bitmap

Ok, I want to open a bitmap,

CString fileName;
fileName = "somefile.bmp";

CBitmap bmCrit;
bmCrit.LoadBitmap(fileName);

when i do above i get an illegal operation when program runs. please tell me where i am going wrong? and i set the file name from the file dialogue(even if i don't i get the same error).

LoadBitmap does not expect a filename, but a resource name (the function's name may be confusing, indeed:)).


If you're using MFC, then first load a bitmap (can be done in the ResourceView), and use it's ID in the LoadBitmap.

{
CBitmap bmp; // Creating CBitmap Object bmp
bmp.LoadBitmap(ID_OF_THE_RESOURCE_BMP);
...
}

Afterwards you can use methods like SetBitmap, SetItemImage, etc. to attach the bitmap to a given control, element (button, treeview, and so on).

Hint:buy Windows programming related books, and forget the old Pascal approach ;).

well the problem is i want the user to be able to select the bitmap they want to insert? how would i go about doing that.

Try this out:

CBitmap* aCBmp = NULL;
if(!aCBmp->LoadBitmap("Bitmaps\\bitmap.bmp"))
{
MessageBox("Cannot load bitmap from file","Load error!", MB_OK);
}

Ok , here is how i am doing it

CDC dcMem;

CBitmap* aCBmp = NULL;

if(!aCBmp->LoadBitmap("setup.bmp"))
{

//**************// an illagal operation is reported by
//**************// windows and program terminates before
//**************// message box comes
MessageBox(NULL, "Cannot load bitmap from file","Load error!", MB_OK);
}



MessageBox(NULL, "1", NULL, MB_OK);




aCBmp->GetObject(sizeof(BITMAP), aCBmp);

dcMem.CreateCompatibleDC(pDC);
VERIFY(dcMem.SelectObject(aCBmp));



why is it generating illegal operation while loading . (setup.bmp is not a defined resource, and the file does exist in the running directory)

Give it a try without pointers.

CBitmap aCBmp;

if(!aCBmp.LoadBitmap("winnt.bmp"))
{

MessageBox("Cannot load bitmap from file","Load error!", MB_OK);
}

The message box

MessageBox("Cannot load bitmap from file","Load error!", MB_OK);


do appear this time, indeed it always appear. so i am still unable to load a file. i have tried to give different file name but still no vain. what should i do now.

Hi

try LoadImage() API with
LR_CREATEDIBSECTION - if you like it as DIB image
and LR_LOADFROMFILE to load it from the file instead of resources

damyan

Quote:

---

"LoadBitmap does not expect a filename, but a resource name "

---

Right after I said this, made myself the mistake !
Ok, I was wrong :(.
Now, the *working* code look like this (there are some checkings, too)
/* --------------------------------------------------
loading the bitmap from file and attaching to a CBitmap
--------------------------------------------------*/
CBitmap aCBmp;
HBITMAP hBmp;
BITMAP mBitmap;

FILE *File=NULL; // File Handle
File = fopen("your_bmp_name_here","r");

// file exists?
if ( File )
{
fclose(File);// Close The Handle
MessageBox("File open ok","Open success", MB_OK);

// Load the Bitmap and return a pointer
hBmp = (HBITMAP)::LoadImage( 0, "your_bmp_name_here", IMAGE_BITMAP, 0, 0,
LR_DEFAULTCOLOR |
LR_LOADFROMFILE |// load flags);
LR_CREATEDIBSECTION
);
}

if ( !hBmp )
{
MessageBox("Bitmap load failed","Load error!", MB_OK);
}

if ( !aCBmp.Attach(hBmp) )
{
MessageBox("Attach failed","Error!", MB_OK);
}

if ( !aCBmp.GetBitmap( &mBitmap ) )
{
MessageBox("GetBitmap failed","Error!", MB_OK);
}
}

/* --------------------------------------------------
Put these in the OnPaint event
to display your bmp
--------------------------------------------------*/
void yourClass::OnPaint
{
// do not modify
if (IsIconic())
{
//do not modify
}
else
// your code comes here!
// which loads CBitmap to a memDC, then copies it to the PaintDC

CDC memDC;
CPaintDC dcPaint(this);

if( memDC.CreateCompatibleDC(&dcPaint) )
{
memDC.SelectObject( &aCBmp );

dcPaint.BitBlt( 0, 0,
iYourWidth,
iYourHeight,
&memDC,
0,
0,
SRCCOPY);
}
CDialog::OnPaint();
}
}

You can make a LoadBmp method, this would be more elegant, passing the filename as parameter.

And don't forget to call the DeleteObject function (e.g. in your destructor) to delete each bitmap handle returned by the LoadBitmap function.

Have fun! (and register yourself here, it's a great site)