Interpret newlines in tooltips

This commit adds support for newlines in tooltips. The implemented behavior matches the behavior of Graphviz SVG output, but is not in-line with Graphviz documentation (i.e. Graphviz documentation differs from implementation). According to the documentation [1], tooltips are only supported for svg and cmap outputs and not xdot (here xdot.py deviates from the documentation, but for good reasons) and the value should be escString. escString should support newlines only for label, headlabel or taillabel attributes, not for tooltips [2]. Nevertheless, the svg output supports them. But, contrary to the documentation, SVG tooltips do not support capital letter escape sequences like \N, \G and \E. Only \n, \l, \r and \\ seem to be supported. The first three are all interpreted as a new line. Different alignments, specified by the documentation, are not distinguished. The same is implemented in this commit. [1]: https://graphviz.org/docs/attrs/tooltip/ [2]: https://graphviz.org/docs/attr-types/escString/
jrfonseca · Nov 24, 2024 · 04712e2 · 04712e2
1 parent 264bfa6
commit 04712e2
Showing 1 changed file with 28 additions and 2 deletions.
diff --git a/xdot/ui/_xdotparser.py b/xdot/ui/_xdotparser.py
@@ -334,6 +334,32 @@ def decode_attr(self, attrs, name):
         else:
             return value.decode(self.charset)
 
+    @staticmethod
+    def interpret_esc_nl(esc_string: str | None):
+        r"""Interpret newline escape sequences.
+
+        \n, \l and \r are replaced with newlines, other escaped
+        characters such as \\ with themselves.
+        """
+        if esc_string is None:
+            return None
+        result = ""
+        was_escape = False
+        for ch in esc_string:
+            if was_escape:
+                was_escape = False
+                if ch in ['n', 'l', 'r']:
+                    result += "\n"
+                else:
+                    result += ch
+            else:
+                if ch == "\\":
+                    was_escape = True
+                else:
+                    result += ch
+        return result
+
+
     def handle_node(self, id, attrs):
         try:
             pos = attrs['pos']
@@ -356,7 +382,7 @@ def handle_node(self, id, attrs):
                 parser = XDotAttrParser(self, attrs[attr], self.broken_backslashes)
                 shapes.extend(parser.parse())
         url = self.decode_attr(attrs, 'URL')
-        tooltip = self.decode_attr(attrs, 'tooltip')
+        tooltip = self.interpret_esc_nl(self.decode_attr(attrs, 'tooltip'))
         node = elements.Node(id, x, y, w, h, shapes, url, tooltip)
         self.node_by_name[id] = node
         if shapes:
@@ -377,7 +403,7 @@ def handle_edge(self, src_id, dst_id, attrs):
         if shapes:
             src = self.node_by_name[src_id]
             dst = self.node_by_name[dst_id]
-            tooltip = self.decode_attr(attrs, 'tooltip')
+            tooltip = self.interpret_esc_nl(self.decode_attr(attrs, 'tooltip'))
             self.edges.append(elements.Edge(src, dst, points, shapes, tooltip))
 
     def parse(self):