cairo-scaled-font.c

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

					     glyphs[i].index,
					     CAIRO_SCALED_GLYPH_INFO_SURFACE,
					     &scaled_glyph);

	if (status)
	    goto CLEANUP_MASK;

	glyph_surface = scaled_glyph->surface;

	/* Create the mask using the format from the first glyph */
	if (mask == NULL) {
	    mask = cairo_image_surface_create (glyph_surface->format,
					       width, height);
	    if (mask->status) {
		status = mask->status;
		goto CLEANUP_MASK;
	    }

	    status = _cairo_surface_fill_rectangle (mask,
						    CAIRO_OPERATOR_CLEAR,
						    CAIRO_COLOR_TRANSPARENT,
						    0, 0,
						    width, height);
	    if (status)
		goto CLEANUP_MASK;
	    if (glyph_surface->format == CAIRO_FORMAT_ARGB32)
		pixman_image_set_component_alpha (((cairo_image_surface_t*) mask)->
						  pixman_image, TRUE);

	}

	/* round glyph locations to the nearest pixel */
	/* XXX: FRAGILE: We're ignoring device_transform scaling here. A bug? */
	x = (int) floor (glyphs[i].x +
                         glyph_surface->base.device_transform.x0 +
                         0.5);
	y = (int) floor (glyphs[i].y +
                         glyph_surface->base.device_transform.y0 +
                         0.5);

	_cairo_pattern_init_for_surface (&glyph_pattern, &glyph_surface->base);

	status = _cairo_surface_composite (CAIRO_OPERATOR_ADD,
					   &glyph_pattern.base,
					   NULL,
					   mask,
					   0, 0,
					   0, 0,
					   x - dest_x,
					   y - dest_y,
					   glyph_surface->width,
					   glyph_surface->height);

	_cairo_pattern_fini (&glyph_pattern.base);
	if (status)
	    break;
    }

    if (mask != NULL) {
	cairo_surface_pattern_t mask_pattern;

	_cairo_pattern_init_for_surface (&mask_pattern, mask);

	status = _cairo_surface_composite (op, pattern, &mask_pattern.base,
					   surface,
					   source_x, source_y,
					   0,        0,
					   dest_x,   dest_y,
					   width,    height);

	_cairo_pattern_fini (&mask_pattern.base);
    }

CLEANUP_MASK:
    _cairo_cache_thaw (scaled_font->glyphs);

    if (mask != NULL)
	cairo_surface_destroy (mask);
    return status;
}

typedef struct _cairo_scaled_glyph_path_closure {
    cairo_point_t	    offset;
    cairo_path_fixed_t	    *path;
} cairo_scaled_glyph_path_closure_t;

static cairo_status_t
_scaled_glyph_path_move_to (void *abstract_closure, cairo_point_t *point)
{
    cairo_scaled_glyph_path_closure_t	*closure = abstract_closure;

    return _cairo_path_fixed_move_to (closure->path,
				      point->x + closure->offset.x,
				      point->y + closure->offset.y);
}

static cairo_status_t
_scaled_glyph_path_line_to (void *abstract_closure, cairo_point_t *point)
{
    cairo_scaled_glyph_path_closure_t	*closure = abstract_closure;

    return _cairo_path_fixed_line_to (closure->path,
				      point->x + closure->offset.x,
				      point->y + closure->offset.y);
}

static cairo_status_t
_scaled_glyph_path_curve_to (void *abstract_closure,
			     cairo_point_t *p0,
			     cairo_point_t *p1,
			     cairo_point_t *p2)
{
    cairo_scaled_glyph_path_closure_t	*closure = abstract_closure;

    return _cairo_path_fixed_curve_to (closure->path,
				       p0->x + closure->offset.x,
				       p0->y + closure->offset.y,
				       p1->x + closure->offset.x,
				       p1->y + closure->offset.y,
				       p2->x + closure->offset.x,
				       p2->y + closure->offset.y);
}

static cairo_status_t
_scaled_glyph_path_close_path (void *abstract_closure)
{
    cairo_scaled_glyph_path_closure_t	*closure = abstract_closure;

    return _cairo_path_fixed_close_path (closure->path);
}

cairo_status_t
_cairo_scaled_font_glyph_path (cairo_scaled_font_t *scaled_font,
			       const cairo_glyph_t *glyphs,
			       int		    num_glyphs,
			       cairo_path_fixed_t  *path)
{
    cairo_status_t status;
    int	i;
    cairo_scaled_glyph_path_closure_t closure;

    if (scaled_font->status)
	return scaled_font->status;

    closure.path = path;
    for (i = 0; i < num_glyphs; i++) {
	cairo_scaled_glyph_t *scaled_glyph;

	status = _cairo_scaled_glyph_lookup (scaled_font,
					     glyphs[i].index,
					     CAIRO_SCALED_GLYPH_INFO_PATH,
					     &scaled_glyph);
	if (status)
	    return status;

	closure.offset.x = _cairo_fixed_from_double (glyphs[i].x);
	closure.offset.y = _cairo_fixed_from_double (glyphs[i].y);

	status = _cairo_path_fixed_interpret (scaled_glyph->path,
					      CAIRO_DIRECTION_FORWARD,
					      _scaled_glyph_path_move_to,
					      _scaled_glyph_path_line_to,
					      _scaled_glyph_path_curve_to,
					      _scaled_glyph_path_close_path,
					      &closure);
    }

    return CAIRO_STATUS_SUCCESS;
}

/**
 * cairo_scaled_glyph_set_metrics:
 * @scaled_glyph: a #cairo_scaled_glyph_t
 * @scaled_font: a #cairo_scaled_font_t
 * @fs_metrics: a #cairo_text_extents_t in font space
 *
 * _cairo_scaled_glyph_set_metrics() stores user space metrics
 * for the specified glyph given font space metrics. It is
 * called by the font backend when initializing a glyph with
 * CAIRO_SCALED_GLYPH_INFO_METRICS.
 **/
void
_cairo_scaled_glyph_set_metrics (cairo_scaled_glyph_t *scaled_glyph,
				 cairo_scaled_font_t *scaled_font,
				 cairo_text_extents_t *fs_metrics)
{
    cairo_bool_t first = TRUE;
    double hm, wm;
    double min_user_x = 0.0, max_user_x = 0.0, min_user_y = 0.0, max_user_y = 0.0;
    double min_device_x = 0.0, max_device_x = 0.0, min_device_y = 0.0, max_device_y = 0.0;

    for (hm = 0.0; hm <= 1.0; hm += 1.0)
	for (wm = 0.0; wm <= 1.0; wm += 1.0) {
	    double x, y;

	    /* Transform this corner to user space */
	    x = fs_metrics->x_bearing + fs_metrics->width * wm;
	    y = fs_metrics->y_bearing + fs_metrics->height * hm;
	    cairo_matrix_transform_point (&scaled_font->font_matrix,
					  &x, &y);
	    if (first) {
		min_user_x = max_user_x = x;
		min_user_y = max_user_y = y;
	    } else {
		if (x < min_user_x) min_user_x = x;
		if (x > max_user_x) max_user_x = x;
		if (y < min_user_y) min_user_y = y;
		if (y > max_user_y) max_user_y = y;
	    }

	    /* Transform this corner to device space from glyph origin */
	    x = fs_metrics->x_bearing + fs_metrics->width * wm;
	    y = fs_metrics->y_bearing + fs_metrics->height * hm;
	    cairo_matrix_transform_distance (&scaled_font->scale,
					     &x, &y);

	    if (first) {
		min_device_x = max_device_x = x;
		min_device_y = max_device_y = y;
	    } else {
		if (x < min_device_x) min_device_x = x;
		if (x > max_device_x) max_device_x = x;
		if (y < min_device_y) min_device_y = y;
		if (y > max_device_y) max_device_y = y;
	    }
	    first = FALSE;
	}
    scaled_glyph->metrics.x_bearing = min_user_x;
    scaled_glyph->metrics.y_bearing = min_user_y;
    scaled_glyph->metrics.width = max_user_x - min_user_x;
    scaled_glyph->metrics.height = max_user_y - min_user_y;

    scaled_glyph->metrics.x_advance = fs_metrics->x_advance;
    scaled_glyph->metrics.y_advance = fs_metrics->y_advance;
    cairo_matrix_transform_point (&scaled_font->font_matrix,
				  &scaled_glyph->metrics.x_advance,
				  &scaled_glyph->metrics.y_advance);

    scaled_glyph->bbox.p1.x = _cairo_fixed_from_double (min_device_x);
    scaled_glyph->bbox.p1.y = _cairo_fixed_from_double (min_device_y);
    scaled_glyph->bbox.p2.x = _cairo_fixed_from_double (max_device_x);
    scaled_glyph->bbox.p2.y = _cairo_fixed_from_double (max_device_y);
}

void
_cairo_scaled_glyph_set_surface (cairo_scaled_glyph_t *scaled_glyph,
				 cairo_scaled_font_t *scaled_font,
				 cairo_image_surface_t *surface)
{
    if (scaled_glyph->surface != NULL)
	cairo_surface_destroy (&scaled_glyph->surface->base);
    scaled_glyph->surface = surface;
}

void
_cairo_scaled_glyph_set_path (cairo_scaled_glyph_t *scaled_glyph,
			      cairo_scaled_font_t *scaled_font,
			      cairo_path_fixed_t *path)
{
    if (scaled_glyph->path != NULL)
	_cairo_path_fixed_destroy (scaled_glyph->path);
    scaled_glyph->path = path;
}

/**
 * _cairo_scaled_glyph_lookup:
 * @scaled_font: a #cairo_scaled_font_t
 * @index: the glyph to create
 * @info: a #cairo_scaled_glyph_info_t marking which portions of
 * the glyph should be filled in.
 * @scaled_glyph_ret: a #cairo_scaled_glyph_t * where the glyph
 * is returned.
 *
 * Returns a glyph with the requested portions filled in. Glyph
 * lookup is cached and glyph will be automatically freed along
 * with the scaled_font so no explicit free is required.
 * @info can be one or more of:
 *  %CAIRO_SCALED_GLYPH_INFO_METRICS - glyph metrics and bounding box
 *  %CAIRO_SCALED_GLYPH_INFO_SURFACE - surface holding glyph image
 *  %CAIRO_SCALED_GLYPH_INFO_PATH - path holding glyph outline in device space
 *
 * If the desired info is not available, (for example, when trying to
 * get INFO_PATH with a bitmapped font), this function will return
 * CAIRO_INT_STATUS_UNSUPPORTED.
 **/
cairo_int_status_t
_cairo_scaled_glyph_lookup (cairo_scaled_font_t *scaled_font,
			    unsigned long index,
			    cairo_scaled_glyph_info_t info,
			    cairo_scaled_glyph_t **scaled_glyph_ret)
{
    cairo_status_t		status = CAIRO_STATUS_SUCCESS;
    cairo_cache_entry_t		key;
    cairo_scaled_glyph_t	*scaled_glyph;
    cairo_scaled_glyph_info_t	need_info;

    if (scaled_font->status)
	return scaled_font->status;

    CAIRO_MUTEX_LOCK (cairo_scaled_font_map_mutex);

    key.hash = index;
    /*
     * Check cache for glyph
     */
    info |= CAIRO_SCALED_GLYPH_INFO_METRICS;
    if (!_cairo_cache_lookup (scaled_font->glyphs, &key,
			      (cairo_cache_entry_t **) &scaled_glyph))
    {
	/*
	 * On miss, create glyph and insert into cache
	 */
	scaled_glyph = malloc (sizeof (cairo_scaled_glyph_t));
	if (scaled_glyph == NULL) {
	    status = CAIRO_STATUS_NO_MEMORY;
	    goto CLEANUP;
	}

	_cairo_scaled_glyph_set_index(scaled_glyph, index);
	scaled_glyph->cache_entry.size = 1;	/* XXX */
	scaled_glyph->scaled_font = scaled_font;
	scaled_glyph->surface = NULL;
	scaled_glyph->path = NULL;
	scaled_glyph->surface_private = NULL;

	/* ask backend to initialize metrics and shape fields */
	status = (*scaled_font->backend->
		  scaled_glyph_init) (scaled_font, scaled_glyph, info);
	if (status) {
	    _cairo_scaled_glyph_destroy (scaled_glyph);
	    goto CLEANUP;
	}

	/* on success, the cache takes ownership of the scaled_glyph */
	status = _cairo_cache_insert (scaled_font->glyphs,
				      &scaled_glyph->cache_entry);
	if (status) {
	    _cairo_scaled_glyph_destroy (scaled_glyph);
	    goto CLEANUP;
	}
    }
    /*
     * Check and see if the glyph, as provided,
     * already has the requested data and ammend it if not
     */
    need_info = 0;
    if ((info & CAIRO_SCALED_GLYPH_INFO_SURFACE) != 0 &&
	scaled_glyph->surface == NULL)
	need_info |= CAIRO_SCALED_GLYPH_INFO_SURFACE;

    if (((info & CAIRO_SCALED_GLYPH_INFO_PATH) != 0 &&
	 scaled_glyph->path == NULL))
	need_info |= CAIRO_SCALED_GLYPH_INFO_PATH;

    if (need_info) {
	status = (*scaled_font->backend->
		  scaled_glyph_init) (scaled_font, scaled_glyph, need_info);
	if (status)
	    goto CLEANUP;
    }

  CLEANUP:
    if (status) {
	/* It's not an error for the backend to not support the info we want. */
	if (status != CAIRO_INT_STATUS_UNSUPPORTED)
	    _cairo_scaled_font_set_error (scaled_font, status);
	*scaled_glyph_ret = NULL;
    } else {
	*scaled_glyph_ret = scaled_glyph;
    }

    CAIRO_MUTEX_UNLOCK (cairo_scaled_font_map_mutex);

    return status;
}

/**
 * cairo_scaled_font_get_font_face:
 * @scaled_font: a #cairo_scaled_font_t
 *
 * Return value: The #cairo_font_face_t with which @scaled_font was
 * created.
 *
 * Since: 1.2
 **/
cairo_font_face_t *
cairo_scaled_font_get_font_face (cairo_scaled_font_t *scaled_font)
{
    if (scaled_font->status)
	return (cairo_font_face_t*) &_cairo_font_face_nil;

    return scaled_font->font_face;
}

/**
 * cairo_scaled_font_get_font_matrix:
 * @scaled_font: a #cairo_scaled_font_t
 * @font_matrix: return value for the matrix
 *
 * Stores the font matrix with which @scaled_font was created into
 * @matrix.
 *
 * Since: 1.2
 **/
void
cairo_scaled_font_get_font_matrix (cairo_scaled_font_t	*scaled_font,
				   cairo_matrix_t	*font_matrix)
{
    if (scaled_font->status) {
	cairo_matrix_init_identity (font_matrix);
	return;
    }

    *font_matrix = scaled_font->font_matrix;
}

/**
 * cairo_scaled_font_get_ctm:
 * @scaled_font: a #cairo_scaled_font_t
 * @ctm: return value for the CTM
 *
 * Stores the CTM with which @scaled_font was created into @ctm.
 *
 * Since: 1.2
 **/
void
cairo_scaled_font_get_ctm (cairo_scaled_font_t	*scaled_font,
			   cairo_matrix_t	*ctm)
{
    if (scaled_font->status) {
	cairo_matrix_init_identity (ctm);
	return;
    }

    *ctm = scaled_font->ctm;
}

/**
 * cairo_scaled_font_get_font_options:
 * @scaled_font: a #cairo_scaled_font_t
 * @options: return value for the font options
 *
 * Stores the font options with which @scaled_font was created into
 * @ctm.
 *
 * Since: 1.2
 **/
void
cairo_scaled_font_get_font_options (cairo_scaled_font_t		*scaled_font,
				    cairo_font_options_t	*options)
{
    if (scaled_font->status) {
	_cairo_font_options_init_default (options);
	return;
    }

    _cairo_font_options_init_copy (options, &scaled_font->options);
}