From 8c187fe3c947a4c6263914753cece0790f2c57c6 Mon Sep 17 00:00:00 2001
From: Daniel Barlow <dan@telent.net>
Date: Thu, 21 Nov 2024 14:32:03 +0000
Subject: [PATCH] downsample the points once, not again for each graph

---
 frontend/src/Main.elm | 31 +++++++++++++------------------
 1 file changed, 13 insertions(+), 18 deletions(-)

diff --git a/frontend/src/Main.elm b/frontend/src/Main.elm
index b4c5bf3..0e8eb93 100644
--- a/frontend/src/Main.elm
+++ b/frontend/src/Main.elm
@@ -303,23 +303,20 @@ tileImg zoom tilenumber = img [ width 256,
 type alias Colour = String
 
 measureView : String -> Colour -> (Point -> Maybe Float) -> List Point -> Svg Msg
-measureView title colour fn allPoints =
-    let filteredPoints = Point.downsample 300 allPoints
-        graphHeight = 180
-        startTime = case allPoints of
-                        (p::_) -> p.time
-                        _ -> 0
+measureView title colour fn points =
+    let graphHeight = 180
+        startTime = Maybe.withDefault 0 (Point.startTime points)
         coords p = case (fn p) of
                        Just c ->
                            (String.fromFloat (p.time - startTime)) ++ "," ++
                            (String.fromFloat c) ++ ", "
                        Nothing -> ""
-        maxY = List.foldr max 0 (List.filterMap fn filteredPoints)
-        minY = List.foldr min maxY (List.filterMap fn filteredPoints)
+        maxY = List.foldr max 0 (List.filterMap fn points)
+        minY = List.foldr min maxY (List.filterMap fn points)
         (minYaxis, maxYaxis, tickY) = looseLabels 4 minY maxY
         rangeYaxis = maxYaxis - minYaxis
-        maxX = Point.duration allPoints
-        string = String.concat (List.map coords filteredPoints)
+        maxX = Point.duration points
+        string = String.concat (List.map coords points)
         ttick = timeTick maxX
         firstTimeTick = (toFloat (floor(startTime / ttick))) * ttick - startTime
         ybar n = line
@@ -409,13 +406,10 @@ measureView title colour fn allPoints =
 timeClickDecoder  =
     D.map Dribble  (D.at ["target", "id"] D.string)
 
-timeAxis allPoints =
-    let filteredPoints = Point.downsample 300 allPoints
-        graphHeight = 30
-        startTime = case allPoints of
-                        (p::_) -> p.time
-                        _ -> 0
-        maxX = Point.duration allPoints
+timeAxis points =
+    let graphHeight = 30
+        startTime = Maybe.withDefault 0 (Point.startTime points)
+        maxX = Point.duration points
         ttick = timeTick maxX
         firstTimeTick = (toFloat (floor(startTime / ttick))) * ttick - startTime
         xtick n =
@@ -532,7 +526,8 @@ ifTrack model content =
             let (dt, _) = dragDelta Graph model.drag
                 dpix = dt * model.duration // portalWidth
                 start = toFloat (model.startTime + dpix)
-                points = Point.subseq t start (toFloat model.duration)
+                points = Point.subseq t start (toFloat model.duration) |>
+                         Point.downsample 300
             in  content points
         Failure f -> Debug.log f (div [] [ Html.text "failure", Html.text f])
         Loading -> div [] [Html.text "loading"]