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@page validator_overview wxValidator overview
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- Classes: #wxValidator, #wxTextValidator,
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+ Classes: #wxValidator, #wxTextValidator,
#wxGenericValidator
The aim of the validator concept is to make dialogs very much easier to write.
A validator is an object that can be plugged into a control (such as a wxTextCtrl), and
and validating it. It also is able to intercept events generated
by the control, providing filtering behaviour without the need to derive a new control class.
You can use a stock validator, such as #wxTextValidator (which does text
- control data transfer, validation and filtering) and
+ control data transfer, validation and filtering) and
#wxGenericValidator (which does data transfer for a range of controls);
or you can write your own.
@b Example
Here is an example of wxTextValidator usage.
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@code
wxTextCtrl *txt1 = new wxTextCtrl(this, -1, wxT(""),
wxPoint(10, 10), wxSize(100, 80), 0,
wxTextValidator(wxFILTER_ALPHA, _data.m_string));
@endcode
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In this example, the text validator object provides the following functionality:
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It transfers the value of g_data.m_string (a wxString variable) to the wxTextCtrl when
the dialog is initialised.
It transfers the wxTextCtrl data back to this variable when the dialog is dismissed.
It filters input characters so that only alphabetic characters are allowed.
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The validation and filtering of input is accomplished in two ways. When a character is input,
wxTextValidator checks the character against the allowed filter flag (wxFILTER_ALPHA in this case). If
the character is inappropriate, it is vetoed (does not appear) and a warning beep sounds.
function finds all the validators in the window's children and calls the TransferToWindow
function for each. Thus, data is transferred from C++ variables to the dialog
just as the dialog is being shown.
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If you are using a window or panel instead of a dialog, you will need to
call wxWindow::InitDialog explicitly before showing the
window.
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When the user clicks on a button, for example the OK button, the application should
first call wxWindow::Validate, which returns @false if
any of the child window validators failed to validate the window data. The button handler
or Show (if modeless).
In fact, wxDialog contains a default command event handler for the wxID_OK button. It goes like
this:
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@code
void wxDialog::OnOK(wxCommandEvent& event)
{
}
}
@endcode
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So if using validators and a normal OK button, you may not even need to write any
code for handling dialog dismissal.
If you load your dialog from a resource file, you will need to iterate through the controls
setting validators, since validators can't be specified in a dialog resource.
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*/
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