Q179696: PRB: Focus and Tab Issues with ATL Subclassed Edit Control
Article: Q179696
Product(s): Microsoft C Compiler
Version(s): 2.0,2.1,5.0
Operating System(s):
Keyword(s): kbActiveX kbATL200 kbATL210 kbCOMt kbCtrlCreate kbEditCtrl kbKeyAccel kbVC500 kbVC600 M
Last Modified: 17-APR-2002
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The information in this article applies to:
- The Microsoft Active Template Library (ATL), versions 2.0, 2.1, used with:
- Microsoft Visual C++, 32-bit Enterprise Edition, version 5.0
- Microsoft Visual C++, 32-bit Professional Edition, version 5.0
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SYMPTOMS
========
If you use the ATL Wizards to create an ActiveX control that subclasses the Edit
common control, you may see one or both of the following problems depending on
where you use the control:
- You cannot use the TAB key to set focus to the ActiveX Edit control. You must
use the mouse to set focus and activate the ActiveX Edit control.
- Once the ActiveX Edit control has the focus, you will hear a beep if you try
to use the TAB key to change the focus away from it.
CAUSE
=====
When an ATL-based ActiveX control subclasses a Windows common control, it
creates a contained window object to subclass the control. When you use the TAB
key to move around an application, the ActiveX control window gets the focus but
never shifts the focus to the Edit window within the ActiveX control. As a
result, you must click the Edit control to activate it.
The second issue results from the way an ATL-based control and its ActiveX
control container handle messages. Because of the way some control containers
handle messages, they do not get the opportunity to process the TAB keystroke,
even if the control itself does not process it.
RESOLUTION
==========
To activate the ATL-based ActiveX Edit control with the TAB key, you can
override the OnSetFocus method and set the focus to the contained Edit window
before returning.
To use the TAB key to shift the focus away from the ATL-based control, you can
override the TranslateAccelerator method. If the message is WM_KEYDOWN and the
key is the TAB key, give the IOleControlSite TranslateAccelerator a chance to
process the message first.
STATUS
======
This problem was corrected in Visual C++ version 6.0 for Windows.
MORE INFORMATION
================
To work around these issues, add the following code to your ATL-based control
class:
Sample Code
-----------
typedef enum tagKEYMODIFIERS
{
KEYMOD_NONE = 0X00000000,
KEYMOD_SHIFT = 0x00000001,
KEYMOD_CONTROL = 0x00000002,
KEYMOD_ALT = 0x00000004
} KEYMODIFIERS;
class ATL_NO_VTABLE Csc_ctrl2 :
...
{
...
BEGIN_MSG_MAP(CAtlEdit)
MESSAGE_HANDLER(WM_PAINT, OnPaint)
MESSAGE_HANDLER(WM_CREATE, OnCreate)
MESSAGE_HANDLER(WM_CTLCOLOREDIT, OnCtlColorEdit)
MESSAGE_HANDLER(WM_SETFOCUS, OnSetFocus)
MESSAGE_HANDLER(WM_KILLFOCUS, OnKillFocus)
MESSAGE_HANDLER(WM_MOUSEACTIVATE, OnMouseActivate)
ALT_MSG_MAP(1)
MESSAGE_HANDLER(WM_SETFOCUS, OnChildSetFocus)
MESSAGE_HANDLER(WM_KILLFOCUS, OnChildKillFocus)
END_MSG_MAP()
...
STDMETHOD(TranslateAccelerator)(LPMSG lpmsg)
{
CComQIPtr<IOleControlSite,&IID_IOleControlSite>
spCtrlSite(m_spClientSite);
if (spCtrlSite)
{
if ((lpmsg->message == WM_KEYDOWN) && (
(LOWORD(lpmsg->wParam) == VK_RETURN) ||
(LOWORD(lpmsg->wParam) == VK_TAB) ))
{
DWORD keymods = 0;
keymods += (GetKeyState(VK_SHIFT) < 0) ? KEYMOD_SHIFT
: KEYMOD_NONE;
keymods +=
(GetKeyState(VK_CONTROL) < 0) ? KEYMOD_CONTROL
: KEYMOD_NONE;
keymods += (GetKeyState(VK_MENU) < 0) ? KEYMOD_ALT
: KEYMOD_NONE;
return spCtrlSite->TranslateAccelerator(lpmsg,keymods);
}
}
return S_FALSE;
}
LRESULT OnSetFocus(UINT /* nMsg */,
WPARAM /* wParam */,
LPARAM /* lParam */,
BOOL& bHandled /* bHandled */)
{
::SetFocus(m_EditCtrl.m_hWnd);
bHandled = TRUE;
return 0;
}
LRESULT OnChildSetFocus(UINT /* nMsg */,
WPARAM /* wParam */,
LPARAM /* lParam */,
BOOL& /* bHandled */)
{
CComQIPtr <IOleControlSite, &IID_IOleControlSite>
spSite(m_spClientSite);
if (m_bInPlaceActive && spSite)
spSite->OnFocus(TRUE);
return 0;
}
LRESULT OnKillFocus(UINT /* nMsg */,
WPARAM /* wParam */,
LPARAM /* lParam */,
BOOL& /* bHandled */)
{
return 0;
}
LRESULT OnChildKillFocus(UINT /* nMsg */,
WPARAM /* wParam */,
LPARAM /* lParam */,
BOOL& /* bHandled */)
{
CComQIPtr <IOleControlSite, &IID_IOleControlSite>
spSite(m_spClientSite);
if (m_bInPlaceActive && spSite)
spSite->OnFocus(FALSE);
return 0;
}
LRESULT OnMouseActivate(UINT /* nMsg */,
WPARAM /* wParam */,
LPARAM /* lParam */,
BOOL& /* bHandled */)
{
InPlaceActivate(OLEIVERB_UIACTIVATE);
return 0;
}
Steps to Reproduce Behavior
---------------------------
1. Use the ATL Wizards to create an ActiveX control project that subclasses an
Edit control.
2. Build the control and place it in different containers with several other
controls.
3. Use the TAB key to move between the controls.
REFERENCES
==========
(c) Microsoft Corporation 1998, All Rights Reserved. Contributions by Shawn
William Karr, Microsoft Corporation
(c) Microsoft Corporation 1998, All Rights Reserved.
Contributions by Shawn William Karr, Microsoft Corporation
Additional query words: Visual Studio C++ Basic subedit
======================================================================
Keywords : kbActiveX kbATL200 kbATL210 kbCOMt kbCtrlCreate kbEditCtrl kbKeyAccel kbVC500 kbVC600 MSGRAPH kbGrpDSMFCATL kbAcceleratorKey
Technology : kbVCsearch kbAudDeveloper kbATLsearch
Version : :2.0,2.1,5.0
Issue type : kbprb
=============================================================================
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