From ff56efd935d3c68fb9db1921819bef43020b9212 Mon Sep 17 00:00:00 2001
From: Daniel Schadt <kingdread@gmx.de>
Date: Fri, 25 Sep 2026 09:38:12 +0200
Subject: code for climb profile rendering

---
 fietsboek/trackmap.py | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 51 insertions(+), 1 deletion(-)

diff --git a/fietsboek/trackmap.py b/fietsboek/trackmap.py
index 4cb13aa..cb88264 100644
--- a/fietsboek/trackmap.py
+++ b/fietsboek/trackmap.py
@@ -145,4 +145,54 @@ def render(
     return TrackMapRenderer(track, requester, size, layer).render()
 
 
-__all__ = ["to_web_mercator", "TrackMapRenderer", "render"]
+def _ascension_to_color(ascension: float) -> str:
+    if ascension >= 0.20:
+        return "#99108a"
+    if ascension >= 0.14:
+        return "#ad1314"
+    if ascension >= 0.11:
+        return "#cb5126"
+    if ascension >= 0.08:
+        return "#c9775b"
+    if ascension >= 0.05:
+        return "#cbc410"
+    if ascension >= 0.02:
+        return "#109874"
+    return "#57bf93"
+
+
+def height_profile(track: geo.Path, size: tuple[int, int] = (300, 300)) -> str:
+    out = io.StringIO()
+
+    width, height = size
+
+    path_len = track.movement_data().length
+    max_elev = max(point.elevation for point in track.points)
+    min_elev = min(point.elevation for point in track.points)
+    delta_elev = max_elev - min_elev
+
+    out.write(
+        '<svg viewBox="0 -1000 1000 1000" '
+        f'width="{width}" height="{height}" preserveAspectRatio="none" '
+        'xmlns="http://www.w3.org/2000/svg">\n'
+    )
+
+    cur_x = 0
+    for left, right in zip(track.points, track.points[1:]):
+        right_x = cur_x + (left.distance(right) / path_len) * 1000
+        left_y = (left.elevation - min_elev) / delta_elev * 1000
+        right_y = (right.elevation - min_elev) / delta_elev * 1000
+        ascension = (right.elevation - left.elevation) / max(left.distance(right), 0.001)
+        color = _ascension_to_color(ascension)
+        out.write(f'<polygon points="{cur_x},0 {cur_x},{-left_y} {right_x},{-right_y} {right_x},0" fill="{color}" stroke="{color}" />\n')
+        cur_x = right_x
+
+    out.write("</svg>")
+
+    result = out.getvalue()
+    out.close()
+    return result
+    return out
+
+
+__all__ = ["to_web_mercator", "TrackMapRenderer", "render", "height_profile"]
-- 
cgit v1.2.3