Waterfall chart to capture history of detections

lib/charts/WaterfallChart.cpp

@@ -0,0 +1,57 @@
+#include "charts.h"
+#include <cstdint>
+
+void WaterfallChart::reset(uint16_t x, uint16_t y, uint16_t w, uint16_t h)
+{
+    Chart::reset(x, y, w, h);
+
+    model->reset(model->times[0], w);
+
+    update_to = model->buckets;
+}
+
+void WaterfallChart::updatePoint(uint64_t t, float x, float y)
+{
+    if (x < min_x || x >= max_x)
+    {
+        return;
+    }
+
+    update_to = max(update_to, model->updateModel(t, x2pos(x), y >= level_y));
+}
+
+void WaterfallChart::draw()
+{
+    size_t h = min(update_to, (size_t)height);
+
+    for (int y = 0; y < h; y++)
+    {
+        for (int x = 0; x < width; x++)
+        {
+            bool b = model->counts[y][x] > 0 &&
+                     (model->events[y][x] >= model->counts[y][x] * threshold);
+            if (b)
+            {
+                display.setColor(WHITE);
+            }
+            else
+            {
+                display.setColor(BLACK);
+            }
+
+            display.setPixel(pos_x + x, pos_y + y);
+        }
+    }
+
+    update_to = 0;
+}
+
+int WaterfallChart::x2pos(float x)
+{
+    if (x < min_x)
+        x = min_x;
+    if (x > max_x)
+        x = max_x;
+
+    return width * (x - min_x) / (max_x - min_x);
+}