From 304528ebc708fb46ddb02c9517ef3bafa69e175c Mon Sep 17 00:00:00 2001
From: Gertjan van Zwieten <gertjanvanzwieten@evalf.nl>
Date: Thu, 15 Feb 2024 16:57:30 +0100
Subject: [PATCH 1/2] make svg graphs clickable

This patch inserts a javascript snippet into generated svg graphs to make nodes
and edges highlightable in capable viewers (such as a web browser).
---
 nutils/_graph.py | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/nutils/_graph.py b/nutils/_graph.py
index 939308c58..1c531713b 100644
--- a/nutils/_graph.py
+++ b/nutils/_graph.py
@@ -68,7 +68,33 @@ def export_graphviz(self, *, fill_color: Optional[GraphvizColorCallback] = None,
                 for i, line in enumerate(src.split('\n'), 1):
                     print('{:04d}  {}'.format(i, line))
                 treelog.warning('graphviz failed for error code', status.returncode)
-            img.write(status.stdout)
+            graph = status.stdout
+            if image_type == 'svg':
+                i = graph.rindex(b'</svg>')
+                graph = graph[:i] + clickHandler + graph[i:]
+            img.write(graph)
+
+clickHandler = b'''
+<style>
+g.edge, g.node { cursor: pointer; }
+.highlight path { stroke: orange; stroke-width: 2; }
+.highlight polygon:first-of-type { fill: orange; }
+.highlight polygon { stroke: orange; }
+.highlight text { fill: white; }
+</style>
+<script>
+document.addEventListener("click", function (event) {
+    const g = event.target.closest("g");
+    if (g.classList.contains("edge")) {
+        g.classList.toggle("highlight"); }
+    else if (g.classList.contains("node")) {
+        const index = g.firstElementChild.textContent;
+        const pattern = new RegExp("(^|[^0-9])" + index + "($|[^0-9])");
+        const isnew = g.classList.toggle("highlight");
+        for (const edge of document.getElementsByClassName("edge")) {
+            if (pattern.test(edge.firstElementChild.textContent)) {
+                edge.classList.toggle("highlight", isnew); } } } });
+</script>'''
 
 
 class RegularNode(Node[Metadata]):

From ad33d53118efe092cc4cc77367e0443c0b2056fa Mon Sep 17 00:00:00 2001
From: Gertjan van Zwieten <gertjanvanzwieten@evalf.nl>
Date: Fri, 16 Feb 2024 15:08:19 +0100
Subject: [PATCH 2/2] scale graphviz svg down to 2/3 of original size

This patch modifies the width and height parameters of the graphviz generated
svg image in order to scale it down to 2/3 the original size. This avoids
having to scale the image via the browser which may affect other tabs as well.
Sadly it does not seem possible to instruct the dot executable to generate an
image at the desired scale directly. The regular expression that is used
instead is fairly sensitive to the generated xml, but that is acceptable given
that the only risk is to leave the svg at its original scale.
---
 nutils/_graph.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/nutils/_graph.py b/nutils/_graph.py
index 1c531713b..f91c7912f 100644
--- a/nutils/_graph.py
+++ b/nutils/_graph.py
@@ -5,6 +5,7 @@
 import subprocess
 import abc
 import html
+import re
 
 Metadata = TypeVar('Metadata')
 GraphvizColorCallback = Callable[['Node'], Optional[str]]
@@ -70,6 +71,8 @@ def export_graphviz(self, *, fill_color: Optional[GraphvizColorCallback] = None,
                 treelog.warning('graphviz failed for error code', status.returncode)
             graph = status.stdout
             if image_type == 'svg':
+                graph = re.sub(b'<svg width="(\d+)pt" height="(\d+)pt"', lambda match:
+                    b'<svg width="%dpt" height="%dpt"' % tuple((int(l)*2)//3 for l in match.groups()), graph, count=1)
                 i = graph.rindex(b'</svg>')
                 graph = graph[:i] + clickHandler + graph[i:]
             img.write(graph)