pango-markup.c

Pango is a library for layout and rendering of text, with an emphasis on internationalization. Pang

/* Pango
 * pango-markup.c: Parse markup into attributed text
 *
 * Copyright (C) 2000 Red Hat Software
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include <config.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>

#include "pango-attributes.h"
#include "pango-font.h"
#include "pango-enum-types.h"
#include "pango-impl-utils.h"

/* FIXME */
#define _(x) x

/* CSS size levels */
typedef enum
{
  XXSmall = -3,
  XSmall = -2,
  Small = -1,
  Medium = 0,
  Large = 1,
  XLarge = 2,
  XXLarge = 3
} SizeLevel;

typedef struct _MarkupData MarkupData;

struct _MarkupData
{
  PangoAttrList *attr_list;
  GString *text;
  GSList *tag_stack;
  gsize index;
  GSList *to_apply;
  gunichar accel_marker;
  gunichar accel_char;
};

typedef struct _OpenTag OpenTag;

struct _OpenTag
{
  GSList *attrs;
  gsize start_index;
  /* Current total scale level; reset whenever
   * an absolute size is set.
   * Each "larger" ups it 1, each "smaller" decrements it 1
   */
  gint scale_level;
  /* Our impact on scale_level, so we know whether we
   * need to create an attribute ourselves on close
   */
  gint scale_level_delta;
  /* Base scale factor currently in effect
   * or size that this tag
   * forces, or parent's scale factor or size.
   */
  double base_scale_factor;
  int base_font_size;
  guint has_base_font_size : 1;
};

typedef gboolean (*TagParseFunc) (MarkupData            *md,
				  OpenTag               *tag,
				  const gchar          **names,
				  const gchar          **values,
				  GMarkupParseContext   *context,
				  GError               **error);

static gboolean b_parse_func        (MarkupData           *md,
				     OpenTag              *tag,
				     const gchar         **names,
				     const gchar         **values,
				     GMarkupParseContext  *context,
				     GError              **error);
static gboolean big_parse_func      (MarkupData           *md,
				     OpenTag              *tag,
				     const gchar         **names,
				     const gchar         **values,
				     GMarkupParseContext  *context,
				     GError              **error);
static gboolean span_parse_func     (MarkupData           *md,
				     OpenTag              *tag,
				     const gchar         **names,
				     const gchar         **values,
				     GMarkupParseContext  *context,
				     GError              **error);
static gboolean i_parse_func        (MarkupData           *md,
				     OpenTag              *tag,
				     const gchar         **names,
				     const gchar         **values,
				     GMarkupParseContext  *context,
				     GError              **error);
static gboolean markup_parse_func   (MarkupData           *md,
				     OpenTag              *tag,
				     const gchar         **names,
				     const gchar         **values,
				     GMarkupParseContext  *context,
				     GError              **error);
static gboolean s_parse_func        (MarkupData           *md,
				     OpenTag              *tag,
				     const gchar         **names,
				     const gchar         **values,
				     GMarkupParseContext  *context,
				     GError              **error);
static gboolean sub_parse_func      (MarkupData           *md,
				     OpenTag              *tag,
				     const gchar         **names,
				     const gchar         **values,
				     GMarkupParseContext  *context,
				     GError              **error);
static gboolean sup_parse_func      (MarkupData           *md,
				     OpenTag              *tag,
				     const gchar         **names,
				     const gchar         **values,
				     GMarkupParseContext  *context,
				     GError              **error);
static gboolean small_parse_func    (MarkupData           *md,
				     OpenTag              *tag,
				     const gchar         **names,
				     const gchar         **values,
				     GMarkupParseContext  *context,
				     GError              **error);
static gboolean tt_parse_func       (MarkupData           *md,
				     OpenTag              *tag,
				     const gchar         **names,
				     const gchar         **values,
				     GMarkupParseContext  *context,
				     GError              **error);
static gboolean u_parse_func        (MarkupData           *md,
				     OpenTag              *tag,
				     const gchar         **names,
				     const gchar         **values,
				     GMarkupParseContext  *context,
				     GError              **error);

static double
scale_factor (int scale_level, double base)
{
  double factor = base;
  int i;

  /* 1.2 is the CSS scale factor between sizes */

  if (scale_level > 0)
    {
      i = 0;
      while (i < scale_level)
	{
	  factor *= 1.2;

	  ++i;
	}
    }
  else if (scale_level < 0)
    {
      i = scale_level;
      while (i < 0)
	{
	  factor /= 1.2;

	  ++i;
	}
    }

  return factor;
}

static void
open_tag_free (OpenTag *ot)
{
  g_slist_foreach (ot->attrs, (GFunc) pango_attribute_destroy, NULL);
  g_slist_free (ot->attrs);
  g_slice_free (OpenTag, ot);
}

static void
open_tag_set_absolute_font_size (OpenTag *ot,
				 int      font_size)
{
  ot->base_font_size = font_size;
  ot->has_base_font_size = TRUE;
  ot->scale_level = 0;
  ot->scale_level_delta = 0;
}

static void
open_tag_set_absolute_font_scale (OpenTag *ot,
				  double   scale)
{
  ot->base_scale_factor = scale;
  ot->has_base_font_size = FALSE;
  ot->scale_level = 0;
  ot->scale_level_delta = 0;
}

static OpenTag*
markup_data_open_tag (MarkupData   *md)
{
  OpenTag *ot;
  OpenTag *parent = NULL;

  if (md->attr_list == NULL)
    return NULL;

  if (md->tag_stack)
    parent = md->tag_stack->data;

  ot = g_slice_new (OpenTag);
  ot->attrs = NULL;
  ot->start_index = md->index;
  ot->scale_level_delta = 0;

  if (parent == NULL)
    {
      ot->base_scale_factor = 1.0;
      ot->base_font_size = 0;
      ot->has_base_font_size = FALSE;
      ot->scale_level = 0;
    }
  else
    {
      ot->base_scale_factor = parent->base_scale_factor;
      ot->base_font_size = parent->base_font_size;
      ot->has_base_font_size = parent->has_base_font_size;
      ot->scale_level = parent->scale_level;
    }

  md->tag_stack = g_slist_prepend (md->tag_stack, ot);

  return ot;
}

static void
markup_data_close_tag (MarkupData *md)
{
  OpenTag *ot;
  GSList *tmp_list;

  if (md->attr_list == NULL)
    return;

  /* pop the stack */
  ot = md->tag_stack->data;
  md->tag_stack = g_slist_delete_link (md->tag_stack,
				       md->tag_stack);

  /* Adjust end indexes, and push each attr onto the front of the
   * to_apply list. This means that outermost tags are on the front of
   * that list; if we apply the list in order, then the innermost
   * tags will "win" which is correct.
   */
  tmp_list = ot->attrs;
  while (tmp_list != NULL)
    {
      PangoAttribute *a = tmp_list->data;

      a->start_index = ot->start_index;
      a->end_index = md->index;

      md->to_apply = g_slist_prepend (md->to_apply, a);

      tmp_list = g_slist_next (tmp_list);
    }

  if (ot->scale_level_delta != 0)
    {
      /* We affected relative font size; create an appropriate
       * attribute and reverse our effects on the current level
       */
      PangoAttribute *a;

      if (ot->has_base_font_size)
	{
	  /* Create a font using the absolute point size
	   * as the base size to be scaled from
	   */
	  a = pango_attr_size_new (scale_factor (ot->scale_level,
						 1.0) *
				   ot->base_font_size);
	}
      else
	{
	  /* Create a font using the current scale factor
	   * as the base size to be scaled from
	   */
	  a = pango_attr_scale_new (scale_factor (ot->scale_level,
						  ot->base_scale_factor));
	}

      a->start_index = ot->start_index;
      a->end_index = md->index;

      md->to_apply = g_slist_prepend (md->to_apply, a);
    }

  g_slist_free (ot->attrs);
  g_slice_free (OpenTag, ot);
}

static void
start_element_handler  (GMarkupParseContext *context,
			const gchar         *element_name,
			const gchar        **attribute_names,
			const gchar        **attribute_values,
			gpointer             user_data,
			GError             **error)
{
  TagParseFunc parse_func = NULL;
  OpenTag *ot;

  switch (*element_name)
    {
    case 'b':
      if (strcmp ("b", element_name) == 0)
	parse_func = b_parse_func;
      else if (strcmp ("big", element_name) == 0)
	parse_func = big_parse_func;
      break;

    case 'i':
      if (strcmp ("i", element_name) == 0)
	parse_func = i_parse_func;
      break;

    case 'm':
      if (strcmp ("markup", element_name) == 0)
	parse_func = markup_parse_func;
      break;

    case 's':
      if (strcmp ("span", element_name) == 0)
	parse_func = span_parse_func;
      else if (strcmp ("s", element_name) == 0)
	parse_func = s_parse_func;
      else if (strcmp ("sub", element_name) == 0)
	parse_func = sub_parse_func;
      else if (strcmp ("sup", element_name) == 0)
	parse_func = sup_parse_func;
      else if (strcmp ("small", element_name) == 0)
	parse_func = small_parse_func;
      break;

    case 't':
      if (strcmp ("tt", element_name) == 0)
	parse_func = tt_parse_func;
      break;

    case 'u':
      if (strcmp ("u", element_name) == 0)
	parse_func = u_parse_func;
      break;
    }

  if (parse_func == NULL)
    {
      gint line_number, char_number;

      g_markup_parse_context_get_position (context,
					   &line_number, &char_number);

      g_set_error (error,
		   G_MARKUP_ERROR,
		   G_MARKUP_ERROR_UNKNOWN_ELEMENT,
		   _("Unknown tag '%s' on line %d char %d"),
		   element_name,
		   line_number, char_number);

      return;
    }

  ot = markup_data_open_tag (user_data);

  /* note ot may be NULL if the user didn't want the attribute list */

  if (!(*parse_func) (user_data, ot,
		      attribute_names, attribute_values,
		      context, error))
    {
      /* there's nothing to do; we return an error, and end up
       * freeing ot off the tag stack later.
       */
    }
}

static void
end_element_handler    (GMarkupParseContext *context,
			const gchar         *element_name,
			gpointer             user_data,
			GError             **error)
{
  markup_data_close_tag (user_data);
}

static void
text_handler           (GMarkupParseContext *context,
			const gchar         *text,
			gsize                text_len,
			gpointer             user_data,
			GError             **error)
{
  MarkupData *md = user_data;

  if (md->accel_marker == 0)
    {
      /* Just append all the text */

      md->index += text_len;

      g_string_append_len (md->text, text, text_len);
    }
  else
    {
      /* Parse the accelerator */
      const gchar *p;
      const gchar *end;
      const gchar *range_start;
      const gchar *range_end;
      gssize uline_index = -1;
      gsize uline_len = 0;	/* Quiet GCC */

      range_end = NULL;
      range_start = text;
      p = text;
      end = text + text_len;

      while (p != end)
	{
	  gunichar c;

	  c = g_utf8_get_char (p);

	  if (range_end)
	    {
	      if (c == md->accel_marker)
		{
		  /* escaped accel marker; move range_end
		   * past the accel marker that came before,
		   * append the whole thing
		   */
		  range_end = g_utf8_next_char (range_end);
		  g_string_append_len (md->text,
				       range_start,
				       range_end - range_start);
		  md->index += range_end - range_start;

		  /* set next range_start, skipping accel marker */
		  range_start = g_utf8_next_char (p);
		}
	      else
		{
		  /* Don't append the accel marker (leave range_end
		   * alone); set the accel char to c; record location for
		   * underline attribute
		   */
		  if (md->accel_char == 0)
		    md->accel_char = c;

		  g_string_append_len (md->text,
				       range_start,
				       range_end - range_start);
		  md->index += range_end - range_start;

		  /* The underline should go underneath the char
		   * we're setting as the next range_start
		   */
		  uline_index = md->index;
		  uline_len = g_utf8_next_char (p) - p;

		  /* set next range_start to include this char */