cairo-ps-surface.c

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

							 width_in_points,
							 height_in_points);
}

static cairo_bool_t
_cairo_surface_is_ps (cairo_surface_t *surface)
{
    return surface->backend == &cairo_ps_surface_backend;
}

/* If the abstract_surface is a paginated surface, and that paginated
 * surface's target is a ps_surface, then set ps_surface to that
 * target. Otherwise return CAIRO_STATUS_SURFACE_TYPE_MISMATCH.
 */
static cairo_status_t
_extract_ps_surface (cairo_surface_t	 *surface,
		     cairo_ps_surface_t **ps_surface)
{
    cairo_surface_t *target;

    if (! _cairo_surface_is_paginated (surface))
	return CAIRO_STATUS_SURFACE_TYPE_MISMATCH;

    target = _cairo_paginated_surface_get_target (surface);

    if (! _cairo_surface_is_ps (target))
	return CAIRO_STATUS_SURFACE_TYPE_MISMATCH;

    *ps_surface = (cairo_ps_surface_t *) target;

    return CAIRO_STATUS_SUCCESS;
}

/**
 * cairo_ps_surface_set_size:
 * @surface: a PostScript cairo_surface_t
 * @width_in_points: new surface width, in points (1 point == 1/72.0 inch)
 * @height_in_points: new surface height, in points (1 point == 1/72.0 inch)
 *
 * Changes the size of a PostScript surface for the current (and
 * subsequent) pages.
 *
 * This function should only be called before any drawing operations
 * have been performed on the current page. The simplest way to do
 * this is to call this function immediately after creating the
 * surface or immediately after completing a page with either
 * cairo_show_page() or cairo_copy_page().
 *
 * Since: 1.2
 **/
void
cairo_ps_surface_set_size (cairo_surface_t	*surface,
			   double		 width_in_points,
			   double		 height_in_points)
{
    cairo_ps_surface_t *ps_surface;
    cairo_status_t status;

    status = _extract_ps_surface (surface, &ps_surface);
    if (status) {
	_cairo_surface_set_error (surface, CAIRO_STATUS_SURFACE_TYPE_MISMATCH);
	return;
    }

    ps_surface->width = width_in_points;
    ps_surface->height = height_in_points;
}

/**
 * cairo_ps_surface_dsc_comment:
 * @surface: a PostScript cairo_surface_t
 * @comment: a comment string to be emitted into the PostScript output
 *
 * Emit a comment into the PostScript output for the given surface.
 *
 * The comment is expected to conform to the PostScript Language
 * Document Structuring Conventions (DSC). Please see that manual for
 * details on the available comments and their meanings. In
 * particular, the %%IncludeFeature comment allows a
 * device-independent means of controlling printer device features. So
 * the PostScript Printer Description Files Specification will also be
 * a useful reference.
 *
 * The comment string must begin with a percent character (%) and the
 * total length of the string (including any initial percent
 * characters) must not exceed 255 characters. Violating either of
 * these conditions will place @surface into an error state. But
 * beyond these two conditions, this function will not enforce
 * conformance of the comment with any particular specification.
 *
 * The comment string should not have a trailing newline.
 *
 * The DSC specifies different sections in which particular comments
 * can appear. This function provides for comments to be emitted
 * within three sections: the header, the Setup section, and the
 * PageSetup section.  Comments appearing in the first two sections
 * apply to the entire document while comments in the BeginPageSetup
 * section apply only to a single page.
 *
 * For comments to appear in the header section, this function should
 * be called after the surface is created, but before a call to
 * cairo_ps_surface_begin_setup().
 *
 * For comments to appear in the Setup section, this function should
 * be called after a call to cairo_ps_surface_begin_setup() but before
 * a call to cairo_ps_surface_begin_page_setup().
 *
 * For comments to appear in the PageSetup section, this function
 * should be called after a call to cairo_ps_surface_begin_page_setup().
 *
 * Note that it is only necessary to call cairo_ps_surface_begin_page_setup()
 * for the first page of any surface. After a call to
 * cairo_show_page() or cairo_copy_page() comments are unambiguously
 * directed to the PageSetup section of the current page. But it
 * doesn't hurt to call this function at the beginning of every page
 * as that consistency may make the calling code simpler.
 *
 * As a final note, cairo automatically generates several comments on
 * its own. As such, applications must not manually generate any of
 * the following comments:
 *
 * Header section: %!PS-Adobe-3.0, %%Creator, %%CreationDate, %%Pages,
 * %%BoundingBox, %%DocumentData, %%LanguageLevel, %%EndComments.
 *
 * Setup section: %%BeginSetup, %%EndSetup
 *
 * PageSetup section: %%BeginPageSetup, %%PageBoundingBox,
 * %%EndPageSetup.
 *
 * Other sections: %%BeginProlog, %%EndProlog, %%Page, %%Trailer, %%EOF
 *
 * Here is an example sequence showing how this function might be used:
 *
 * <informalexample><programlisting>
 * cairo_surface_t *surface = cairo_ps_surface_create (filename, width, height);
 * ...
 * cairo_ps_surface_dsc_comment (surface, "%%Title: My excellent document");
 * cairo_ps_surface_dsc_comment (surface, "%%Copyright: Copyright (C) 2006 Cairo Lover")
 * ...
 * cairo_ps_surface_dsc_begin_setup (surface);
 * cairo_ps_surface_dsc_comment (surface, "%%IncludeFeature: *MediaColor White");
 * ...
 * cairo_ps_surface_dsc_begin_page_setup (surface);
 * cairo_ps_surface_dsc_comment (surface, "%%IncludeFeature: *PageSize A3");
 * cairo_ps_surface_dsc_comment (surface, "%%IncludeFeature: *InputSlot LargeCapacity");
 * cairo_ps_surface_dsc_comment (surface, "%%IncludeFeature: *MediaType Glossy");
 * cairo_ps_surface_dsc_comment (surface, "%%IncludeFeature: *MediaColor Blue");
 * ... draw to first page here ..
 * cairo_show_page (cr);
 * ...
 * cairo_ps_surface_dsc_comment (surface, "%%IncludeFeature: *PageSize A5");
 * ...
 * </programlisting></informalexample>
 *
 * Since: 1.2
 **/
void
cairo_ps_surface_dsc_comment (cairo_surface_t	*surface,
			      const char	*comment)
{
    cairo_ps_surface_t *ps_surface;
    cairo_status_t status;
    char *comment_copy;

    status = _extract_ps_surface (surface, &ps_surface);
    if (status) {
	_cairo_surface_set_error (surface, CAIRO_STATUS_SURFACE_TYPE_MISMATCH);
	return;
    }

    /* A couple of sanity checks on the comment value. */
    if (comment == NULL) {
	_cairo_surface_set_error (surface, CAIRO_STATUS_NULL_POINTER);
	return;
    }

    if (comment[0] != '%' || strlen (comment) > 255) {
	_cairo_surface_set_error (surface, CAIRO_STATUS_INVALID_DSC_COMMENT);
	return;
    }

    /* Then, copy the comment and store it in the appropriate array. */
    comment_copy = strdup (comment);
    if (comment_copy == NULL) {
	_cairo_surface_set_error (surface, CAIRO_STATUS_NO_MEMORY);
	return;
    }

    status = _cairo_array_append (ps_surface->dsc_comment_target, &comment_copy);
    if (status) {
	free (comment_copy);
	_cairo_surface_set_error (surface, status);
	return;
    }
}

/**
 * cairo_ps_surface_dsc_begin_setup:
 * @surface: a PostScript cairo_surface_t
 *
 * This function indicates that subsequent calls to
 * cairo_ps_surface_dsc_comment() should direct comments to the Setup
 * section of the PostScript output.
 *
 * This function should be called at most once per surface, and must
 * be called before any call to cairo_ps_surface_dsc_begin_page_setup()
 * and before any drawing is performed to the surface.
 *
 * See cairo_ps_surface_dsc_comment() for more details.
 *
 * Since: 1.2
 **/
void
cairo_ps_surface_dsc_begin_setup (cairo_surface_t *surface)
{
    cairo_ps_surface_t *ps_surface;
    cairo_status_t status;

    status = _extract_ps_surface (surface, &ps_surface);
    if (status) {
	_cairo_surface_set_error (surface, CAIRO_STATUS_SURFACE_TYPE_MISMATCH);
	return;
    }

    if (ps_surface->dsc_comment_target == &ps_surface->dsc_header_comments)
    {
	ps_surface->dsc_comment_target = &ps_surface->dsc_setup_comments;
    }
}

/**
 * cairo_ps_surface_dsc_begin_page_setup:
 * @surface: a PostScript cairo_surface_t
 *
 * This function indicates that subsequent calls to
 * cairo_ps_surface_dsc_comment() should direct comments to the
 * PageSetup section of the PostScript output.
 *
 * This function call is only needed for the first page of a
 * surface. It should be called after any call to
 * cairo_ps_surface_dsc_begin_setup() and before any drawing is
 * performed to the surface.
 *
 * See cairo_ps_surface_dsc_comment() for more details.
 *
 * Since: 1.2
 **/
void
cairo_ps_surface_dsc_begin_page_setup (cairo_surface_t *surface)
{
    cairo_ps_surface_t *ps_surface;
    cairo_status_t status;

    status = _extract_ps_surface (surface, &ps_surface);
    if (status) {
	_cairo_surface_set_error (surface, CAIRO_STATUS_SURFACE_TYPE_MISMATCH);
	return;
    }

    if (ps_surface->dsc_comment_target == &ps_surface->dsc_header_comments ||
	ps_surface->dsc_comment_target == &ps_surface->dsc_setup_comments)
    {
	ps_surface->dsc_comment_target = &ps_surface->dsc_page_setup_comments;
    }
}

static cairo_surface_t *
_cairo_ps_surface_create_similar (void		       *abstract_src,
				   cairo_content_t	content,
				   int			width,
				   int			height)
{
    cairo_format_t format = _cairo_format_from_content (content);

    /* Just return an image for now, until PS surface can be used
     * as source. */
    return cairo_image_surface_create (format, width, height);
}

static cairo_status_t
_cairo_ps_surface_finish (void *abstract_surface)
{
    cairo_status_t status;
    cairo_ps_surface_t *surface = abstract_surface;
    int i, num_comments;
    char **comments;

    _cairo_ps_surface_emit_header (surface);

    _cairo_ps_surface_emit_font_subsets (surface);

    _cairo_ps_surface_emit_body (surface);

    _cairo_ps_surface_emit_footer (surface);

    _cairo_output_stream_close (surface->stream);
    status = _cairo_output_stream_get_status (surface->stream);
    _cairo_output_stream_destroy (surface->stream);

    fclose (surface->tmpfile);

    _cairo_output_stream_close (surface->final_stream);
    if (status == CAIRO_STATUS_SUCCESS)
	status = _cairo_output_stream_get_status (surface->final_stream);
    _cairo_output_stream_destroy (surface->final_stream);

    num_comments = _cairo_array_num_elements (&surface->dsc_header_comments);
    comments = _cairo_array_index (&surface->dsc_header_comments, 0);
    for (i = 0; i < num_comments; i++)
	free (comments[i]);
    _cairo_array_fini (&surface->dsc_header_comments);

    num_comments = _cairo_array_num_elements (&surface->dsc_setup_comments);
    comments = _cairo_array_index (&surface->dsc_setup_comments, 0);
    for (i = 0; i < num_comments; i++)
	free (comments[i]);
    _cairo_array_fini (&surface->dsc_setup_comments);

    num_comments = _cairo_array_num_elements (&surface->dsc_page_setup_comments);
    comments = _cairo_array_index (&surface->dsc_page_setup_comments, 0);
    for (i = 0; i < num_comments; i++)
	free (comments[i]);
    _cairo_array_fini (&surface->dsc_page_setup_comments);

    return status;
}

static cairo_int_status_t
_cairo_ps_surface_start_page (void *abstract_surface)
{
    cairo_ps_surface_t *surface = abstract_surface;
    int i, num_comments;
    char **comments;

    /* Increment before print so page numbers start at 1. */
    surface->num_pages++;
    _cairo_output_stream_printf (surface->stream,
				 "%%%%Page: %d %d\n",
				 surface->num_pages,
				 surface->num_pages);

    _cairo_output_stream_printf (surface->stream,
				 "%%%%BeginPageSetup\n");

    num_comments = _cairo_array_num_elements (&surface->dsc_page_setup_comments);
    comments = _cairo_array_index (&surface->dsc_page_setup_comments, 0);
    for (i = 0; i < num_comments; i++) {
	_cairo_output_stream_printf (surface->stream,
				     "%s\n", comments[i]);
	free (comments[i]);
	comments[i] = NULL;
    }
    _cairo_array_truncate (&surface->dsc_page_setup_comments, 0);

    _cairo_output_stream_printf (surface->stream,
				 "%%%%PageBoundingBox: %d %d %d %d\n",
				 0, 0,
				 (int) ceil (surface->width),
				 (int) ceil (surface->height));

    _cairo_output_stream_printf (surface->stream,
				 "gsave %f %f translate 1.0 -1.0 scale \n",
				 0.0, surface->height);

    _cairo_output_stream_printf (surface->stream,
				 "%%%%EndPageSetup\n");

    if (surface->width > surface->max_width)
	surface->max_width = surface->width;
    if (surface->height > surface->max_height)
	surface->max_height = surface->height;

    return _cairo_output_stream_get_status (surface->stream);
}

static void
_cairo_ps_surface_end_page (cairo_ps_surface_t *surface)
{
    _cairo_output_stream_printf (surface->stream,
				 "grestore\n");
}

static cairo_int_status_t
_cairo_ps_surface_copy_page (void *abstract_surface)
{
    cairo_ps_surface_t *surface = abstract_surface;

    _cairo_ps_surface_end_page (surface);

    _cairo_output_stream_printf (surface->stream, "copypage\n");

    return CAIRO_STATUS_SUCCESS;
}

static cairo_int_status_t
_cairo_ps_surface_show_page (void *abstract_surface)
{
    cairo_ps_surface_t *surface = abstract_surface;

    _cairo_ps_surface_end_page (surface);

    _cairo_output_stream_printf (surface->stream, "showpage\n");

    return CAIRO_STATUS_SUCCESS;
}

static cairo_bool_t
color_is_gray (cairo_color_t *color)
{
    const double epsilon = 0.00001;

    return (fabs (color->red - color->green) < epsilon &&
	    fabs (color->red - color->blue) < epsilon);
}

static cairo_bool_t
surface_pattern_supported (const cairo_surface_pattern_t *pattern)
{
    if (pattern->surface->backend->acquire_source_image != NULL)
	return TRUE;

    return FALSE;
}

static cairo_bool_t
pattern_supported (const cairo_pattern_t *pattern)
{
    if (pattern->type == CAIRO_PATTERN_TYPE_SOLID)
	return TRUE;

    if (pattern->type == CAIRO_PATTERN_TYPE_SURFACE)