src/common/textmeasurecmn.cpp

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // Name:        src/common/textmeasurecmn.cpp
   3 // Purpose:     wxTextMeasureBase implementation
   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 // ============================================================================
  12 // declarations
  13 // ============================================================================
  14
  15 // ----------------------------------------------------------------------------
  16 // headers
  17 // ----------------------------------------------------------------------------
  18
  19 // for compilers that support precompilation, includes "wx.h".
  20 #include "wx/wxprec.h"
  21
  22 #ifndef WX_PRECOMP
  23     #include "wx/dc.h"
  24     #include "wx/window.h"
  25 #endif //WX_PRECOMP
  26
  27 #include "wx/private/textmeasure.h"
  28
  29 // ============================================================================
  30 // wxTextMeasureBase implementation
  31 // ============================================================================
  32
  33 wxTextMeasureBase::wxTextMeasureBase(const wxDC *dc, const wxFont *theFont)
  34     : m_dc(dc),
  35       m_win(NULL),
  36       m_font(theFont)
  37 {
  38     wxASSERT_MSG( dc, wxS("wxTextMeasure needs a valid wxDC") );
  39
  40     // By default, use wxDC version, we'll explicitly reset this to false in
  41     // the derived classes if the DC is of native variety.
  42     m_useDCImpl = true;
  43 }
  44
  45 wxTextMeasureBase::wxTextMeasureBase(const wxWindow *win, const wxFont *theFont)
  46     : m_dc(NULL),
  47       m_win(win),
  48       m_font(theFont)
  49 {
  50     wxASSERT_MSG( win, wxS("wxTextMeasure needs a valid wxWindow") );
  51
  52     // We don't have any wxDC so we can't forward to it.
  53     m_useDCImpl = false;
  54 }
  55
  56 wxFont wxTextMeasureBase::GetFont() const
  57 {
  58     return m_font ? *m_font
  59                   : m_win ? m_win->GetFont()
  60                           : m_dc->GetFont();
  61 }
  62
  63 void wxTextMeasureBase::CallGetTextExtent(const wxString& string,
  64                                           wxCoord *width,
  65                                           wxCoord *height,
  66                                           wxCoord *descent,
  67                                           wxCoord *externalLeading)
  68 {
  69     if ( m_useDCImpl )
  70         m_dc->GetTextExtent(string, width, height, descent, externalLeading);
  71     else
  72         DoGetTextExtent(string, width, height, descent, externalLeading);
  73 }
  74
  75 void wxTextMeasureBase::GetTextExtent(const wxString& string,
  76                                       wxCoord *width,
  77                                       wxCoord *height,
  78                                       wxCoord *descent,
  79                                       wxCoord *externalLeading)
  80 {
  81     // To make the code simpler, make sure that the width and height pointers
  82     // are always valid, even if they point to dummy variables.
  83     int unusedWidth, unusedHeight;
  84     if ( !width )
  85         width = &unusedWidth;
  86     if ( !height )
  87         height = &unusedHeight;
  88
  89     if ( string.empty() )
  90     {
  91         *width =
  92         *height = 0;
  93
  94         return;
  95     }
  96
  97     MeasuringGuard guard(*this);
  98
  99     CallGetTextExtent(string, width, height, descent, externalLeading);
 100 }
 101
 102 void wxTextMeasureBase::GetMultiLineTextExtent(const wxString& text,
 103                                                wxCoord *width,
 104                                                wxCoord *height,
 105                                                wxCoord *heightOneLine)
 106 {
 107     MeasuringGuard guard(*this);
 108
 109     wxCoord widthTextMax = 0, widthLine,
 110             heightTextTotal = 0, heightLineDefault = 0, heightLine = 0;
 111
 112     wxString curLine;
 113     for ( wxString::const_iterator pc = text.begin(); ; ++pc )
 114     {
 115         if ( pc == text.end() || *pc == wxS('\n') )
 116         {
 117             if ( curLine.empty() )
 118             {
 119                 // we can't use GetTextExtent - it will return 0 for both width
 120                 // and height and an empty line should count in height
 121                 // calculation
 122
 123                 // assume that this line has the same height as the previous
 124                 // one
 125                 if ( !heightLineDefault )
 126                     heightLineDefault = heightLine;
 127
 128                 if ( !heightLineDefault )
 129                 {
 130                     // but we don't know it yet - choose something reasonable
 131                     int dummy;
 132                     CallGetTextExtent(wxS("W"), &dummy, &heightLineDefault);
 133                 }
 134
 135                 heightTextTotal += heightLineDefault;
 136             }
 137             else
 138             {
 139                 CallGetTextExtent(curLine, &widthLine, &heightLine);
 140                 if ( widthLine > widthTextMax )
 141                     widthTextMax = widthLine;
 142                 heightTextTotal += heightLine;
 143             }
 144
 145             if ( pc == text.end() )
 146             {
 147                break;
 148             }
 149             else // '\n'
 150             {
 151                curLine.clear();
 152             }
 153         }
 154         else
 155         {
 156             curLine += *pc;
 157         }
 158     }
 159
 160     if ( width )
 161         *width = widthTextMax;
 162     if ( height )
 163         *height = heightTextTotal;
 164     if ( heightOneLine )
 165         *heightOneLine = heightLine;
 166 }
 167
 168 wxSize wxTextMeasureBase::GetLargestStringExtent(size_t n,
 169                                                  const wxString* strings)
 170 {
 171     MeasuringGuard guard(*this);
 172
 173     wxCoord w, h, widthMax = 0, heightMax = 0;
 174     for ( size_t i = 0; i < n; ++i )
 175     {
 176         CallGetTextExtent(strings[i], &w, &h);
 177
 178         if ( w > widthMax )
 179             widthMax = w;
 180         if ( h > heightMax )
 181             heightMax = h;
 182     }
 183
 184     return wxSize(widthMax, heightMax);
 185 }
 186
 187 bool wxTextMeasureBase::GetPartialTextExtents(const wxString& text,
 188                                               wxArrayInt& widths,
 189                                               double scaleX)
 190 {
 191     widths.Empty();
 192     if ( text.empty() )
 193         return true;
 194
 195     MeasuringGuard guard(*this);
 196
 197     widths.Add(0, text.length());
 198
 199     return DoGetPartialTextExtents(text, widths, scaleX);
 200 }
 201
 202 // ----------------------------------------------------------------------------
 203 // Generic and inefficient DoGetPartialTextExtents() implementation.
 204 // ----------------------------------------------------------------------------
 205
 206 // Each element of the widths array will be the width of the string up to and
 207 // including the corresponding character in text.  This is the generic
 208 // implementation, the port-specific classes should do this with native APIs
 209 // if available and if faster.  Note: pango_layout_index_to_pos is much slower
 210 // than calling GetTextExtent!!
 211
 212 #define FWC_SIZE 256
 213
 214 class FontWidthCache
 215 {
 216 public:
 217     FontWidthCache() : m_scaleX(1), m_widths(NULL) { }
 218     ~FontWidthCache() { delete []m_widths; }
 219
 220     void Reset()
 221     {
 222         if ( !m_widths )
 223             m_widths = new int[FWC_SIZE];
 224
 225         memset(m_widths, 0, sizeof(int)*FWC_SIZE);
 226     }
 227
 228     wxFont m_font;
 229     double m_scaleX;
 230     int *m_widths;
 231 };
 232
 233 static FontWidthCache s_fontWidthCache;
 234
 235 bool wxTextMeasureBase::DoGetPartialTextExtents(const wxString& text,
 236                                                 wxArrayInt& widths,
 237                                                 double scaleX)
 238 {
 239     int totalWidth = 0;
 240
 241     // reset the cache if font or horizontal scale have changed
 242     if ( !s_fontWidthCache.m_widths ||
 243          !wxIsSameDouble(s_fontWidthCache.m_scaleX, scaleX) ||
 244          (s_fontWidthCache.m_font != *m_font) )
 245     {
 246         s_fontWidthCache.Reset();
 247         s_fontWidthCache.m_font = *m_font;
 248         s_fontWidthCache.m_scaleX = scaleX;
 249     }
 250
 251     // Calculate the position of each character based on the widths of
 252     // the previous characters. This is inexact for not fixed fonts.
 253     int n = 0;
 254     for ( wxString::const_iterator it = text.begin();
 255           it != text.end();
 256           ++it )
 257     {
 258         const wxChar c = *it;
 259         unsigned int c_int = (unsigned int)c;
 260
 261         int w;
 262         if ((c_int < FWC_SIZE) && (s_fontWidthCache.m_widths[c_int] != 0))
 263         {
 264             w = s_fontWidthCache.m_widths[c_int];
 265         }
 266         else
 267         {
 268             DoGetTextExtent(c, &w, NULL);
 269             if (c_int < FWC_SIZE)
 270                 s_fontWidthCache.m_widths[c_int] = w;
 271         }
 272
 273         totalWidth += w;
 274         widths[n++] = totalWidth;
 275     }
 276
 277     return true;
 278 }
 279