examples/custom-drawings.html

<!doctype html>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Gauge Test</title>
    <link rel="stylesheet" href="../fonts/fonts.css">
    <script src="../gauge.min.js"></script>
</head>
<body style="background: #222">

<button onclick="animateGauges()">Animate</button>
<button onclick="stopGaugesAnimation()">Stop animation</button>
<input type="text" id="gauge-size" value="400">
<button onclick="resize()">Resize</button>
<button onclick="updateUnits()">Change units</button>

<hr>

<canvas data-type="radial-gauge"
        data-width="400"
        data-height="400"
        data-units="°C"
        data-title="Temperature"
        data-min-value="-50"
        data-max-value="50"
        data-major-ticks="[-50,-40,-30,-20,-10,0,10,20,30,40,50]"
        data-minor-ticks="2"
        data-stroke-ticks="true"
        data-highlights='[
                    {"from": -50, "to": 0, "color": "rgba(0,0, 255, .3)"},
                    {"from": 0, "to": 50, "color": "rgba(255, 0, 0, .3)"}
                ]'
        data-ticks-angle="225"
        data-start-angle="67.5"
        data-color-major-ticks="#ddd"
        data-color-minor-ticks="#ddd"
        data-color-title="#eee"
        data-color-units="#ccc"
        data-color-numbers="#eee"
        data-color-plate="#222"
        data-border-shadow-width="0"
        data-borders="true"
        data-needle-type="arrow"
        data-needle-width="2"
        data-needle-circle-size="7"
        data-needle-circle-outer="true"
        data-needle-circle-inner="false"
        data-animation-duration="1500"
        data-animation-rule="linear"
        data-color-border-outer="#333"
        data-color-border-outer-end="#111"
        data-color-border-middle="#222"
        data-color-border-middle-end="#111"
        data-color-border-inner="#111"
        data-color-border-inner-end="#333"
        data-color-needle-shadow-down="#333"
        data-color-needle-circle-outer="#333"
        data-color-needle-circle-outer-end="#111"
        data-color-needle-circle-inner="#111"
        data-color-needle-circle-inner-end="#222"
        data-value-box-border-radius="0"
        data-color-value-box-rect="#222"
        data-color-value-box-rect-end="#333"
        data-font-value="Led"
        data-font-numbers="Led"
        data-font-title="Led"
        data-font-units="Led"
></canvas>

<script>
if (!Array.prototype.forEach) {
    Array.prototype.forEach = function(cb) {
        var i = 0, s = this.length;
        for (; i < s; i++) {
            cb && cb(this[i], i, this);
        }
    }
}

document.fonts && document.fonts.forEach(function(font) {
    font.loaded.then(function() {
        if (font.family.match(/Led/)) {
            document.gauges.forEach(function(gauge) {
                gauge.update();
                gauge.options.renderTo.style.visibility = 'visible';
            });
        }
    });
});

var timers = [];

function animateGauges() {
    document.gauges.forEach(function(gauge) {
        timers.push(setInterval(function() {
            gauge.value = Math.random() *
                (gauge.options.maxValue - gauge.options.minValue) +
                gauge.options.minValue;
        }, gauge.animation.duration + 50));
    });
}

function stopGaugesAnimation() {
    timers.forEach(function(timer) {
        clearInterval(timer);
    });
}

function resize() {
    var size = parseFloat(document.getElementById('gauge-size').value) || 400;

    document.gauges.forEach(function (gauge) {
        gauge.update({ width: size, height: size });
    });
}

function updateUnits() {
    document.gauges.forEach(function (gauge) {
        gauge.update({ units: 'Miles' });
    });
}

function setText() {
    var text = document.getElementById('gauge-text').value;

    document.gauges.forEach(function (gauge) {
        gauge.update({ valueText: text });
    });
}

window.onload = function() {
    // refer gauge
    var gauge = document.gauges[0];

    // this will draw red or blue circle on a gauge plate depending on
    // current value
    gauge.on('beforeNeedle', function () {
        // getting canvas 2d drawing context
        var context = this.canvas.context;

        // we can use gauge context special 'max' property which represents
        // gauge radius in a real pixels and calculate size of relative pixel
        // for our drawing needs
        var pixel = context.max / 100;

        // step out our circle center coordinate by 30% of its radius from
        // gauge center
        var centerX = 30 * pixel;

        // stay in center by Y-coordinate
        var centerY = 0;

        // use circle radius equal to 5%
        var radius = 5 * pixel;

        // save previous context state
        context.save();

        // draw circle using canvas JS API
        context.beginPath();
        context.arc(centerX, centerY, radius, 0, 2 * Math.PI, false);

        var gradient = context.createRadialGradient(
            centerX, centerY, 0,
            centerX, centerY, radius);
        gradient.addColorStop(0, this.options.value <= 0 ? '#aaf' : '#faa');
        gradient.addColorStop(0.82, this.options.value <= 0 ? '#00f' : '#f00');
        gradient.addColorStop(1, this.options.value <= 0 ? '#88a' : '#a88');

        context.fillStyle = gradient;
        context.fill();
        context.closePath();

        // restore previous context state to prevent break of
        // further drawings
        context.restore();
    });

    // redraw the gauge if it has been already drawn
    gauge.draw();
}
</script>
</body>
</html>