Question

Okay I am having some problems with being able to change bitmaps when a certain parameter is greater than another. I am a massive newbie to this and my coding isn’t great (at all). I have code that reads the limits (parameters) and displays as text which is this:

CFont* def_font = argDC->SelectObject(&m_Font);
   CString csText;
   int StartPos = WindowRect.Width()/5;
   CRect TextRect(StartPos, WindowRect.top + 5, StartPos + 100, WindowRect.top + 35);
   csText.Format(_T("%.2ft"), argSystemDataPtr->GetMaxSWL());
   int32_t iSWLDigits = csText.GetLength();
   if (iSWLDigits < m_SWLDigitsNum)
   {
      m_RedPanelBitmap.LoadBitmapW(IDB_BITMAP_PANEL_RED);
      //argDC->FillSolidRect(TextRect, RGB(255, 255, 255));
   }
   m_SWLDigitsNum = iSWLDigits;
   argDC->DrawText(csText, TextRect, DT_LEFT);

The bitmaps that are usually displayed are green but if a limit is breached like the one above then I want the bitmap to change to a red one. Here is what I’ve got for the green ones.

CRect PanelRect1, PanelRect2;

         CRect PanelsRect(WindowRect);

         const int BarHeight = 30;
         PanelsRect.OffsetRect(0,m_bShowTitleBar?BarHeight:-BarHeight);
         PanelsRect.DeflateRect(0,m_bShowTitleBar?BarHeight*-1:BarHeight);


         m_GreenPanelBitmap.Detach();


         m_GreenPanelBitmap.LoadBitmapW(IDB_BITMAP_PANEL_GREEN);

         CBitmap* pOld = memDC.SelectObject(&m_GreenPanelBitmap);

         BITMAP bits;

         m_GreenPanelBitmap.GetObject(sizeof(BITMAP),&bits);

         PanelRect1.SetRect(0,PanelsRect.top, PanelsRect.right /2 , PanelsRect.Height()/3);
         PanelRect2.SetRect(0,PanelsRect.top+PanelRect1.Height(), PanelsRect.right /2 ,(PanelsRect.Height()/3) + PanelRect1.Height());


         //Now draw the Panels
         if (pOld != NULL)
         {

            argDC->StretchBlt(PanelRect1.left ,PanelRect1.top,PanelRect1.Width(),PanelRect1.Height(),
            &memDC,0,0,bits.bmWidth-1, bits.bmHeight-1, SRCCOPY);

            argDC->StretchBlt(PanelRect2.left,PanelRect2.top,PanelRect2.Width(),PanelRect2.Height(),
            &memDC,0,0,bits.bmWidth-1, bits.bmHeight-1, SRCCOPY);


            memDC.SelectObject(pOld);

I would be extremely grateful for any help, I understand there probably is a simple answer but I’ve been scratching my head over it and can’t seem to find an answer anywhere else on how change the m_GreenPanelBitmap to m_RedPanelBitmap when this statement is true.

 `if (iSWLDigits < m_SWLDigitsNum).`

Answer 1

Well, I do think your question is a bit messy but…

On the second code snippet you posted (I suppose from a OnPaint method in a dialog) you are displaying the green bitmap by using StretchBlt.
If your problem is you need to display one bitmap or another depending on a condition you should load both images (maybe you can do that elsewhere to avoid loading the images everytime the dialog is painted) and then display the one you really need based on the condition. Something like that:

bool bCondition = /*whatever*/

m_GreenPanelBitmap.LoadBitmapW(IDB_BITMAP_PANEL_GREEN);
m_RedPanelBitmap.LoadBitmapW(IDB_BITMAP_PANEL_RED);

CBitmap* pBitmapToDisplay = bCondition ? &m_GreenPanelBitmap : &m_RedPanelBitmap;

CBitmap* pOld = memDC.SelectObject(pBitmapToDisplay);

BITMAP bits;
pBitmapToDisplay->GetObject(sizeof(BITMAP),&bits);

PanelRect1.SetRect(0,PanelsRect.top, PanelsRect.right /2 , PanelsRect.Height()/3);
PanelRect2.SetRect(0,PanelsRect.top+PanelRect1.Height(), PanelsRect.right /2, PanelsRect.Height()/3) + PanelRect1.Height());

argDC->StretchBlt(PanelRect1.left ,PanelRect1.top,PanelRect1.Width(),PanelRect1.Height(),
            &memDC,0,0,bits.bmWidth-1, bits.bmHeight-1, SRCCOPY);

memDC.SelectObject(pOld);

Maybe with a more detailed question we would be able to help you more.