrBits = 4;
else if (cClrBits <= 8)
cClrBits = 8;
else if (cClrBits <= 16)
cClrBits = 16;
else if (cClrBits <= 24)
cClrBits = 24;
else cClrBits = 32;

// Allocate memory for the BITMAPINFO structure. (This structure
// contains a BITMAPINFOHEADER structure and an array of RGBQUAD
// data structures.)

if (cClrBits != 24)
pbmi = (PBITMAPINFO) LocalAlloc(LPTR,
sizeof(BITMAPINFOHEADER) +
sizeof(RGBQUAD) * (1<< cClrBits));

// There is no RGBQUAD array for the 24-bit-per-pixel format.

else
pbmi = (PBITMAPINFO) LocalAlloc(LPTR,
sizeof(BITMAPINFOHEADER));

// Initialize the fields in the BITMAPINFO structure.

pbmi->bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
pbmi->bmiHeader.biWidth = bmp.bmWidth;
pbmi->bmiHeader.biHeight = bmp.bmHeight;
pbmi->bmiHeader.biPlanes = bmp.bmPlanes;
pbmi->bmiHeader.biBitCount = bmp.bmBitsPixel;
if (cClrBits < 24)
pbmi->bmiHeader.biClrUsed = (1<<cClrBits);

// If the bitmap is not compressed, set the BI_RGB flag.
pbmi->bmiHeader.biCompression = BI_RGB;

// Compute the number of bytes in the array of color
// indices and store the result in biSizeImage.
// For Windows NT, the width must be DWORD aligned unless
// the bitmap is RLE compressed. This example shows this.
// For Windows 95/98/Me, the width must be WORD aligned unless the
// bitmap is RLE compressed.
pbmi->bmiHeader.biSizeImage = ((pbmi->bmiHeader.biWidth * cClrBits +31) & ~31) /8
* pbmi->bmiHeader.biHeight;
// Set biClrImportant to 0, indicating that all of the
// device colors are important.
pbmi->bmiHeader.biClrImportant = 0;

lpBits = (LPBYTE) GlobalAlloc(GMEM_FIXED, pbmi->bmiHeader.biSizeImage);

if (!lpBits)
return; //Send some message to your log about this issue!

// Retrieve the color table (RGBQUAD array) and the bits
// (array of palette indices) from the DIB.
if (!GetDIBits(hDC, hBmp, 0, (WORD) pbmi->bmiHeader.biHeight, lpBits, pbmi,
DIB_RGB_COLORS))
{
return; //Send some message to your log about this issue!
}

//lpBits have your bitmap so here you can send raw bytes to your SQLServer Database

// Free memory.
GlobalFree((HGLOBAL)lpBits);
LocalFree((HLOCAL)pbmi);
}



 
 
DJO





PostPosted: Visual C++ General, Bitmap -> blob Top

Actually what I have is of type Bitmap.
 
 
Harold Jimenez





PostPosted: Visual C++ General, Bitmap -> blob Top

you can use CreateBitmapIndirect to acquire a Handle from your Bitmap structure.

 
 
Rajesh Prabhu. R





PostPosted: Visual C++ General, Bitmap -> blob Top

Dear Jimenez,

Your Answer was youseful for me also.

And I am also new to GDI+. So Please let me know how to get back the original Bitmap from the LPBYTE (raw data).