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 // Copyright:   (c) 1997-2012 wxWidgets team
   7 // Licence:     wxWindows licence
   8 ///////////////////////////////////////////////////////////////////////////////
   9
  10 // ============================================================================
  11 // declarations
  12 // ============================================================================
  13
  14 // ----------------------------------------------------------------------------
  15 // headers
  16 // ----------------------------------------------------------------------------
  17
  18 // for compilers that support precompilation, includes "wx.h".
  19 #include "wx/wxprec.h"
  20
  21 #ifndef WX_PRECOMP
  22     #include "wx/window.h"
  23     #include "wx/log.h"
  24 #endif //WX_PRECOMP
  25
  26 #include "wx/private/textmeasure.h"
  27
  28 #include "wx/fontutil.h"
  29 #include "wx/gtk/private.h"
  30 #include "wx/gtk/dc.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     m_context = NULL;
  43     m_layout = NULL;
  44
  45 #ifndef __WXGTK3__
  46     m_wdc = NULL;
  47
  48     if ( m_dc )
  49     {
  50         wxClassInfo* const ci = m_dc->GetImpl()->GetClassInfo();
  51
  52         // Currently the code here only works with wxWindowDCImpl and only in
  53         // wxGTK2 as wxGTK3 uses Cairo and not Pango for all its DCs.
  54         if ( ci->IsKindOf(wxCLASSINFO(wxWindowDCImpl)))
  55         {
  56             m_useDCImpl = false;
  57         }
  58     }
  59 #endif // GTK+ < 3
  60 }
  61
  62 // Get Gtk needed elements, if we have not them yet.
  63 void wxTextMeasure::BeginMeasuring()
  64 {
  65     if ( m_dc )
  66     {
  67 #ifndef __WXGTK3__
  68         m_wdc = wxDynamicCast(m_dc->GetImpl(), wxWindowDCImpl);
  69         if ( m_wdc )
  70         {
  71             m_context = m_wdc->m_context;
  72             m_layout = m_wdc->m_layout;
  73         }
  74 #endif // GTK+ < 3
  75     }
  76     else if ( m_win )
  77     {
  78         m_context = gtk_widget_get_pango_context( m_win->GetHandle() );
  79         if ( m_context )
  80             m_layout = pango_layout_new(m_context);
  81     }
  82
  83     // set the font to use
  84     if ( m_layout )
  85     {
  86         pango_layout_set_font_description(m_layout,
  87                                           GetFont().GetNativeFontInfo()->description);
  88     }
  89 }
  90
  91 void wxTextMeasure::EndMeasuring()
  92 {
  93     if ( !m_layout )
  94         return;
  95
  96 #ifndef __WXGTK3__
  97     if ( m_wdc )
  98     {
  99         // Reset dc own font description
 100         pango_layout_set_font_description( m_wdc->m_layout, m_wdc->m_fontdesc );
 101     }
 102     else
 103 #endif // GTK+ < 3
 104     {
 105         g_object_unref (m_layout);
 106     }
 107 }
 108
 109 // Notice we don't check here the font. It is supposed to be OK before the call.
 110 void wxTextMeasure::DoGetTextExtent(const wxString& string,
 111                                     wxCoord *width,
 112                                     wxCoord *height,
 113                                     wxCoord *descent,
 114                                     wxCoord *externalLeading)
 115 {
 116     if ( !m_context )
 117     {
 118         if ( width )
 119             *width = 0;
 120
 121         if ( height )
 122             *height = 0;
 123         return;
 124     }
 125
 126     // Set layout's text
 127     const wxCharBuffer dataUTF8 = wxGTK_CONV_FONT(string, GetFont());
 128     if ( !dataUTF8 && !string.empty() )
 129     {
 130         // hardly ideal, but what else can we do if conversion failed?
 131         wxLogLastError(wxT("GetTextExtent"));
 132         return;
 133     }
 134     pango_layout_set_text(m_layout, dataUTF8, -1);
 135
 136     if ( m_dc )
 137     {
 138         // in device units
 139         pango_layout_get_pixel_size(m_layout, width, height);
 140     }
 141     else // win
 142     {
 143         // the logical rect bounds the ink rect
 144         PangoRectangle rect;
 145         pango_layout_get_extents(m_layout, NULL, &rect);
 146         *width = PANGO_PIXELS(rect.width);
 147         *height = PANGO_PIXELS(rect.height);
 148     }
 149
 150     if (descent)
 151     {
 152         PangoLayoutIter *iter = pango_layout_get_iter(m_layout);
 153         int baseline = pango_layout_iter_get_baseline(iter);
 154         pango_layout_iter_free(iter);
 155         *descent = *height - PANGO_PIXELS(baseline);
 156     }
 157
 158     if (externalLeading)
 159     {
 160         // No support for MSW-like "external leading" in Pango.
 161         *externalLeading = 0;
 162     }
 163 }
 164
 165 bool wxTextMeasure::DoGetPartialTextExtents(const wxString& text,
 166                                             wxArrayInt& widths,
 167                                             double scaleX)
 168 {
 169     if ( !m_layout )
 170         return wxTextMeasureBase::DoGetPartialTextExtents(text, widths, scaleX);
 171
 172     // Set layout's text
 173     const wxCharBuffer dataUTF8 = wxGTK_CONV_FONT(text, GetFont());
 174     if ( !dataUTF8 )
 175     {
 176         // hardly ideal, but what else can we do if conversion failed?
 177         wxLogLastError(wxT("GetPartialTextExtents"));
 178         return false;
 179     }
 180
 181     pango_layout_set_text(m_layout, dataUTF8, -1);
 182
 183     // Calculate the position of each character based on the widths of
 184     // the previous characters
 185
 186     // Code borrowed from Scintilla's PlatGTK
 187     PangoLayoutIter *iter = pango_layout_get_iter(m_layout);
 188     PangoRectangle pos;
 189     pango_layout_iter_get_cluster_extents(iter, NULL, &pos);
 190     size_t i = 0;
 191     while (pango_layout_iter_next_cluster(iter))
 192     {
 193         pango_layout_iter_get_cluster_extents(iter, NULL, &pos);
 194         int position = PANGO_PIXELS(pos.x);
 195         widths[i++] = position;
 196     }
 197
 198     const size_t len = text.length();
 199     while (i < len)
 200         widths[i++] = PANGO_PIXELS(pos.x + pos.width);
 201     pango_layout_iter_free(iter);
 202
 203     return true;
 204 }