Add graphing component for shotpoint timing visualisations.

It operates in one of these modes:

* facet="bars" (default): shows a barplot.

* facet="lines": shows a lineplot.

* facet="area": shows a lineplot where the area between the
  line(s) and y=0 is filled with a colour.

lib/www/client/source/src/components/graphs/project/sequence/shotpoint-timing.vue

@@ -0,0 +1,196 @@
+<template>
+  <div ref="graph"
+    class="graph-container"
+  ></div>
+</template>
+
+<style scoped>
+.graph-container {
+  width: 100%;
+  height: 100%;
+}
+</style>
+
+<script>
+import Plotly from 'plotly.js-dist';
+import unpack from '@/lib/unpack.js';
+
+export default {
+  name: "DougalGraphProjectSequenceShotpointTiming",
+
+  props: {
+    items: Array,
+    gunDataFormat: { type: String, default: "smsrc" },
+    facet: { type: String, default: "bars" }
+  },
+
+  data () {
+    return {
+      plotted: false,
+      resizeObserver: null
+    };
+  },
+
+  computed: {
+
+    config () {
+      return {
+        editable: false,
+        displayLogo: false
+      };
+    },
+
+    layout () {
+      return {
+        font: {
+          color: this.$vuetify.theme.isDark ? "#fff" : undefined
+        },
+        title: {text: "Shotpoint timing %{data[0].meta.subtitle}"},
+        xaxis: {
+          title: "Shotpoint"
+        },
+        yaxis: {
+          title: "Time (s)"
+        },
+        plot_bgcolor:"rgba(0,0,0,0)",
+        paper_bgcolor:"rgba(0,0,0,0)"
+      };
+    },
+
+    data () {
+
+      const items = this.items.map(i => {
+        return {
+          point: i.point,
+          tstamp: new Date(i.tstamp)
+        }
+      }).sort( (a, b) => a.tstamp - b.tstamp );
+      const x = [...unpack(items, "point")];
+      const y = items.map( (i, idx, ary) => (ary[idx+1]?.tstamp - i.tstamp)/1000 );
+      const src_number = unpack(this.items, ["meta", "raw", this.gunDataFormat, "src_number"]);
+
+      // We're dealing with intervals not points
+      x.pop(); y.pop(); src_number.pop();
+
+      const meta = {};
+
+      const stats = this.stats(x, y, src_number);
+
+      // We need to do the subtitle here rather than in layout as layout knows nothing
+      // about the number of arrays
+
+      if (stats.src_ids.length == 1) {
+        meta.subtitle = `<span style="font-size:smaller;">(μ = ${stats.avg.all.toFixed(2)} ±${stats.std.all.toFixed(2)} s)</span>`;
+      } else {
+        meta.subtitle = `<span style="font-size:smaller;">(μ = ${stats.avg.all.toFixed(2)} ±${stats.std.all.toFixed(2)} s)</span>`;
+        const per_source = [];
+        for (const key in stats.avg) {
+          if (key == "all") continue;
+          const s = `μ<sub>${key}</sub> = ${stats.avg[key].toFixed(2)} ±${stats.std[key].toFixed(2)} s`;
+          per_source.push(s);
+        }
+        meta.subtitle += `<br><span style="font-size:smaller;">` + per_source.join("; ") + "</span>";
+      }
+
+
+      const trace0 = {
+        type: "bar",
+        x,
+        y,
+        transforms: [{
+          type: "groupby",
+          groups: src_number,
+          styles: [
+            {target: 1, value: {line: {color: "green"}}},
+            {target: 2, value: {line: {color: "red"}}},
+            {target: 3, value: {line: {color: "blue"}}}
+          ]
+        }],
+        meta
+      };
+
+      switch (this.facet) {
+        case "lines":
+          trace0.type = "scatter";
+          break;
+        case "area":
+          trace0.type = "scatter";
+          trace0.fill = "tozeroy";
+          break;
+        case "bars":
+        default:
+          // Nothing
+      }
+
+      return [trace0]
+    }
+  },
+
+  watch: {
+    items (cur, prev) {
+      if (cur != prev) {
+        this.plot();
+      }
+    },
+
+    "$vuetify.theme.isDark" () {
+      this.plot();
+    }
+  },
+
+  methods: {
+
+    plot () {
+      Plotly.newPlot(this.$refs.graph, this.data, this.layout, this.config);
+      this.plotted = true;
+    },
+
+    replot () {
+      if (this.plotted) {
+        const ref = this.$refs.graph;
+        Plotly.relayout(ref, {
+          width: ref.clientWidth,
+          height: ref.clientHeight
+        });
+      }
+    },
+
+    stats (x, y, src_number) {
+      const avg = {};
+      const std = {};
+
+      const avg_all = (y.reduce((acc, cur) => acc + cur, 0) / y.length);
+      const std_all = Math.sqrt(y.reduce((acc, cur) => (cur-avg_all)**2 + acc, 0) / y.length);
+
+      avg.all = avg_all;
+      std.all = std_all;
+
+      const src_ids = new Set(src_number);
+
+      for (const src of src_ids) {
+        const v = y.filter((i, idx) => src_number[idx] == src);
+        const μ = (v.reduce((acc, cur) => acc + cur, 0) / v.length);
+        const σ = Math.sqrt(v.reduce((acc, cur) => (cur-μ)**2 + acc, 0) / v.length);
+        avg[src] = μ;
+        std[src] = σ;
+      }
+
+      return { avg, std, src_ids };
+    }
+
+  },
+
+  mounted () {
+    this.resizeObserver = new ResizeObserver(this.replot)
+    this.resizeObserver.observe(this.$refs.graph);
+  },
+
+  beforeDestroy () {
+    if (this.resizeObserver) {
+      this.resizeObserver.unobserve(this.$refs.graph);
+    }
+  }
+
+}
+
+</script>