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