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     // Default ctor which needs to be defined just because we use
  27     // wxDECLARE_NO_COPY_CLASS() below.
  28     wxGDIRefData() { }
  29
  30     // override this in the derived classes to check if this data object is
  31     // really fully initialized
  32     virtual bool IsOk() const { return true; }
  33
  34 private:
  35     wxDECLARE_NO_COPY_CLASS(wxGDIRefData);
  36 };
  37
  38 // ----------------------------------------------------------------------------
  39 // wxGDIObject: base class for bitmaps, pens, brushes, ...
  40 // ----------------------------------------------------------------------------
  41
  42 class WXDLLIMPEXP_CORE wxGDIObject : public wxObject
  43 {
  44 public:
  45     // checks if the object can be used
  46     virtual bool IsOk() const
  47     {
  48         // the cast here is safe because the derived classes always create
  49         // wxGDIRefData objects
  50         return m_refData && static_cast<wxGDIRefData *>(m_refData)->IsOk();
  51     }
  52
  53     // don't use in the new code, use IsOk() instead
  54     bool IsNull() const { return m_refData == NULL; }
  55
  56     // older version, for backwards compatibility only (but not deprecated
  57     // because it's still widely used)
  58     bool Ok() const { return IsOk(); }
  59
  60 #if defined(__WXMSW__) || defined(__WXPM__) || defined(__WXPALMOS__)
  61     // Creates the resource
  62     virtual bool RealizeResource() { return false; }
  63
  64     // Frees the resource
  65     virtual bool FreeResource(bool WXUNUSED(force) = false) { return false; }
  66
  67     virtual bool IsFree() const { return false; }
  68
  69     // Returns handle.
  70     virtual WXHANDLE GetResourceHandle() const { return 0; }
  71 #endif // defined(__WXMSW__) || defined(__WXPM__)
  72
  73 protected:
  74     // replace base class functions using wxObjectRefData with our own which
  75     // use wxGDIRefData to ensure that we always work with data objects of the
  76     // correct type (i.e. derived from wxGDIRefData)
  77     virtual wxObjectRefData *CreateRefData() const
  78     {
  79         return CreateGDIRefData();
  80     }
  81
  82     virtual wxObjectRefData *CloneRefData(const wxObjectRefData *data) const
  83     {
  84         return CloneGDIRefData(static_cast<const wxGDIRefData *>(data));
  85     }
  86
  87     virtual wxGDIRefData *CreateGDIRefData() const = 0;
  88     virtual wxGDIRefData *CloneGDIRefData(const wxGDIRefData *data) const = 0;
  89
  90     DECLARE_DYNAMIC_CLASS(wxGDIObject)
  91 };
  92
  93 #endif // _WX_GDIOBJ_H_BASE_