Without resources I can create my UI with a complex array of CreateWindow() and CreateWindowEx(), and WndProc() to process my events.
I noticed if I right-click in the resource view and click "add resource", I can draw a dialog box with all the controls. This would save me a huge amount of time if I could draw the interface like I normally do with C#.
After I've drawn the interface with the resource editor, how do I then create the window from code? Can someone provide a very simple example with a button, and show how to handle a WM_COMMAND event on that button please?
Also, is this generally how people create the GUI? Is there any loss in flexible to do this way? Even in C# I often have to supplement designer-generated UI with my own code-generated UI, but the majority of the time I'm quite happy to use designer.
After creating the dialog in the resource editor, call CreateDialog(modeless dialog;you need to dispatch the messages manually just like when you use CreateWindow) or DialogBox(modal dialog; the function does not return until you close the dialog. it does the dispatching for you) to make the dialog show up. Just like you pass in the window proc to RegisterClass, you pass the dialog proc to those functions for the dialog call back. An example of DialogProc looks likes this:
BOOL DialogProc( HWND hDlg, UINT iMessage, WPARAM wParam, LPARAM lParam ){
switch( iMessage ){
case WM_COMMAND:
switch( LOWORD( wParam ) ){
case BTOK:
MessageBox( hDlg, "Hello, World!", NULL, NULL );
return TRUE;
break;
}
break;
}
return FALSE;
}
This is a basic way of creating a dialog. More sophisticated method would normally involve OOP, usually wrapping each resource( button, window, etc) as a C++ object or using MFC.
If you have placed your button or any control on some dialog, that control is already in created state. For handling the messages of these child controls on this dialog , you have to override OnCommand Method in the class which is implementing your dialog.
For Example:
//CDialog_ControlDlg is my Dialog class derived from CDialog
//IDC_BUTTON_SAMPLE is the ID of the button which was palced on the dialog in the resource Editor..
BOOL CDialog_ControlDlg::OnCommand(WPARAM wParam,LPARAM lparam){
int iNotiFicationMsg=HIWORD(wParam);//This is thenotification Msg from the child control
int iCommandId=LOWORD(wParam);//And Control ID of the Child control which caused that Msg
BOOL result=FALSE;
switch(iCommandId){
case IDC_BUTTON_SAMPLE:
if(iNotiFicationMsg==BN_CLICKED)
{
//Your Code for handling this type of Msg for this control..
}
break;
default:
{
//Specific Code;
}
return result;
}
}
Related
This is a Windows Desktop Application project created by Visual Studio.
I have a Dialog resource created from the Resource View that has a Static Text.
I'm using this dialog in order to show errors to the user:
DialogBox(hInst, MAKEINTRESOURCE(IDD_MY_MESSAGE_BOX), hWnd, MyMessageBoxProc);
The reason I'm using a DialogBox is that I need it to stop the code execution, because the next line of code will close the application I mean the user should be aware of the error message before application exits. I know a way to change the Static Text:
HWND myMessageBox = CreateDialog(hInst, MAKEINTRESOURCE(IDD_MY_MESSAGE_BOX), nullptr, MyMessageBoxProc);
HWND staticText = GetDlgItem(myMessageBox, IDC_STATIC);
SetWindowText(staticText, L"Text changed.");
But that approach doesn't stop code execution.
Since it's a Windows Desktop Application project I cannot create MFC classes and try the following approach:
// Find the Static Text.
// If called from within MyMessageBox class.
CWnd *staticText = GetDlgItem(IDC_STATIC);
staticText->SetWindowText("Text changed.");
// If called from elsewhere.
MyMessageBox myMessageBox;
CWnd *staticText = myMessageBox.GetDlgItem(IDC_STATIC);
staticText->SetWindowText("Text changed.");
So what would be a workaround in order to change the Static Text using a DialogBox without the need of MFC classes or even another approach that allows me to change the Static Text and still stop code execution like a DialogBox.
Just change the text in your window procedure (MyMessageBoxProc) by handling WM_INITDIALOG message. If you wish to supply the text to the dialog, then create it using DialogBoxParam instead, which is then accessible via the lParam parameter.
e.g.
INT_PTR MyMessageBoxProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
if (message == WM_INITDIALOG) {
HWND hCtrl = GetDlgItem(hWnd, IDC_STATIC);
SetWindowText(hCtrl, reinterpret_cast<LPCTSTR>(lParam));
}
return FALSE;
}
The creation would be something like:
LPCTSTR text = _T("Text changed.");
DialogBoxParam(hInst, MAKEINTRESOURCE(IDD_MY_MESSAGE_BOX), hWnd, MyMessageBoxProc,
reinterpret_cast<LPARAM>(text));
Note that there is a standard message box that ships with windows, which you may want to use instead of writing your own. That's available via the function MessageBox
I'm trying to close dialog box (which is basically derived from propertysheet class) from code. following is my code:
LRESULT CSettingsSheet::OnCloseSettings(WPARAM wParam, LPARAM lParam)
{
EndDialog(IDCANCEL);
return 0;
}
the issue is endDialog terminates not only dialog box but also main application window. what could be the reason for this problem?
BTW i create this dialog box in main window as follow
if(settingsSheet.DoModal() == IDOK)
{
}
else
{
}
ideally i should set this domodal value with IDCANCEL instead of calling end dialog.
Thanks,
Khurram.
You need to send PSM_PRESSBUTTON message to the property sheet window:
Simulates the selection of a property sheet button. You can send this message explicitly or by using the PropSheet_PressButton macro.
PSBTN_CANCEL - Selects the Cancel button.
PSBTN_OK - Selects the OK button. This value is not valid when using the Aero wizard style (PSH_AEROWIZARD).
The MFC has a function for this CPropertySheet::PressButton.
In a certain dialog I would like when the user presses the enter key for it to act as an "apply" button. So far I have at least been able to make the dialog not close upon pressing enter by overriding CWnd::PreTranslateMessage, so currently it just does nothing and I'm not sure how to send apply command from there.
Every dialog should have one and only one button with the BS_DEFPUSHBUTTON style, which indicates to the dialog that this is the button to activate with the Enter key. Usually this is the OK button, but you can make it the Apply button if you want to.
As Mark pointed out above the dialog manager already has all the logic built in to handle the Enter key by invoking the command associated with the default button. You can statically assign the BS_DEFPUSHBUTTON style or handle the DM_GETDEFID message.
The former is trivially easy and the latter is fairly simple to implement. Make sure you set the Default Button property to False for all buttons on your dialog. Now add a message handler for the DM_GETDEFID message. There is no dedicated macro for this message so you have to use the generic handler:
BEGIN_MESSAGE_MAP(CMyDialog, CDialogEx)
...
ON_MESSAGE(DM_GETDEFID, OnGetDefId)
END_MESSAGE_MAP()
The message handler is equally simple and uses the default message handler signature:
LRESULT CMyDialog::OnGetDefId(WPARAM wParam, LPARAM lParam)
{
return MAKELRESULT(ID_APPLY, DC_HASDEFID);
}
The message handler must return a value whose high-order word contains DC_HASDEFID and the low-order word contains the control ID.
If you navigate over the controls of the dialog you will see that the Apply button has the typical default button visual cue while focus is not on another command button. Pressing Enter while a non-button control has the input focus invokes the default button's command handler. No additional code required.
If your intent is to handle the Enter key without dismissing the dialog, you may be going about it incorrectly. Please take a look at this MSDN article. While using PreTranslateMessage should work, it is not the best way to handle these types of events.
You'll need to handle the OnKeyDown message, and handle the VK_RETURN character inside that function.
void MyCtrl::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)
{
if(nChar == VK_RETURN)
{
// Do Stuff
return;
}
CWnd::OnKeyDown(nChar, nRepCnt, nFlags);
}
Another way to overwrite the message.
BOOL CMyDialog::PreTranslateMessage(MSG* pMsg)
{
if (pMsg->message == WM_KEYDOWN)
{
switch (pMsg->wParam)
{
case VK_RETURN:
{
UINT nID = ::GetDlgCtrlID(pMsg->hwnd);
if (nID == ID_APPLY)
{
//DO YOUR STUFF HERE
}
}
break;
default:
break;
}
}
return CDialog::PreTranslateMessage(pMsg);
}
Also, you don't need to use PreTranslateMessage if you are using ::OnKeyDown
The Window is non DialogBox based so WS_TABSTOP doesn't work. Moreover I don't want to Tab through all the controls, I just want to Tab through few Edit controls.
What I did is I superclassed the Edit control and handled the WM_KEYDOWN message, switching between edit controls, by getting next window in the line thorugh ::GetWindow(hwnd,GW_HWNDNEXT); Also I would like to switch focus back to the first Edit control when I have reached the last one.
The Code doesn't work for when I have reached the last Edit control, the ::GetWindow simply returns the next window in the line(?), which happens to be a non superclassed edit control. And there are more hidden child windows(SW_HIDE).
Maybe if I know how to know the class name of the window's HWND ?
Note: Pure Win32 api, c++ oop.
else if ( ( int ) wParam == VK_TAB )
{
HWND nextInLine;
nextInLine = ::GetWindow ( hwnd, GW_HWNDNEXT );
if ( hwnd == NULL ) nextInLine = ::GetWindow ( hwnd, GW_HWNDPREV );
::SendMessage ( nextInLine, EM_SETSEL, ( WPARAM ) 0, ( LPARAM ) -1 );
::SetFocus ( nextInLine );
return 0;
}
You get keyboard navigation for free in any window by using the IsDialogMessage API call. To consume the service a window message loop has to be modified to include a call to IsDialogMessage and only pass the message on to regular message handling if it hasn't been handled by the dialog manager already.
MSG msg = { 0 };
while (GetMessage(&msg, NULL, 0, 0)) {
if (IsDialogMessage(hwnd, &msg)) {
/* Already handled by dialog manager */
} else {
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
Don't forget to set the WS_EX_CONTROLPARENT extended window style on the parent window, so that the dialog manager recurses into child windows.
It's possible to get away with just calling IsDialogMessage, but the result isn't quite 100% dialog-like. To make an ordinary window behave like a dialog:
Specify DLGWINDOWEXTRA as the cbWndExtra field of your WNDCLASS (don't forget to add on extra space you might already be using and offset your data's indexes)
Call DefDlgProc rather than DefWindowProc
Since this makes your window a dialog, you need to use the DWLP_USER window long instead of GWLP_USERDATA, if you're using that, when calling GetWindowLongPtr or SetWindowLongPtr.
(From memory, the main thing you get from doing the above is support for WM_NEXTDLGCTL, which I've found useful to use for supporting changing focus using the Enter key, using Method I described in http://support.microsoft.com/kb/102589.)
Then in your message pump, call IsDialogMessage for each dialog-like window in your message pump.
Finally, when creating controls for your dialog-like window, set the WS_TABSTOP window style for each window you want to participate in the tabbing, and set the WS_EX_CONTROLPARENT window exstyle (aka Control Parent in the resource editor) for child windows that contain dialog controls.
Using Visual Studio C++ with MFC. How do I center a MessageBox to it's parent window? Currently it centers to the desktop.
You need to install a hook and change the dialog box position on creation.
int MessageBoxCentered(HWND hWnd, LPCTSTR lpText, LPCTSTR lpCaption, UINT uType)
{
// Center message box at its parent window
static HHOOK hHookCBT{};
hHookCBT = SetWindowsHookEx(WH_CBT,
[](int nCode, WPARAM wParam, LPARAM lParam) -> LRESULT
{
if (nCode == HCBT_CREATEWND)
{
if (((LPCBT_CREATEWND)lParam)->lpcs->lpszClass == (LPWSTR)(ATOM)32770) // #32770 = dialog box class
{
RECT rcParent{};
GetWindowRect(((LPCBT_CREATEWND)lParam)->lpcs->hwndParent, &rcParent);
((LPCBT_CREATEWND)lParam)->lpcs->x = rcParent.left + ((rcParent.right - rcParent.left) - ((LPCBT_CREATEWND)lParam)->lpcs->cx) / 2;
((LPCBT_CREATEWND)lParam)->lpcs->y = rcParent.top + ((rcParent.bottom - rcParent.top) - ((LPCBT_CREATEWND)lParam)->lpcs->cy) / 2;
}
}
return CallNextHookEx(hHookCBT, nCode, wParam, lParam);
},
0, GetCurrentThreadId());
int iRet{ MessageBox(hWnd, lpText, lpCaption, uType) };
UnhookWindowsHookEx(hHookCBT);
return iRet;
}
::AfxMessageBox() appears on the center of the MainFrame for me. Which is basically a call to ::MessageBox() with a handle to the MainFrame as the first parameter. Isn't that working for you?
You can't. That's why a lot of people write their own MessageBox classes.
Who said "can't"?
Try this:
This is for Win32 API, written in C. Translate it as you need...
case WM_NOTIFY:{
HWND X=FindWindow("#32770",NULL);
if(GetParent(X)==H_frame){int Px,Py,Sx,Sy; RECT R1,R2;
GetWindowRect(hwnd,&R1); GetWindowRect(X,&R2);
Sx=R2.right-R2.left,Px=R1.left+(R1.right-R1.left)/2-Sx/2;
Sy=R2.bottom-R2.top,Py=R1.top+(R1.bottom-R1.top)/2-Sy/2;
MoveWindow(X,Px,Py,Sx,Sy,1);
}
} break;
Add that to the WndProc code... You can set position as you like, in this case it just centres over the main program window. It will do this for any messagebox, or file open/save dialog, and likely some other native controls. I'm not sure, but I think you may need to include COMMCTRL or COMMDLG to use this, at least, you will if you want open/save dialogs.
I experimented with looking at the notify codes and hwndFrom of NMHDR, then decided it was just as effective, and far easier, not to. If you really want to be very specific, tell FindWindow to look for a unique caption (title) you give to the window you want it to find.
This fires before the messagebox is drawn onscreen, so if you set a global flag to indicate when action is done by your code, and look for a unique caption, you be sure that actions you take will only occur once (there will likely be multiple notifiers). I haven't explored this in detail, but I managed get CreateWindow to put an edit box on a messagebox dialog. It looked as out of place as a rat's ear grafted onto the spine of a cloned pig, but it works. Doing things this way may be far easier than having to roll your own.
Crow.
EDIT: Small correction to handle the problem raised by Raymond Chen. Make sure that parent handles agree throughout, and this should work ok. It does for me, even with two instances of the same program...