harfbuzz/src/hb-fallback-shape.cc

/*
 * Copyright © 2011  Google, Inc.
 *
 *  This is part of HarfBuzz, a text shaping library.
 *
 * Permission is hereby granted, without written agreement and without
 * license or royalty fees, to use, copy, modify, and distribute this
 * software and its documentation for any purpose, provided that the
 * above copyright notice and the following two paragraphs appear in
 * all copies of this software.
 *
 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 *
 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
 *
 * Google Author(s): Behdad Esfahbod
 */

#define HB_SHAPER fallback
#include "hb-shaper-impl-private.hh"


/*
 * shaper face data
 */

struct hb_fallback_shaper_face_data_t {};

hb_fallback_shaper_face_data_t *
_hb_fallback_shaper_face_data_create (hb_face_t *face HB_UNUSED)
{
  return (hb_fallback_shaper_face_data_t *) HB_SHAPER_DATA_SUCCEEDED;
}

void
_hb_fallback_shaper_face_data_destroy (hb_fallback_shaper_face_data_t *data HB_UNUSED)
{
}


/*
 * shaper font data
 */

struct hb_fallback_shaper_font_data_t {};

hb_fallback_shaper_font_data_t *
_hb_fallback_shaper_font_data_create (hb_font_t *font HB_UNUSED)
{
  return (hb_fallback_shaper_font_data_t *) HB_SHAPER_DATA_SUCCEEDED;
}

void
_hb_fallback_shaper_font_data_destroy (hb_fallback_shaper_font_data_t *data HB_UNUSED)
{
}


/*
 * shaper shape_plan data
 */

struct hb_fallback_shaper_shape_plan_data_t {};

hb_fallback_shaper_shape_plan_data_t *
_hb_fallback_shaper_shape_plan_data_create (hb_shape_plan_t    *shape_plan HB_UNUSED,
					    const hb_feature_t *user_features HB_UNUSED,
					    unsigned int        num_user_features HB_UNUSED)
{
  return (hb_fallback_shaper_shape_plan_data_t *) HB_SHAPER_DATA_SUCCEEDED;
}

void
_hb_fallback_shaper_shape_plan_data_destroy (hb_fallback_shaper_shape_plan_data_t *data HB_UNUSED)
{
}


/*
 * shaper
 */

hb_bool_t
_hb_fallback_shape (hb_shape_plan_t    *shape_plan HB_UNUSED,
		    hb_font_t          *font,
		    hb_buffer_t        *buffer,
		    const hb_feature_t *features HB_UNUSED,
		    unsigned int        num_features HB_UNUSED)
{
  /* TODO
   *
   * - Apply fallback kern.
   * - Handle Variation Selectors?
   * - Apply normalization?
   *
   * This will make the fallback shaper into a dumb "TrueType"
   * shaper which many people unfortunately still request.
   */

  hb_codepoint_t space;
  bool has_space = (bool) font->get_glyph (' ', 0, &space);

  buffer->clear_positions ();

  hb_direction_t direction = buffer->props.direction;
  hb_unicode_funcs_t *unicode = buffer->unicode;
  unsigned int count = buffer->len;
  hb_glyph_info_t *info = buffer->info;
  hb_glyph_position_t *pos = buffer->pos;
  for (unsigned int i = 0; i < count; i++)
  {
    if (has_space && unicode->is_default_ignorable (info[i].codepoint)) {
      info[i].codepoint = space;
      pos[i].x_advance = 0;
      pos[i].y_advance = 0;
      continue;
    }
    font->get_glyph (info[i].codepoint, 0, &info[i].codepoint);
    font->get_glyph_advance_for_direction (info[i].codepoint,
					   direction,
					   &pos[i].x_advance,
					   &pos[i].y_advance);
    font->subtract_glyph_origin_for_direction (info[i].codepoint,
					       direction,
					       &pos[i].x_offset,
					       &pos[i].y_offset);
  }

  if (HB_DIRECTION_IS_BACKWARD (direction))
    hb_buffer_reverse (buffer);

  return true;
}