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Function to load a bitmap on a dialog

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6 Apr 2006CPOL 61.8K   1.8K   13   2
Here is a function to load a bitmap on any dialog.

Sample Image - codepr.jpg

Introduction

Here, I am introducing a function SBitdraw(CDC *pDC, UINT nIDResource, int i) to load any bitmap to a dialog. There are so many ways by which we can load a bitmap. Here, I am giving a function which you can just add to your project and get the result. No need to add any other header files or .cpp files.

Using the function

First, bring the bitmap to your project.

  1. Put the function SBitdraw() as a member function of your main dialog class. Example: bool CSBitDialogDlg::SBitdraw(CDC *pDC, UINT nIDResource, int i).
  2. Add Messagemap ON_WM_ERASEBKGND() using the MFC ClassWizard.
  3. Then, call SBitdraw() from OnEraseBkgnd(CDC* pDC) to load any bitmap on the dialog.
  4. (Or, you can call from anywhere, and then you use OnEraseBkgnd() and Invalidate() to force refreshing your dialog.

C++
-------------------------------------------------------
Parameters of the function::
SBitdraw(CDC *pDC, UINT nIDResource, int i);
1. pDC  take the device context obj.
2. nIDResource  is the ID of the bitmap.
3. Int i  will take integer 1-3  
   (1 for center, 2 for Stretch, And 3 for title) 
    to get how bitmap will load.
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Function defination:
 bool SBitdraw(CDC *pDC, UINT nIDResource, int i) 
{
            CBitmap* m_bitmap;
            m_bitmap=new CBitmap();
            m_bitmap->LoadBitmap(nIDResource);
            if(!m_bitmap->m_hObject)
                        return true;
    CRect rect;
            GetClientRect(&rect);
            CDC dc;
            dc.CreateCompatibleDC(pDC);    
            dc.SelectObject(m_bitmap);
            int bmw, bmh ;
            BITMAP bmap;
            m_bitmap->GetBitmap(&bmap);
            bmw = bmap.bmWidth;
            bmh = bmap.bmHeight;
            int xo=0, yo=0;
            switch(i){
            case 1:
            	pDC->StretchBlt(xo, yo, rect.Width(),
                                    rect.Height(), &dc,
                                    0, 0,bmw,bmh, SRCCOPY);
                break;
            case 2:
                if(bmw < rect.Width())
                    xo = (rect.Width() - bmw)/2;
                else 
                    xo=0;
                if(bmh < rect.Height())
                    yo = (rect.Height()-bmh)/2;
                else
                    yo=0;
                pDC->BitBlt (xo, yo, rect.Width(),
                            rect.Height(), &dc,
                            0, 0, SRCCOPY);
                break;
             case 3:
                for (yo = 0; yo < rect.Height(); yo += bmh)
                {
                    for (xo = 0; xo < rect.Width(); xo += bmw)
                    {
                        pDC->BitBlt (xo, yo, rect.Width(),
                                    rect.Height(), &dc,
                                    0, 0, SRCCOPY);
                    }
                }
            }
            return true;
 
}
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Note: In my demo project, UserId & Password both are "trek". First login and then change the background.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


Written By
Web Developer
India India
This is Saday Chand Sarkar , New in MFC world.
Working in Trek Technology Pte.Ltd.

Comments and Discussions

 
GeneralAnother problem is memory leaks Pin
Jun Du3-Mar-06 3:25
Jun Du3-Mar-06 3:25 
All the m_bitmap objects created in the redraw handler will not be freed. However, the tricky thing is that you code may not work if you delete m_bitmap, becuase the SelectObject() may need it even outside the function. As indicated by YoSilver, you should load the bitmap only once. You normally place it to a memory DC and copy the memory to the screen each time you redraw. BTW, this technique is called "double buffering", which also helps to avoid flickering.
GeneralIssues Pin
YoSilver2-Mar-06 5:57
YoSilver2-Mar-06 5:57 

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