cairo_text_helpers.c

   1 #include "cairo_text_helpers.h"
   2
   3 #include <cairo.h>
   4 #include <gtk/gtk.h>
   5 #include <math.h>
   6
   7 static void draw_aligned_text(cairo_t *cr, const char *font, double x, double y,
   8                                double fontsize, const char *text, int alignment)
   9 {
  10 #define CENTERED 0
  11 #define LEFT_JUSTIFIED 1
  12 #define RIGHT_JUSTIFIED 2
  13
  14         double factor, direction;
  15         cairo_text_extents_t extents;
  16
  17         switch (alignment) {
  18                 case CENTERED:
  19                         direction = -1.0;
  20                         factor = 0.5;
  21                         break;
  22                 case RIGHT_JUSTIFIED:
  23                         direction = -1.0;
  24                         factor = 1.0;
  25                         break;
  26                 case LEFT_JUSTIFIED:
  27                 default:
  28                         direction = 1.0;
  29                         factor = 0.0;
  30                         break;
  31         }
  32         cairo_select_font_face(cr, font, CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_NORMAL);
  33
  34         cairo_set_font_size(cr, fontsize);
  35         cairo_text_extents(cr, text, &extents);
  36         x = x + direction * (factor * extents.width  + extents.x_bearing);
  37         y = y - (extents.height / 2 + extents.y_bearing);
  38
  39         cairo_move_to(cr, x, y);
  40         cairo_show_text(cr, text);
  41 }
  42
  43 void draw_centered_text(cairo_t *cr, const char *font, double x, double y,
  44                                double fontsize, const char *text)
  45 {
  46         draw_aligned_text(cr, font, x, y, fontsize, text, CENTERED);
  47 }
  48
  49 void draw_right_justified_text(cairo_t *cr, const char *font,
  50                                 double x, double y,
  51                                 double fontsize, const char *text)
  52 {
  53         draw_aligned_text(cr, font, x, y, fontsize, text, RIGHT_JUSTIFIED);
  54 }
  55
  56 void draw_left_justified_text(cairo_t *cr, const char *font,
  57                                 double x, double y,
  58                                 double fontsize, const char *text)
  59 {
  60         draw_aligned_text(cr, font, x, y, fontsize, text, LEFT_JUSTIFIED);
  61 }
  62
  63 void draw_vertical_centered_text(cairo_t *cr, const char *font, double x,
  64                                         double y, double fontsize,
  65                                         const char *text)
  66 {
  67         double sx, sy;
  68         cairo_text_extents_t extents;
  69
  70         cairo_select_font_face(cr, font, CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_NORMAL);
  71
  72         cairo_set_font_size(cr, fontsize);
  73         cairo_text_extents(cr, text, &extents);
  74         sx = x;
  75         sy = y;
  76         y = y + (extents.width / 2.0 + extents.x_bearing);
  77         x = x - (extents.height / 2.0 + extents.y_bearing);
  78
  79         cairo_move_to(cr, x, y);
  80         cairo_save(cr);
  81         cairo_translate(cr, -sx, -sy);
  82         cairo_rotate(cr, -90.0 * M_PI / 180.0);
  83         cairo_translate(cr, sx, sy);
  84         cairo_show_text(cr, text);
  85         cairo_restore(cr);
  86 }
  87