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MouseWheelZoom.js
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MouseWheelZoom.js
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/**
* @module ol/interaction/MouseWheelZoom
*/
import EventType from '../events/EventType.js';
import Interaction, {zoomByDelta} from './Interaction.js';
import {DEVICE_PIXEL_RATIO, FIREFOX} from '../has.js';
import {all, always, focusWithTabindex} from '../events/condition.js';
import {clamp} from '../math.js';
/**
* @typedef {'trackpad' | 'wheel'} Mode
*/
/**
* @typedef {Object} Options
* @property {import("../events/condition.js").Condition} [condition] A function that
* takes a {@link module:ol/MapBrowserEvent~MapBrowserEvent} and returns a
* boolean to indicate whether that event should be handled. Default is
* {@link module:ol/events/condition.always}.
* @property {boolean} [onFocusOnly=false] When the map's target has a `tabindex` attribute set,
* the interaction will only handle events when the map has the focus.
* @property {number} [maxDelta=1] Maximum mouse wheel delta.
* @property {number} [duration=250] Animation duration in milliseconds.
* @property {number} [timeout=80] Mouse wheel timeout duration in milliseconds.
* @property {boolean} [useAnchor=true] Enable zooming using the mouse's
* location as the anchor. When set to `false`, zooming in and out will zoom to
* the center of the screen instead of zooming on the mouse's location.
* @property {boolean} [constrainResolution=false] If true, the mouse wheel zoom
* event will always animate to the closest zoom level after an interaction;
* false means intermediary zoom levels are allowed.
*/
/**
* @classdesc
* Allows the user to zoom the map by scrolling the mouse wheel.
* @api
*/
class MouseWheelZoom extends Interaction {
/**
* @param {Options} [options] Options.
*/
constructor(options) {
options = options ? options : {};
super(
/** @type {import("./Interaction.js").InteractionOptions} */ (options),
);
/**
* @private
* @type {number}
*/
this.totalDelta_ = 0;
/**
* @private
* @type {number}
*/
this.lastDelta_ = 0;
/**
* @private
* @type {number}
*/
this.maxDelta_ = options.maxDelta !== undefined ? options.maxDelta : 1;
/**
* @private
* @type {number}
*/
this.duration_ = options.duration !== undefined ? options.duration : 250;
/**
* @private
* @type {number}
*/
this.timeout_ = options.timeout !== undefined ? options.timeout : 80;
/**
* @private
* @type {boolean}
*/
this.useAnchor_ =
options.useAnchor !== undefined ? options.useAnchor : true;
/**
* @private
* @type {boolean}
*/
this.constrainResolution_ =
options.constrainResolution !== undefined
? options.constrainResolution
: false;
const condition = options.condition ? options.condition : always;
/**
* @private
* @type {import("../events/condition.js").Condition}
*/
this.condition_ = options.onFocusOnly
? all(focusWithTabindex, condition)
: condition;
/**
* @private
* @type {?import("../pixel.js").Pixel}
*/
this.lastAnchor_ = null;
/**
* @private
* @type {number|undefined}
*/
this.startTime_ = undefined;
/**
* @private
* @type {ReturnType<typeof setTimeout>}
*/
this.timeoutId_;
/**
* @private
* @type {Mode|undefined}
*/
this.mode_ = undefined;
/**
* Trackpad events separated by this delay will be considered separate
* interactions.
* @private
* @type {number}
*/
this.trackpadEventGap_ = 400;
/**
* @private
* @type {ReturnType<typeof setTimeout>}
*/
this.trackpadTimeoutId_;
/**
* The number of delta values per zoom level
* @private
* @type {number}
*/
this.deltaPerZoom_ = 300;
}
/**
* @private
*/
endInteraction_() {
this.trackpadTimeoutId_ = undefined;
const map = this.getMap();
if (!map) {
return;
}
const view = map.getView();
view.endInteraction(
undefined,
this.lastDelta_ ? (this.lastDelta_ > 0 ? 1 : -1) : 0,
this.lastAnchor_ ? map.getCoordinateFromPixel(this.lastAnchor_) : null,
);
}
/**
* Handles the {@link module:ol/MapBrowserEvent~MapBrowserEvent map browser event} (if it was a mousewheel-event) and eventually
* zooms the map.
* @param {import("../MapBrowserEvent.js").default} mapBrowserEvent Map browser event.
* @return {boolean} `false` to stop event propagation.
* @override
*/
handleEvent(mapBrowserEvent) {
if (!this.condition_(mapBrowserEvent)) {
return true;
}
const type = mapBrowserEvent.type;
if (type !== EventType.WHEEL) {
return true;
}
const map = mapBrowserEvent.map;
const wheelEvent = /** @type {WheelEvent} */ (
mapBrowserEvent.originalEvent
);
wheelEvent.preventDefault();
if (this.useAnchor_) {
this.lastAnchor_ = mapBrowserEvent.pixel;
}
// Delta normalisation inspired by
// https://github.com/mapbox/mapbox-gl-js/blob/001c7b9/js/ui/handler/scroll_zoom.js
let delta;
if (mapBrowserEvent.type == EventType.WHEEL) {
delta = wheelEvent.deltaY;
if (FIREFOX && wheelEvent.deltaMode === WheelEvent.DOM_DELTA_PIXEL) {
delta /= DEVICE_PIXEL_RATIO;
}
if (wheelEvent.deltaMode === WheelEvent.DOM_DELTA_LINE) {
delta *= 40;
}
}
if (delta === 0) {
return false;
}
this.lastDelta_ = delta;
const now = Date.now();
if (this.startTime_ === undefined) {
this.startTime_ = now;
}
if (!this.mode_ || now - this.startTime_ > this.trackpadEventGap_) {
this.mode_ = Math.abs(delta) < 4 ? 'trackpad' : 'wheel';
}
const view = map.getView();
if (
this.mode_ === 'trackpad' &&
!(view.getConstrainResolution() || this.constrainResolution_)
) {
if (this.trackpadTimeoutId_) {
clearTimeout(this.trackpadTimeoutId_);
} else {
if (view.getAnimating()) {
view.cancelAnimations();
}
view.beginInteraction();
}
this.trackpadTimeoutId_ = setTimeout(
this.endInteraction_.bind(this),
this.timeout_,
);
view.adjustZoom(
-delta / this.deltaPerZoom_,
this.lastAnchor_ ? map.getCoordinateFromPixel(this.lastAnchor_) : null,
);
this.startTime_ = now;
return false;
}
this.totalDelta_ += delta;
const timeLeft = Math.max(this.timeout_ - (now - this.startTime_), 0);
clearTimeout(this.timeoutId_);
this.timeoutId_ = setTimeout(
this.handleWheelZoom_.bind(this, map),
timeLeft,
);
return false;
}
/**
* @private
* @param {import("../Map.js").default} map Map.
*/
handleWheelZoom_(map) {
const view = map.getView();
if (view.getAnimating()) {
view.cancelAnimations();
}
let delta =
-clamp(
this.totalDelta_,
-this.maxDelta_ * this.deltaPerZoom_,
this.maxDelta_ * this.deltaPerZoom_,
) / this.deltaPerZoom_;
if (view.getConstrainResolution() || this.constrainResolution_) {
// view has a zoom constraint, zoom by 1
delta = delta ? (delta > 0 ? 1 : -1) : 0;
}
zoomByDelta(
view,
delta,
this.lastAnchor_ ? map.getCoordinateFromPixel(this.lastAnchor_) : null,
this.duration_,
);
this.mode_ = undefined;
this.totalDelta_ = 0;
this.lastAnchor_ = null;
this.startTime_ = undefined;
this.timeoutId_ = undefined;
}
/**
* Enable or disable using the mouse's location as an anchor when zooming
* @param {boolean} useAnchor true to zoom to the mouse's location, false
* to zoom to the center of the map
* @api
*/
setMouseAnchor(useAnchor) {
this.useAnchor_ = useAnchor;
if (!useAnchor) {
this.lastAnchor_ = null;
}
}
}
export default MouseWheelZoom;