Allow links to specify 'dest' and 'uri'

- If a link has both 'dest' and 'uri', the 'dest' will be used if it
  exists, otherwise it will fallback to using the 'uri'.

- Ensure that a missing 'dest' does not result in an error. Instead a
  warning is printed if CAIRO_DEBUG_TAG is set, and a link to the
  current location is embedded in the PDF. ie the link does
  nothing. Cairo needs to embed a link even if no destination is
  available because when links are embedded at the end of the
  document, the content stream already contains link tags.

- Remove cairo_pdf_interchange_write_forward_links. This code was
  originally used prior to !463 when cairo wrote the links at the end
  of each page. Now the links are written at the end of the document
  so there are no longer any forward links with an unknown
  destination, unless the destination does not exist.

- When 'internal' is not used, use the 'dest' name to reference the
  link. Ensure non ASCII names are correctly encoded.

1 files changed, 40 insertions, 6 deletions

diff --git a/test/pdf-tagged-text.c b/test/pdf-tagged-text.c
index 3883d418e..094b1c8b0 100644
--- a/test/pdf-tagged-text.c
+++ b/test/pdf-tagged-text.c
@@ -113,6 +113,8 @@ static const char *roman_numerals[] = {
 
 #define MAX_PARAGRAPH_LINES 20
 
+static const char *utf8_destination = "l\xc3\xa4nk";
+
 static int paragraph_num_lines;
 static char *paragraph_text[MAX_PARAGRAPH_LINES];
 static double paragraph_height;
@@ -329,20 +331,20 @@ draw_cover (cairo_surface_t *surface, cairo_t *cr)
 
     cairo_select_font_face (cr, "Sans", CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_BOLD);
     cairo_set_font_size(cr, 16);
-    cairo_move_to (cr, PAGE_WIDTH/3, PAGE_HEIGHT/3);
+    cairo_move_to (cr, PAGE_WIDTH/3, 0.15*PAGE_HEIGHT);
     cairo_tag_begin (cr, "Span", NULL);
     cairo_show_text (cr, "PDF Features Test");
     cairo_tag_end (cr, "Span");
 
     /* Test URL link using "rect" attribute. The entire rectangle surrounding the URL should be a clickable link.  */
-    cairo_move_to (cr, PAGE_WIDTH/3, 2*PAGE_HEIGHT/3);
+    cairo_move_to (cr, PAGE_WIDTH/3, 0.2*PAGE_HEIGHT);
     cairo_select_font_face (cr, "Sans", CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_NORMAL);
     cairo_set_font_size(cr, TEXT_SIZE);
     cairo_set_source_rgb (cr, 0, 0, 1);
     cairo_show_text (cr, cairo_url);
     cairo_text_extents (cr, cairo_url, &text_extents);
     url_box.x = PAGE_WIDTH/3 - url_box_margin;
-    url_box.y = 2*PAGE_HEIGHT/3 - url_box_margin;
+    url_box.y = 0.2*PAGE_HEIGHT - url_box_margin;
     url_box.width = text_extents.width + 2*url_box_margin;
     url_box.height = -text_extents.height + 2*url_box_margin;
     cairo_rectangle(cr, url_box.x, url_box.y, url_box.width, url_box.height);
@@ -355,28 +357,52 @@ draw_cover (cairo_surface_t *surface, cairo_t *cr)
 
     /* Create link to not yet emmited page number */
     cairo_tag_begin (cr, CAIRO_TAG_LINK, "page=5");
-    cairo_move_to (cr, PAGE_WIDTH/3, 4*PAGE_HEIGHT/5);
+    cairo_move_to (cr, PAGE_WIDTH/3, 0.25*PAGE_HEIGHT);
     cairo_show_text (cr, "link to page 5");
     cairo_tag_end (cr, CAIRO_TAG_LINK);
 
     /* Create link to not yet emmited destination */
     cairo_tag_begin (cr, CAIRO_TAG_LINK, "dest='Section 3.3'");
-    cairo_move_to (cr, PAGE_WIDTH/3, 4.2*PAGE_HEIGHT/5);
+    cairo_move_to (cr, PAGE_WIDTH/3, 0.3*PAGE_HEIGHT);
     cairo_show_text (cr, "link to page section 3.3");
     cairo_tag_end (cr, CAIRO_TAG_LINK);
 
     /* Create link to external file */
+    cairo_move_to (cr, PAGE_WIDTH/3, 0.35*PAGE_HEIGHT);
     cairo_tag_begin (cr, CAIRO_TAG_LINK, "file='foo.pdf' page=1");
-    cairo_move_to (cr, PAGE_WIDTH/3, 4.4*PAGE_HEIGHT/5);
     cairo_show_text (cr, "link file 'foo.pdf'");
     cairo_tag_end (cr, CAIRO_TAG_LINK);
 
+    /* Create link to missing dest */
+    cairo_move_to (cr, PAGE_WIDTH/3, 0.4*PAGE_HEIGHT);
+    cairo_tag_begin (cr, CAIRO_TAG_LINK, "dest='I don\\'t exist'");
+    cairo_show_text (cr, "link to missing dest");
+    cairo_tag_end (cr, CAIRO_TAG_LINK);
+
+    /* Create link to missing dest with URI fallback*/
+    cairo_move_to (cr, PAGE_WIDTH/3, 0.45*PAGE_HEIGHT);
+    xasprintf(&attrib, "dest='I also don\\'t exist' uri='%s'", cairo_url);
+    cairo_tag_begin (cr, CAIRO_TAG_LINK, attrib);
+    cairo_show_text (cr, "link to missing dest with uri fallback");
+    cairo_tag_end (cr, CAIRO_TAG_LINK);
+    free (attrib);
+
+    /* Create link to utf8 dest */
+    cairo_move_to (cr, PAGE_WIDTH/3, 0.5*PAGE_HEIGHT);
+    xasprintf(&attrib, "dest='%s'", utf8_destination);
+    cairo_tag_begin (cr, CAIRO_TAG_LINK, attrib);
+    cairo_show_text (cr, "link to utf8 dest");
+    cairo_tag_end (cr, CAIRO_TAG_LINK);
+    free (attrib);
+
     draw_page_num (surface, cr, "cover", 0);
 }
 
 static void
 create_document (cairo_surface_t *surface, cairo_t *cr)
 {
+    char *attrib;
+
     layout_paragraph (cr);
 
     cairo_pdf_surface_set_thumbnail_size (surface, PAGE_WIDTH/10, PAGE_HEIGHT/10);
@@ -491,6 +517,14 @@ create_document (cairo_surface_t *surface, cairo_t *cr)
     cairo_show_text (cr, "link to page 3");
     cairo_tag_end (cr, CAIRO_TAG_LINK);
 
+    /* Create utf8 dest */
+    cairo_move_to (cr, PAGE_WIDTH/3, 4*PAGE_HEIGHT/5);
+    xasprintf(&attrib, "name='%s'", utf8_destination);
+    cairo_tag_begin (cr, CAIRO_TAG_DEST, attrib);
+    cairo_show_text (cr, utf8_destination);
+    cairo_tag_end (cr, CAIRO_TAG_DEST);
+    free (attrib);
+
     cairo_tag_end (cr, "Document");
 }