# FlowFuse `ui-gauge` Manual (EVOLV Reference)

Source: https://dashboard.flowfuse.com/nodes/widgets/ui-gauge.html

## Gauge Types

| `gtype` value | Visual | Best For |
|---------------|--------|----------|
| `gauge-tile` | Compact square with value | KPI tiles |
| `gauge-battery` | Horizontal battery bar | Charge / capacity |
| `gauge-tank` | Vertical tank with fill gradient | Liquid levels |
| `gauge-half` | 180° arc | Setpoint / range display |
| `gauge-34` | 270° arc | Primary process gauge |

## Properties

| Property | Type | Dynamic | Notes |
|----------|------|---------|-------|
| `group` | ref | No | Parent ui-group |
| `width` | int | No | Columns (max = group width) |
| `height` | int | No | Row units |
| `gtype` | string | Yes | See table above |
| `gstyle` | string | Yes | `"Needle"` or `"Rounded"` (half/3-4 only) |
| `min` | number | Yes | Range minimum |
| `max` | number | Yes | Range maximum |
| `segments` | array | Yes | `[{color: "#hex", from: number}, …]` |
| `title` | string | Yes | Label above gauge |
| `prefix` | string | Yes | Before value (half/3-4 only) |
| `suffix` | string | Yes | After value (half/3-4 only) |
| `units` | string | Yes | Small text below value (half/3-4 only) |
| `icon` | string | Yes | Material Design icon (half/3-4 only) |
| `sizeGauge` | int | No | Arc thickness px |
| `sizeGap` | int | No | Gap between arc & segments px |
| `sizeSegments` | int | No | Segment ring thickness px |

## Input

`msg.payload` — numeric value to display.

## Dynamic Properties (`msg.ui_update`)

```js
msg.ui_update = {
  label: "Tank A",
  gtype: "gauge-tank",
  gstyle: "Rounded",
  min: 0, max: 100,
  segments: [{color:"#f44336", from:0}, {color:"#4caf50", from:25}, {color:"#f44336", from:90}],
  prefix: "", suffix: "%", units: "fill"
};
```

## Segments

Array of `{color, from}` objects sorted ascending by `from`. Each segment colors the range from its `from` up to the next segment's `from` (or `max`).

**Tank default segments** (auto-applied when switching to tank type):
```json
[{"color":"#A8F5FF","from":0},{"color":"#55DBEC","from":15},
 {"color":"#53B4FD","from":35},{"color":"#2397D1","from":50}]
```

## CSS Selectors

| Selector | Target |
|----------|--------|
| `.nrdb-ui-gauge-value span` | Central value text |
| `.nrdb-ui-gauge-value label` | Unit label |
| `.nrdb-ui-gauge-value i` | Icon |
| `.nrdb-ui-gauge #limits` | Min/max labels |

## EVOLV Key Rules

1. **Tank gauge** for basin level: set `gtype:"gauge-tank"`, `min:0`, `max:<basin height>`, custom segments by safety thresholds.
2. **3/4 gauge** for fill %: set `gtype:"gauge-34"`, `gstyle:"Rounded"`, `min:0`, `max:100`, segments for low/normal/high.
3. Recommended sizing: tank `width:2, height:4`; 3/4 arc `width:2, height:3`.
4. Send plain numeric `msg.payload` — no topic needed (gauge has no series concept).
5. Segments must be provided as array even for a single color range.

## Node JSON Example (tank)

```json
{
  "id": "demo_gauge_tank_west",
  "type": "ui-gauge",
  "z": "demo_tab_dashboard",
  "group": "demo_ui_grp_ps_west",
  "name": "West Tank Level",
  "gtype": "gauge-tank",
  "gstyle": "Rounded",
  "title": "Level",
  "units": "m",
  "prefix": "",
  "suffix": "m",
  "min": 0, "max": 4,
  "segments": [
    {"color":"#f44336","from":0},
    {"color":"#ff9800","from":0.3},
    {"color":"#2196f3","from":1.0},
    {"color":"#ff9800","from":2.5},
    {"color":"#f44336","from":3.2}
  ],
  "width": 2, "height": 4,
  "order": 2,
  "x": 700, "y": 400,
  "wires": []
}
```