Implementing OWNERDRAWN Edit Controls in MFC/Multipad
         -----------------------------------------------------

The Magma Edit DLL/VBX comes with replacement drop-in classes for MFC.
The CMagmaEdit and CMagmaEditView classes can be used instead of
the CEdit and CEditView classes which comes as part of MFC.

Many users of the Magma Edit DLL like to take advantage of the
ownerdrawn style which the edit control supports. Using the ownerdrawn 
style, the application is given the first crack at drawing a line of 
text. Ownerdrawn lines are good for things like syntax highlighting, 
custom coloring, etc.

This technote summarizes experiences with getting the MFC Multipad
sample to work with an ownerdrawn MagmaEdit control. 

We need a way to create a CMagmaEditView control with the ES_OWNERDRAW
style in it. Since the Magma Editor DLL sends the ME_DRAWITEM message
to the parent of the edit control, we need to derive a new parent window
class whose main job is to process the ownerdraw messages. In this example,
the new class processes only the ME_DRAWITEM and ME_MEASUREITEM messages ---
you can expand it so that it processes the ME_DELETEITEM message too. 


In MULTIPAD.H, we added the following two classes :

class COwnerDrawEditView : public CMagmaEditView
{
  DECLARE_DYNCREATE(COwnerDrawEditView)

protected:
  virtual BOOL PreCreateWindow(CREATESTRUCT& cs);
};


class CMDIOwnerDrawChildWnd : public CMDIChildWnd
{
  DECLARE_DYNCREATE(CMDIOwnerDrawChildWnd)

  //{{AFX_MSG(CMDIOwnerDrawChildWnd)
  afx_msg long OnMEDrawItem(UINT nIDCtl, long lpMIS);
  afx_msg long OnMEMeasureItem(UINT nIDCtl, long lpMIS);
  //}}AFX_MSG

  DECLARE_MESSAGE_MAP()
};



The main purpose of COwnerDrawEditView is to force the ES_OWNERDRAW style
to be passed to the Magma Editor DLL when we create an edit control.
Therefore, COwnerDrawEditView merely 'front-ends' the PreCreateWindow
function.

CMDIOwnerDrawChildWnd contains the code to process the various
ownerdrawn messages, such as ME_DRAWITEM, ME_MEASUREITEM, and
ME_DELETEITEM.

In DOCVIEW.CPP, we added 

#ifdef USE_MAGMA
IMPLEMENT_DYNCREATE(COwnerDrawEditView, CMagmaEditView)

BOOL COwnerDrawEditView::PreCreateWindow(CREATESTRUCT& cs)
{
  cs.style |= ES_OWNERDRAW | ES_HASSTRINGS;
  return CMagmaEditView::PreCreateWindow(cs);
}

IMPLEMENT_DYNCREATE(CMDIOwnerDrawChildWnd, CMDIChildWnd)
BEGIN_MESSAGE_MAP(CMDIOwnerDrawChildWnd, CMDIChildWnd)
  //{{AFX_MSG_MAP(CMDIOwnerDrawChildWnd)
    ON_MESSAGE(ME_DRAWITEM, OnMEDrawItem)
    ON_MESSAGE(ME_MEASUREITEM, OnMEMeasureItem)
  //}}AFX_MSG_MAP
END_MESSAGE_MAP()

long CMDIOwnerDrawChildWnd::OnMEDrawItem(UINT nIDCtl, long lpMIS)
{
  LPMEDRAWITEMSTRUCT lpMID = (LPMEDRAWITEMSTRUCT) lpMIS;

  // Highlight C++ comments which start at column 1
  if (lpMID->lpText[0] == '/' && lpMID->lpText[1] == '/')
  {
    COLORREF rgbOld = ::SetTextColor(lpMID->hDC, RGB(0, 128, 0));
    ::TextOut(lpMID->hDC, 
              lpMID->rcItem.left, lpMID->rcItem.top, 
              lpMID->lpText, lstrlen(lpMID->lpText)); 
    ::SetTextColor(lpMID->hDC, rgbOld);
    return TRUE;
  }
  else
  {
    return FALSE;
  }
}

long CMDIOwnerDrawChildWnd::OnMEMeasureItem(UINT nIDCtl, long lpMIS)
{
  LPMEASUREITEMSTRUCT lpMID = (LPMEASUREITEMSTRUCT) lpMIS;
  return FALSE;  // let the edit control use the height
}
#endif


In Multipad, we need to create a document template using the new
classes we derived. In MULTIPAD.CPP, we used the following call 
to AddDocTemplate :

         AddDocTemplate(new CMultiDocTemplate(IDR_TEXTTYPE,
          RUNTIME_CLASS(CPadDoc), 
                RUNTIME_CLASS(CMDIOwnerDrawChildWnd),
          RUNTIME_CLASS(COwnerDrawEditView)));


The processing of the ME_DRAWITEM message is very simplistic. You
can choose to implement more complicated processing. The source code
to the MEWIN sample program (available with the Magma Edit DLL)
contains some code to do syntax highlighting for C programs.

For more info on the Magma Edit DLL :

Demos : GO MAGMA on Compuserve
        ftp.uu.net, directory /vendor/uno

Compuserve mail : 75300,2062
Internet        : 75300.2062@compuserve.com
                  magma@bix.com

Magma Systems also sells the MEWEL User Interface Library, an
implementatiom of the Windows API, MFC and OWL for Dos text,
DOs graphics, UNIX Text, and MOTIF.