src/gtk/textmeasure.cpp

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // Name:        src/gtk/textmeasure.cpp
   3 // Purpose:     wxTextMeasure implementation for wxGTK
   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/window.h"
  24     #include "wx/log.h"
  25 #endif //WX_PRECOMP
  26
  27 #include "wx/private/textmeasure.h"
  28
  29 #include "wx/fontutil.h"
  30 #include "wx/gtk/private.h"
  31 #include "wx/gtk/dc.h"
  32
  33 #ifndef __WXGTK3__
  34     #include "wx/gtk/dcclient.h"
  35 #endif
  36
  37 // ============================================================================
  38 // wxTextMeasure implementation
  39 // ============================================================================
  40
  41 void wxTextMeasure::Init()
  42 {
  43     m_context = NULL;
  44     m_layout = NULL;
  45
  46 #ifndef __WXGTK3__
  47     m_wdc = NULL;
  48
  49     if ( m_dc )
  50     {
  51         wxClassInfo* const ci = m_dc->GetImpl()->GetClassInfo();
  52
  53         // Currently the code here only works with wxWindowDCImpl and only in
  54         // wxGTK2 as wxGTK3 uses Cairo and not Pango for all its DCs.
  55         if ( ci->IsKindOf(wxCLASSINFO(wxWindowDCImpl)))
  56         {
  57             m_useDCImpl = false;
  58         }
  59     }
  60 #endif // GTK+ < 3
  61 }
  62
  63 // Get Gtk needed elements, if we have not them yet.
  64 void wxTextMeasure::BeginMeasuring()
  65 {
  66     if ( m_dc )
  67     {
  68 #ifndef __WXGTK3__
  69         m_wdc = wxDynamicCast(m_dc->GetImpl(), wxWindowDCImpl);
  70         if ( m_wdc )
  71         {
  72             m_context = m_wdc->m_context;
  73             m_layout = m_wdc->m_layout;
  74         }
  75 #endif // GTK+ < 3
  76     }
  77     else if ( m_win )
  78     {
  79         m_context = gtk_widget_get_pango_context( m_win->GetHandle() );
  80         if ( m_context )
  81             m_layout = pango_layout_new(m_context);
  82     }
  83
  84     // set the font to use
  85     if ( m_layout )
  86     {
  87         pango_layout_set_font_description(m_layout,
  88                                           GetFont().GetNativeFontInfo()->description);
  89     }
  90 }
  91
  92 void wxTextMeasure::EndMeasuring()
  93 {
  94     if ( !m_layout )
  95         return;
  96
  97 #ifndef __WXGTK3__
  98     if ( m_wdc )
  99     {
 100         // Reset dc own font description
 101         pango_layout_set_font_description( m_wdc->m_layout, m_wdc->m_fontdesc );
 102     }
 103     else
 104 #endif // GTK+ < 3
 105     {
 106         g_object_unref (m_layout);
 107     }
 108 }
 109
 110 // Notice we don't check here the font. It is supposed to be OK before the call.
 111 void wxTextMeasure::DoGetTextExtent(const wxString& string,
 112                                     wxCoord *width,
 113                                     wxCoord *height,
 114                                     wxCoord *descent,
 115                                     wxCoord *externalLeading)
 116 {
 117     if ( !m_context )
 118     {
 119         if ( width )
 120             *width = 0;
 121
 122         if ( height )
 123             *height = 0;
 124         return;
 125     }
 126
 127     // Set layout's text
 128     const wxCharBuffer dataUTF8 = wxGTK_CONV_FONT(string, GetFont());
 129     if ( !dataUTF8 )
 130     {
 131         // hardly ideal, but what else can we do if conversion failed?
 132         wxLogLastError(wxT("GetTextExtent"));
 133         return;
 134     }
 135     pango_layout_set_text(m_layout, dataUTF8, -1);
 136
 137     if ( m_dc )
 138     {
 139         // in device units
 140         pango_layout_get_pixel_size(m_layout, width, height);
 141     }
 142     else // win
 143     {
 144         // the logical rect bounds the ink rect
 145         PangoRectangle rect;
 146         pango_layout_get_extents(m_layout, NULL, &rect);
 147         *width = PANGO_PIXELS(rect.width);
 148         *height = PANGO_PIXELS(rect.height);
 149     }
 150
 151     if (descent)
 152     {
 153         PangoLayoutIter *iter = pango_layout_get_iter(m_layout);
 154         int baseline = pango_layout_iter_get_baseline(iter);
 155         pango_layout_iter_free(iter);
 156         *descent = *height - PANGO_PIXELS(baseline);
 157     }
 158
 159     if (externalLeading)
 160     {
 161         // No support for MSW-like "external leading" in Pango.
 162         *externalLeading = 0;
 163     }
 164 }
 165
 166 bool wxTextMeasure::DoGetPartialTextExtents(const wxString& text,
 167                                             wxArrayInt& widths,
 168                                             double scaleX)
 169 {
 170     if ( !m_layout )
 171         return wxTextMeasureBase::DoGetPartialTextExtents(text, widths, scaleX);
 172
 173     // Set layout's text
 174     const wxCharBuffer dataUTF8 = wxGTK_CONV_FONT(text, GetFont());
 175     if ( !dataUTF8 )
 176     {
 177         // hardly ideal, but what else can we do if conversion failed?
 178         wxLogLastError(wxT("GetPartialTextExtents"));
 179         return false;
 180     }
 181
 182     pango_layout_set_text(m_layout, dataUTF8, -1);
 183
 184     // Calculate the position of each character based on the widths of
 185     // the previous characters
 186
 187     // Code borrowed from Scintilla's PlatGTK
 188     PangoLayoutIter *iter = pango_layout_get_iter(m_layout);
 189     PangoRectangle pos;
 190     pango_layout_iter_get_cluster_extents(iter, NULL, &pos);
 191     size_t i = 0;
 192     while (pango_layout_iter_next_cluster(iter))
 193     {
 194         pango_layout_iter_get_cluster_extents(iter, NULL, &pos);
 195         int position = PANGO_PIXELS(pos.x);
 196         widths[i++] = position;
 197     }
 198
 199     const size_t len = text.length();
 200     while (i < len)
 201         widths[i++] = PANGO_PIXELS(pos.x + pos.width);
 202     pango_layout_iter_free(iter);
 203
 204     return true;
 205 }