netsurf/monkey/font.c

/*
 * Copyright 2011 Daniel Silverstone <dsilvers@digital-scurf.org>
 *
 * This file is part of NetSurf, http://www.netsurf-browser.org/
 *
 * NetSurf is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * NetSurf is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "css/css.h"
#include "render/font.h"
#include "utils/nsoption.h"
#include "utils/utf8.h"


static bool nsfont_width(const plot_font_style_t *fstyle,
                         const char *string, size_t length,
                         int *width)
{
  *width = (fstyle->size * utf8_bounded_length(string, length)) / FONT_SIZE_SCALE;
  return true;
}

/**
 * Find the position in a string where an x coordinate falls.
 *
 * \param  fstyle       style for this text
 * \param  string       UTF-8 string to measure
 * \param  length       length of string
 * \param  x            x coordinate to search for
 * \param  char_offset  updated to offset in string of actual_x, [0..length]
 * \param  actual_x     updated to x coordinate of character closest to x
 * \return  true on success, false on error and error reported
 */

static bool nsfont_position_in_string(const plot_font_style_t *fstyle,
		const char *string, size_t length,
		int x, size_t *char_offset, int *actual_x)
{
  *char_offset = x / (fstyle->size / FONT_SIZE_SCALE);
  if (*char_offset > length)
    *char_offset = length;
  *actual_x = *char_offset * (fstyle->size / FONT_SIZE_SCALE);
  return true;
}


/**
 * Find where to split a string to make it fit a width.
 *
 * \param  fstyle       style for this text
 * \param  string       UTF-8 string to measure
 * \param  length       length of string, in bytes
 * \param  x            width available
 * \param  char_offset  updated to offset in string of actual_x, [1..length]
 * \param  actual_x     updated to x coordinate of character closest to x
 * \return  true on success, false on error and error reported
 *
 * On exit, char_offset indicates first character after split point.
 *
 * Note: char_offset of 0 should never be returned.
 *
 *   Returns:
 *     char_offset giving split point closest to x, where actual_x <= x
 *   else
 *     char_offset giving split point closest to x, where actual_x > x
 *
 * Returning char_offset == length means no split possible
 */

static bool nsfont_split(const plot_font_style_t *fstyle,
		const char *string, size_t length,
		int x, size_t *char_offset, int *actual_x)
{
  int c_off = *char_offset = x / (fstyle->size / FONT_SIZE_SCALE);
  if (*char_offset > length) {
    *char_offset = length;
  } else {
    while (*char_offset > 0) {
      if (string[*char_offset] == ' ')
        break;
      (*char_offset)--;
    }
    if (*char_offset == 0) {
      *char_offset = c_off;
      while (*char_offset < length && string[*char_offset] != ' ') {
        (*char_offset)++;
      }
    }
  }
  *actual_x = *char_offset * (fstyle->size / FONT_SIZE_SCALE);
  return true;
}

const struct font_functions nsfont = {
	nsfont_width,
	nsfont_position_in_string,
	nsfont_split
};