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