pdf: fix link positions

Converting the link position from cairo to pdf coordinates requires
the page height. Since the link may point to a different page, build
an array of the height of each page and use the target page height for
the conversion.

Don't default to a [0,0] position if "pos" is not specified. PDF
allows a null destination position to be specified which means don't
change the position if the page is already displayed or show top left
if switching to a different page. This is more useful default
particularly for external files where the coordinates (which must be
in PDF coordinates as we don't know the page height) of the top left
corner may not be known.

1 files changed, 33 insertions, 17 deletions

diff --git a/src/cairo-pdf-interchange.c b/src/cairo-pdf-interchange.c
index baf3e0fe0..1521fc25a 100644
--- a/src/cairo-pdf-interchange.c
+++ b/src/cairo-pdf-interchange.c
@@ -239,6 +239,7 @@ cairo_pdf_interchange_write_annot (cairo_pdf_surface_t            *surface,
     int sp;
     char *dest = NULL;
     int i, num_rects;
+    double height;
 
     num_rects = _cairo_array_num_elements (&node->annot.link_attrs.rects);
     if (strcmp (node->name, CAIRO_TAG_LINK) == 0 &&
@@ -266,6 +267,7 @@ cairo_pdf_interchange_write_annot (cairo_pdf_surface_t            *surface,
 				     res.id,
 				     sp);
 
+	_cairo_array_copy_element (&surface->page_heights, node->annot.src_page - 1, &height);
 	if (num_rects > 0) {
 	    cairo_rectangle_int_t bbox_rect;
 
@@ -282,18 +284,18 @@ cairo_pdf_interchange_write_annot (cairo_pdf_surface_t            *surface,
 		else
 		    _cairo_rectangle_union (&bbox_rect, &recti);
 
-		write_rect_to_pdf_quad_points (surface->output, &rectf, node->annot.page_height);
+		write_rect_to_pdf_quad_points (surface->output, &rectf, height);
 		_cairo_output_stream_printf (surface->output, " ");
 	    }
 	    _cairo_output_stream_printf (surface->output,
 					 "]\n"
 					 "   /Rect [ ");
-	    write_rect_int_to_pdf_bbox (surface->output, &bbox_rect, node->annot.page_height);
+	    write_rect_int_to_pdf_bbox (surface->output, &bbox_rect, height);
 	    _cairo_output_stream_printf (surface->output, " ]\n");
 	} else {
 	    _cairo_output_stream_printf (surface->output,
 					 "   /Rect [ ");
-	    write_rect_int_to_pdf_bbox (surface->output, &node->annot.extents.extents, node->annot.page_height);
+	    write_rect_int_to_pdf_bbox (surface->output, &node->annot.extents.extents, height);
 	    _cairo_output_stream_printf (surface->output, " ]\n");
 	}
 
@@ -315,12 +317,19 @@ cairo_pdf_interchange_write_annot (cairo_pdf_surface_t            *surface,
 		if (page < 1 || page > (int)_cairo_array_num_elements (&surface->pages))
 		    return CAIRO_INT_STATUS_TAG_ERROR;
 
+		_cairo_array_copy_element (&surface->page_heights, page - 1, &height);
 		_cairo_array_copy_element (&surface->pages, page - 1, &res);
-		_cairo_output_stream_printf (surface->output,
-					     "   /Dest [%d 0 R /XYZ %f %f 0]\n",
-					     res.id,
-					     node->annot.link_attrs.pos.x,
-					     node->annot.page_height - node->annot.link_attrs.pos.y);
+		if (node->annot.link_attrs.has_pos) {
+		    _cairo_output_stream_printf (surface->output,
+						 "   /Dest [%d 0 R /XYZ %f %f 0]\n",
+						 res.id,
+						 node->annot.link_attrs.pos.x,
+						 height - node->annot.link_attrs.pos.y);
+		} else {
+		    _cairo_output_stream_printf (surface->output,
+						 "   /Dest [%d 0 R /XYZ null null 0]\n",
+						 res.id);
+		}
 	    }
 	} else if (node->annot.link_attrs.link_type == TAG_LINK_URI) {
 	    _cairo_output_stream_printf (surface->output,
@@ -342,11 +351,17 @@ cairo_pdf_interchange_write_annot (cairo_pdf_surface_t            *surface,
 					     "      /D %s\n",
 					     dest);
 	    } else {
-		_cairo_output_stream_printf (surface->output,
-					     "      /D [%d %f %f ]\n",
-					     node->annot.link_attrs.page,
-					     node->annot.link_attrs.pos.x,
-					     node->annot.link_attrs.pos.y);
+		if (node->annot.link_attrs.has_pos) {
+		    _cairo_output_stream_printf (surface->output,
+						 "      /D [%d %f %f 0]\n",
+						 node->annot.link_attrs.page,
+						 node->annot.link_attrs.pos.x,
+						 node->annot.link_attrs.pos.y);
+		} else {
+		    _cairo_output_stream_printf (surface->output,
+						 "      /D [%d null null 0]\n",
+						 node->annot.link_attrs.page);
+		}
 	    }
 	    _cairo_output_stream_printf (surface->output,
 					 "   >>\n");
@@ -769,6 +784,7 @@ _cairo_pdf_interchange_write_document_dests (cairo_pdf_surface_t *surface)
 	cairo_pdf_resource_t page_res;
 	double x = 0;
 	double y = 0;
+	double height;
 
 	if (dest->extents.valid) {
 	    x = dest->extents.extents.x;
@@ -782,12 +798,13 @@ _cairo_pdf_interchange_write_document_dests (cairo_pdf_surface_t *surface)
 	    y = dest->attrs.y;
 
 	_cairo_array_copy_element (&surface->pages, dest->page - 1, &page_res);
+	_cairo_array_copy_element (&surface->page_heights, dest->page - 1, &height);
 	_cairo_output_stream_printf (surface->output,
-				     "   (%s) [ %d 0 R /XYZ %f %f ]\n",
+				     "   (%s) [%d 0 R /XYZ %f %f 0]\n",
 				     dest->attrs.name,
 				     page_res.id,
 				     x,
-				     surface->height - y);
+				     height - y);
     }
     _cairo_output_stream_printf (surface->output,
 				     "  ]\n"
@@ -914,7 +931,7 @@ _cairo_pdf_interchange_begin_structure_tag (cairo_pdf_surface_t    *surface,
 	    if (unlikely (status))
 		return status;
 
-	    ic->current_node->annot.page_height = surface->height;
+	    ic->current_node->annot.src_page = _cairo_array_num_elements (&surface->pages);;
 	    cairo_list_add_tail (&ic->current_node->annot.extents.link, &ic->extents_list);
 	}
 
@@ -950,7 +967,6 @@ _cairo_pdf_interchange_begin_dest_tag (cairo_pdf_surface_t    *surface,
 	if (unlikely (status))
 	    return status;
 
-	dest->page_height = surface->height;
 	dest->page = _cairo_array_num_elements (&surface->pages);
 	init_named_dest_key (dest);
 	status = _cairo_hash_table_insert (ic->named_dests, &dest->base);