Search icon in edit control overlapped by input area

Question

I am trying to make a search edit control in MFC that has an icon displayed in the control window all the time (regardless the state and text of the control). I have written something like this many years ago and worked very well, but the code no longer works on Windows 7 and newer (maybe even Vista, but did not try that). What happens is that the image shown in the control is overlapped with the input area (see the picture below).

The idea behind the code:

• have a class derived from CEdit (that handles painting in OnPaint)
• the icon is displayed on the right and the edit area is shrunk based on the size of the icon
• resizing is done differently for single-line and multiline edits. For single line I call SetMargins and for multiline edits I call SetRect.
• this edit resizing is applied in PreSubclassWindow(), OnSize() and OnSetFont()

This is how the edit input size is applied:

void CSymbolEdit::RecalcLayout()
{
    int width = GetSystemMetrics( SM_CXSMICON );

    if(m_hSymbolIcon)
    {
      if (GetStyle() & ES_MULTILINE)
      {
         CRect editRect;
         GetRect(&editRect);

         editRect.right -= (width + 6);

         SetRect(&editRect);
      }
      else
      {
         DWORD dwMargins = GetMargins();
         SetMargins(LOWORD(dwMargins), width + 6);
      }
    }
}

The following image shows the problem with the single line edits (the images have been zoomed in for a better view). The yellow background is for highlighting purposes only, in real code I am using the COLOR_WINDOW system color. You can see that when the single line edit has text and has the input the left side image is painted over. This does not happen with the multiline edit where SetRect correctly sets the formatting rectangle.

I have tried using ExcludeClipRect to remove the area of the edit where the image is being displayed.

CRect rc;
GetClientRect(rc);

CPaintDC dc(this);
ExcludeClipRect(dc.m_hDC, rc.right - width - 6, rc.top, rc.right, rc.bottom);

DWORD dwMargins = GetMargins();
SetMargins(LOWORD(dwMargins), width + 6);

This does not seem to have any effect on the result.

For reference, this is the painting method, written years ago and used to work well on Windows XP, but not correct any more.

void CSymbolEdit::OnPaint()
{
    CPaintDC dc(this);

    CRect rect;
    GetClientRect( &rect );

    // Clearing the background
    dc.FillSolidRect( rect, GetSysColor(COLOR_WINDOW) );

    DWORD dwMargins = GetMargins();

    if( m_hSymbolIcon )
    {
        // Drawing the icon
        int width = GetSystemMetrics( SM_CXSMICON );
        int height = GetSystemMetrics( SM_CYSMICON );

        ::DrawIconEx( 
            dc.m_hDC, 
            rect.right - width - 1, 
            1,
            m_hSymbolIcon, 
            width, 
            height, 
            0, 
            NULL, 
            DI_NORMAL);

        rect.left += LOWORD(dwMargins) + 1;
        rect.right -= (width + 7);
    }
    else
    {
        rect.left += (LOWORD(dwMargins) + 1);
        rect.right -= (HIWORD(dwMargins) + 1);
    }

    CString text;
    GetWindowText(text);
    CFont* oldFont = NULL;

   rect.top += 1;

    if(text.GetLength() == 0)
    {       
        if(this != GetFocus() && m_strPromptText.GetLength() > 0)
        {
            oldFont = dc.SelectObject(&m_fontPrompt);
            COLORREF color = dc.GetTextColor();
            dc.SetTextColor(m_colorPromptText);
            dc.DrawText(m_strPromptText, rect, DT_LEFT|DT_SINGLELINE|DT_EDITCONTROL);
            dc.SetTextColor(color);
            dc.SelectObject(oldFont);
        }
    }
    else
    {
      if(GetStyle() & ES_MULTILINE)
         CEdit::OnPaint();
      else
      {
         oldFont = dc.SelectObject(GetFont());
         dc.DrawText(text, rect, DT_SINGLELINE | DT_INTERNAL | DT_EDITCONTROL);
         dc.SelectObject(oldFont);
      }
    }
}

I have looked at other implementations of similar edit controls and they all have the same fault now.

Obviously, the question is how do I exclude the image area from the input area of the control?

Fides

Your OnPaint override is fighting against Edit control's paint routine. It uses CPaintDC to paint the control manually, sometimes it calls CEdit::OnPaint, which in turn calls CPaintDC again, followed by default processing which repaints the client area. This will fail when Edit control goes in and out of focus, or when any paint message is received. – Concert

CEdit::OnPaint() is only called for multiline edits, which is not my concern. I am using only single line edit controls. I have mentioned multiline edits because in this case setting the bounds works correctly. – Fides

What if you override CWnd::OnCtlColor() and call ExcludeClipRect() from there? Seems to work fine here with a quick test, but without MFC. You might have to change clipping again in your OnPaint() to show your own stuff. – Chelsae

Did my answer help at all? You had a "draw attention" notice with a bounty, but you haven't said anything since. – Chelsae

I apologize for ignoring this, it was completely out of my focus lately. I will check what you posted and if it works I will grant you the bounty points (will have to create a new one, hope that works). – Fides

You forgot to mention me, so I didn't see your comment. I don't care much for the bounty or the mark, I was just wondering if my answer worked :) – Chelsae

Answer 1

I think what's going on is that CPaintDC calls BeginPaint(), which sends a WM_ERASEBKGND to the edit box. I wasn't able to ignore it, so I guess it's being sent to maybe an internal STATIC window? Not sure.

Calling ExcludeClipRect() in your OnPaint() handler won't do anything because EDIT will reset the clipping region to the whole client area in either BeginPaint() or its own WM_PAINT handler.

However, EDIT sends a WM_CTRCOLOREDIT to its parent just before painting itself, but seemingly after setting the clipping region. So you can call ExcludeClipRect() there. Sounds like an implementation detail which may change with future versions of the common controls. Indeed, it seems to have done so already.

I did a quick test without MFC on Windows 7, here's my window procedure:

LRESULT CALLBACK wnd_proc(HWND h, UINT m, WPARAM wp, LPARAM lp)
{
    switch (m)
    {
        case WM_CTLCOLOREDIT:
        {
            const auto dc = (HDC)wp;
            const auto hwnd = (HWND)lp;

            RECT r;
            GetClientRect(hwnd, &r);

            // excluding the margin, but not the border; this assumes
            // a one pixel wide border
            r.left = r.right - some_margin;
            --r.right;
            ++r.top;
            --r.bottom;

            ExcludeClipRect(dc, r.left, r.top, r.right, r.bottom);

            return (LRESULT)GetStockObject(DC_BRUSH);
        }
    }

    return ::DefWindowProc(h, m, wp, lp);
}

I then subclassed the EDIT window to draw my own icon in WM_PAINT, and then forwarded the message so I didn't have to draw everything else myself.

LRESULT CALLBACK edit_wnd_proc(
    HWND h, UINT m, WPARAM wp, LPARAM lp,
    UINT_PTR  id, DWORD_PTR data)
{
    switch (m)
    {
        case WM_PAINT:
        {
            const auto dc = GetDC(h);

            // draw an icon

            ReleaseDC(h, dc);
            break;
        }
    }

    return DefSubclassProc(h, m, wp, lp);
}

Note that I couldn't call BeginPaint() and EndPaint() (the equivalent of constructing a CPaintDC) in WM_PAINT because the border wouldn't get drawn. I'm guessing it has something to do with calling BeginPaint() twice (once manually, once by EDIT) and the handling of WM_ERASEBKGND. YMMV, especially with MFC.

Finally, I set the margins right after creating the EDIT:

SendMessage(
    e, EM_SETMARGINS,
    EC_LEFTMARGIN | EC_RIGHTMARGIN, MAKELPARAM(0, margin));

You might also have to update the margins again if the system font changes.

Chelsae

Answer 2

Have a look at this tutorial... from www.catch22.net. It gives a clear picture of how to insert a button into edit control. Though it is an Win32 example, this can be improvised to MFC as the basic structure of MFC is using win32 apis.

http://www.catch22.net/tuts/win32/2001-05-20-insert-buttons-into-an-edit-control/#

It uses WM_NCCALCSIZE to restrict the text control.

Towrey