HWND button = CreateWindowEx(0, "BUTTON", ...);
SetFocus(button); // Button no get focus! :(
Also, I have other controls on my form that I am able to SetFocus() to.
Thanks, Martin
It has been FOREVER since I've had to do this, but...
Were this a dialog, I would tell you to send a WM_NEXTDLGCTL via PostMessage(). The default dialog item message handler would take care of the rest for you setting keyboard focus and selection activation. However, this is a different case if I read this correctly. You're creating both parent and child windows raw on the fly. If this is the case, SetFocus() to the parent window, and handle WM_SETFOCUS on the parent window by bringing it to top, then setting focus on the child window. WM_SETFOCUS, and WM_KILLFOCUS were designed to allow you to switch the 'activated' state of your controls, and most handle it for you (unless your window is an owner draw control or some such). But in a raw window, when your base parent window is sent the focus, you need to appropriately ensure the proper child has it if you're hosting any (think of it as managing your own 'dialog'). Again, normally this is done by the default dialog procedure for you if this were a dialog, but being raw windows you're kind of stuck managing it all yourself.
Though I can't imagine how, I hope that helped somewhat.
SetFocus is a function, not a procedure. Call it as a function and check its returned value. Either the retuned value is null because you made an error in the CreateWindowEx() call and "button" isn't a valid handle or it's a window not associated with your thread's message queue, or the return value is not null (it's now the prior focused window's handle) and you do have the focus (but are somehow failing to detect it).
Try setting the WS_TABSTOP style on the button.
If you create that button in respond of the WM_INITDIALOG message you should return FALSE to prevent dialog box procedure to change the focus.
Related
I have created a modeless dialog as a main window, but the window procedure isn't being sent WM_INITDIALOG messages.
Here's what I've done.
Created a dialog template using Visual Studio's resource editor, and
set its class name to a custom class.
Used WNDCLASSEX to register the class, window procedure, as well as
some icons and brush etc.
Used CreateDialog() with the last two parameters set to NULL, (Parent
window, and window procedure).
Created the message loop using IsDialogMessage(), TranslateMessage()
and DispatchMessage();
Returned DefDlgProc() in the window procedure as the default if no
messages were processed.
I can't think of anything else significant. Everything works well except for not receiving WM_INITDIALOG messages.
I've done it this way so the app minimises to the task bar, and I can have a menu if needed.
So my first question is, Have I done anything stupid?
Secondly, should I expect to receive WM_INITDIALOG messages using this system?
And if not, what is a good way to initialise say a combobox with strings.
(I've looked at things like WM_ACTIVATE, WM_ACTIVATEAPP etc, but nothing seems appropriate.
And the combobox isn't created yet at WM_CREATE.)
Thanks in advance.
I realised the answer shortly after posting.
As mentioned in the comments above, it's a window procedure, not a dialog procedure, so I shouldn't have been trying to initialize child windows within the procedure.
So I initialized them outside the procedure, after creating the dialog box and before the message loop.
All the dialog features are working as expected, but it's a main window that can have a menu and minimizes to the taskbar.
I'm using and improving on an open source MFC work-alike library called FFC. Sometimes the library associates the wrong window handle to a dialog object, which means the C++ object can't be found later when the correct handle is looked up. In particular, this is happening when the application opens its root window, which is a dialog that it opens with a call to DoModal.
In its DoModal function, the FFC library uses a... "surprising" way to attach the handle to the dialog object. It stashes the "this" pointer in a global variable and hooks a function to be called on all window messages before calling the DialogBox function. This hook function it registered in term assumes the handle from the first message it receives is the handle for the window in the global variable, and attaches that handle to it.
Sometimes, this works. Often - and I don't know if it's because of intrusive things done by the McAfee scanner on my work computer, or because my program starts from a console window, or something else - many unrelated messages will be captured before a message actually meant for the modal dialog comes through.
At first I thought it was because FFC wasn't making sure the message it looks for is "WM_CREATE". I added this check, but it didn't fix the problem. Turns out one or more of the spurious messages are also WM_CREATE messages! Before it gets the one for the real dialog, the first WM_CREATE it receives is a handle for a window with blank window text and rectangle 0,0-0,0.
So is this really the correct or canonical way to get the handle for a modal dialog? It seems unreliable. (Note that because the dialog is modal, you can't use the return value from CreateWindowEx because the DialogBox function doesn't return until the modal dialog is closed.) Is this really how MFC does it? Is there a better way? Could I associate some data with the dialog or look for data that should be associated with it to make sure I have the right window handle? (For instance checking the template parameter passed to the dialog box call, if I can get that back from the handle somehow.)
I am sure this is published in books, but MFC sets a windows hook (WH_CBT) and then looks for the HCBT_CREATEWND code in the hook to marry the C++ object to the HWND.
Generally I have some button that opens child window and the second press on this button should close it. I use a touch screen.
The problem is when I try to press the button for closing the child window, it is not pressed the first time, so I need another click.
In order to fix this I am trying to return the focus to the parent window after the child window is opened.
I register the OnShowWindow message and call SetFocus on the parent window:
void CFlashGuidanceSteps::OnShowWindow(BOOL bShow, UINT nStatus)
{
CDialog::OnShowWindow(bShow, nStatus);
GetParent()->SetFocus();
}
While the function is called (I can see it in debugger), the focus is not returned to the parent window.
However, it works with the OnSetFocus event:
void CFlashGuidanceSteps::OnSetFocus(CWnd* pOldWnd)
{
CDialog::OnSetFocus(pOldWnd);
GetParent()->SetFocus();
}
Why is the focus is not retained with the OnShowWindow event?
The explanation
The usual rule in MFC is that OnXxx functions are called in response to similarly named window messages, e.g. WM_Xxx. So OnShowWindow would be called in response to WM_SHOWWINDOW.
And according to the documentation, WM_SHOWWINDOW is
Sent to a window when the window is about to be hidden or shown.
That means it is sent before the window is actually shown. So when you set the focus to the parent window inside of the OnShowWindow function, nothing actually happens because the parent window already has the focus. Then, after OnShowWindow finishes running, the child window is displayed and demands the focus. It is as if you never made any attempt to change the focus.
By contrast, OnSetFocus, which corresponds to WM_SETFOCUS, is not called until after the window has gained the focus. So when you reassign the focus here, it works because the child window doesn't steal the focus back.
The better idea
That explains the behavior you are seeing, and as you know, things work fine when you adjust the focus in OnSetFocus. But this really isn't the best way of solving the problem.
Manually changing the focus when a window gets and/or loses the focus is approaching the problem the wrong way around, and generally error-prone. You'll get all kinds of focus-related bugs that are difficult to debug. You are better off looking for ways to prevent the focus from changing when you don't want it to.
It sounds to me like you want to prevent the child window from getting the focus when it is created. And there is a way to do precisely that.
When you display the child window, presumably by calling the ShowWindow function or its moral equivalent in MFC, you should pass the SW_SHOWNA flag. That causes the window to be shown without activating it (i.e., granting it the focus).
I have "n" dialogs which have the same base dialog. Each dialog has its own controls
edit boxes
combo boxes
list controls
etc.
In base dialog, how do I set focus messages of each control and,for example, give a Message box with
text("Hello I got focus, my ID is %d")?
The easiest way is using the classical subclassing method. The problem is that WM_SETFOCUS is not pumped through the message Loop, so PreTranslateMessage will not help.
Thee are some nice classes that help to do additional subclassing without disturbing the MFC stuff.
Paul Di Lascia wrote CSubclassWnd. PJ Naughter wrote CHookWnd. And with the ATL has CWindowsImpl.
All this classes allow easy additional subclassing even if a window is already subclassed by the MFC.
You can use "standard subclassing" GetWindowLong/SetWindowLong too.
According to this SO article, you can hook the WM_SETFOCUS message.
You can get the Control ID by using GetDlgCtrlID with the hwnd returned by the hook.
But beware of popping up a MessageBox, that will change the focus and trigger your hook proc, making it go into a loop!
As Jerry already said make a hook, get parent window handler via GetParent() and SendMessage(hParentWND, WM_MESSAGE, lParam, wParam).
Of course, you should handle WM_MESSAGE in your parent window.
Btw, framework calls OnSetFocus function when window gained focus.
I have a custom CWnd-derived MFC control, which works like this:
the control has its own OnPaint, and a black background
clicking anywhere on the control causes an edit control to appear at that location, borderless and with black-background, so it blends in
the user types in this box and hits enter, the box disappears and the control's custom paint functionality renders the same text in the same position on the background.
So our control owns a CCustomEdit, when you click on the background the control is either created or moved, and made visible:
CCustomEdit::Show(Rect &rc,CCustomControl *pParent)
{
if ( !::IsWindow( m_hWnd ) )
{
Create( ES_LEFT | ES_AUTOHSCROLL | WS_CHILD | ES_NOHIDESEL | ES_CENTER | ES_UPPERCASE, rc, pParent, 999 );
}
else
MoveWindow( &rc );
}
The main parts actually work OK (and we're stuck with the approach). But one thing that's not working is that CCustomEdit self-registers for EN_CHANGE events and so on. When CCustomEdit is created as a normal dialog control (CEdit on the dialog template, DDX-bound to a CCustomEdit variable) these work, but within CCustomControl they are not.
CCustomEdit::PreSubclassWindow() calls SetEventmask() and is being called. And CCustomEdit's ON_CHAR handler is also being called for key-presses in the edit box, however the handlers for edit-box messages like EN_CHANGE are not.
Are there any obvious things like changing the style flags? Otherwise, why is my custom control stopping these events reaching the contained edit control?
I'm not sure I understand the situation, but I have a number of control that work roughly in the same way as what I think is happening and they all work, it is possible.
EN_CHANGE for the edit control is send to your CWnd-derived control. Are you reflecting the messages? Have you tried if EN_CHANGE gets to the custom control? From what you are describing, you are expecting EN_CHANGE to end up in CCustomEdit's message dispatcher macro chain automatically, but it doesn't; you need the help of the containing window. Now MFC does most of that for you in a CDialog, but if you roll your own you need to do it manually, or use the message reflection macro's.
I found it... somehow, my SetEventMask() was being overriden. I don't know how or where but when I added an extra call later on to test, most event handlers started getting called.
I can only assume some part of the init code in MFC is responsible.