include/wx/gdiobj.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        wx/gdiobj.h
   3 // Purpose:     wxGDIObject base header
   4 // Author:      Julian Smart
   5 // Modified by:
   6 // Created:
   7 // Copyright:   (c) Julian Smart
   8 // RCS-ID:      $Id$
   9 // Licence:     wxWindows Licence
  10 /////////////////////////////////////////////////////////////////////////////
  11
  12 #ifndef _WX_GDIOBJ_H_BASE_
  13 #define _WX_GDIOBJ_H_BASE_
  14
  15 #include "wx/object.h"
  16
  17 // ----------------------------------------------------------------------------
  18 // wxGDIRefData is the base class for wxXXXData structures which contain the
  19 // real data for the GDI object and are shared among all wxWin objects sharing
  20 // the same native GDI object
  21 // ----------------------------------------------------------------------------
  22
  23 class WXDLLIMPEXP_CORE wxGDIRefData : public wxObjectRefData
  24 {
  25 public:
  26     // override this in the derived classes to check if this data object is
  27     // really fully initialized
  28     virtual bool IsOk() const { return true; }
  29 };
  30
  31 // ----------------------------------------------------------------------------
  32 // wxGDIObject: base class for bitmaps, pens, brushes, ...
  33 // ----------------------------------------------------------------------------
  34
  35 class WXDLLIMPEXP_CORE wxGDIObject : public wxObject
  36 {
  37 public:
  38     // checks if the object can be used
  39     virtual bool IsOk() const
  40     {
  41         // the cast here is safe because the derived classes always create
  42         // wxGDIRefData objects
  43         return m_refData && static_cast<wxGDIRefData *>(m_refData)->IsOk();
  44     }
  45
  46     // don't use in the new code, use IsOk() instead
  47     bool IsNull() const { return m_refData == NULL; }
  48
  49     // older version, for backwards compatibility only (but not deprecated
  50     // because it's still widely used)
  51     bool Ok() const { return IsOk(); }
  52
  53 #if defined(__WXMSW__) || defined(__WXPM__) || defined(__WXPALMOS__)
  54     // Creates the resource
  55     virtual bool RealizeResource() { return false; }
  56
  57     // Frees the resource
  58     virtual bool FreeResource(bool WXUNUSED(force) = false) { return false; }
  59
  60     virtual bool IsFree() const { return false; }
  61
  62     // Returns handle.
  63     virtual WXHANDLE GetResourceHandle() const { return 0; }
  64 #endif // defined(__WXMSW__) || defined(__WXPM__)
  65
  66 protected:
  67     // replace base class functions using wxObjectRefData with our own which
  68     // use wxGDIRefData to ensure that we always work with data objects of the
  69     // correct type (i.e. derived from wxGDIRefData)
  70     virtual wxObjectRefData *CreateRefData() const
  71     {
  72         return CreateGDIRefData();
  73     }
  74
  75     virtual wxObjectRefData *CloneRefData(const wxObjectRefData *data) const
  76     {
  77         return CloneGDIRefData(static_cast<const wxGDIRefData *>(data));
  78     }
  79
  80     virtual wxGDIRefData *CreateGDIRefData() const = 0;
  81     virtual wxGDIRefData *CloneGDIRefData(const wxGDIRefData *data) const = 0;
  82
  83     DECLARE_DYNAMIC_CLASS(wxGDIObject)
  84 };
  85
  86 #endif // _WX_GDIOBJ_H_BASE_