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 // Licence:     wxWindows Licence
   9 /////////////////////////////////////////////////////////////////////////////
  10
  11 #ifndef _WX_GDIOBJ_H_BASE_
  12 #define _WX_GDIOBJ_H_BASE_
  13
  14 #include "wx/object.h"
  15
  16 // ----------------------------------------------------------------------------
  17 // wxGDIRefData is the base class for wxXXXData structures which contain the
  18 // real data for the GDI object and are shared among all wxWin objects sharing
  19 // the same native GDI object
  20 // ----------------------------------------------------------------------------
  21
  22 class WXDLLIMPEXP_CORE wxGDIRefData : public wxObjectRefData
  23 {
  24 public:
  25     // Default ctor which needs to be defined just because we use
  26     // wxDECLARE_NO_COPY_CLASS() below.
  27     wxGDIRefData() { }
  28
  29     // override this in the derived classes to check if this data object is
  30     // really fully initialized
  31     virtual bool IsOk() const { return true; }
  32
  33 private:
  34     wxDECLARE_NO_COPY_CLASS(wxGDIRefData);
  35 };
  36
  37 // ----------------------------------------------------------------------------
  38 // wxGDIObject: base class for bitmaps, pens, brushes, ...
  39 // ----------------------------------------------------------------------------
  40
  41 class WXDLLIMPEXP_CORE wxGDIObject : public wxObject
  42 {
  43 public:
  44     // checks if the object can be used
  45     virtual bool IsOk() const
  46     {
  47         // the cast here is safe because the derived classes always create
  48         // wxGDIRefData objects
  49         return m_refData && static_cast<wxGDIRefData *>(m_refData)->IsOk();
  50     }
  51
  52     // don't use in the new code, use IsOk() instead
  53     bool IsNull() const { return m_refData == NULL; }
  54
  55     // older version, for backwards compatibility only (but not deprecated
  56     // because it's still widely used)
  57     bool Ok() const { return IsOk(); }
  58
  59 #if defined(__WXMSW__) || defined(__WXPM__)
  60     // Creates the resource
  61     virtual bool RealizeResource() { return false; }
  62
  63     // Frees the resource
  64     virtual bool FreeResource(bool WXUNUSED(force) = false) { return false; }
  65
  66     virtual bool IsFree() const { return false; }
  67
  68     // Returns handle.
  69     virtual WXHANDLE GetResourceHandle() const { return 0; }
  70 #endif // defined(__WXMSW__) || defined(__WXPM__)
  71
  72 protected:
  73     // replace base class functions using wxObjectRefData with our own which
  74     // use wxGDIRefData to ensure that we always work with data objects of the
  75     // correct type (i.e. derived from wxGDIRefData)
  76     virtual wxObjectRefData *CreateRefData() const
  77     {
  78         return CreateGDIRefData();
  79     }
  80
  81     virtual wxObjectRefData *CloneRefData(const wxObjectRefData *data) const
  82     {
  83         return CloneGDIRefData(static_cast<const wxGDIRefData *>(data));
  84     }
  85
  86     virtual wxGDIRefData *CreateGDIRefData() const = 0;
  87     virtual wxGDIRefData *CloneGDIRefData(const wxGDIRefData *data) const = 0;
  88
  89     DECLARE_DYNAMIC_CLASS(wxGDIObject)
  90 };
  91
  92 #endif // _WX_GDIOBJ_H_BASE_