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 // RCS-ID:      $Id:
   7 // Copyright:   (c) 1997-2012 wxWidgets team
   8 // Licence:     wxWindows licence
   9 ///////////////////////////////////////////////////////////////////////////////
  10
  11 #ifndef _WX_PRIVATE_TEXTMEASURE_H_
  12 #define _WX_PRIVATE_TEXTMEASURE_H_
  13
  14 class WXDLLIMPEXP_FWD_CORE wxDC;
  15 class WXDLLIMPEXP_FWD_CORE wxFont;
  16 class WXDLLIMPEXP_FWD_CORE wxWindow;
  17
  18 // ----------------------------------------------------------------------------
  19 // wxTextMeasure: class used to measure text extent.
  20 // ----------------------------------------------------------------------------
  21
  22 class wxTextMeasureBase
  23 {
  24 public:
  25     // The first ctor argument must be non-NULL, i.e. each object of this class
  26     // is associated with either a valid wxDC or a valid wxWindow.
  27     wxTextMeasureBase(const wxDC *dc, const wxFont *theFont);
  28     wxTextMeasureBase(const wxWindow *win, const wxFont *theFont);
  29
  30     // Even though this class is not supposed to be used polymorphically, give
  31     // it a virtual dtor to avoid compiler warnings.
  32     virtual ~wxTextMeasureBase() { }
  33
  34
  35     // Return the extent of a single line string.
  36     void GetTextExtent(const wxString& string,
  37                        wxCoord *width,
  38                        wxCoord *height,
  39                        wxCoord *descent = NULL,
  40                        wxCoord *externalLeading = NULL);
  41
  42     // The same for a multiline (with '\n') string.
  43     void GetMultiLineTextExtent(const wxString& text,
  44                                 wxCoord *width,
  45                                 wxCoord *height,
  46                                 wxCoord *heightOneLine = NULL);
  47
  48     // Find the dimensions of the largest string.
  49     wxSize GetLargestStringExtent(size_t n, const wxString* strings);
  50     wxSize GetLargestStringExtent(const wxArrayString& strings)
  51     {
  52         return GetLargestStringExtent(strings.size(), &strings[0]);
  53     }
  54
  55     // Fill the array with the widths for each "0..N" substrings for N from 1
  56     // to text.length().
  57     //
  58     // The scaleX argument is the horizontal scale used by wxDC and is only
  59     // used in the generic implementation.
  60     bool GetPartialTextExtents(const wxString& text,
  61                                wxArrayInt& widths,
  62                                double scaleX);
  63
  64 protected:
  65     // These functions are called by our public methods before and after each
  66     // call to DoGetTextExtent(). Derived classes may override them to prepare
  67     // for -- possibly several -- subsequent calls to DoGetTextExtent().
  68     //
  69     // As these calls must be always paired, they're never called directly but
  70     // only by our friend MeasuringGuard class.
  71     virtual void BeginMeasuring() { }
  72     virtual void EndMeasuring() { }
  73
  74     friend class MeasuringGuard;
  75
  76     // RAII wrapper for the two methods above.
  77     class MeasuringGuard
  78     {
  79     public:
  80         MeasuringGuard(wxTextMeasureBase& tm) : m_tm(tm)
  81         {
  82             m_tm.BeginMeasuring();
  83         }
  84
  85         ~MeasuringGuard()
  86         {
  87             m_tm.EndMeasuring();
  88         }
  89
  90     private:
  91         wxTextMeasureBase& m_tm;
  92     };
  93
  94
  95     // The main function of this class, to be implemented in platform-specific
  96     // way used by all our public methods.
  97     //
  98     // The width and height pointers here are never NULL and the input string
  99     // is not empty.
 100     virtual void DoGetTextExtent(const wxString& string,
 101                                  wxCoord *width,
 102                                  wxCoord *height,
 103                                  wxCoord *descent = NULL,
 104                                  wxCoord *externalLeading = NULL) = 0;
 105
 106     // The real implementation of GetPartialTextExtents().
 107     //
 108     // On input, widths array contains text.length() zero elements and the text
 109     // is guaranteed to be non-empty.
 110     virtual bool DoGetPartialTextExtents(const wxString& text,
 111                                          wxArrayInt& widths,
 112                                          double scaleX) = 0;
 113
 114     // Call either DoGetTextExtent() or wxDC::GetTextExtent() depending on the
 115     // value of m_useDCImpl.
 116     //
 117     // This must be always used instead of calling DoGetTextExtent() directly!
 118     void CallGetTextExtent(const wxString& string,
 119                            wxCoord *width,
 120                            wxCoord *height,
 121                            wxCoord *descent = NULL,
 122                            wxCoord *externalLeading = NULL);
 123
 124
 125     // Exactly one of m_dc and m_win is non-NULL for any given object of this
 126     // class.
 127     const wxDC* const m_dc;
 128     const wxWindow* const m_win;
 129
 130     // If this is true, simply forward to wxDC::GetTextExtent() from our
 131     // CallGetTextExtent() instead of calling our own DoGetTextExtent().
 132     //
 133     // We need this because our DoGetTextExtent() typically only works with
 134     // native DCs, i.e. those having an HDC under Windows or using Pango under
 135     // GTK+. However wxTextMeasure object can be constructed for any wxDC, not
 136     // necessarily a native one and in this case we must call back into the DC
 137     // implementation of text measuring itself.
 138     bool m_useDCImpl;
 139
 140     // This one can be NULL or not.
 141     const wxFont* const m_font;
 142
 143     wxDECLARE_NO_COPY_CLASS(wxTextMeasureBase);
 144 };
 145
 146 // Include the platform dependant class declaration, if any.
 147 #if defined(__WXGTK20__)
 148     #include "wx/gtk/private/textmeasure.h"
 149 #elif defined(__WXMSW__)
 150     #include "wx/msw/private/textmeasure.h"
 151 #else // no platform-specific implementation of wxTextMeasure yet
 152     #include "wx/generic/private/textmeasure.h"
 153
 154     #define wxUSE_GENERIC_TEXTMEASURE 1
 155 #endif
 156
 157 #ifndef wxUSE_GENERIC_TEXTMEASURE
 158     #define wxUSE_GENERIC_TEXTMEASURE 0
 159 #endif
 160
 161 #endif // _WX_PRIVATE_TEXTMEASURE_H_