I have created a timer with SetTimer( 1 , 25 , 0 ); during CChildView::PreSubclassWindow().
In CChildView::OnTimer() I do InvalidateRect( 0 , 0 ); to cause an CChildView::OnPaint(). This causes a record from a file to be read and painted.
All of this works just fine.
During MyApp::InitInstance() I created a modeless dialog with several controls that all work as expected.
What I want to do is control the timer running in CChildView from a dialog control.
The problem is, I can't find or have access to the instance of CChildView.
Hence I can't call my SetTimerSpeed() function in CChildView.
How can I do this, please?
When creating the dialog store a pointer to your view in the dialog object. You can just use this one to access the view instance. Add a view-pointer member in your dialog class declaration:
class CMyDialog : public CDialogEx
{
public:
CChildView *pView;
.
.
}
And when calling it:
CMyDialog ctDlg;
ctDlg.pView = this;
ctDlg.DoModal();
// or ctDlg.Create();
The code above of course can be called from a handler (function) in CChildView.
If the application is SDI you don't even need this, you can just store the pointer to the view in a global variable, it is very much OK:
// Declaration in the .h file
extern CChildView *pChldVw;
// Definition in the .cpp file
CChildView *pChldVw;
// CChildView constructor
CChildView::CChildView() noexcept
{
pChldVw = this;
}
If the application is MDI and the dialog is not created in the CChildView code, it is still possible to find the view instance by calling something like:
CMDIFrameWnd *pFrame = (CMDIFrameWnd*)AfxGetApp()->GetMainWnd();
// Get the active MDI child window.
CMDIChildWnd *pChild = (CMDIChildWnd*)pFrame->GetActiveFrame();
// Get the active view attached to the active MDI child window.
CChildView *pView = (CChildView)pChild->GetActiveView();
There are also some "enumeration" functions, like:
GetFirstDocTemplatePosition() / GetNextDocTemplate()
GetFirstDocPosition() / GetNextDoc()
GetFirstViewPosition() / GetNextView()
Related
I am making a doc/view arch SDI application.
I invoke a COptionsDialog in CSquaresView.
void CSquaresView::OnOptions()
{
COptionsDialog dlg(this);
if (dlg.DoModal() == IDOK)
...
}
In COptionsDialog I want to access CSquaresView.
BOOL COptionsDialog::OnInitDialog()
{
CDialog::OnInitDialog();
CWnd *pParent = GetParent();
if (pParent) {
CSquaresView *pView = dynamic_cast<CSquaresView*>(pParent); //pView is always NULL
if (pView != NULL)
{
CSquaresDoc* pDoc = pView->GetDocument();
...
}
But I always get pView as NULL;
Please help me to solve this problem.
The observed behavior makes sense. A (modal) dialog's owner must be
an overlapped or pop-up window [...]; a child window cannot be an owner window.
CView-derived class instances generally are child windows. As such they cannot be the owner of a (modal) dialog. When you pass a child window into the c'tor of a CDialog-derived class, the system walks up the window hierarchy until it finds an overlapped or pop-up window, and uses that as the owner of the dialog. Regardless of whether you then call GetParent, GetAncestor, or CWnd::GetOwner, it is this true owner (usually your CFrameWnd-derived implementation) where window traversal starts.
Thus, you cannot generally use standard window traversal to find the window passed into a (modal) dialog's constructor. However, MFC records the CWnd(-derived) class instance you pass into your COptionsDialog constructor and stores it in a protected member variable m_pParentWnd, inherited from the CDialog class.
As long as COptionsDialog derives public/protected from CDialog or CDialogEx, the implementation can access this class member.
The following OnInitDialog implementation will do what you're looking for:
BOOL COptionsDialog::OnInitDialog()
{
CDialog::OnInitDialog();
CSquaresView *pView = dynamic_cast<CSquaresView*>(m_pParentWnd);
if (pView != NULL)
{
CSquaresDoc* pDoc = pView->GetDocument();
...
}
There are other options available. For example, you could supply a COptionsDialog constructor that takes both a CWnd* and a CSquaresDoc*, delegating the first onto the base class c'tor and storing the document pointer in a (private) class member. This makes for code that's easier to follow in that it explicitly spells out, that the dialog depends on the document.
Add a static method GetCurrentView() to your view class:
.cpp file
CSquaresView* CSquaresView::GetCurrentView()
{
CFrameWnd* pFrame = (CFrameWnd*)(AfxGetApp()->m_pMainWnd);
return dynamic_cast<CSquaresView*>(pFrame->GetActiveView());
}
.h file
class CSquaresView : public CView
{
...
static CSquaresView* GetCurrentView();
...
};
Now you can just call GetCurrentView() from anywhere you want:
...
CSquaresView *pView = CSquaresView::GetCurrentView();
...
This works for SDI applications. For MDI applications the solution might be somewhat different.
Another thing you could do is just create a public member CSquaresView *m_pView in COptionsDialog and set that to this like:
void CSquaresView::OnOptions()
{
COptionsDialog dlg(this);
dlg.m_pView = this;
if (dlg.DoModal() == IDOK)
...
}
or modify the COptionsDialog constructor so m_pView is set directly by the constructor, or something similar.
Use GetOwner(). Only WS_CHILD windows have parents, other windows have owners.
I'm working on the library, that wraps some MFC classes and methods. I want the user to be able to dynamically create a CDialogEx using a template in memory. For the modal dialogs, I call CDialog::InitModalIndirect and then CDialog::DoModal. For the modeless dialogs, I call CDialog::CreateIndirect and then CWnd::Show.
The code looks something like this:
// inside my library
class MyDialog : public CDialogEx
{
public:
MyDialog(CWnd* parent) : CDialogEx()
{
parent_ = parent;
my_template_data_ = CreateSomeGenericTemplate();
// OnInitDialog should be preferably called here
}
void ShowModal()
{
InitModalIndirect(my_template_data_, parent_);
DoModal(); // but it's called here - too late
}
void ShowModeless()
{
CreateIndirect(my_template_data_, parent_);
Show(); // but it's called here - too late
}
MyButton* GetButton(int id)
{
// returns the instance of my MyButton, which is a subclassed CButton
}
private:
BOOL MyDialog::OnInitDialog() override
{
CDialogEx::OnInitDialog();
// CWnd::Create for the UI controls can only be called here
}
};
// user's code
// user creates the dialog - in the constructor it's not clear if modal or modeless
1. MyDialog user_dialog(some_parent); // here, I need the controls to be created
2. user_dialog.GetButton(42)->SetWindowText(L"new text"); // user wants to initialize his controls
// but he can't, because MyButton::Create was not called yet
3. user_dialog.ShowModal(); // and only then display the dialog
//by default, here the MFC calls OnInitDialog - too late,
//the SetText method needed to be set on line 2.
My problem is, that the dialog's controls (buttons etc.) can only be created inside the CDialog::OnInitDialog method, which is called automatically after DoModal (for modal)/Show (for modeless) methods. I need the controls to be created and properly initialized (with the CWnd::Create method) preferably inside the constructor. I thought about calling Show/DoModal directly inside the constructor but I don't yet know if it's going to be modal or modeless dialog. It there a solution to this? Many thanks in advance.
Why don't you refactor your code and put the common code in a InitUI() method and call it from both sides?
And don't init interface on the constructor. Do it in OnInitDialog for modal; and in Create, or OnCreate (which implies a ON_WM_CREATE() map entry) for modeless dialogs.
I have a dialog in which after pressing button OK, the program uses the data in the dialog and draws a plot. I need to draw the plot without having to close the dialog as with IDOK, hence the apply button.
The code with drawing the dialog is,
INT_PTR val = dlg->DoModal();
if ( val == IDOK) {
//draw plot
}
The code of onOK and onApply
void DLg::OnOK() {
GetDataGrid();
CDialog::OnOK();
}
void DLg::OnBnClickedApply()
{
GetDataGrid();
}
How do I get DoModal() to return a value on onApply() without closing the dialog?
Any help would be appreciated.
A modal dialog can't return a value and leave the dialog open. You could either make your dialog non-modal, or post your main window a message from the OnBnClickedApply function that makes it draw the plot.
I tend to put drawing into a separate thread and would call it wherever needed. So you can either
(1) call the OnDrawPlot again in your Apply button
if ( val == IDOK) {
AfxBeginThread(...);//draw plot
}
void DLg::OnBnClickedApply()
{
AfxBeginThread(...);//draw plot
}
(2) send the return value back to the DoModal using EndDialog method
What parameters are there in EndDialog ?
An example can be found here.
Declare a variable in CDialog derived class preferably public. Then just at OnOK assign this variable to appropriate value. The caller would use it directly.
class Dlg : public CDialog
{
public:
int TheVariable;
...
};
Call site:
if(dlg.DoModal()==IDOK)
{
dlg.TheVariable; // Use the variable
}
However, if you need to draw on the dialog itself (and not to other window, which has launched the dialog), then don't call CDialog::OnOK or EndDialog in your OnOK override. In this case, you need to do painting in dialog itself.
In my SDI application i need to get this behawiour. After I click on a button on the FormView, a CDialog opens. When I press the OK button on the CDialog, I call a function of the FormView. I don't want to close the CDialog. I try to do it with modeless dialog, but when i call formview function from dialog, i can't access to formview's control, like it's lost hwnd; the error is can't read memory of m_hwnd, the hwnd is ???.
This is my code:
Open modeless dialog:
CCampiDlg *m_pDialog = NULL;
HWND hCampi = NULL;
// Invoking the Dialog
m_pDialog = new CCampiDlg;
if (m_pDialog != NULL)
{
BOOL ret = m_pDialog->Create(m_pDialog->IDD, this);
if (!ret) //Create failed.
{
AfxMessageBox(_T("Error creating Dialog"));
}
m_pDialog->ShowWindow(SW_SHOW);
}
when i press the ok button in the dialog i do:
CEditorTxView pView;
box2 = (CEdit*)(GetDlgItem(IDC_CAMPI_BOX2));
box2->GetWindowTextW(campo);
pView.inserisciCampo(1, campo);
In inserisciCampo function in CEditorTxView (CFormView) i have to do operation with my control txtCtrl, but it's lost hwnd. The declaration of txtCtrl is in the CEditorTxView.h
CTx1 txtCtrl;
And initialize it in DoDataExchange function:
void CEditorTxView::DoDataExchange(CDataExchange* pDX)
{
CFormView::DoDataExchange(pDX);
DDX_Control(pDX, IDC_TX1, txtCtrl);
}
Someone can help me plz?
I can give you two answers here:
How to do what you are asking (get access to a control of the CFormView from a modeless dialog)
How to solve your underlying problem (communicate changes in a modeless dialog to the owner view)
For the first one, you have to declare a pointer to the view in the dialog class and initialize it in the constructor of the view:
class CCampiDlg : public CDialog
{
public:
CCampiDlg(CEditorTxView* pView, CWnd*pParent = NULL) // Change declaration to add pointer to view
: m_pView(pView)
{
}
// ... Whatever
private:
CEditorTxView* m_pView;
}
Now in your button handler:
CEdit* box2 = (CEdit*)(GetDlgItem(IDC_CAMPI_BOX2)); // Why not use a control variable?
box2->GetWindowTextW(campo);
m_pView->inserisciCampo(1, campo);
This should do what you are asking for. However, it is the wrong way to do it.
The problem with this approach is that the dialog knows way too much about its parent. It knows it is of type CEditorTxView and that it has a member called inserisciCampo, that takes a number and some text.
It shouldn't know that much. In fact, knowing anything about it, other than it is of type CView or even CWnd, is too much.
If the dialog knows about the view, you can't reuse the dialog with other views, and anytime the view changes its representation (what now is a textbox may be a combobox in the future, for example) the dialog must change accordingly.
The solution would be to send a message to the parent, explaining what's happened. Then the parent (the view) should know haw to handle that event. For example:
class CCampiDlg : public CDialog
{
public:
CCampiDlg(CWnd*pParent = NULL) {}
protected:
OnOk()
{
CString campo;
c_CampiBox2.GetWindowText(campo);
GetParent()->SendMessage(UWM_CAMPO2_SET, 0, (LPARAM)&campo);
}
}
In the view:
// It can be ON_REGISTERED_MESSAGE:
ON_MESSAGE(UWM_CAMPO2_SET, OnCampo2Set)
//...
LRESULT CEditorTxView::OnCampo2Set(WPARAM, LPARAM lParam)
{
CString* s = (CString*) lParam;
inserisciCampo(1, *campo);
return 0;
}
Now, you have decoupled the view and the dialog. The dialog knows nothing about the view. You can change its type, change the representation, even make it a dialog, and you don't have to change anything in the dialog. And if you need that same modeless dialog somewhere else, you just drop it there, create a message handler in the parent, and voilà!
For further explanations and better examples, check these articles:
Dialog and control design (Your case is explained in the section "Notifications to the environment")
Message management
On Ok button click the below code is running:
CEditorTxView pView;
box2 = (CEdit*)(GetDlgItem(IDC_CAMPI_BOX2));
box2->GetWindowTextW(campo);
pView.inserisciCampo(1, campo);
Note that, you are creating the new pView in stack and it does't attach with any window. You are not actually referring the view that already created and launched your dialog acting a parent. Revisit the above code and try the get the view:
Try the below code, if it is not working (Google it)
CFrameWnd * pFrame = (CFrameWnd *)(AfxGetApp()->m_pMainWnd);
CView * pView = pFrame->GetActiveView();
How do I check if a window/dialog is already open? I used this code to open a new dialog box but everytime I click it the dialog keeps on opening. Obviously not the way settings dialog works.
Class *someClass = new Class();
someclass->show();
In your code you create a new window/widget/dialog everytime.
Initialize *someClass somewhere else and then only show it.
class Foo
{
public:
Foo() { someClass = new SomeClass() }
void fooClicked() { someClass->show() }
private:
SomeClass *someClass;
};
In your calling class (or main application class, or something similar) define a pointer to the class:
dialogclass *someclass;
In the constructor of that main class, initialize the dialog class:
someclass = NULL;
When you want to show the dialog, do something along these lines:
if (!someclass) someclass = new dialogclass(); // Creates a dialog instance if it does not already exist
if (!someclass->isVisible()) someclass->show(); // Only shows the dialog if it is not already shown.
Use QPointer:
QPointer<MyDialog> dialog = new MyDialog(this);
dialog->show();
...
if (dialog) dialog->show();
If dialog exists it will be shown. If it is deleted in the meantime, it will hold 0 instead of an invalid address, and the last line will never be executed - it will not be shown but you can recreate it if needed.
You can make an static pointer on your window class. It allows you to store last opened window object.
class MyWindow : public QWidget {
public :
static MyWindow* instance;
...
}
Whenever you make a new instance you can set instance. When the instance is null you can make a new window. When you want to close the opened window, you should make instance null again. This allows you to have only one open window.
if (MyWindow::instance == NULL) {
MyWindow *w = new MyWindow(...);
MyWindow::instance = w;
}
This design pattern is called Singleton and it allows you to have only one object per a class. Also, this is a bit different because in Singleton, constructor is not public and factory method should be used for making an object but it is similar.