cairo-ft-font.c

按照官方的说法：Cairo is a vector graphics library with cross-device output support. 翻译过来

		fs_metrics.x_advance = 0;
		fs_metrics.y_advance = DOUBLE_FROM_26_6 (advance) * y_factor;
	    }
	 } else {
	    fs_metrics.width  = DOUBLE_FROM_26_6 (metrics->width) * x_factor;
	    fs_metrics.height = DOUBLE_FROM_26_6 (metrics->height) * y_factor;

	    if (!vertical_layout) {
		fs_metrics.x_bearing = DOUBLE_FROM_26_6 (metrics->horiBearingX) * x_factor;
		fs_metrics.y_bearing = DOUBLE_FROM_26_6 (-metrics->horiBearingY) * y_factor;
		
		fs_metrics.x_advance = DOUBLE_FROM_26_6 (metrics->horiAdvance) * x_factor;
		fs_metrics.y_advance = 0 * y_factor;
	    } else {
		fs_metrics.x_bearing = DOUBLE_FROM_26_6 (metrics->vertBearingX) * x_factor;
		fs_metrics.y_bearing = DOUBLE_FROM_26_6 (metrics->vertBearingY) * y_factor;
		
		fs_metrics.x_advance = 0 * x_factor;
		fs_metrics.y_advance = DOUBLE_FROM_26_6 (metrics->vertAdvance) * y_factor;
	    }
	 }

	_cairo_scaled_glyph_set_metrics (scaled_glyph,
					 &scaled_font->base,
					 &fs_metrics);
    }

    if ((info & CAIRO_SCALED_GLYPH_INFO_SURFACE) != 0) {
	cairo_image_surface_t	*surface;

	if (glyph->format == FT_GLYPH_FORMAT_OUTLINE) {
	    status = _render_glyph_outline (face, &scaled_font->ft_options.base,
					    &surface);
	} else {
	    status = _render_glyph_bitmap (face, &scaled_font->ft_options.base,
					   &surface);
	    if (status == CAIRO_STATUS_SUCCESS && unscaled->have_shape)
		status = _transform_glyph_bitmap (&unscaled->current_shape,
						  &surface);
	}
	if (status)
	    goto FAIL;

	_cairo_scaled_glyph_set_surface (scaled_glyph,
					 &scaled_font->base,
					 surface);
    }

    if (info & CAIRO_SCALED_GLYPH_INFO_PATH) {
	cairo_path_fixed_t *path;

	/*
	 * A kludge -- the above code will trash the outline,
	 * so reload it. This will probably never occur though
	 */
	if ((info & CAIRO_SCALED_GLYPH_INFO_SURFACE) != 0) {
	    error = FT_Load_Glyph (face,
				   _cairo_scaled_glyph_index(scaled_glyph),
				   load_flags | FT_LOAD_NO_BITMAP);

	    if (error) {
		cairo_ft_scaled_font_unlock_face (abstract_font);
		return CAIRO_STATUS_NO_MEMORY;
	    }
#if HAVE_FT_GLYPHSLOT_EMBOLDEN
	    /*
	     * embolden glyphs if requested
	     */
	    if (scaled_font->ft_options.extra_flags & CAIRO_FT_OPTIONS_EMBOLDEN)
		FT_GlyphSlot_Embolden (glyph);
#endif
	    if (vertical_layout)
		_cairo_ft_scaled_glyph_vertical_layout_bearing_fix (glyph);

	}
	if (glyph->format == FT_GLYPH_FORMAT_OUTLINE)
	    status = _decompose_glyph_outline (face, &scaled_font->ft_options.base,
					       &path);
	else
	    status = CAIRO_INT_STATUS_UNSUPPORTED;

	if (status)
	    goto FAIL;

	_cairo_scaled_glyph_set_path (scaled_glyph,
				      &scaled_font->base,
				      path);
    }
 FAIL:
    cairo_ft_scaled_font_unlock_face (abstract_font);

    return status;
}

static unsigned long
_cairo_ft_ucs4_to_index (void	    *abstract_font,
			 uint32_t    ucs4)
{
    cairo_ft_scaled_font_t *scaled_font = abstract_font;
    cairo_ft_unscaled_font_t *unscaled = scaled_font->unscaled;
    FT_Face face;
    FT_UInt index;

    face = _cairo_ft_unscaled_font_lock_face (unscaled);
    if (!face)
	return 0;
    index = FT_Get_Char_Index (face, ucs4);
    _cairo_ft_unscaled_font_unlock_face (unscaled);
    return index;
}

static cairo_int_status_t
_cairo_ft_show_glyphs (void		       *abstract_font,
		       cairo_operator_t    	op,
		       cairo_pattern_t     *pattern,
		       cairo_surface_t     *surface,
		       int                 	source_x,
		       int                 	source_y,
		       int			dest_x,
		       int			dest_y,
		       unsigned int		width,
		       unsigned int		height,
		       const cairo_glyph_t *glyphs,
		       int                 	num_glyphs)
{
    return CAIRO_INT_STATUS_UNSUPPORTED;
}

const cairo_scaled_font_backend_t cairo_ft_scaled_font_backend = {
    CAIRO_FONT_TYPE_FT,
    _cairo_ft_scaled_font_create_toy,
    _cairo_ft_scaled_font_fini,
    _cairo_ft_scaled_glyph_init,
    NULL,			/* text_to_glyphs */
    _cairo_ft_ucs4_to_index,
    _cairo_ft_show_glyphs,
};

/* cairo_ft_font_face_t */

static void
_cairo_ft_font_face_destroy (void *abstract_face)
{
    cairo_ft_font_face_t *font_face = abstract_face;

    cairo_ft_font_face_t *tmp_face = NULL;
    cairo_ft_font_face_t *last_face = NULL;

    if (font_face == NULL)
	return;

    /* When destroying the face created by cairo_ft_font_face_create_for_ft_face,
     * we have a special "zombie" state for the face when the unscaled font
     * is still alive but there are no public references to the font face.
     *
     * We go from:
     *
     *   font_face ------> unscaled
     *        <-....weak....../
     *
     * To:
     *
     *    font_face <------- unscaled
     */

    if (font_face->unscaled &&
	font_face->unscaled->from_face &&
	font_face->unscaled->base.ref_count > 1)
    {
	cairo_font_face_reference (&font_face->base);

	_cairo_unscaled_font_destroy (&font_face->unscaled->base);
	font_face->unscaled = NULL;

	return;
    }

    if (font_face->unscaled) {
	/* Remove face from linked list */
	for (tmp_face = font_face->unscaled->faces;
	     tmp_face;
	     tmp_face = tmp_face->next)
	{
	    if (tmp_face == font_face) {
		if (last_face)
		    last_face->next = tmp_face->next;
		else
		    font_face->unscaled->faces = tmp_face->next;
	    }

	    last_face = tmp_face;
	}

	_cairo_unscaled_font_destroy (&font_face->unscaled->base);
	font_face->unscaled = NULL;
    }
}

static cairo_status_t
_cairo_ft_font_face_scaled_font_create (void                     *abstract_face,
					const cairo_matrix_t       *font_matrix,
					const cairo_matrix_t       *ctm,
					const cairo_font_options_t *options,
					cairo_scaled_font_t       **scaled_font)
{
    cairo_ft_font_face_t *font_face = abstract_face;
    cairo_ft_options_t ft_options;

    /* The handling of font options is different depending on how the
     * font face was created. When the user creates a font face with
     * cairo_ft_font_face_create_for_ft_face(), then the load flags
     * passed in augment the load flags for the options.  But for
     * cairo_ft_font_face_create_for_pattern(), the load flags are
     * derived from a pattern where the user has called
     * cairo_ft_font_options_substitute(), so *just* use those load
     * flags and ignore the options.
     */

    ft_options = font_face->ft_options;

    *scaled_font = _cairo_ft_scaled_font_create (font_face->unscaled,
						 &font_face->base,
						 font_matrix, ctm,
						 options, ft_options);
    if (*scaled_font)
	return CAIRO_STATUS_SUCCESS;
    else
	return CAIRO_STATUS_NO_MEMORY;
}

static const cairo_font_face_backend_t _cairo_ft_font_face_backend = {
    CAIRO_FONT_TYPE_FT,
    _cairo_ft_font_face_destroy,
    _cairo_ft_font_face_scaled_font_create
};

static cairo_font_face_t *
_cairo_ft_font_face_create (cairo_ft_unscaled_font_t *unscaled,
			    cairo_ft_options_t	      ft_options)
{
    cairo_ft_font_face_t *font_face;

    /* Looked for an existing matching font face */
    for (font_face = unscaled->faces;
	 font_face;
	 font_face = font_face->next)
    {
	if (font_face->ft_options.load_flags == ft_options.load_flags &&
	    font_face->ft_options.extra_flags == ft_options.extra_flags &&
	    cairo_font_options_equal (&font_face->ft_options.base, &ft_options.base))
	    return cairo_font_face_reference (&font_face->base);
    }

    /* No match found, create a new one */
    font_face = malloc (sizeof (cairo_ft_font_face_t));
    if (!font_face)
	return NULL;

    font_face->unscaled = unscaled;
    _cairo_unscaled_font_reference (&unscaled->base);

    font_face->ft_options = ft_options;

    font_face->next = unscaled->faces;
    unscaled->faces = font_face;

    _cairo_font_face_init (&font_face->base, &_cairo_ft_font_face_backend);

    return &font_face->base;
}

/* implement the platform-specific interface */

/**
 * cairo_ft_font_options_substitute:
 * @options: a #cairo_font_options_t object
 * @pattern: an existing #FcPattern
 *
 * Add options to a #FcPattern based on a #cairo_font_options_t font
 * options object. Options that are already in the pattern, are not overriden,
 * so you should call this function after calling FcConfigSubstitute() (the
 * user's settings should override options based on the surface type), but
 * before calling FcDefaultSubstitute().
 **/
void
cairo_ft_font_options_substitute (const cairo_font_options_t *options,
				  FcPattern                  *pattern)
{
    FcValue v;

    if (options->antialias != CAIRO_ANTIALIAS_DEFAULT)
    {
	if (FcPatternGet (pattern, FC_ANTIALIAS, 0, &v) == FcResultNoMatch)
	{
	    FcPatternAddBool (pattern, FC_ANTIALIAS, options->antialias != CAIRO_ANTIALIAS_NONE);
	}
    }

    if (options->antialias != CAIRO_ANTIALIAS_DEFAULT)
    {
	if (FcPatternGet (pattern, FC_RGBA, 0, &v) == FcResultNoMatch)
	{
	    int rgba;

	    if (options->antialias == CAIRO_ANTIALIAS_SUBPIXEL) {
		switch (options->subpixel_order) {
		case CAIRO_SUBPIXEL_ORDER_DEFAULT:
		case CAIRO_SUBPIXEL_ORDER_RGB:
		default:
		    rgba = FC_RGBA_RGB;
		    break;
		case CAIRO_SUBPIXEL_ORDER_BGR:
		    rgba = FC_RGBA_BGR;
		    break;
		case CAIRO_SUBPIXEL_ORDER_VRGB:
		    rgba = FC_RGBA_VRGB;
		    break;
		case CAIRO_SUBPIXEL_ORDER_VBGR:
		    rgba = FC_RGBA_VBGR;
		    break;
		}
	    } else {
		rgba = FC_RGBA_NONE;
	    }

	    FcPatternAddInteger (pattern, FC_RGBA, rgba);
	}
    }

    if (options->hint_style != CAIRO_HINT_STYLE_DEFAULT)
    {
	if (FcPatternGet (pattern, FC_HINTING, 0, &v) == FcResultNoMatch)
	{
	    FcPatternAddBool (pattern, FC_HINTING, options->hint_style != CAIRO_HINT_STYLE_NONE);
	}

#ifdef FC_HINT_STYLE
	if (FcPatternGet (pattern, FC_HINT_STYLE, 0, &v) == FcResultNoMatch)
	{
	    int hint_style;

	    switch (options->hint_style) {
	    case CAIRO_HINT_STYLE_SLIGHT:
		hint_style = FC_HINT_SLIGHT;
		break;
	    case CAIRO_HINT_STYLE_MEDIUM:
		hint_style = FC_HINT_MEDIUM;
		break;
	    case CAIRO_HINT_STYLE_FULL:
	    default:
		hint_style = FC_HINT_FULL;
		break;
	    }

	    FcPatternAddInteger (pattern, FC_HINT_STYLE, hint_style);
	}
#endif
    }
}

/**
 * cairo_ft_font_face_create_for_pattern:
 * @pattern: A fully resolved fontconfig
 *   pattern. A pattern can be resolved, by, among other things, calling
 *   FcConfigSubstitute(), FcDefaultSubstitute(), then
 *   FcFontMatch(). Cairo will call FcPatternReference() on this
 *   pattern, so you should not further modify the pattern, but you can
 *   release your reference to the pattern with FcPatternDestroy() if
 *   you no longer need to access it.
 *
 * Creates a new font face for the FreeType font backend based on a
 * fontconfig pattern. This font can then be used with
 * cairo_set_font_face() or cairo_scaled_font_create(). The
 * #cairo_scaled_font_t returned from cairo_scaled_font_create() is
 * also for the FreeType backend and can be used with functions such
 * as cairo_ft_font_lock_face().
 *
 * Font rendering options are representated both here and when you
 * call cairo_scaled_font_create(). Font options that have a representation
 * in a #FcPattern must be passed in here; to modify #FcPattern
 * appropriately to reflect the options in a #cairo_font_options_t, call
 * cairo_ft_font_options_substitute().
 *
 * Return value: a newly created #cairo_font_face_t. Free with
 *  cairo_font_face_destroy() when you are done using it.
 **/
cairo_font_face_t *
cairo_ft_font_face_create_for_pattern (FcPattern *pattern)
{
    cairo_ft_unscaled_font_t *unscaled;
    cairo_font_face_t *font_face;

    unscaled = _cairo_ft_unscaled_font_create_for_pattern (pattern);
    if (unscaled == NULL) {
	_cairo_error (CAIRO_STATUS_NO_MEMORY);
	return (cairo_font_face_t *)&_cairo_font_face_nil;
    }

    font_face = _cairo_ft_font_face_create (unscaled,
					    _get_pattern_ft_options (pattern));
    _cairo_unscaled_font_destroy (&unscaled->base);

    if (font_face)
	return font_face;
    else {
	_cairo_error (CAIRO_STATUS_NO_MEMORY);
	return (cairo_font_face_t *)&_cairo_font_face_nil;
    }
}

/**
 * cairo_ft_font_face_create_for_ft_face:
 * @face: A FreeType face object, already opened. This must
 *   be kept around until the face's ref_count drops to
 *   zero and it is freed. Since the face may be referenced
 *   internally to Cairo, the best way to determine when it
 *   is safe to free the face is to pass a
 *   #cairo_destroy_func_t to cairo_font_face_set_user_data()
 * @load_flags: flags to pass to FT_Load_Glyph when loading
 *   glyphs from the font. These flags are OR'ed together with
 *   the flags derived from the #cairo_font_options_t passed
 *   to cairo_scaled_font_create(), so only a few values such
 *   as %FT_LOAD_VERTICAL_LAYOUT, and %FT_LOAD_FORCE_AUTOHINT
 *   are useful. You should not pass any of the flags affecting
 *   the load target, such as %FT_LOAD_TARGET_LIGHT.
 *
 * Creates a new font face for the FreeType font backend from a
 * pre-opened FreeType face. This font can then be used with
 * cairo_set_font_face() or cairo_scaled_font_create(). The
 * #cairo_scaled_font_t returned from cairo_scaled_font_create() is
 * also for the FreeType backend and can be used with functions such
 * as cairo_ft_font_lock_face().
 *
 * Return value: a newly created #cairo_font_face_t. Free with
 *  cairo_font_face_destroy() when you are done using it.
 **/
cairo_font_face_t *
cairo_ft_font_face_create_for_ft_face (FT_Face         face,
				       int             load_flags)
{
    cairo_ft_unscaled_font_t *unscaled;
    cairo_font_face_t *font_face;
    cairo_ft_options_t ft_options;

    unscaled = _cairo_ft_unscaled_font_create_from_face (face);
    if (unscaled == NULL) {
	_cairo_error (CAIRO_STATUS_NO_MEMORY);
	return (cairo_font_face_t *)&_cairo_font_face_nil;
    }

    ft_options.load_flags = load_flags;
    ft_options.extra_flags = 0;
    _cairo_font_options_init_default (&ft_options.base);

    font_face = _cairo_ft_font_face_create (unscaled, ft_options);
    _cairo_unscaled_font_destroy (&unscaled->base);

    if (font_face) {
	return font_face;
    } else {
	_cairo_error (CAIRO_STATUS_NO_MEMORY);
	return (cairo_font_face_t *)&_cairo_font_face_nil;
    }