mediator.c

Design Pattern C Source Code

/*
*/
#include "List.H"
class MouseEvent;
class Widget;

/*
*/
class DialogDirector {
public:
    virtual ~DialogDirector();

    virtual void ShowDialog();
    virtual void WidgetChanged(Widget*) = 0;
/*
*/
protected:
    DialogDirector();
    virtual void CreateWidgets() = 0;
};
/*
*/
class Widget {
public:
    Widget(DialogDirector*);
    virtual void Changed();

    virtual void HandleMouse(MouseEvent& event);
    // ...
private:
    DialogDirector* _director;
};
/*
*/
void Widget::Changed () {
    _director->WidgetChanged(this);
}
/*
*/
class ListBox : public Widget {
public:
    ListBox(DialogDirector*);

    virtual const char* GetSelection();
    virtual void SetList(List<char*>* listItems);
    virtual void HandleMouse(MouseEvent& event);
    // ...
};
/*
*/
class EntryField : public Widget {
public:
    EntryField(DialogDirector*);

    virtual void SetText(const char* text);
    virtual const char* GetText();
    virtual void HandleMouse(MouseEvent& event);
    // ...
};
/*
*/
class Button : public Widget {
public:
    Button(DialogDirector*);

    virtual void SetText(const char* text);
    virtual void HandleMouse(MouseEvent& event);
    // ...
};
/*
*/
void Button::HandleMouse (MouseEvent& event) {
    // ...
    Changed();
}
/*
*/
class FontDialogDirector : public DialogDirector {
public:
    FontDialogDirector();
    virtual ~FontDialogDirector();
    virtual void WidgetChanged(Widget*);
/*
*/
protected:
    virtual void CreateWidgets();
/*
*/
private:
    Button* _ok;
    Button* _cancel;
    ListBox* _fontList;
    EntryField* _fontName;
};
/*
*/
void FontDialogDirector::CreateWidgets () {
    _ok = new Button(this);
    _cancel = new Button(this);
    _fontList = new ListBox(this);
    _fontName = new EntryField(this);

    // fill the listBox with the available font names

    // assemble the widgets in the dialog
}
/*
*/
void FontDialogDirector::WidgetChanged (
    Widget* theChangedWidget
) {
    if (theChangedWidget == _fontList) {
        _fontName->SetText(_fontList->GetSelection());
/*
*/
    } else if (theChangedWidget == _ok) {
        // apply font change and dismiss dialog
        // ...
/*
*/
    } else if (theChangedWidget == _cancel) {
        // dismiss dialog
    }
}
/*
*/