Re: How to add a Dialog in a View

From:

=?Utf-8?B?OTc2MTI=?= <97612@discussions.microsoft.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Mon, 19 Jan 2009 18:05:01 -0800

Message-ID:

<E8D3B653-98CC-43B6-934A-4255436FE8A7@microsoft.com>

Thanks. I know what's wrong with the problem.

"Joseph M. Newcomer" wrote:

See below...
On Mon, 19 Jan 2009 07:30:01 -0800, 97612 <97612@discussions.microsoft.com> wrote:

Below is the code that I modified. But it doesn't show the preview of a image
in the View(CPreView), and the program will crash when exit.

//********* code *************
void CPreView::OnDraw(CDC* pDC)
{
CMyDoc *pDoc = (CMyDoc*)((CMainFrame*)AfxGetMainWnd())->GetActiveDocument();

*****
There are so many things wrong with this that the mind boggles. Too many casts, for
example. And since this is in a view, the ONLY valid document it can address is
GetDocument(), and the convoluted mechanism above will probably fail if the view is not
the ACTIVE view, but still needs to be redrawn. So throw that line out and replace it
with
CMyDoc * pDoc = GetDocument();

If this doesn't work, you have deeper and much more serious problems.
*****

LPRECT rect = NULL;
GetClientRect(rect);

*****
The above cannot possibly ever make sense under any circumstances imaginable. Did you
read the description of GetClientRect? What does it require as a parameter? An LPRECT,
right? So why didn't you GIVE IT ONE? That, is, a POINTER TO A RECT STRUCTURE! What you
have it was the same as writing
    GetClientRect(NULL);
which should crash with an access fault. What you CLEARLY meant to write was
    CRect rect;
    GetClientRect(&rect);
and I suggest that you get a book on remedial C/C++ programming if you think that the
lines you wrote could ever have made sense. Learn what a pointer is. And remember that
the parameter types define the type of an EXPRESSION to be used, not the type of a
VARIABLE to be declared! This is first-week-C-programming knowledge.
*****

         if( pDoc->m_pSelectedImage != NULL )
        {

            Graphics graphics( pDC->m_hDC );
            graphics.SetInterpolationMode(InterpolationModeHighQualityBicubic);
            graphics.DrawImage( pDoc->m_pSelectedImage,
                                Rect( rect->left,
                                      rect->top,
                                      rect->right - rect->left,
                                      rect->bottom - rect->top));
        }

*****
Given that your document is probably wrong and your rectangle is certainly wrong, the
above code cannot work. Fix the elementary bugs in your code and it will probably work.
joe
*****

}
//********* code *************

Another question:
I use Invalidate() in the OnUpdate() ( I've overwritten OnUpdate() ) of the
View(CPreView) that show the preview of a image, or OnDraw() won't be
triggered. Is that OK?

Thanks for your replies.

"Scott McPhillips [MVP]" wrote:

Do not ever call OnDraw. The framework will call it for you. You will see
that OnUpdate calls Invalidate. That causes the framework to call OnDraw.

The sample code you are hoping to imitate is very different from OnDraw.
Instead of using lpDrawItemStruct->hDC you should use the CDC* that is
passed to OnDraw. Instead of using pDrawItemStruct coordinates you will
need to compute the rectangle yourself, using GetClientRect and then
computing the image location so it is centered.

"97612" <97612@discussions.microsoft.com> wrote in message
news:05C248CA-5F97-4BDE-8BB5-8300508AE544@microsoft.com...

Thanks for everyone gives the suggestions.

I'm only want to show the thumbnail image, and there is no other needs.

My working now is let the OnUpdate()(other view will call the DOC's
UpdateAllViews() ) in the view(for show the thumbnail image) calling the
OnDraw() and draw the image.

First problem is that I don't know this is the correct way of doing so.

Sencond problem is that I can't draw the thumbnail image by imitating
other's source code("ImageTool" from code project) from the Internet. The
source code is as following:

//************ code ******************
The project include a memdc.h which the author writes himself.

void CPreviewDlg::OnDrawItem( int nIDCtl, LPDRAWITEMSTRUCT
lpDrawItemStruct )
{
if( lpDrawItemStruct->itemAction & ODA_DRAWENTIRE )
{
CMemDC *pMemDC = NULL;
pMemDC = new CMemDC( lpDrawItemStruct->hDC );
lpDrawItemStruct->hDC = pMemDC->m_hDC;

CRect rect; GetClientRect( rect );
HBRUSH hBrush = ::CreateSolidBrush( RGB(255, 255, 255) );

::FillRect( lpDrawItemStruct->hDC, rect, hBrush );

DeleteObject( hBrush );
CImageToolDoc *pDoc = (CImageToolDoc*)
((CMainFrame*)AfxGetMainWnd())->GetActiveDocument();

if( pDoc->m_pSelectedImage != NULL )
{
Graphics graphics( lpDrawItemStruct->hDC );
graphics.SetInterpolationMode(InterpolationModeHighQualityBicubic);
graphics.DrawImage( pDoc->m_pSelectedImage,
                 Rect( lpDrawItemStruct->rcItem.left,
   lpDrawItemStruct->rcItem.top,
   lpDrawItemStruct->rcItem.right - lpDrawItemStruct->rcItem.left,
   lpDrawItemStruct->rcItem.bottom - lpDrawItemStruct->rcItem.top));
}

delete pMemDC;
}
}
//************ code ******************
The problem is that there's no "int nIDCtl" and "LPDRAWITEMSTRUCT
lpDrawItemStruct" parameter for OnDraw()!!!

"Tom Serface" wrote:

The only argument for using a form view is if there would ever be a
chance
of needing more controls added. Resizing a picture control in a formview
is
easy and looks about the same as the solution you are demonstrating. If
OP
is sure they will never need any other controls (like description info,
path
info, ability to select image, etc.) then this method is likely easier to
implement (although not a lot easier).

Tom

"AliR (VC++ MVP)" <AliR@online.nospam> wrote in message
news:aQIbl.1210$PE4.32@nlpi061.nbdc.sbc.com...

I disagree with doing it this way. If he is only going to display an
image
on a window why go through the overhead of CFormView and a CStatic. Why
not simply draw the image himself in the views paint routine. This way
he
has full control, if later he wants to add scrolling he can do that
(where
if he had a CFormView with a static control it would be difficult), and
also can avoid flickering by overriding the erasebackground message.

void CMyView::OnPaint()
{
       CPaintDC dc(this);
       CMemDC MemDC;
       MemDC.CreateCompatibleDC(&dc);
       int Saved = MemDC.SaveDC();
       MemDC.SelectObject(m_Bmp);
       //calculate X, and Y based on the window size and Width and
Height
of bitmap
       ....
       dc.BitBlt(X,Y,Width,Height,&MemDC,0,0,SRCCOPY);
       MemDC.RestoreDC(Saved);
}

AliR.

--
Scott McPhillips [VC++ MVP]

Joseph M. Newcomer [MVP]
email: newcomer@flounder.com
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm