Load image from binary in MFC
Usually I do the image-loading using LoadImage with path or L开发者_如何学PythonoadBitmap with resource ID. But now the target image resource is stored in database(SQLite). So how can I use the binary data directly(avoiding store temporary file) retrieved from the db in MFC?
Here's the solution I found out ,and it works fine in my project.
1.function for retrieve binary data from sqlite database.
int CSqlite::retrieveBinaryData(int id , byte *pdata)
{
ASSERT(pdata != NULL);
int rc,size;
sqlite3_stmt * stmt;
sqlite3_prepare(dbh,"select id,content,size from images where id = ?",-1,&stmt,0);
sqlite3_bind_int(stmt,1,id);
rc = sqlite3_step(stmt);
if(rc == SQLITE_ROW)
{
num = sqlite3_column_int(stmt,0);
size = sqlite3_column_int(stmt,2);
byte *tmpdata = (byte * )sqlite3_column_blob(stmt,1);
memcpy(pdata,tmpdata,size);
return size;
}
return 0;
}
2.receive the data from function above and convert it to CBitmap so we can use it.
byte *tdata = new BYTE[BMP_MAX_SIZE];
CSqlite *sq = new CSqlite("mysqlite.db");
int size = sq->retrieveBinaryDatas(myid,tdata);
/* using the resource mentioned by alfonso in the comment */
BITMAPFILEHEADER* bmfh;
bmfh = (BITMAPFILEHEADER*)tdata;
BITMAPINFOHEADER* bmih;
bmih = (BITMAPINFOHEADER*)(tdata + sizeof(BITMAPFILEHEADER));
BITMAPINFO* bmi;
bmi = (BITMAPINFO*)bmih;
void* bits;
bits = (void*)(tdata + bmfh->bfOffBits);
HDC hdc = ::GetDC(NULL);
HBITMAP hbmp = CreateDIBitmap(hdc, bmih, CBM_INIT, bits, bmi, DIB_RGB_COLORS) ;
::ReleaseDC(NULL, hdc);
delete tdata;
BITMAP bitmap;
CBitmap *bmpBackground = CBitmap::FromHandle(hbmp);
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