BorlandTalk.com

poojo hackma · Guest

First, I must say that this is being done in eMbedded VC 4.0 for a Pocket
PC, not in Borland; however, the techniques should be the same for native
API usage, so I wanted to post the question here.

It has taken me a little time, but I have narrowed my problem down to
CBitmap::GetObject.

My application loads many images. The frequently used ones have been
converted to bitmaps and are loaded as resources, but the rest are still in
JPEG format on the device's Compact Flash storage card.

To load a JPEG, I use SHLoadImageFile from the Pocket PC SDK. To load a
resource bitmap, I use the LoadBitmap API (see code below).

The problem comes when I attempt to call GetObject on a jpeg file. The image
displays correctly, but parts of my program get overwritten whenever it
happens. (Currently, CStringList files is being overwritten, but if the
declaration order gets changed around somewhat, it will go to something
else.)

Could someone look at my use of GetObject and tell me what I am doing wrong?
Could you suggest a way to fix it?

void CForm1Dlg::OnPaint()
{
CBitmap bitmap, *pOldbmp;
CPaintDC dc(this);
BITMAP BMP;
CDC mDC;
DWORD ok;
HBITMAP hBMP;
if (bImageIsJpegFile)
hBMP = SHLoadImageFile(szImageFile);
else
hBMP = LoadBitmap(AfxGetApp()->m_hInstance,
MAKEINTRESOURCE(IDB_IMAGE2));
if (hBMP == NULL)
return;
ok = bitmap.Attach(hBMP);
if (!ok)
return;
// Help says if I pass NULL as param2, GetObject returns the
// size needed to allocate for the bitmap object:
ok = bitmap.GetObject(sizeof(BITMAP), NULL);
// problem is, GetObject above always returns ok=84.
// Any idea what that would mean?
if (!ok)
return;
// In the GetObject below, if hBMP is to a JPEG file,
// other areas of my application get overwritten.
// Does anyone know why?
ok = bitmap.GetObject(ok, &BMP);
// CStringList files was 56, now it is 0.
if (!ok)
return;
mDC.CreateCompatibleDC(&dc);
pOldbmp = mDC.SelectObject(&bitmap);
if (pOldbmp != NULL)
{
dc.StretchBlt(r.left, r.top, r.Width(), r.Height(), &mDC,
0, 0, BMP.bmWidth, BMP.bmHeight, SRCCOPY);
mDC.SelectObject(pOldbmp);
mDC.DeleteDC();
}
mDC.ReleaseAttribDC();
}

Thanks in advance!
~Joe

Thomas Maeder [TeamB] · Guest

"poojo hackma" <poojo.com/mail> writes:

poojo hackma · Guest

CBitmap is an MFC bitmap class that "encapsulates the functionality of a
Windows CE graphics device interface (GDI) bitmap."

I suppose if no one here knows what a CBitmap is, I'm not going to be able
to get much help.

Thanks anyway.

"Thomas Maeder [TeamB]" wrote:

Bob Gonder · Guest

poojo hackma wrote:

Thomas Maeder [TeamB] · Guest

"poojo hackma" <poojo.com/mail> writes:

poojo hackma · Guest

Hi Mr. Gonder.

Thanks for the info!

What should be allocated 84 bytes? My CBitmap object "bitmap" and my BITMAP
structure "BMP" are both heap allocated.

There is an "LPVOID bmBits" in the BITMAP structure. Should I allocate 84
bytes of data, then point the bmBits to it?

typedef struct tagBITMAP {
LONG bmType;
LONG bmWidth;
LONG bmHeight;
LONG bmWidthBytes;
WORD bmPlanes;
WORD bmBitsPixel;
LPVOID bmBits;
} BITMAP;

"Bob Gonder" wrote:

poojo hackma · Guest

Oh, I did! But they get flooded with so many messages that if no one can
answer it in a day, it gets stuffed so far back in the queue that no one
will ever see it again.

And, they don't typically like to share their information or take the time
to show someone how to do it correctly, which is one of the things I've
always liked about this board.

Speaking of which, someone say hello to Gambit for me.

"Thomas Maeder [TeamB]" writes:

Bruce Salzman · Guest

"poojo hackma" <poojo.com/mail> wrote in message
news:4613f4bc (AT) newsgroups (DOT) borland.com...

Bob Gonder · Guest

poojo hackma wrote:

poojo hackma · Guest

"Bob Gonder" wrote:

poojo hackma · Guest

Thanks for the pointer, Bruce. I had originally passed over this method,
thinking I could not use it if I was opening a JPEG file. Later, I learned
that the SDK tool SHLoadImageFile actually returns a bitmap that I can use
with GetBitmap.

I think the problem is solved.

Thanks again!
~Joe

" Bruce Salzman" wrote: