don't use annoying and unneeded in C++ casts of NULL to "T *"

[wxWidgets.git] / include / wx / cshelp.h

/////////////////////////////////////////////////////////////////////////////
// Name:        wx/cshelp.h
// Purpose:     Context-sensitive help support classes
// Author:      Julian Smart, Vadim Zeitlin
// Modified by:
// Created:     08/09/2000
// RCS-ID:      $Id$
// Copyright:   (c) 2000 Julian Smart, Vadim Zeitlin
// Licence:     wxWindows licence
/////////////////////////////////////////////////////////////////////////////

#ifndef _WX_CSHELP_H_
#define _WX_CSHELP_H_

#include "wx/defs.h"

#if wxUSE_HELP

#include "wx/help.h"

#include "wx/hashmap.h"
#if wxUSE_BMPBUTTON
#include "wx/bmpbuttn.h"
#endif

#include "wx/event.h"

// ----------------------------------------------------------------------------
// classes used to implement context help UI
// ----------------------------------------------------------------------------

/*
 * wxContextHelp
 * Invokes context-sensitive help. When the user
 * clicks on a window, a wxEVT_HELP event will be sent to that
 * window for the application to display help for.
 */

class WXDLLIMPEXP_CORE wxContextHelp : public wxObject
{
public:
    wxContextHelp(wxWindow* win = NULL, bool beginHelp = true);
    virtual ~wxContextHelp();

    bool BeginContextHelp(wxWindow* win);
    bool EndContextHelp();

    bool EventLoop();
    bool DispatchEvent(wxWindow* win, const wxPoint& pt);

    void SetStatus(bool status) { m_status = status; }

protected:
    bool    m_inHelp;
    bool    m_status; // true if the user left-clicked

private:
    DECLARE_DYNAMIC_CLASS(wxContextHelp)
};

#if wxUSE_BMPBUTTON
/*
 * wxContextHelpButton
 * You can add this to your dialogs (especially on non-Windows platforms)
 * to put the application into context help mode.
 */

class WXDLLIMPEXP_CORE wxContextHelpButton : public wxBitmapButton
{
public:
    wxContextHelpButton(wxWindow* parent,
                        wxWindowID id = wxID_CONTEXT_HELP,
                        const wxPoint& pos = wxDefaultPosition,
                        const wxSize& size = wxDefaultSize,
                        long style = wxBU_AUTODRAW);

    void OnContextHelp(wxCommandEvent& event);

private:
    DECLARE_DYNAMIC_CLASS_NO_COPY(wxContextHelpButton)
    DECLARE_EVENT_TABLE()
};

#endif

// ----------------------------------------------------------------------------
// classes used to implement context help support
// ----------------------------------------------------------------------------

// wxHelpProvider is an abstract class used by the program implementing context help to
// show the help text (or whatever: it may be HTML page or anything else) for
// the given window.
//
// The current help provider must be explicitly set by the application using
// wxHelpProvider::Set().
//
// Special note about ShowHelpAtPoint() and ShowHelp(): we want to be able to
// override ShowHelpAtPoint() when we need to use different help messages for
// different parts of the window, but it should also be possible to override
// just ShowHelp() both for backwards compatibility and just because most
// often the help does not, in fact, depend on the position and so
// implementing just ShowHelp() is simpler and more natural, so by default
// ShowHelpAtPoint() forwards to ShowHelp(). But this means that
// wxSimpleHelpProvider has to override ShowHelp() and not ShowHelpAtPoint()
// for backwards compatibility as otherwise the existing code deriving from it
// and overriding ShowHelp() but calling the base class version wouldn't work
// any more, which forces us to use a rather ugly hack and pass the extra
// parameters of ShowHelpAtPoint() to ShowHelp() via member variables.
class WXDLLIMPEXP_CORE wxHelpProvider
{
public:
    // get/set the current (application-global) help provider (Set() returns
    // the previous one)
    static wxHelpProvider *Set(wxHelpProvider *helpProvider)
    {
        wxHelpProvider *helpProviderOld = ms_helpProvider;
        ms_helpProvider = helpProvider;
        return helpProviderOld;
    }

    // unlike some other class, the help provider is not created on demand,
    // this must be explicitly done by the application
    static wxHelpProvider *Get() { return ms_helpProvider; }

    // get the help string (whose interpretation is help provider dependent
    // except that empty string always means that no help is associated with
    // the window) for this window
    virtual wxString GetHelp(const wxWindowBase *window) = 0;

    // do show help for the given window (uses window->GetHelpAtPoint()
    // internally if applicable), return true if it was done or false
    // if no help available for this window
    virtual bool ShowHelpAtPoint(wxWindowBase *window,
                                 const wxPoint& pt,
                                 wxHelpEvent::Origin origin)
    {
        wxCHECK_MSG( window, false, _T("window must not be NULL") );

        m_helptextAtPoint = pt;
        m_helptextOrigin = origin;

        return ShowHelp(window);
    }

    // show help for the given window, see ShowHelpAtPoint() above
    virtual bool ShowHelp(wxWindowBase * WXUNUSED(window)) { return false; }

    // associate the text with the given window or id: although all help
    // providers have these functions to allow making wxWindow::SetHelpText()
    // work, not all of them implement them
    virtual void AddHelp(wxWindowBase *window, const wxString& text);

    // this version associates the given text with all window with this id
    // (may be used to set the same help string for all [Cancel] buttons in
    // the application, for example)
    virtual void AddHelp(wxWindowID id, const wxString& text);

    // removes the association
    virtual void RemoveHelp(wxWindowBase* window);

    // virtual dtor for any base class
    virtual ~wxHelpProvider();

protected:
    wxHelpProvider()
        : m_helptextAtPoint(wxDefaultPosition),
          m_helptextOrigin(wxHelpEvent::Origin_Unknown)
    {
    }

    // helper method used by ShowHelp(): returns the help string to use by
    // using m_helptextAtPoint/m_helptextOrigin if they're set or just GetHelp
    // otherwise
    wxString GetHelpTextMaybeAtPoint(wxWindowBase *window);


    // parameters of the last ShowHelpAtPoint() call, used by ShowHelp()
    wxPoint m_helptextAtPoint;
    wxHelpEvent::Origin m_helptextOrigin;

private:
    static wxHelpProvider *ms_helpProvider;
};

WX_DECLARE_EXPORTED_HASH_MAP( wxUIntPtr, wxString, wxIntegerHash,
                              wxIntegerEqual, wxSimpleHelpProviderHashMap );

// wxSimpleHelpProvider is an implementation of wxHelpProvider which supports
// only plain text help strings and shows the string associated with the
// control (if any) in a tooltip
class WXDLLIMPEXP_CORE wxSimpleHelpProvider : public wxHelpProvider
{
public:
    // implement wxHelpProvider methods
    virtual wxString GetHelp(const wxWindowBase *window);

    // override ShowHelp() and not ShowHelpAtPoint() as explained above
    virtual bool ShowHelp(wxWindowBase *window);

    virtual void AddHelp(wxWindowBase *window, const wxString& text);
    virtual void AddHelp(wxWindowID id, const wxString& text);
    virtual void RemoveHelp(wxWindowBase* window);

protected:
    // we use 2 hashes for storing the help strings associated with windows
    // and the ids
    wxSimpleHelpProviderHashMap m_hashWindows,
                                m_hashIds;
};

// wxHelpControllerHelpProvider is an implementation of wxHelpProvider which supports
// both context identifiers and plain text help strings. If the help text is an integer,
// it is passed to wxHelpController::DisplayContextPopup. Otherwise, it shows the string
// in a tooltip as per wxSimpleHelpProvider.
class WXDLLIMPEXP_CORE wxHelpControllerHelpProvider : public wxSimpleHelpProvider
{
public:
    // Note that it doesn't own the help controller. The help controller
    // should be deleted separately.
    wxHelpControllerHelpProvider(wxHelpControllerBase* hc = (wxHelpControllerBase*) NULL);

    // implement wxHelpProvider methods

    // again (see above): this should be ShowHelpAtPoint() but we need to
    // override ShowHelp() to avoid breaking existing code
    virtual bool ShowHelp(wxWindowBase *window);

    // Other accessors
    void SetHelpController(wxHelpControllerBase* hc) { m_helpController = hc; }
    wxHelpControllerBase* GetHelpController() const { return m_helpController; }

protected:
    wxHelpControllerBase*   m_helpController;

    DECLARE_NO_COPY_CLASS(wxHelpControllerHelpProvider)
};

// Convenience function for turning context id into wxString
WXDLLIMPEXP_CORE wxString wxContextId(int id);

#endif // wxUSE_HELP

#endif // _WX_CSHELP_H_