include/wx/private/textmeasure.h

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // Name:        wx/private/textmeasure.h
   3 // Purpose:     declaration of wxTextMeasure class
   4 // Author:      Manuel Martin
   5 // Created:     2012-10-05
   6 // Copyright:   (c) 1997-2012 wxWidgets team
   7 // Licence:     wxWindows licence
   8 ///////////////////////////////////////////////////////////////////////////////
   9
  10 #ifndef _WX_PRIVATE_TEXTMEASURE_H_
  11 #define _WX_PRIVATE_TEXTMEASURE_H_
  12
  13 #include "wx/vector.h"
  14
  15 class WXDLLIMPEXP_FWD_CORE wxDC;
  16 class WXDLLIMPEXP_FWD_CORE wxFont;
  17 class WXDLLIMPEXP_FWD_CORE wxWindow;
  18
  19 // ----------------------------------------------------------------------------
  20 // wxTextMeasure: class used to measure text extent.
  21 // ----------------------------------------------------------------------------
  22
  23 class wxTextMeasureBase
  24 {
  25 public:
  26     // The first ctor argument must be non-NULL, i.e. each object of this class
  27     // is associated with either a valid wxDC or a valid wxWindow.
  28     wxTextMeasureBase(const wxDC *dc, const wxFont *theFont);
  29     wxTextMeasureBase(const wxWindow *win, const wxFont *theFont);
  30
  31     // Even though this class is not supposed to be used polymorphically, give
  32     // it a virtual dtor to avoid compiler warnings.
  33     virtual ~wxTextMeasureBase() { }
  34
  35
  36     // Return the extent of a single line string.
  37     void GetTextExtent(const wxString& string,
  38                        wxCoord *width,
  39                        wxCoord *height,
  40                        wxCoord *descent = NULL,
  41                        wxCoord *externalLeading = NULL);
  42
  43     // The same for a multiline (with '\n') string.
  44     void GetMultiLineTextExtent(const wxString& text,
  45                                 wxCoord *width,
  46                                 wxCoord *height,
  47                                 wxCoord *heightOneLine = NULL);
  48
  49     // Find the dimensions of the largest string.
  50     void GetLargestStringExtent(const wxVector<wxString>& strings,
  51                                 wxCoord *width,
  52                                 wxCoord *height);
  53
  54     // Fill the array with the widths for each "0..N" substrings for N from 1
  55     // to text.length().
  56     //
  57     // The scaleX argument is the horizontal scale used by wxDC and is only
  58     // used in the generic implementation.
  59     bool GetPartialTextExtents(const wxString& text,
  60                                wxArrayInt& widths,
  61                                double scaleX);
  62
  63 protected:
  64     // These functions are called by our public methods before and after each
  65     // call to DoGetTextExtent(). Derived classes may override them to prepare
  66     // for -- possibly several -- subsequent calls to DoGetTextExtent().
  67     //
  68     // As these calls must be always paired, they're never called directly but
  69     // only by our friend MeasuringGuard class.
  70     virtual void BeginMeasuring() { }
  71     virtual void EndMeasuring() { }
  72
  73     // RAII wrapper for the two methods above.
  74     class MeasuringGuard
  75     {
  76     public:
  77         MeasuringGuard(wxTextMeasureBase& tm) : m_tm(tm)
  78         {
  79             m_tm.BeginMeasuring();
  80         }
  81
  82         ~MeasuringGuard()
  83         {
  84             m_tm.EndMeasuring();
  85         }
  86
  87     private:
  88         wxTextMeasureBase& m_tm;
  89     };
  90
  91
  92     // The main function of this class, to be implemented in platform-specific
  93     // way used by all our public methods except GetLargestStringExtents().
  94     //
  95     // The width and height pointers here are never NULL and the input string
  96     // is not empty.
  97     virtual void DoGetTextExtent(const wxString& string,
  98                                  wxCoord *width,
  99                                  wxCoord *height,
 100                                  wxCoord *descent = NULL,
 101                                  wxCoord *externalLeading = NULL) = 0;
 102
 103     // The real implementation of GetPartialTextExtents().
 104     //
 105     // On input, widths array contains text.length() zero elements and the text
 106     // is guaranteed to be non-empty.
 107     virtual bool DoGetPartialTextExtents(const wxString& text,
 108                                          wxArrayInt& widths,
 109                                          double scaleX) = 0;
 110
 111
 112     // Exactly one of m_dc and m_win is non-NULL for any given object of this
 113     // class.
 114     const wxDC* const m_dc;
 115     const wxWindow* const m_win;
 116
 117     // This one can be NULL or not.
 118     const wxFont* const m_font;
 119
 120     wxDECLARE_NO_COPY_CLASS(wxTextMeasureBase);
 121 };
 122
 123 // Include the platform dependant class declaration, if any.
 124 #if defined(__WXGTK20__)
 125     #include "wx/gtk/private/textmeasure.h"
 126 #elif defined(__WXMSW__)
 127     #include "wx/msw/private/textmeasure.h"
 128 #else // no platform-specific implementation of wxTextMeasure yet
 129     #include "wx/generic/private/textmeasure.h"
 130
 131     #define wxUSE_GENERIC_TEXTMEASURE 1
 132 #endif
 133
 134 #ifndef wxUSE_GENERIC_TEXTMEASURE
 135     #define wxUSE_GENERIC_TEXTMEASURE 0
 136 #endif
 137
 138 #endif // _WX_PRIVATE_TEXTMEASURE_H_