leaflet/src/map/handler/Map.BoxZoom.js

JavaScript library for mobile-friendly interactive maps

/*
 * L.Handler.ShiftDragZoom is used to add shift-drag zoom interaction to the map
  * (zoom to a selected bounding box), enabled by default.
 */

L.Map.mergeOptions({
	boxZoom: true
});

L.Map.BoxZoom = L.Handler.extend({
	initialize: function (map) {
		this._map = map;
		this._container = map._container;
		this._pane = map._panes.overlayPane;
		this._moved = false;
	},

	addHooks: function () {
		L.DomEvent.on(this._container, 'mousedown', this._onMouseDown, this);
	},

	removeHooks: function () {
		L.DomEvent.off(this._container, 'mousedown', this._onMouseDown);
		this._moved = false;
	},

	moved: function () {
		return this._moved;
	},

	_onMouseDown: function (e) {
		this._moved = false;

		if (!e.shiftKey || ((e.which !== 1) && (e.button !== 1))) { return false; }

		L.DomUtil.disableTextSelection();
		L.DomUtil.disableImageDrag();

		this._startLayerPoint = this._map.mouseEventToLayerPoint(e);

		L.DomEvent
		    .on(document, 'mousemove', this._onMouseMove, this)
		    .on(document, 'mouseup', this._onMouseUp, this)
		    .on(document, 'keydown', this._onKeyDown, this);
	},

	_onMouseMove: function (e) {
		if (!this._moved) {
			this._box = L.DomUtil.create('div', 'leaflet-zoom-box', this._pane);
			L.DomUtil.setPosition(this._box, this._startLayerPoint);

			//TODO refactor: move cursor to styles
			this._container.style.cursor = 'crosshair';
			this._map.fire('boxzoomstart');
		}

		var startPoint = this._startLayerPoint,
		    box = this._box,

		    layerPoint = this._map.mouseEventToLayerPoint(e),
		    offset = layerPoint.subtract(startPoint),

		    newPos = new L.Point(
		        Math.min(layerPoint.x, startPoint.x),
		        Math.min(layerPoint.y, startPoint.y));

		L.DomUtil.setPosition(box, newPos);

		this._moved = true;

		// TODO refactor: remove hardcoded 4 pixels
		box.style.width  = (Math.max(0, Math.abs(offset.x) - 4)) + 'px';
		box.style.height = (Math.max(0, Math.abs(offset.y) - 4)) + 'px';
	},

	_finish: function () {
		if (this._moved) {
			this._pane.removeChild(this._box);
			this._container.style.cursor = '';
		}

		L.DomUtil.enableTextSelection();
		L.DomUtil.enableImageDrag();

		L.DomEvent
		    .off(document, 'mousemove', this._onMouseMove)
		    .off(document, 'mouseup', this._onMouseUp)
		    .off(document, 'keydown', this._onKeyDown);
	},

	_onMouseUp: function (e) {

		this._finish();

		var map = this._map,
		    layerPoint = map.mouseEventToLayerPoint(e);

		if (this._startLayerPoint.equals(layerPoint)) { return; }

		var bounds = new L.LatLngBounds(
		        map.layerPointToLatLng(this._startLayerPoint),
		        map.layerPointToLatLng(layerPoint));

		map.fitBounds(bounds);

		map.fire('boxzoomend', {
			boxZoomBounds: bounds
		});
	},

	_onKeyDown: function (e) {
		if (e.keyCode === 27) {
			this._finish();
		}
	}
});

L.Map.addInitHook('addHandler', 'boxZoom', L.Map.BoxZoom);