StyleImageInterface

Interface for dynamically generated style images. This is a specification for implementers to model: it is not an exported method or class.

Images implementing this interface can be redrawn for every frame. They can be used to animate icons and patterns or make them respond to user input. Style images can implement a StyleImageInterface#render method. The method is called every frame and can be used to update the image.

See

Add an animated icon to the map.

Example

let flashingSquare = {
    width: 64,
    height: 64,
    data: new Uint8Array(64 * 64 * 4),

    onAdd: function(map) {
        this.map = map;
    },

    render: function() {
        // keep repainting while the icon is on the map
        this.map.triggerRepaint();

        // alternate between black and white based on the time
        let value = Math.round(Date.now() / 1000) % 2 === 0  ? 255 : 0;

        // check if image needs to be changed
        if (value !== this.previousValue) {
            this.previousValue = value;

            let bytesPerPixel = 4;
            for (let x = 0; x < this.width; x++) {
                for (let y = 0; y < this.height; y++) {
                    let offset = (y * this.width + x) * bytesPerPixel;
                    this.data[offset + 0] = value;
                    this.data[offset + 1] = value;
                    this.data[offset + 2] = value;
                    this.data[offset + 3] = 255;
                }
            }

            // return true to indicate that the image changed
            return true;
        }
    }
 }

 map.addImage('flashing_square', flashingSquare);

Properties

onAdd()?

optional onAdd: (map: Map, id: string) => void

Optional method called when the layer has been added to the Map with Map#addImage.

Parameters

Parameter	Type	Description
map	Map	The Map this custom layer was just added to.
id	string	-

Returns

void

Defined in

src/style/style_image.ts:170

---

onRemove()?

optional onRemove: () => void

Optional method called when the icon is removed from the map with Map#removeImage. This gives the image a chance to clean up resources and event listeners.

Returns

void

Defined in

src/style/style_image.ts:175

---

render()?

optional render: () => boolean

This method is called once before every frame where the icon will be used. The method can optionally update the image's data member with a new image.

If the method updates the image it must return true to commit the change. If the method returns false or nothing the image is assumed to not have changed.

If updates are infrequent it maybe easier to use Map#updateImage to update the image instead of implementing this method.

Returns

boolean

true if this method updated the image. false if the image was not changed.

Defined in

src/style/style_image.ts:164