pangocairo-font.c

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

    mini_size = size / 2.4;
    if (is_hinted)
      {
	mini_size = HINT_Y (mini_size);

	if (mini_size < 5.0)
	  {
	    rows = 1;
	    mini_size = MIN (MAX (size - 1, 0), 5.0);
	  }
      }

    pango_font_description_set_absolute_size (desc, pango_units_from_double (mini_size));

    /* load mini_font */

    context = pango_cairo_font_map_create_context ((PangoCairoFontMap *) (fontmap));

    pango_context_set_matrix (context, &pango_ctm);
    pango_context_set_language (context, pango_script_get_sample_language (PANGO_SCRIPT_LATIN));
    pango_cairo_context_set_font_options (context, font_options);
    mini_font = pango_font_map_load_font (fontmap, context, desc);

    g_object_unref (context);
  }

  pango_font_description_free (desc);
  cairo_font_options_destroy (font_options);


  scaled_mini_font = pango_cairo_font_get_scaled_font ((PangoCairoFont *) mini_font);

  for (i = 0 ; i < 16 ; i++)
    {
      cairo_text_extents_t extents;

      c[0] = hexdigits[i];
      cairo_scaled_font_text_extents (scaled_mini_font, c, &extents);
      width = MAX (width, extents.width);
      height = MAX (height, extents.height);
    }

  cairo_scaled_font_extents (scaled_font, &font_extents);
  if (font_extents.ascent + font_extents.descent <= 0)
    {
      font_extents.ascent = PANGO_UNKNOWN_GLYPH_HEIGHT;
      font_extents.descent = 0;
    }

  pad = (font_extents.ascent + font_extents.descent) / 43;
  pad = MIN (pad, mini_size);

  hbi = g_slice_new (PangoCairoFontHexBoxInfo);
  hbi->font = (PangoCairoFont *) mini_font;
  hbi->rows = rows;

  hbi->digit_width  = width;
  hbi->digit_height = height;

  hbi->pad_x = pad;
  hbi->pad_y = pad;

  if (is_hinted)
    {
      hbi->digit_width  = HINT_X (hbi->digit_width);
      hbi->digit_height = HINT_Y (hbi->digit_height);
      hbi->pad_x = HINT_X (hbi->pad_x);
      hbi->pad_y = HINT_Y (hbi->pad_y);
    }

  hbi->line_width = MIN (hbi->pad_x, hbi->pad_y);

  hbi->box_height = 3 * hbi->pad_y + rows * (hbi->pad_y + hbi->digit_height);

  if (rows == 1 || hbi->box_height <= font_extents.ascent)
    {
      hbi->box_descent = 2 * hbi->pad_y;
    }
  else if (hbi->box_height <= font_extents.ascent + font_extents.descent - 2 * hbi->pad_y)
    {
      hbi->box_descent = 2 * hbi->pad_y + hbi->box_height - font_extents.ascent;
    }
  else
    {
      hbi->box_descent = font_extents.descent * hbi->box_height /
			 (font_extents.ascent + font_extents.descent);
    }
  if (is_hinted)
    {
       hbi->box_descent = HINT_Y (hbi->box_descent);
    }

  cf_priv->hbi = hbi;
  return hbi;
}

static void
_pango_cairo_font_hex_box_info_destroy (PangoCairoFontHexBoxInfo *hbi)
{
  if (hbi)
    {
      g_object_unref (hbi->font);
      g_slice_free (PangoCairoFontHexBoxInfo, hbi);
    }
}

PangoCairoFontHexBoxInfo *
_pango_cairo_font_get_hex_box_info (PangoCairoFont *cfont)
{
  PangoCairoFontPrivate *cf_priv = PANGO_CAIRO_FONT_PRIVATE (cfont);

  return _pango_cairo_font_private_get_hex_box_info (cf_priv);
}

void
_pango_cairo_font_private_initialize (PangoCairoFontPrivate      *cf_priv,
				      PangoCairoFont             *cfont,
				      PangoContext               *context,
				      const PangoFontDescription *desc,
				      const cairo_matrix_t       *font_matrix)
{
  const cairo_font_options_t *font_options;
  cairo_matrix_t gravity_matrix;
  const PangoMatrix *pango_ctm;

  cf_priv->cfont = cfont;
  cf_priv->gravity = pango_font_description_get_gravity (desc);

  cf_priv->data = _pango_cairo_font_private_scaled_font_data_create (); 

  /* first apply gravity rotation, then font_matrix, such that
   * vertical italic text comes out "correct".  we don't do anything
   * like baseline adjustment etc though.  should be specially
   * handled when we support italic correction. */
  cairo_matrix_init_rotate(&gravity_matrix,
			   pango_gravity_to_rotation (cf_priv->gravity));
  cairo_matrix_multiply (&cf_priv->data->font_matrix,
			 font_matrix,
			 &gravity_matrix);

  pango_ctm = pango_context_get_matrix (context);
  if (pango_ctm)
    cairo_matrix_init (&cf_priv->data->ctm,
		       pango_ctm->xx,
		       pango_ctm->yx,
		       pango_ctm->xy,
		       pango_ctm->yy,
		       0., 0.);
  else
    cairo_matrix_init_identity (&cf_priv->data->ctm);

  font_options = _pango_cairo_context_get_merged_font_options (context);
  cf_priv->data->options = cairo_font_options_copy (font_options);
  cf_priv->is_hinted = cairo_font_options_get_hint_metrics (font_options) != CAIRO_HINT_METRICS_OFF;

  cf_priv->scaled_font = NULL;
  cf_priv->hbi = NULL;
  cf_priv->glyph_extents_cache = NULL;
  cf_priv->metrics_by_lang = NULL;
}

static void
free_metrics_info (PangoCairoFontMetricsInfo *info)
{
  pango_font_metrics_unref (info->metrics);
  g_slice_free (PangoCairoFontMetricsInfo, info);
}

void
_pango_cairo_font_private_finalize (PangoCairoFontPrivate *cf_priv)
{
  _pango_cairo_font_private_scaled_font_data_destroy (cf_priv->data);

  if (cf_priv->scaled_font)
    cairo_scaled_font_destroy (cf_priv->scaled_font);

  _pango_cairo_font_hex_box_info_destroy (cf_priv->hbi);

  if (cf_priv->glyph_extents_cache)
    g_free (cf_priv->glyph_extents_cache);

  g_slist_foreach (cf_priv->metrics_by_lang, (GFunc)free_metrics_info, NULL);
  g_slist_free (cf_priv->metrics_by_lang);
}

gboolean
_pango_cairo_font_private_is_metrics_hinted (PangoCairoFontPrivate *cf_priv)
{
  return cf_priv->is_hinted;
}

static void
_pango_cairo_font_private_get_glyph_extents_missing (PangoCairoFontPrivate *cf_priv,
						     PangoGlyph             glyph,
						     PangoRectangle        *ink_rect,
						     PangoRectangle        *logical_rect)
{
  PangoCairoFontHexBoxInfo *hbi;
  gunichar ch;
  gint rows, cols;

  hbi = _pango_cairo_font_private_get_hex_box_info (cf_priv);
  if (!hbi)
    {
      pango_font_get_glyph_extents (NULL, glyph, ink_rect, logical_rect);
      return;
    }

  ch = glyph & ~PANGO_GLYPH_UNKNOWN_FLAG;

  rows = hbi->rows;
  if (G_UNLIKELY (glyph == PANGO_GLYPH_INVALID_INPUT || ch > 0x10FFFF))
    cols = 1;
  else
    cols = ((glyph & ~PANGO_GLYPH_UNKNOWN_FLAG) > 0xffff ? 6 : 4) / rows;

  if (ink_rect)
    {
      ink_rect->x = PANGO_SCALE * hbi->pad_x;
      ink_rect->y = PANGO_SCALE * (hbi->box_descent - hbi->box_height);
      ink_rect->width = PANGO_SCALE * (3 * hbi->pad_x + cols * (hbi->digit_width + hbi->pad_x));
      ink_rect->height = PANGO_SCALE * hbi->box_height;
    }

  if (logical_rect)
    {
      logical_rect->x = 0;
      logical_rect->y = PANGO_SCALE * (hbi->box_descent - (hbi->box_height + hbi->pad_y));
      logical_rect->width = PANGO_SCALE * (5 * hbi->pad_x + cols * (hbi->digit_width + hbi->pad_x));
      logical_rect->height = PANGO_SCALE * (hbi->box_height + 2 * hbi->pad_y);
    }
}

#define GLYPH_CACHE_NUM_ENTRIES 256 /* should be power of two */
#define GLYPH_CACHE_MASK (GLYPH_CACHE_NUM_ENTRIES - 1)
/* An entry in the fixed-size cache for the glyph->extents mapping.
 * The cache is indexed by the lower N bits of the glyph (see
 * GLYPH_CACHE_NUM_ENTRIES).  For scripts with few glyphs,
 * this should provide pretty much instant lookups.
 */
struct _PangoCairoFontGlyphExtentsCacheEntry
{
  PangoGlyph     glyph;
  int            width;
  PangoRectangle ink_rect;
};

static gboolean
_pango_cairo_font_private_glyph_extents_cache_init (PangoCairoFontPrivate *cf_priv)
{
  cairo_scaled_font_t *scaled_font = _pango_cairo_font_private_get_scaled_font (cf_priv);
  cairo_font_extents_t font_extents;

  if (G_UNLIKELY (scaled_font == NULL || cairo_scaled_font_status (scaled_font) != CAIRO_STATUS_SUCCESS))
    return FALSE;

  cairo_scaled_font_extents (scaled_font, &font_extents);

  cf_priv->font_extents.x = 0;
  cf_priv->font_extents.width = 0;
  cf_priv->font_extents.height = pango_units_from_double (font_extents.ascent + font_extents.descent);
  switch (cf_priv->gravity)
    {
      default:
      case PANGO_GRAVITY_AUTO:
      case PANGO_GRAVITY_SOUTH:
	cf_priv->font_extents.y = - pango_units_from_double (font_extents.ascent);
	break;
      case PANGO_GRAVITY_NORTH:
	cf_priv->font_extents.y = - pango_units_from_double (font_extents.descent);
	break;
      case PANGO_GRAVITY_EAST:
      case PANGO_GRAVITY_WEST:
	{
	  int ascent = pango_units_from_double (font_extents.ascent + font_extents.descent) / 2;
	  if (cf_priv->is_hinted)
	    ascent = PANGO_UNITS_ROUND (ascent);
	  cf_priv->font_extents.y = - ascent;
	}
    }

  cf_priv->glyph_extents_cache = g_new0 (PangoCairoFontGlyphExtentsCacheEntry, GLYPH_CACHE_NUM_ENTRIES);
  /* Make sure all cache entries are invalid initially */
  cf_priv->glyph_extents_cache[0].glyph = 1; /* glyph 1 cannot happen in bucket 0 */

  return TRUE;
}

/* Fills in the glyph extents cache entry
 */
static void
compute_glyph_extents (PangoCairoFontPrivate  *cf_priv,
		       PangoGlyph              glyph,
		       PangoCairoFontGlyphExtentsCacheEntry *entry)
{
  cairo_text_extents_t extents;
  cairo_glyph_t cairo_glyph;

  cairo_glyph.index = glyph;
  cairo_glyph.x = 0;
  cairo_glyph.y = 0;

  cairo_scaled_font_glyph_extents (_pango_cairo_font_private_get_scaled_font (cf_priv),
				   &cairo_glyph, 1, &extents);

  entry->glyph = glyph;
  entry->width = pango_units_from_double (extents.x_advance);
  entry->ink_rect.x = pango_units_from_double (extents.x_bearing);
  entry->ink_rect.y = pango_units_from_double (extents.y_bearing);
  entry->ink_rect.width = pango_units_from_double (extents.width);
  entry->ink_rect.height = pango_units_from_double (extents.height);
}

static PangoCairoFontGlyphExtentsCacheEntry *
_pango_cairo_font_private_get_glyph_extents_cache_entry (PangoCairoFontPrivate  *cf_priv,
							 PangoGlyph              glyph)
{
  PangoCairoFontGlyphExtentsCacheEntry *entry;
  guint idx;

  idx = glyph & GLYPH_CACHE_MASK;
  entry = cf_priv->glyph_extents_cache + idx;

  if (entry->glyph != glyph)
    {
      compute_glyph_extents (cf_priv, glyph, entry);
    }

  return entry;
}

void
_pango_cairo_font_private_get_glyph_extents (PangoCairoFontPrivate *cf_priv,
					     PangoGlyph             glyph,
					     PangoRectangle        *ink_rect,
					     PangoRectangle        *logical_rect)
{
  PangoCairoFontGlyphExtentsCacheEntry *entry;

  if (!cf_priv ||
      (cf_priv->glyph_extents_cache == NULL &&
       !_pango_cairo_font_private_glyph_extents_cache_init (cf_priv)))
    {
      /* Get generic unknown-glyph extents. */
      pango_font_get_glyph_extents (NULL, glyph, ink_rect, logical_rect);
      return;
    }

  if (glyph == PANGO_GLYPH_EMPTY)
    {
      if (ink_rect)
	ink_rect->x = ink_rect->y = ink_rect->width = ink_rect->height = 0;
      if (logical_rect)
	*logical_rect = cf_priv->font_extents;
      return;
    }
  else if (glyph & PANGO_GLYPH_UNKNOWN_FLAG)
    {
      _pango_cairo_font_private_get_glyph_extents_missing(cf_priv, glyph, ink_rect, logical_rect);
      return;
    }

  entry = _pango_cairo_font_private_get_glyph_extents_cache_entry (cf_priv, glyph);

  if (ink_rect)
    *ink_rect = entry->ink_rect;
  if (logical_rect)
    {
      *logical_rect = cf_priv->font_extents;
      logical_rect->width = entry->width;
    }
}