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