cairo_text_helpers.c

   1 #include <cairo.h>
   2 #include <gtk/gtk.h>
   3 #include <math.h>
   4
   5 static void draw_aligned_text(cairo_t *cr, const char *font, double x, double y,
   6                                double fontsize, const char *text, int alignment)
   7 {
   8 #define CENTERED 0
   9 #define LEFT_JUSTIFIED 1
  10 #define RIGHT_JUSTIFIED 2
  11
  12         double factor, direction;
  13         cairo_text_extents_t extents;
  14
  15         switch (alignment) {
  16                 case CENTERED:
  17                         direction = -1.0;
  18                         factor = 0.5;
  19                         break;
  20                 case RIGHT_JUSTIFIED:
  21                         direction = -1.0;
  22                         factor = 1.0;
  23                         break;
  24                 case LEFT_JUSTIFIED:
  25                 default:
  26                         direction = 1.0;
  27                         factor = 0.0;
  28                         break;
  29         }
  30         cairo_select_font_face(cr, font, CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_NORMAL);
  31
  32         cairo_set_font_size(cr, fontsize);
  33         cairo_text_extents(cr, text, &extents);
  34         x = x + direction * (factor * extents.width  + extents.x_bearing);
  35         y = y - (extents.height / 2 + extents.y_bearing);
  36
  37         cairo_move_to(cr, x, y);
  38         cairo_show_text(cr, text);
  39 }
  40
  41 void draw_centered_text(cairo_t *cr, const char *font, double x, double y,
  42                                double fontsize, const char *text)
  43 {
  44         draw_aligned_text(cr, font, x, y, fontsize, text, CENTERED);
  45 }
  46
  47 void draw_right_justified_text(cairo_t *cr, const char *font,
  48                                 double x, double y,
  49                                 double fontsize, const char *text)
  50 {
  51         draw_aligned_text(cr, font, x, y, fontsize, text, RIGHT_JUSTIFIED);
  52 }
  53
  54 void draw_left_justified_text(cairo_t *cr, const char *font,
  55                                 double x, double y,
  56                                 double fontsize, const char *text)
  57 {
  58         draw_aligned_text(cr, font, x, y, fontsize, text, LEFT_JUSTIFIED);
  59 }
  60
  61 void draw_vertical_centered_text(cairo_t *cr, const char *font, double x,
  62                                         double y, double fontsize,
  63                                         const char *text)
  64 {
  65         double sx, sy;
  66         cairo_text_extents_t extents;
  67
  68         cairo_select_font_face(cr, font, CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_NORMAL);
  69
  70         cairo_set_font_size(cr, fontsize);
  71         cairo_text_extents(cr, text, &extents);
  72         sx = x;
  73         sy = y;
  74         y = y + (extents.width / 2.0 + extents.x_bearing);
  75         x = x - (extents.height / 2.0 + extents.y_bearing);
  76
  77         cairo_move_to(cr, x, y);
  78         cairo_save(cr);
  79         cairo_translate(cr, -sx, -sy);
  80         cairo_rotate(cr, -90.0 * M_PI / 180.0);
  81         cairo_translate(cr, sx, sy);
  82         cairo_show_text(cr, text);
  83         cairo_restore(cr);
  84 }
  85