From 4f6bd093d6292cea66a0152b3083ce898dab0772 Mon Sep 17 00:00:00 2001
From: Tor Andersson <tor.andersson@artifex.com>
Date: Wed, 14 Mar 2012 16:24:44 +0100
Subject: Support alternate content / markup compatibility tags in XPS.

---
 xps/muxps-internal.h |  2 ++
 xps/muxps.h          |  1 +
 xps/xps_common.c     | 26 ++++++++++++++++++++++++++
 xps/xps_doc.c        | 13 +++++++++++++
 xps/xps_xml.c        |  6 ++++++
 5 files changed, 48 insertions(+)

(limited to 'xps')

diff --git a/xps/muxps-internal.h b/xps/muxps-internal.h
index 37dd6f96..5a354555 100644
--- a/xps/muxps-internal.h
+++ b/xps/muxps-internal.h
@@ -165,6 +165,8 @@ void xps_parse_element(xps_document *doc, fz_matrix ctm, fz_rect area, char *bas
 
 void xps_clip(xps_document *doc, fz_matrix ctm, xps_resource *dict, char *clip_att, xml_element *clip_tag);
 
+xml_element *xps_lookup_alternate_content(xml_element *node);
+
 /*
  * The interpreter context.
  */
diff --git a/xps/muxps.h b/xps/muxps.h
index a485adca..128ed35f 100644
--- a/xps/muxps.h
+++ b/xps/muxps.h
@@ -19,6 +19,7 @@ char *xml_tag(xml_element *item);
 char *xml_att(xml_element *item, const char *att);
 void xml_free_element(fz_context *doc, xml_element *item);
 void xml_print_element(xml_element *item, int level);
+void xml_detach(xml_element *node);
 
 /*
 	xps_open_document: Open a document.
diff --git a/xps/xps_common.c b/xps/xps_common.c
index 4829ef9c..eddef1b0 100644
--- a/xps/xps_common.c
+++ b/xps/xps_common.c
@@ -8,6 +8,26 @@ static inline int unhex(int a)
 	return 0;
 }
 
+xml_element *
+xps_lookup_alternate_content(xml_element *node)
+{
+	for (node = xml_down(node); node; node = xml_next(node))
+	{
+		if (!strcmp(xml_tag(node), "mc:Choice") && xml_att(node, "Requires"))
+		{
+			char list[64];
+			char *next = list, *item;
+			fz_strlcpy(list, xml_att(node, "Requires"), sizeof(list));
+			while ((item = fz_strsep(&next, " \t\r\n")) && (!*item || !strcmp(item, "xps")));
+			if (!item)
+				return xml_down(node);
+		}
+		else if (!strcmp(xml_tag(node), "mc:Fallback"))
+			return xml_down(node);
+	}
+	return NULL;
+}
+
 void
 xps_parse_brush(xps_document *doc, fz_matrix ctm, fz_rect area, char *base_uri, xps_resource *dict, xml_element *node)
 {
@@ -37,6 +57,12 @@ xps_parse_element(xps_document *doc, fz_matrix ctm, fz_rect area, char *base_uri
 		xps_parse_glyphs(doc, ctm, base_uri, dict, node);
 	if (!strcmp(xml_tag(node), "Canvas"))
 		xps_parse_canvas(doc, ctm, area, base_uri, dict, node);
+	if (!strcmp(xml_tag(node), "mc:AlternateContent"))
+	{
+		node = xps_lookup_alternate_content(node);
+		if (node)
+			xps_parse_element(doc, ctm, area, base_uri, dict, node);
+	}
 	/* skip unknown tags (like Foo.Resources and similar) */
 }
 
diff --git a/xps/xps_doc.c b/xps/xps_doc.c
index 69609eb2..54e90186 100644
--- a/xps/xps_doc.c
+++ b/xps/xps_doc.c
@@ -422,6 +422,19 @@ xps_load_fixed_page(xps_document *doc, xps_page *page)
 	if (!root)
 		fz_throw(doc->ctx, "FixedPage missing root element");
 
+	if (!strcmp(xml_tag(root), "mc:AlternateContent"))
+	{
+		xml_element *node = xps_lookup_alternate_content(root);
+		if (!node)
+		{
+			xml_free_element(doc->ctx, root);
+			fz_throw(doc->ctx, "FixedPage missing alternate root element");
+		}
+		xml_detach(node);
+		xml_free_element(doc->ctx, root);
+		root = node;
+	}
+
 	if (strcmp(xml_tag(root), "FixedPage"))
 	{
 		xml_free_element(doc->ctx, root);
diff --git a/xps/xps_xml.c b/xps/xps_xml.c
index e2e958c8..8daee00b 100644
--- a/xps/xps_xml.c
+++ b/xps/xps_xml.c
@@ -94,6 +94,12 @@ void xml_free_element(fz_context *ctx, struct element *item)
 	}
 }
 
+void xml_detach(xml_element *node)
+{
+	if (node->up)
+		node->up->down = NULL;
+}
+
 static int xml_parse_entity(int *c, char *a)
 {
 	char *b;
-- 
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