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     wxASSERT_MSG( m_font, wxT("wxTextMeasure needs a valid wxFont") );
  44
  45     m_context = NULL;
  46     m_layout = NULL;
  47
  48 #ifndef __WXGTK3__
  49     m_wdc = NULL;
  50
  51     if ( m_dc )
  52     {
  53         wxClassInfo* const ci = m_dc->GetImpl()->GetClassInfo();
  54
  55         // Currently the code here only works with wxWindowDCImpl and only in
  56         // wxGTK2 as wxGTK3 uses Cairo and not Pango for all its DCs.
  57         if ( ci->IsKindOf(wxCLASSINFO(wxWindowDCImpl)))
  58         {
  59             m_useDCImpl = false;
  60         }
  61     }
  62 #endif // GTK+ < 3
  63 }
  64
  65 // Get Gtk needed elements, if we have not them yet.
  66 void wxTextMeasure::BeginMeasuring()
  67 {
  68     if ( m_dc )
  69     {
  70 #ifndef __WXGTK3__
  71         m_wdc = wxDynamicCast(m_dc->GetImpl(), wxWindowDCImpl);
  72         if ( m_wdc )
  73         {
  74             m_context = m_wdc->m_context;
  75             m_layout = m_wdc->m_layout;
  76         }
  77 #endif // GTK+ < 3
  78     }
  79     else if ( m_win )
  80     {
  81         m_context = gtk_widget_get_pango_context( m_win->GetHandle() );
  82         if ( m_context )
  83             m_layout = pango_layout_new(m_context);
  84     }
  85
  86     // set the font to use
  87     if ( m_layout )
  88     {
  89         pango_layout_set_font_description(m_layout,
  90                                           m_font->GetNativeFontInfo()->description);
  91     }
  92 }
  93
  94 void wxTextMeasure::EndMeasuring()
  95 {
  96     if ( !m_layout )
  97         return;
  98
  99 #ifndef __WXGTK3__
 100     if ( m_wdc )
 101     {
 102         // Reset dc own font description
 103         pango_layout_set_font_description( m_wdc->m_layout, m_wdc->m_fontdesc );
 104     }
 105     else
 106 #endif // GTK+ < 3
 107     {
 108         g_object_unref (m_layout);
 109     }
 110 }
 111
 112 // Notice we don't check here the font. It is supposed to be OK before the call.
 113 void wxTextMeasure::DoGetTextExtent(const wxString& string,
 114                                     wxCoord *width,
 115                                     wxCoord *height,
 116                                     wxCoord *descent,
 117                                     wxCoord *externalLeading)
 118 {
 119     if ( !m_context )
 120     {
 121         *width =
 122         *height = 0;
 123         return;
 124     }
 125
 126     // Set layout's text
 127     const wxCharBuffer dataUTF8 = wxGTK_CONV_FONT(string, *m_font);
 128     if ( !dataUTF8 )
 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 WXUNUSED(scaleX))
 168 {
 169     // Set layout's text
 170     const wxCharBuffer dataUTF8 = wxGTK_CONV_FONT(text, *m_font);
 171     if ( !dataUTF8 )
 172     {
 173         // hardly ideal, but what else can we do if conversion failed?
 174         wxLogLastError(wxT("GetPartialTextExtents"));
 175         return false;
 176     }
 177
 178     pango_layout_set_text(m_layout, dataUTF8, -1);
 179
 180     // Calculate the position of each character based on the widths of
 181     // the previous characters
 182
 183     // Code borrowed from Scintilla's PlatGTK
 184     PangoLayoutIter *iter = pango_layout_get_iter(m_layout);
 185     PangoRectangle pos;
 186     pango_layout_iter_get_cluster_extents(iter, NULL, &pos);
 187     size_t i = 0;
 188     while (pango_layout_iter_next_cluster(iter))
 189     {
 190         pango_layout_iter_get_cluster_extents(iter, NULL, &pos);
 191         int position = PANGO_PIXELS(pos.x);
 192         widths[i++] = position;
 193     }
 194
 195     const size_t len = text.length();
 196     while (i < len)
 197         widths[i++] = PANGO_PIXELS(pos.x + pos.width);
 198     pango_layout_iter_free(iter);
 199
 200     return true;
 201 }