Skip to content

Create gauges using the canvas gauges library

Jump to bottom Edit New page
Julian Knight edited this page Feb 13, 2023 · 2 revisions

The canvas-gauges library allows you to create a nice-looking gauge (dial or linear) using vanilla HTML and JavaScript. Here is an example.

UPDATE: Please also see this Node-RED Forum thread for extended versions of this along with a low-code method and a more complete coded method that automatically creates the gauges for you. 🧙‍♂️

Add a uibuilder node by importing from the Node-RED examples - the "blank" example is fine. Change the inject node, add a topic and change the payload to be a JSONata expression field containing $formatInteger($random() * 100, "0") so that you get a new random number each time you press the input button. Set it to auto-repeat if you prefer.

Once the uibuilder node has been given a url and deployed, you can now edit your front-end code like so:

index.html

<!doctype html>
<html lang="en"><head>

    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">

    <title>Canvas Gauges Example - Node-RED uibuilder</title>
    <meta name="description" content="Node-RED uibuilder - Canvas Gauges Example">
    <link rel="icon" href="./images/node-blue.ico">

    <!-- Your own CSS (defaults to loading uibuilders css)-->
    <link type="text/css" rel="stylesheet" href="./index.css" media="all">

    <!-- #region Supporting Scripts. These MUST be in the right order. Note no leading / - socket.io no longer needed  -->
    <script defer src="../uibuilder/uibuilder.iife.min.js"></script>
    <script defer src="https://cdn.jsdelivr.net/npm/canvas-gauges@2.1.7/gauge.min.js"></script>
    <script defer src="./index.js">/* OPTIONAL: Put your custom code in that */</script>
    <!-- #endregion -->

</head><body class="uib">
    
    <h1>uibuilder Canvas Gauges Example</h1>

    <div id="more"><!-- '#more' is used as a parent for dynamic HTML content in examples --></div>

    <canvas id="gauge-radial-1"></canvas>

    <pre id="msg" class="syntax-highlight">Waiting for a message from Node-RED</pre>

</body></html>

index.js

// @ts-nocheck

'use strict'

// https://github.com/Mikhus/canvas-gauges
var gauge = new RadialGauge({
    renderTo: 'gauge-radial-1',
    highlights: [
        { "from": 0, "to": 60, "color": "rgba(0,255,0)" },
        { "from": 60, "to": 80, "color": "rgba(255,255,0)" },
        { "from": 80, "to": 100, "color": "rgba(255,0,0)" }
    ],
    width: 300,
    height: 300,
    units: "°C",
    minValue: 0,
    maxValue: 100,
    majorTicks: [0,10,20,30,40,50,60,70,80,90,100],
    minorTicks: 10,
    strokeTicks: true,
    colorPlate: "#fff",
    borderShadowWidth: 0,
    borders: false,
    needleType: "arrow",
    needleWidth: 2,
    needleCircleSize: 7,
    needlCircleOuter: true,
    needleCircleInner: false,
    animationDuration: 1500,
    animationRule: "linear",
    valueBox: true,
    valueInt: 2,
    valueDec: 2,
}).draw()
// var gauge = new LinearGauge({
//     renderTo: 'gauge-radial-1'
// }).draw()

// Listen for incoming messages from Node-RED
uibuilder.onChange('msg', function(msg) {
    // Dump the msg as text to the "msg" html element
    const eMsg = $('#msg')
    if (eMsg) eMsg.innerHTML = uibuilder.syntaxHighlight(msg)

    gauge.value = msg.payload
    gauge.update({
        title: msg.topic
    })
})

Note that while the gauge value can be dynamically updated, most of the gauge does not dynamically update (for efficiency - this is part of the gauge design, not uibuilder). To update other parts of the gauge dynamically, you need to use the gauge.update function. See the canvas-gauges documentation for details.

Customisation

See the canvas-gauge documentation for details on how to customise the display.

Note that this WIKI entry was written using uibuilder v6.

Please feel free to add comments to the page (clearly mark with your initials & please add a commit msg so we know what has changed). You can contact me in the Discourse forum, or raise an issue here in GitHub! I will make sure all comments & suggestions are represented here.

Clone this wiki locally