L.GridLayer

GridLayer

Generic class for handling a tiled grid of HTML elements. This is the base class for all tile layers and replaces TileLayer.Canvas. GridLayer can be extended to create a tiled grid of HTML elements like <canvas>, <img> or <div>. GridLayer will handle creating and animating these DOM elements for you.

Usage example

Synchronous usage

To create a custom layer, extend GridLayer and implement the createTile() method, which will be passed a Point object with the x, y, and z (zoom level) coordinates to draw your tile.

var CanvasLayer = L.GridLayer.extend({
    createTile: function(coords){
        // create a <canvas> element for drawing
        var tile = L.DomUtil.create('canvas', 'leaflet-tile');
        // setup tile width and height according to the options
        var size = this.getTileSize();
        tile.width = size.x;
        tile.height = size.y;
        // get a canvas context and draw something on it using coords.x, coords.y and coords.z
        var ctx = tile.getContext('2d');
        // return the tile so it can be rendered on screen
        return tile;
    }
});

Asynchronous usage

Tile creation can also be asynchronous, this is useful when using a third-party drawing library. Once the tile is finished drawing it can be passed to the done() callback.

var CanvasLayer = L.GridLayer.extend({
    createTile: function(coords, done){
        var error;
        // create a <canvas> element for drawing
        var tile = L.DomUtil.create('canvas', 'leaflet-tile');
        // setup tile width and height according to the options
        var size = this.getTileSize();
        tile.width = size.x;
        tile.height = size.y;
        // draw something asynchronously and pass the tile to the done() callback
        setTimeout(function() {
            done(error, tile);
        }, 1000);
        return tile;
    }
});

Creation

Factory	Description
`L.gridLayer(<GridLayer options> options?)`	Creates a new instance of GridLayer with the supplied options.

Options

Option	Type	Default	Description
`tileSize`	`Number\|Point`	`256`	Width and height of tiles in the grid. Use a number if width and height are equal, or `L.point(width, height)` otherwise.
`opacity`	`Number`	`1.0`	Opacity of the tiles. Can be used in the `createTile()` function.
`updateWhenIdle`	`Boolean`	`depends`	If `false`, new tiles are loaded during panning, otherwise only after it (for better performance). `true` by default on mobile browsers, otherwise `false`.
`updateWhenZooming`	`Boolean`	`true`	By default, a smooth zoom animation (during a touch zoom or a `flyTo()`) will update grid layers every integer zoom level. Setting this option to `false` will update the grid layer only when the smooth animation ends.
`updateInterval`	`Number`	`200`	Tiles will not update more than once every `updateInterval` milliseconds when panning.
`attribution`	`String`	`null`	String to be shown in the attribution control, describes the layer data, e.g. "© OpenStreetMap contributors".
`zIndex`	`Number`	`1`	The explicit zIndex of the tile layer.
`bounds`	`LatLngBounds`	`undefined`	If set, tiles will only be loaded inside the set `LatLngBounds`.
`minZoom`	`Number`	`0`	The minimum zoom level that tiles will be loaded at. By default the entire map.
`maxZoom`	`Number`	`undefined`	The maximum zoom level that tiles will be loaded at.
`noWrap`	`Boolean`	`false`	Whether the layer is wrapped around the antimeridian. If `true`, the GridLayer will only be displayed once at low zoom levels. Has no effect when the map CRS doesn't wrap around.
`pane`	`String`	`'tilePane'`	`Map pane` where the grid layer will be added.
`className`	`String`	`''`	A custom class name to assign to the tile layer. Empty by default.
`keepBuffer`	`Number`	`2`	When panning the map, keep this many rows and columns of tiles before unloading them.

Events

Event	Data	Description
`loading`	`Event`	Fired when the grid layer starts loading tiles.
`tileunload`	`TileEvent`	Fired when a tile is removed (e.g. when a tile goes off the screen).
`tileloadstart`	`TileEvent`	Fired when a tile is requested and starts loading.
`tileerror`	`TileErrorEvent`	Fired when there is an error loading a tile.
`tileload`	`TileEvent`	Fired when a tile loads.
`load`	`Event`	Fired when the grid layer loaded all visible tiles.

▶ Events inherited from Layer

Event	Data	Description
`add`	`Event`	Fired after the layer is added to a map
`remove`	`Event`	Fired after the layer is removed from a map

▶ Popup events inherited from Layer

Event	Data	Description
`popupopen`	`PopupEvent`	Fired when a popup bound to this layer is opened
`popupclose`	`PopupEvent`	Fired when a popup bound to this layer is closed

▶ Tooltip events inherited from Layer

Event	Data	Description
`tooltipopen`	`TooltipEvent`	Fired when a tooltip bound to this layer is opened.
`tooltipclose`	`TooltipEvent`	Fired when a tooltip bound to this layer is closed.

Methods

Method	Returns	Description
`bringToFront()`	`this`	Brings the tile layer to the top of all tile layers.
`bringToBack()`	`this`	Brings the tile layer to the bottom of all tile layers.
`getAttribution()`	`String`	Used by the `attribution control`, returns the attribution option.
`getContainer()`	`HTMLElement`	Returns the HTML element that contains the tiles for this layer.
`setOpacity(<Number> opacity)`	`this`	Changes the opacity of the grid layer.
`setZIndex(<Number> zIndex)`	`this`	Changes the zIndex of the grid layer.
`isLoading()`	`Boolean`	Returns `true` if any tile in the grid layer has not finished loading.
`redraw()`	`this`	Causes the layer to clear all the tiles and request them again.
`getTileSize()`	`Point`	Normalizes the tileSize option into a point. Used by the `createTile()` method.

Extension methods

Layers extending GridLayer shall reimplement the following method.

Method	Returns	Description
`createTile(<Object> coords, <Function> done?)`	`HTMLElement`	Called only internally, must be overriden by classes extending `GridLayer`. Returns the `HTMLElement` corresponding to the given `coords`. If the `done` callback is specified, it must be called when the tile has finished loading and drawing.

▶ Popup methods inherited from Layer

Method	Returns	Description
`bindPopup(<String\|HTMLElement\|Function\|Popup> content, <Popup options> options?)`	`this`	Binds a popup to the layer with the passed `content` and sets up the neccessary event listeners. If a `Function` is passed it will receive the layer as the first argument and should return a `String` or `HTMLElement`.
`unbindPopup()`	`this`	Removes the popup previously bound with `bindPopup`.
`openPopup(<LatLng> latlng?)`	`this`	Opens the bound popup at the specificed `latlng` or at the default popup anchor if no `latlng` is passed.
`closePopup()`	`this`	Closes the popup bound to this layer if it is open.
`togglePopup()`	`this`	Opens or closes the popup bound to this layer depending on its current state.
`isPopupOpen()`	`boolean`	Returns `true` if the popup bound to this layer is currently open.
`setPopupContent(<String\|HTMLElement\|Popup> content)`	`this`	Sets the content of the popup bound to this layer.
`getPopup()`	`Popup`	Returns the popup bound to this layer.

▶ Tooltip methods inherited from Layer

Method	Returns	Description
`bindTooltip(<String\|HTMLElement\|Function\|Tooltip> content, <Tooltip options> options?)`	`this`	Binds a tooltip to the layer with the passed `content` and sets up the neccessary event listeners. If a `Function` is passed it will receive the layer as the first argument and should return a `String` or `HTMLElement`.
`unbindTooltip()`	`this`	Removes the tooltip previously bound with `bindTooltip`.
`openTooltip(<LatLng> latlng?)`	`this`	Opens the bound tooltip at the specificed `latlng` or at the default tooltip anchor if no `latlng` is passed.
`closeTooltip()`	`this`	Closes the tooltip bound to this layer if it is open.
`toggleTooltip()`	`this`	Opens or closes the tooltip bound to this layer depending on its current state.
`isTooltipOpen()`	`boolean`	Returns `true` if the tooltip bound to this layer is currently open.
`setTooltipContent(<String\|HTMLElement\|Tooltip> content)`	`this`	Sets the content of the tooltip bound to this layer.
`getTooltip()`	`Tooltip`	Returns the tooltip bound to this layer.

▶ Methods inherited from Layer

Method	Returns	Description
`addTo(<Map> map)`	`this`	Adds the layer to the given map
`remove()`	`this`	Removes the layer from the map it is currently active on.
`removeFrom(<Map> map)`	`this`	Removes the layer from the given map
`getPane(<String> name?)`	`HTMLElement`	Returns the `HTMLElement` representing the named pane on the map. If `name` is omitted, returns the pane for this layer.

▶ Methods inherited from Evented

Method	Returns	Description
`on(<String> type, <Function> fn, <Object> context?)`	`this`	Adds a listener function (`fn`) to a particular event type of the object. You can optionally specify the context of the listener (object the this keyword will point to). You can also pass several space-separated types (e.g. `'click dblclick'`).
`on(<Object> eventMap)`	`this`	Adds a set of type/listener pairs, e.g. `{click: onClick, mousemove: onMouseMove}`
`off(<String> type, <Function> fn?, <Object> context?)`	`this`	Removes a previously added listener function. If no function is specified, it will remove all the listeners of that particular event from the object. Note that if you passed a custom context to `on`, you must pass the same context to `off` in order to remove the listener.
`off(<Object> eventMap)`	`this`	Removes a set of type/listener pairs.
`off()`	`this`	Removes all listeners to all events on the object.
`fire(<String> type, <Object> data?, <Boolean> propagate?)`	`this`	Fires an event of the specified type. You can optionally provide an data object — the first argument of the listener function will contain its properties. The event might can optionally be propagated to event parents.
`listens(<String> type)`	`Boolean`	Returns `true` if a particular event type has any listeners attached to it.
`once(…)`	`this`	Behaves as `on(…)`, except the listener will only get fired once and then removed.
`addEventParent(<Evented> obj)`	`this`	Adds an event parent - an `Evented` that will receive propagated events
`removeEventParent(<Evented> obj)`	`this`	Removes an event parent, so it will stop receiving propagated events
`addEventListener(…)`	`this`	Alias to `on(…)`
`removeEventListener(…)`	`this`	Alias to `off(…)`
`clearAllEventListeners(…)`	`this`	Alias to `off()`
`addOneTimeEventListener(…)`	`this`	Alias to `once(…)`
`fireEvent(…)`	`this`	Alias to `fire(…)`
`hasEventListeners(…)`	`Boolean`	Alias to `listens(…)`