Symbols (Vector-Based Icons)

  • Google Maps JavaScript API uses customizable, vector-based icons, called Symbols, to enhance markers and polylines.

  • Symbols are defined using SVG path notation and offer properties to control appearance, such as path, fill color, and scale.

  • Predefined symbols like circles and arrows are available through the SymbolPath class for easy integration.

  • Symbols can be animated along polylines to create dynamic visual effects, often using window.setInterval() for position updates.

  • Developers can leverage the icon property for markers and the icons[] array within PolylineOptions for polylines to implement symbols effectively.
  1. Introduction
  2. Properties of a symbol
  3. Predefined symbols
  4. Add a symbol to a marker
  5. Add a symbol to a polyline
  6. Animate a symbol

Introduction

A Symbol is a vector-based icon that can be displayed on a Marker or a Polyline object. The symbol's shape is defined by a path using SVG path notation. While path is the only required property, the Symbol object supports a variety of properties allowing you to customize visual aspects, such as the color and weight of the stroke and fill. See the list of properties.

Several predefined symbols are available via the SymbolPath class. See the list below.

Properties of a symbol

Note that the default behavior of a Symbol varies slightly depending upon whether it appears on a marker or a polyline. These variances are described in the list of properties below.

A Symbol supports the following properties:

  • path (required) is the path defining the shape of the symbol. You can use one of the predefined paths in google.maps.SymbolPath or define a custom path using SVG path notation. Note: Vector paths on a polyline must fit within a 22x22px square. If your path includes points outside this square, then you must adjust the symbol's scale property to a fractional value, such as 0.2, so that the resulting scaled points fit within the square.
  • anchor sets the position of the symbol relative to the marker or polyline. The coordinates of the symbol's path are translated left and up by the anchor's x and y coordinates respectively. By default, a symbol is anchored at (0, 0). The position is expressed in the same coordinate system as the symbol's path.
  • fillColor is the color of the symbol's fill (that is, the region bordered by the stroke). All CSS3 colors are supported except for extended named colors. For symbols on markers, the default is 'black'. For symbols on polylines, the default is the stroke color of the corresponding polyline.
  • fillOpacity defines the relative opacity (that is, lack of transparency) of the symbol's fill. The values range from 0.0 (fully transparent) to 1.0 (fully opaque). The default is 0.0.
  • rotation is the angle by which to rotate the symbol, expressed clockwise in degrees. By default, a symbol marker has a rotation of 0, and a symbol on a polyline is rotated by the angle of the edge on which it lies. Setting the rotation of a symbol on a polyline will fix the rotation of the symbol such that it will no longer follow the curve of the line.
  • scale sets the amount by which the symbol is scaled in size. For symbol markers, the default scale is 1. After scaling the symbol may be of any size. For symbols on a polyline, the default scale is the stroke weight of the polyline. After scaling, the symbol must lie inside a 22x22px square, centered at the symbol's anchor.
  • strokeColor is the color of the symbol's outline. All CSS3 colors are supported except for extended named colors. For symbols on markers, the default is 'black'. For symbols on a polyline, the default color is the stroke color of the polyline.
  • strokeOpacity determines the relative opacity (that is, lack of transparency) of the symbol's stroke. The values range from 0.0 (fully transparent) to 1.0 (fully opaque). For symbol markers, the default is 1.0. For symbols on polylines, the default is the stroke opacity of the polyline.
  • strokeWeight defines the weight of the symbol's outline. The default is the scale of the symbol.

Predefined symbols

The Maps JavaScript API provides some built-in symbols that you can add to markers or polylines via the SymbolPath class.

The default symbols include a circle and two types of arrows. Both forward and backward facing arrows are available. This is especially useful for polylines, because the orientation of a symbol on a polyline is fixed. Forward is considered to be in the direction of the terminus of the polyline.

You can modify the stroke or fill of the predefined symbols using any of the default symbol options.

The following predefined symbols are included:

Name Description Example
google.maps.SymbolPath.CIRCLE A circle.
google.maps.SymbolPath.BACKWARD_CLOSED_ARROW A backward-pointing arrow that is closed on all sides.
google.maps.SymbolPath.FORWARD_CLOSED_ARROW A forward-pointing arrow that is closed on all sides.
google.maps.SymbolPath.BACKWARD_OPEN_ARROW A backward-pointing arrow that is open on one side.
google.maps.SymbolPath.FORWARD_OPEN_ARROW A forward-pointing arrow that is open on one side.

Add a symbol to a marker

To display a vector-based icon on an AdvancedMarkerElement, use an SVG XML element. The following example shows how to append an SVG XML element to an AdvancedMarkerElement.

TypeScript

const parser = new DOMParser();

// A marker with a custom inline SVG.
const pinSvgString =
    '<svg xmlns="http://www.w3.org/2000/svg" width="56" height="56" viewBox="0 0 56 56" fill="none"><rect width="56" height="56" rx="28" fill="#7837FF"></rect><path d="M46.0675 22.1319L44.0601 22.7843" stroke="white" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"></path><path d="M11.9402 33.2201L9.93262 33.8723" stroke="white" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"></path><path d="M27.9999 47.0046V44.8933" stroke="white" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"></path><path d="M27.9999 9V11.1113" stroke="white" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"></path><path d="M39.1583 43.3597L37.9186 41.6532" stroke="white" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"></path><path d="M16.8419 12.6442L18.0816 14.3506" stroke="white" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"></path><path d="M9.93262 22.1319L11.9402 22.7843" stroke="white" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"></path><path d="M46.0676 33.8724L44.0601 33.2201" stroke="white" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"></path><path d="M39.1583 12.6442L37.9186 14.3506" stroke="white" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"></path><path d="M16.8419 43.3597L18.0816 41.6532" stroke="white" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"></path><path d="M28 39L26.8725 37.9904C24.9292 36.226 23.325 34.7026 22.06 33.4202C20.795 32.1378 19.7867 30.9918 19.035 29.9823C18.2833 28.9727 17.7562 28.0587 17.4537 27.2401C17.1512 26.4216 17 25.5939 17 24.7572C17 23.1201 17.5546 21.7513 18.6638 20.6508C19.7729 19.5502 21.1433 19 22.775 19C23.82 19 24.7871 19.2456 25.6762 19.7367C26.5654 20.2278 27.34 20.9372 28 21.8649C28.77 20.8827 29.5858 20.1596 30.4475 19.6958C31.3092 19.2319 32.235 19 33.225 19C34.8567 19 36.2271 19.5502 37.3362 20.6508C38.4454 21.7513 39 23.1201 39 24.7572C39 25.5939 38.8488 26.4216 38.5463 27.2401C38.2438 28.0587 37.7167 28.9727 36.965 29.9823C36.2133 30.9918 35.205 32.1378 33.94 33.4202C32.675 34.7026 31.0708 36.226 29.1275 37.9904L28 39Z" fill="#FF7878"></path></svg>';

const pinSvg = parser.parseFromString(
    pinSvgString,
    'image/svg+xml'
).documentElement;
const pinSvgMarker = new AdvancedMarkerElement({
    position: { lat: 37.42475, lng: -122.094 },
    title: 'A marker using a custom SVG image.',
    anchorLeft: '-50%',
    anchorTop: '-50%',
});
pinSvgMarker.append(pinSvg);
mapElement.append(pinSvgMarker);

JavaScript

const parser = new DOMParser();

// A marker with a custom inline SVG.
const pinSvgString =
    '<svg xmlns="http://www.w3.org/2000/svg" width="56" height="56" viewBox="0 0 56 56" fill="none"><rect width="56" height="56" rx="28" fill="#7837FF"></rect><path d="M46.0675 22.1319L44.0601 22.7843" stroke="white" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"></path><path d="M11.9402 33.2201L9.93262 33.8723" stroke="white" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"></path><path d="M27.9999 47.0046V44.8933" stroke="white" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"></path><path d="M27.9999 9V11.1113" stroke="white" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"></path><path d="M39.1583 43.3597L37.9186 41.6532" stroke="white" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"></path><path d="M16.8419 12.6442L18.0816 14.3506" stroke="white" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"></path><path d="M9.93262 22.1319L11.9402 22.7843" stroke="white" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"></path><path d="M46.0676 33.8724L44.0601 33.2201" stroke="white" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"></path><path d="M39.1583 12.6442L37.9186 14.3506" stroke="white" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"></path><path d="M16.8419 43.3597L18.0816 41.6532" stroke="white" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"></path><path d="M28 39L26.8725 37.9904C24.9292 36.226 23.325 34.7026 22.06 33.4202C20.795 32.1378 19.7867 30.9918 19.035 29.9823C18.2833 28.9727 17.7562 28.0587 17.4537 27.2401C17.1512 26.4216 17 25.5939 17 24.7572C17 23.1201 17.5546 21.7513 18.6638 20.6508C19.7729 19.5502 21.1433 19 22.775 19C23.82 19 24.7871 19.2456 25.6762 19.7367C26.5654 20.2278 27.34 20.9372 28 21.8649C28.77 20.8827 29.5858 20.1596 30.4475 19.6958C31.3092 19.2319 32.235 19 33.225 19C34.8567 19 36.2271 19.5502 37.3362 20.6508C38.4454 21.7513 39 23.1201 39 24.7572C39 25.5939 38.8488 26.4216 38.5463 27.2401C38.2438 28.0587 37.7167 28.9727 36.965 29.9823C36.2133 30.9918 35.205 32.1378 33.94 33.4202C32.675 34.7026 31.0708 36.226 29.1275 37.9904L28 39Z" fill="#FF7878"></path></svg>';

const pinSvg = parser.parseFromString(
    pinSvgString,
    'image/svg+xml'
).documentElement;
const pinSvgMarker = new AdvancedMarkerElement({
    position: { lat: 37.42475, lng: -122.094 },
    title: 'A marker using a custom SVG image.',
    anchorLeft: '-50%',
    anchorTop: '-50%',
});
pinSvgMarker.append(pinSvg);
mapElement.append(pinSvgMarker);

Add a symbol to a polyline

To display symbols on a polyline, set the icons[] property of the PolylineOptions object. The icons[] array takes one or more IconSequence object literals, with the following properties:

  • icon (required) is the symbol to render on the line.
  • offset determines the distance from the start of the line at which an icon is to be rendered. This distance may be expressed as a percentage of the line's length (for example, '50%') or in pixels (for example, '50px'). The default is '100%'.
  • repeat determines the distance between consecutive icons on the line. This distance may be expressed as a percentage of the line's length (for example, '50%') or in pixels (for example, '50px'). To disable repeating of the icon, specify '0'. The default is '0'.

With a combination of symbols and the PolylineOptions class, you have a lot of control over the look and feel of polylines on your map. Below are some examples of customizations you can apply.

Arrows

Use the IconSequence.offset property to add arrows to the start or end of your polyline.

// Define a symbol using a predefined path (an arrow)
// supplied by the Google Maps JavaScript API.
var lineSymbol = {
  path: google.maps.SymbolPath.FORWARD_CLOSED_ARROW
};

// Create the polyline and add the symbol via the 'icons' property.
var line = new google.maps.Polyline({
  path: [{lat: 22.291, lng: 153.027}, {lat: 18.291, lng: 153.027}],
  icons: [{
    icon: lineSymbol,
    offset: '100%'
  }],
  map: map
});

View example

Dashed lines

You can achieve a dashed line effect by setting the opacity of your polyline to 0, and overlaying an opaque symbol over the line at regular intervals.

// Define a symbol using SVG path notation, with an opacity of 1.
var lineSymbol = {
  path: 'M 0,-1 0,1',
  strokeOpacity: 1,
  scale: 4
};

// Create the polyline, passing the symbol in the 'icons' property.
// Give the line an opacity of 0.
// Repeat the symbol at intervals of 20 pixels to create the dashed effect.
var line = new google.maps.Polyline({
  path: [{lat: 22.291, lng: 153.027}, {lat: 18.291, lng: 153.027}],
  strokeOpacity: 0,
  icons: [{
    icon: lineSymbol,
    offset: '0',
    repeat: '20px'
  }],
  map: map
});

View example

Custom paths

Custom symbols allow you to add many different shapes to a polyline.

// Define the custom symbols. All symbols are defined via SVG path notation.
// They have varying stroke color, fill color, stroke weight,
// opacity and rotation properties.
  var symbolOne = {
    path: 'M -2,0 0,-2 2,0 0,2 z',
    strokeColor: '#F00',
    fillColor: '#F00',
    fillOpacity: 1
  };

  var symbolTwo = {
    path: 'M -1,0 A 1,1 0 0 0 -3,0 1,1 0 0 0 -1,0M 1,0 A 1,1 0 0 0 3,0 1,1 0 0 0 1,0M -3,3 Q 0,5 3,3',
    strokeColor: '#00F',
    rotation: 45
  };

  var symbolThree = {
    path: 'M -2,-2 2,2 M 2,-2 -2,2',
    strokeColor: '#292',
    strokeWeight: 4
  };

  // Create the polyline and add the symbols via the 'icons' property.
  var line = new google.maps.Polyline({
    path: [{lat: 22.291, lng: 153.027}, {lat: 18.291, lng: 153.027}],
    icons: [
      {
        icon: symbolOne,
        offset: '0%'
      }, {
        icon: symbolTwo,
        offset: '50%'
      }, {
        icon: symbolThree,
        offset: '100%'
      }
    ],
    map: map
  });

View example

Animate a symbol

You can animate a symbol along a path by using the DOM's window.setInterval() function to change the offset of the symbol at fixed intervals.

TypeScript

// This example adds an animated symbol to a polyline.

function initMap(): void {
  const map = new google.maps.Map(
    document.getElementById("map") as HTMLElement,
    {
      center: { lat: 20.291, lng: 153.027 },
      zoom: 6,
      mapTypeId: "terrain",
    }
  );

  // Define the symbol, using one of the predefined paths ('CIRCLE')
  // supplied by the Google Maps JavaScript API.
  const lineSymbol = {
    path: google.maps.SymbolPath.CIRCLE,
    scale: 8,
    strokeColor: "#393",
  };

  // Create the polyline and add the symbol to it via the 'icons' property.
  const line = new google.maps.Polyline({
    path: [
      { lat: 22.291, lng: 153.027 },
      { lat: 18.291, lng: 153.027 },
    ],
    icons: [
      {
        icon: lineSymbol,
        offset: "100%",
      },
    ],
    map: map,
  });

  animateCircle(line);
}

// Use the DOM setInterval() function to change the offset of the symbol
// at fixed intervals.
function animateCircle(line: google.maps.Polyline) {
  let count = 0;

  window.setInterval(() => {
    count = (count + 1) % 200;

    const icons = line.get("icons");

    icons[0].offset = count / 2 + "%";
    line.set("icons", icons);
  }, 20);
}

declare global {
  interface Window {
    initMap: () => void;
  }
}
window.initMap = initMap;

JavaScript

// This example adds an animated symbol to a polyline.
function initMap() {
  const map = new google.maps.Map(document.getElementById("map"), {
    center: { lat: 20.291, lng: 153.027 },
    zoom: 6,
    mapTypeId: "terrain",
  });
  // Define the symbol, using one of the predefined paths ('CIRCLE')
  // supplied by the Google Maps JavaScript API.
  const lineSymbol = {
    path: google.maps.SymbolPath.CIRCLE,
    scale: 8,
    strokeColor: "#393",
  };
  // Create the polyline and add the symbol to it via the 'icons' property.
  const line = new google.maps.Polyline({
    path: [
      { lat: 22.291, lng: 153.027 },
      { lat: 18.291, lng: 153.027 },
    ],
    icons: [
      {
        icon: lineSymbol,
        offset: "100%",
      },
    ],
    map: map,
  });

  animateCircle(line);
}

// Use the DOM setInterval() function to change the offset of the symbol
// at fixed intervals.
function animateCircle(line) {
  let count = 0;

  window.setInterval(() => {
    count = (count + 1) % 200;

    const icons = line.get("icons");

    icons[0].offset = count / 2 + "%";
    line.set("icons", icons);
  }, 20);
}

window.initMap = initMap;
View example