gfx/harfbuzz/src/hb-draw.hh

   1 /*
   2  * Copyright © 2020  Ebrahim Byagowi
   3  *
   4  *  This is part of HarfBuzz, a text shaping library.
   5  *
   6  * Permission is hereby granted, without written agreement and without
   7  * license or royalty fees, to use, copy, modify, and distribute this
   8  * software and its documentation for any purpose, provided that the
   9  * above copyright notice and the following two paragraphs appear in
  10  * all copies of this software.
  11  *
  12  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
  13  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
  14  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
  15  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
  16  * DAMAGE.
  17  *
  18  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
  19  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
  20  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
  21  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
  22  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  23  */
  24
  25 #ifndef HB_DRAW_HH
  26 #define HB_DRAW_HH
  27
  28 #include "hb.hh"
  29
  30 #ifdef HB_EXPERIMENTAL_API
  31 struct hb_draw_funcs_t
  32 {
  33   hb_object_header_t header;
  34
  35   hb_draw_move_to_func_t move_to;
  36   hb_draw_line_to_func_t line_to;
  37   hb_draw_quadratic_to_func_t quadratic_to;
  38   bool is_quadratic_to_set;
  39   hb_draw_cubic_to_func_t cubic_to;
  40   hb_draw_close_path_func_t close_path;
  41 };
  42
  43 struct draw_helper_t
  44 {
  45   draw_helper_t (const hb_draw_funcs_t *funcs_, void *user_data_)
  46   {
  47     funcs = funcs_;
  48     user_data = user_data_;
  49     path_open = false;
  50     path_start_x = current_x = path_start_y = current_y = 0;
  51   }
  52   ~draw_helper_t () { end_path (); }
  53
  54   void move_to (hb_position_t x, hb_position_t y)
  55   {
  56     if (path_open) end_path ();
  57     current_x = path_start_x = x;
  58     current_y = path_start_y = y;
  59   }
  60
  61   void line_to (hb_position_t x, hb_position_t y)
  62   {
  63     if (equal_to_current (x, y)) return;
  64     if (!path_open) start_path ();
  65     funcs->line_to (x, y, user_data);
  66     current_x = x;
  67     current_y = y;
  68   }
  69
  70   void
  71   quadratic_to (hb_position_t control_x, hb_position_t control_y,
  72                 hb_position_t to_x, hb_position_t to_y)
  73   {
  74     if (equal_to_current (control_x, control_y) && equal_to_current (to_x, to_y))
  75       return;
  76     if (!path_open) start_path ();
  77     if (funcs->is_quadratic_to_set)
  78       funcs->quadratic_to (control_x, control_y, to_x, to_y, user_data);
  79     else
  80       funcs->cubic_to (roundf ((current_x + 2.f * control_x) / 3.f),
  81                        roundf ((current_y + 2.f * control_y) / 3.f),
  82                        roundf ((to_x + 2.f * control_x) / 3.f),
  83                        roundf ((to_y + 2.f * control_y) / 3.f),
  84                        to_x, to_y, user_data);
  85     current_x = to_x;
  86     current_y = to_y;
  87   }
  88
  89   void
  90   cubic_to (hb_position_t control1_x, hb_position_t control1_y,
  91             hb_position_t control2_x, hb_position_t control2_y,
  92             hb_position_t to_x, hb_position_t to_y)
  93   {
  94     if (equal_to_current (control1_x, control1_y) &&
  95         equal_to_current (control2_x, control2_y) &&
  96         equal_to_current (to_x, to_y))
  97       return;
  98     if (!path_open) start_path ();
  99     funcs->cubic_to (control1_x, control1_y, control2_x, control2_y, to_x, to_y, user_data);
 100     current_x = to_x;
 101     current_y = to_y;
 102   }
 103
 104   void end_path ()
 105   {
 106     if (path_open)
 107     {
 108       if ((path_start_x != current_x) || (path_start_y != current_y))
 109         funcs->line_to (path_start_x, path_start_y, user_data);
 110       funcs->close_path (user_data);
 111     }
 112     path_open = false;
 113     path_start_x = current_x = path_start_y = current_y = 0;
 114   }
 115
 116   protected:
 117   bool equal_to_current (hb_position_t x, hb_position_t y)
 118   { return current_x == x && current_y == y; }
 119
 120   void start_path ()
 121   {
 122     if (path_open) end_path ();
 123     path_open = true;
 124     funcs->move_to (path_start_x, path_start_y, user_data);
 125   }
 126
 127   hb_position_t path_start_x;
 128   hb_position_t path_start_y;
 129
 130   hb_position_t current_x;
 131   hb_position_t current_y;
 132
 133   bool path_open;
 134   const hb_draw_funcs_t *funcs;
 135   void *user_data;
 136 };
 137 #endif
 138
 139 #endif /* HB_DRAW_HH */