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* @module Watchers/GestureWatcher
*/
import * as MC from "@lisn/globals/minification-constants";
import * as MH from "@lisn/globals/minification-helpers";
import {
Direction,
GestureIntent,
GestureDevice,
CommaSeparatedStr,
} from "@lisn/globals/types";
import {
addClasses,
removeClasses,
setNumericStyleJsVars,
} from "@lisn/utils/css-alter";
import { isValidDirection } from "@lisn/utils/directions";
import {
addEventListenerTo,
removeEventListenerFrom,
preventSelect,
undoPreventSelect,
} from "@lisn/utils/event";
import { getDebouncedHandler } from "@lisn/utils/tasks";
import { addDeltaZ } from "@lisn/utils/gesture";
import {
isValidInputDevice,
isValidIntent,
GestureFragment,
DEVICES,
INTENTS,
} from "@lisn/utils/gesture";
import { getKeyGestureFragment } from "@lisn/utils/gesture-key";
import { getPointerGestureFragment } from "@lisn/utils/gesture-pointer";
import { getTouchGestureFragment } from "@lisn/utils/gesture-touch";
import { getWheelGestureFragment } from "@lisn/utils/gesture-wheel";
import { logError } from "@lisn/utils/log";
import {
maxAbs,
toNonNegNum,
toPosNum,
toNumWithBounds,
} from "@lisn/utils/math";
import { randId, objToStrKey } from "@lisn/utils/text";
import { validateStrList } from "@lisn/utils/validation";
import {
CallbackHandler,
Callback,
wrapCallback,
} from "@lisn/modules/callback";
import { newXWeakMap } from "@lisn/modules/x-map";
import { LoggerInterface } from "@lisn/debug/types";
import debug from "@lisn/debug/debug";
/**
* {@link GestureWatcher} listens for user gestures resulting from wheel,
* pointer, touch or key input events.
*
* It supports scroll, zoom or drag type gestures.
*
* It manages registered callbacks globally and reuses event listeners for more
* efficient performance.
*/
export class GestureWatcher {
/**
* Call the given handler whenever the user performs a gesture on the target
* matching the given options.
*
* **IMPORTANT:** The same handler can _not_ be added multiple times for the
* same event target, even if the options differ. If the handler has already
* been added for this target, either using {@link onGesture} or
* {@link trackGesture}, then it will be removed and re-added with the
* current options.
*
* @throws {@link Errors.LisnUsageError | LisnUsageError}
* If the options are invalid.
*/
readonly onGesture: (
target: EventTarget,
handler: OnGestureHandler,
options?: OnGestureOptions,
) => Promise<void>;
/**
* Removes a previously added handler.
*/
readonly offGesture: (target: EventTarget, handler: OnGestureHandler) => void;
/**
* This is the same as {@link onGesture} except that if `handler` is not
* given, then it defaults to an internal handler that updates a set of CSS
* variables on the target's style:
*
* - `--lisn-js--<Intent>-delta-x`
* - `--lisn-js--<Intent>-delta-y`
* - `--lisn-js--<Intent>-delta-z`
*
* where and `<Intent>` is one of {@link GestureIntent} and the delta X, Y
* and Z are the _total summed up_ `deltaX`, `deltaY` and `deltaZ` since the
* callback was added, summed over all devices used (key, touch, etc).
*
* **IMPORTANT:** The same handler can _not_ be added multiple times for the
* same target, even if the options differ. If the handler has already been
* added for this target, either using {@link trackGesture} or using
* {@link onGesture}, then it will be removed and re-added with the current
* options.
*
* @throws {@link Errors.LisnUsageError | LisnUsageError}
* If the options are invalid.
*/
readonly trackGesture: (
element: Element,
handler?: OnGestureHandler | null,
options?: OnGestureOptions,
) => Promise<void>;
/**
* Removes a previously added handler for {@link trackGesture}.
*/
readonly noTrackGesture: (
element: Element,
handler?: OnGestureHandler | null,
) => void;
/**
* Creates a new instance of GestureWatcher with the given
* {@link GestureWatcherConfig}. It does not save it for future reuse.
*/
static create(config?: GestureWatcherConfig) {
return new GestureWatcher(getConfig(config), CONSTRUCTOR_KEY);
}
/**
* Returns an existing instance of GestureWatcher with the given
* {@link GestureWatcherConfig}, or creates a new one.
*
* **NOTE:** It saves it for future reuse, so don't use this for temporary
* short-lived watchers.
*/
static reuse(config?: GestureWatcherConfig) {
const myConfig = getConfig(config);
const configStrKey = objToStrKey(myConfig);
let instance = instances.get(configStrKey);
if (!instance) {
instance = new GestureWatcher(myConfig, CONSTRUCTOR_KEY);
instances.set(configStrKey, instance);
}
return instance;
}
private constructor(
config: GestureWatcherConfigInternal,
key: typeof CONSTRUCTOR_KEY,
) {
if (key !== CONSTRUCTOR_KEY) {
throw MH.illegalConstructorError("GestureWatcher.create");
}
const logger = debug
? new debug.Logger({ name: "GestureWatcher", logAtCreation: config })
: null;
const allCallbacks = newXWeakMap<
EventTarget,
Map<
OnGestureHandler,
{
_callback: OnGestureCallback;
_wrapper: OnGestureHandlerWrapper;
_options: OnGestureOptionsInternal;
}
>
>(() => MH.newMap());
// For each target and event type, add only 1 global listener that will then
// manage the event queues and callbacks.
const allListeners = newXWeakMap<
EventTarget,
Map<GestureDevice, DeviceListeners>
>(() => MH.newMap());
// ----------
const createCallback = (
target: EventTarget,
handler: OnGestureHandler,
options: OnGestureOptionsInternal,
): OnGestureCallback => {
MH.remove(allCallbacks.get(target)?.get(handler)?._callback);
debug: logger?.debug5("Adding/updating handler for", options);
const { _callback, _wrapper } = getCallbackAndWrapper(
handler,
options,
logger,
);
_callback.onRemove(() => deleteHandler(target, handler, options));
allCallbacks.sGet(target).set(handler, {
_callback,
_wrapper,
_options: options,
});
return _callback;
};
// ----------
// async for consistency with other watchers and future compatibility in
// case of change needed
const setupOnGesture = async (
target: EventTarget,
handler: OnGestureHandler,
userOptions: OnGestureOptions | undefined,
) => {
const options = getOptions(config, userOptions ?? {});
createCallback(target, handler, options);
for (const device of options._devices ?? DEVICES) {
let listeners = allListeners.get(target)?.get(device);
if (listeners) {
debug: logger?.debug4(
`Listeners already added for ${device}`,
target,
options,
);
} else {
debug: logger?.debug4(
`Adding listeners for ${device}`,
target,
options,
);
listeners = setupListeners(target, device, options);
allListeners.sGet(target).set(device, listeners);
}
listeners._nCallbacks++;
if (options._preventDefault) {
listeners._nPreventDefault++;
}
}
};
// ----------
const deleteHandler = (
target: EventTarget,
handler: OnGestureHandler,
options: OnGestureOptionsInternal,
) => {
MH.deleteKey(allCallbacks.get(target), handler);
allCallbacks.prune(target);
for (const device of options._devices ?? DEVICES) {
const listeners = allListeners.get(target)?.get(device);
if (listeners) {
listeners._nCallbacks--;
if (options._preventDefault) {
listeners._nPreventDefault--;
}
if (!listeners._nCallbacks) {
debug: logger?.debug4(
`No more callbacks for target and device ${device}; removing listeners`,
target,
);
MH.deleteKey(allListeners.get(target), device);
listeners._remove();
}
}
}
};
// ----------
const invokeCallbacks = (
target: EventTarget,
device: GestureDevice,
event: Event,
): boolean /* true if terminated */ => {
const preventDefault =
(allListeners.get(target)?.get(device)?._nPreventDefault ?? 0) > 0;
let isTerminated = false;
for (const { _wrapper } of allCallbacks.get(target)?.values() || []) {
isTerminated =
_wrapper(target, device, event, preventDefault) || isTerminated;
}
return isTerminated;
};
// ----------
const setupListeners = (
target: EventTarget,
device: GestureDevice,
options: OnGestureOptionsInternal,
): DeviceListeners => {
const intents = options._intents;
let hasAddedTabIndex = false;
let hasPreventedSelect = false;
if (
device === MC.S_KEY &&
MH.isElement(target) &&
!MH.getTabIndex(target)
) {
hasAddedTabIndex = true;
// enable element to receive keydown events
MH.setTabIndex(target);
} else if (MH.isElement(target) && device === MC.S_TOUCH) {
if (options._preventDefault) {
addClasses(target, MC.PREFIX_NO_TOUCH_ACTION);
}
if (!intents || MH.includes(intents, MC.S_DRAG)) {
hasPreventedSelect = true;
preventSelect(target);
}
}
const addOrRemoveListeners = (
action: "add" | "remove",
listener: EventListener,
eventTypes: readonly (keyof GlobalEventHandlersEventMap)[],
) => {
const method =
action === "add" ? addEventListenerTo : removeEventListenerFrom;
for (const eventType of eventTypes) {
debug: logger?.debug8(`${action} listener for ${eventType}`, target);
method(target, eventType, listener, {
passive: false,
capture: true,
});
}
};
const addInitialListener = () =>
addOrRemoveListeners("add", initialListener, initiatingEvents[device]);
const removeInitialListener = () =>
addOrRemoveListeners(
"remove",
initialListener,
initiatingEvents[device],
);
const addOngoingListener = () =>
addOrRemoveListeners("add", processEvent, ongoingEvents[device]);
const removeOngoingListener = () =>
addOrRemoveListeners("remove", processEvent, ongoingEvents[device]);
const initialListener = (event: Event) => {
processEvent(event);
removeInitialListener();
addOngoingListener();
};
const processEvent = (event: Event) => {
const isTerminated = invokeCallbacks(target, device, event);
if (isTerminated) {
removeOngoingListener();
addInitialListener();
}
};
addInitialListener();
return {
_nCallbacks: 0,
_nPreventDefault: 0,
_remove: () => {
if (MH.isElement(target)) {
if (hasAddedTabIndex) {
MH.unsetTabIndex(target);
}
removeClasses(target, MC.PREFIX_NO_TOUCH_ACTION);
if (hasPreventedSelect) {
undoPreventSelect(target);
}
}
removeOngoingListener();
removeInitialListener();
},
};
};
// ----------
this.trackGesture = (element, handler?, options?) => {
if (!handler) {
handler = setGestureCssProps;
// initial values
for (const intent of INTENTS) {
setGestureCssProps(element, {
intent,
totalDeltaX: 0,
totalDeltaY: 0,
totalDeltaZ: 1,
});
}
}
return setupOnGesture(element, handler, options);
};
// ----------
this.noTrackGesture = (element, handler?) => {
if (!handler) {
handler = setGestureCssProps;
// delete the properties
for (const intent of INTENTS) {
setGestureCssProps(element, { intent });
}
}
this.offGesture(element, handler);
};
// ----------
this.onGesture = setupOnGesture;
// ----------
this.offGesture = (target, handler) => {
debug: logger?.debug5("Removing handler");
MH.remove(allCallbacks.get(target)?.get(handler)?._callback);
};
}
}
/**
* @interface
*/
export type GestureWatcherConfig = {
/**
* The default value for
* {@link OnGestureOptions.preventDefault | preventDefault} in calls to
* {@link GestureWatcher.onGesture}.
*
* @defaultValue true
*/
preventDefault?: boolean;
/**
* The default value for
* {@link OnGestureOptions.debounceWindow | debounceWindow} in calls to
* {@link GestureWatcher.onGesture}.
*
* @defaultValue 150
*/
debounceWindow?: number;
/**
* The default value for
* {@link OnGestureOptions.deltaThreshold | deltaThreshold} in calls to
* {@link GestureWatcher.onGesture}.
*
* @defaultValue 5
*/
deltaThreshold?: number;
/**
* The default value for
* {@link OnGestureOptions.angleDiffThreshold | angleDiffThreshold} in calls to
* {@link GestureWatcher.onGesture}.
*
* It does not make much sense to set this to 0.
*
* The value is in _degrees_, not radians.
*
* @defaultValue 35
*/
angleDiffThreshold?: number;
/**
* The default value for
* {@link OnGestureOptions.naturalTouchScroll | naturalTouchScroll} in calls to
* {@link GestureWatcher.onGesture}.
*
* @defaultValue true
*/
naturalTouchScroll?: boolean;
/**
* The default value for
* {@link OnGestureOptions.touchDragHoldTime | touchDragHoldTime} in calls to
* {@link GestureWatcher.onGesture}.
*
* @defaultValue 500
*/
touchDragHoldTime?: number;
/**
* The default value for
* {@link OnGestureOptions.touchDragNumFingers | touchDragNumFingers} in calls to
* {@link GestureWatcher.onGesture}.
*
* @defaultValue 1
*/
touchDragNumFingers?: number;
};
/**
* @interface
*/
export type OnGestureOptions = {
/**
* One or more device types to listen for. If not specified, then all devices
* are enabled.
*
* It can be a comma-separated list of {@link GestureDevice}s or an array of
* such devices.
*
* @defaultValue undefined
*/
devices?: CommaSeparatedStr<GestureDevice> | GestureDevice[];
/**
* If given, callback will only be called if the gesture's direction is one
* of the given ones.
*
* It can be a comma-separated list of {@link Direction}s or an array of such
* directions.
*
* @defaultValue undefined
*/
directions?: CommaSeparatedStr<Direction> | Direction[];
/**
* If given, callback will only be called if the gesture's intent is one
* of the given ones.
*
* It can be a comma-separated list of {@link GestureIntent}s or an
* array of such intents.
*
* @defaultValue undefined
*/
intents?: CommaSeparatedStr<GestureIntent> | GestureIntent[];
/**
* Set minimum total delta X. Further reductions in delta X below this value
* will be ignored.
*
* The value is in pixels and can be negative.
*
* @defaultValue undefined
*/
minTotalDeltaX?: number;
/**
* Set maximum total delta X. Further increase in delta X above this value
* will be ignored.
*
* The value is in pixels.
*
* @defaultValue undefined
*/
maxTotalDeltaX?: number;
/**
* Set minimum total delta Y. Further reductions in delta Y below this value
* will be ignored.
*
* The value is in pixels and can be negative.
*
* @defaultValue undefined
*/
minTotalDeltaY?: number;
/**
* Set maximum total delta Y. Further increase in delta Y above this value
* will be ignored.
*
* The value is in pixels.
*
* @defaultValue undefined
*/
maxTotalDeltaY?: number;
/**
* Set minimum total delta Z. Further reductions in delta Z below this value
* will be ignored.
*
* The value is in percentage zoom, relative to 1, and can be less than 1 but
* must be > 0.1 which is a hard minimum.
*
* @defaultValue undefined
*/
minTotalDeltaZ?: number;
/**
* Set maximum total delta Z. Further increase in delta Z above this value
* will be ignored.
*
* The value is in percentage zoom, relative to 1, and must be positive.
*
* @defaultValue undefined
*/
maxTotalDeltaZ?: number;
/**
* If true, the events of the gesture, e.g. relevant key presses or touch
* moves, etc, will have their default action prevented.
*
* **IMPORTANT:** For pointer gestures, then pointer/mouse down and click
* will be prevented.
*
* @defaultValue {@link GestureWatcherConfig.preventDefault}
*/
preventDefault?: boolean;
/**
* If given, callback will be called at most once every `debounceWindow`
* milliseconds.
*
* Note that if both `debounceWindow` and `deltaThreshold` are set, _both_
* must be exceeded before callback is called.
*
* @defaultValue {@link GestureWatcherConfig.debounceWindow}
*/
debounceWindow?: number;
/**
* Callback will only be called when the gesture's accumulated delta, since
* the last time callback was called, exceeds `deltaThreshold`.
*
* At least one of the three deltas (X, Y or Z) must exceed this number (in
* absolute value). Note that when comparing `deltaZ`, it is multiplied by
* 100 since it represents fractions of 1 (100%). So supplying
* `deltaThreshold` of 10 means is equivalent to the following condition:
*
* ```
* abs(deltaX) >= 10 || abs(deltaY) >= 10 || abs(1 - deltaZ) >= 0.1
* ```
*
* Accumulation of the delta ends if the gesture is terminated, for example,
* in case of touch gestures, by a "touchcancel" event of by the final finger
* lifting off..
*
* Note that if both `debounceWindow` and `deltaThreshold` are set, _both_
* must be exceeded before callback is called.
*
* @defaultValue {@link GestureWatcherConfig.deltaThreshold}
*/
deltaThreshold?: number;
/**
* See {@link Utils.getVectorDirection | getVectorDirection}.
*
* @defaultValue {@link GestureWatcherConfig.angleDiffThreshold}
*/
angleDiffThreshold?: number;
/**
* Whether touch scroll gestures follow the natural direction: swipe up
* with scroll intent results in direction down and swipe down results in
* direction up.
*
* @defaultValue {@link GestureWatcherConfig.naturalTouchScroll}
*/
naturalTouchScroll?: boolean;
/**
* If the user presses and holds on a touchscreen for at least the given
* amount of milliseconds before moving the finger(s), touch gestures other
* than pinch will be treated as a drag intent instead of scroll as long as
* the number of fingers touching the screen is {@link touchDragNumFingers}.
*
* Set to 0 in order to treat _all_ non-pinch touch gestures as drag.
*
* Set to a negative number in order to treat _all_ non-pinch touch gestures
* as scroll.
*
* @defaultValue {@link GestureWatcherConfig.touchDragHoldTime}
*/
touchDragHoldTime?: number;
/**
* The number of fingers that could be considered a drag intent for touch
* gestures.
*
* @defaultValue {@link GestureWatcherConfig.touchDragHoldTime}
*/
touchDragNumFingers?: number;
};
/**
* The handler is invoked with two arguments:
*
* - the event target that was passed to the {@link GestureWatcher.onGesture}
* call (equivalent to
* {@link https://developer.mozilla.org/en-US/docs/Web/API/Event/currentTarget | Event:currentTarget}).
* - the {@link GestureData} that describes the gesture's progression since the
* last time the callback was called and since the callback was added.
*/
export type OnGestureHandlerArgs = [EventTarget, GestureData, Event[]];
export type OnGestureCallback = Callback<OnGestureHandlerArgs>;
export type OnGestureHandler =
| CallbackHandler<OnGestureHandlerArgs>
| OnGestureCallback;
export type GestureData = {
device: GestureDevice;
direction: Direction;
intent: GestureIntent;
/**
* Delta in the horizontal direction since the start of the gesture.
*/
deltaX: number;
/**
* Delta in the vertical direction since the start of the gesture.
*/
deltaY: number;
/**
* Relative fractional zoom in or out for zoom intents since the start of
* the gesture.
*
* For zoom in, `deltaZ` is always > 1, and for zoom out it is < 1.
*
* For non-zoom gestures it is 1.
*/
deltaZ: number;
/**
* The time in milliseconds it took for the gesture. This will be the
* difference in timestamps between the first and last event that composed
* the gesture. For key and wheel gestures this could be 0, since 1 event is
* sufficient for them.
*/
time: number;
// TODO totalTime, velocity (bound by max), averageVelocity (bound by max)
/**
* Delta in the horizontal direction since the callback was added.
*/
totalDeltaX: number;
/**
* Delta in the vertical direction since the callback was added.
*/
totalDeltaY: number;
/**
* Percentage (relative) zoom in or out for zoom intents since the callback
* was added.
*/
totalDeltaZ: number;
};
// ----------------------------------------
type GestureWatcherConfigInternal = {
_preventDefault: boolean;
_debounceWindow: number;
_deltaThreshold: number;
_angleDiffThreshold: number;
_naturalTouchScroll: boolean;
_touchDragHoldTime: number;
_touchDragNumFingers: number;
};
type OnGestureOptionsInternal = {
_devices: GestureDevice[] | null;
_directions: Direction[] | null;
_intents: GestureIntent[] | null;
_minTotalDeltaX: number | null;
_maxTotalDeltaX: number | null;
_minTotalDeltaY: number | null;
_maxTotalDeltaY: number | null;
_minTotalDeltaZ: number | null;
_maxTotalDeltaZ: number | null;
_preventDefault: boolean;
_debounceWindow: number;
_deltaThreshold: number;
_angleDiffThreshold: number;
_naturalTouchScroll: boolean;
_touchDragHoldTime: number;
_touchDragNumFingers: number;
};
type OnGestureHandlerWrapper = (
_target: EventTarget,
_device: GestureDevice,
_event: Event,
_preventDefault: boolean,
) => boolean;
// Specific to a combination of target + device
type DeviceListeners = {
_nCallbacks: number; // total number of callbacks
_nPreventDefault: number; // total number wanting to prevent default action
_remove: () => void;
};
const CONSTRUCTOR_KEY: unique symbol = MC.SYMBOL() as typeof CONSTRUCTOR_KEY;
const instances = MH.newMap<string, GestureWatcher>();
const getConfig = (
config: GestureWatcherConfig | undefined,
): GestureWatcherConfigInternal => {
config ??= {};
return {
_preventDefault: config.preventDefault ?? true,
_debounceWindow: toNonNegNum(config[MC.S_DEBOUNCE_WINDOW], 150),
_deltaThreshold: toNonNegNum(config.deltaThreshold, 5),
_angleDiffThreshold: toPosNum(config.angleDiffThreshold, 35),
_naturalTouchScroll: config.naturalTouchScroll ?? true,
_touchDragHoldTime: config.touchDragHoldTime ?? 500,
_touchDragNumFingers: config.touchDragNumFingers ?? 1,
};
};
const initiatingEvents: {
[D in GestureDevice]: readonly (keyof GlobalEventHandlersEventMap)[];
} = {
key: [MC.S_KEYDOWN],
// If the browser doesn't support pointer events, then
// addEventListenerTo will transform it into mousedown
//
// We need to listen for click, since that occurs after a pointerup (i.e.
// after a gesure is terminated and the ongoing listeners removed), but it
// needs to have its default action prevented.
pointer: [MC.S_POINTERDOWN, MC.S_CLICK],
touch: [MC.S_TOUCHSTART],
wheel: [MC.S_WHEEL],
} as const;
const ongoingEvents: {
[D in GestureDevice]: readonly (keyof GlobalEventHandlersEventMap)[];
} = {
key: [MC.S_KEYDOWN],
pointer: [
// If the browser doesn't support point events, then
// addEventListenerTo will transform them into mouse*
MC.S_POINTERDOWN,
MC.S_POINTERUP, // would terminate
MC.S_POINTERMOVE,
MC.S_POINTERCANCEL, // would terminate
MC.S_CLICK, // would terminate; can be default-prevented
],
touch: [MC.S_TOUCHSTART, MC.S_TOUCHEND, MC.S_TOUCHMOVE, MC.S_TOUCHCANCEL],
wheel: [MC.S_WHEEL],
} as const;
const fragmentGetters: {
[D in GestureDevice]: (
events: Event[],
options: {
deltaThreshold?: number;
angleDiffThreshold?: number;
reverseScroll?: boolean;
dragHoldTime?: number;
dragNumFingers?: number;
},
) => GestureFragment | null | false;
} = {
[MC.S_KEY]: getKeyGestureFragment,
[MC.S_POINTER]: getPointerGestureFragment,
[MC.S_TOUCH]: getTouchGestureFragment,
[MC.S_WHEEL]: getWheelGestureFragment,
};
const getOptions = (
config: GestureWatcherConfigInternal,
options: OnGestureOptions,
): OnGestureOptionsInternal => {
const debounceWindow = toNonNegNum(
options[MC.S_DEBOUNCE_WINDOW],
config._debounceWindow, // watcher is never debounced, so apply default here
);
const deltaThreshold = toNonNegNum(
options.deltaThreshold,
config._deltaThreshold,
);
return {
_devices:
validateStrList("devices", options.devices, isValidInputDevice) ?? null,
_directions:
validateStrList("directions", options.directions, isValidDirection) ??
null,
_intents:
validateStrList("intents", options.intents, isValidIntent) ?? null,
_minTotalDeltaX: options.minTotalDeltaX ?? null,
_maxTotalDeltaX: options.maxTotalDeltaX ?? null,
_minTotalDeltaY: options.minTotalDeltaY ?? null,
_maxTotalDeltaY: options.maxTotalDeltaY ?? null,
_minTotalDeltaZ: options.minTotalDeltaZ ?? null,
_maxTotalDeltaZ: options.maxTotalDeltaZ ?? null,
_preventDefault: options.preventDefault ?? config._preventDefault,
_debounceWindow: debounceWindow,
_deltaThreshold: deltaThreshold,
_angleDiffThreshold: toNonNegNum(
options.angleDiffThreshold,
config._angleDiffThreshold,
),
_naturalTouchScroll:
options.naturalTouchScroll ?? config._naturalTouchScroll,
_touchDragHoldTime: options.touchDragHoldTime ?? config._touchDragHoldTime,
_touchDragNumFingers:
options.touchDragNumFingers ?? config._touchDragNumFingers,
};
};
// Since each callback needs to accumulate events during its debounce window
// and until its threshold is exceeded, we use a wrapper around the
// user-supplied handler to do that.
const getCallbackAndWrapper = (
handler: OnGestureHandler,
options: OnGestureOptionsInternal,
logger: LoggerInterface | null,
): { _callback: OnGestureCallback; _wrapper: OnGestureHandlerWrapper } => {
let totalDeltaX = 0,
totalDeltaY = 0,
totalDeltaZ = 1;
// When there's a pointer down, drag then pointerup, since we prevent
// pointerdown default action, this results in a click event shortly
// afterwards even when there's been a movement of the mouse. We detect that
// and prevent this click.
let preventNextClick = false;
const directions = options._directions;
const intents = options._intents;
const minTotalDeltaX = options._minTotalDeltaX;
const maxTotalDeltaX = options._maxTotalDeltaX;
const minTotalDeltaY = options._minTotalDeltaY;
const maxTotalDeltaY = options._maxTotalDeltaY;
const minTotalDeltaZ = options._minTotalDeltaZ;
const maxTotalDeltaZ = options._maxTotalDeltaZ;
const deltaThreshold = options._deltaThreshold;
const angleDiffThreshold = options._angleDiffThreshold;
const reverseScroll = !options._naturalTouchScroll;
const dragHoldTime = options._touchDragHoldTime;
const dragNumFingers = options._touchDragNumFingers;
// The event queue is cleared when the threshold is exceeded AND the debounce
// window has passed. It's not necessary for the actual handler to be called
// then (e.g. if the direction or intent doesn't match, it won't be).
const eventQueue: Event[] = [];
const id = randId();
// Since handler could be a function or a callback (not callable), we wrap it
// so that in case it's already a callback, its removal will result in
// deleteHandler getting called. It is not debounced itself, instead there's
// a debounced wrapper that invokes it.
const callback = wrapCallback(handler);
// The debounced callback wrapper is what is debounced.
// It accumulates total deltas and checks if the conditions (of threshold,
// direction and intent) are satisfied before calling the real handler.
//
// Most importantly, since it is only called when the debounce window has
// expired it can clear the event queue if the threshold is also exceeded.
const debouncedWrapper = getDebouncedHandler(
options._debounceWindow,
(
target: EventTarget,
fragment: GestureFragment,
eventQueueCopy: Event[],
) => {
Iif (callback.isRemoved()) {
return;
}
const deltaX = fragment.deltaX;
const deltaY = fragment.deltaY;
const deltaZ = fragment.deltaZ;
const device = fragment.device;
if (
MH.round(maxAbs(deltaX, deltaY, (1 - deltaZ) * 100)) < deltaThreshold
) {
debug: logger?.debug7(
`[${id}] Delta threshold not exceeded for callback`,
);
return;
}
debug: logger?.debug9(`[${id}] Done summing events for ${device}`);
clearEventQueue(device, eventQueue);
const newTotalDeltaX = toNumWithBounds(totalDeltaX + deltaX, {
min: minTotalDeltaX,
max: maxTotalDeltaX,
});
const newTotalDeltaY = toNumWithBounds(totalDeltaY + deltaY, {
min: minTotalDeltaY,
max: maxTotalDeltaY,
});
const newTotalDeltaZ = toNumWithBounds(addDeltaZ(totalDeltaZ, deltaZ), {
min: minTotalDeltaZ,
max: maxTotalDeltaZ,
});
if (
newTotalDeltaX === totalDeltaX &&
newTotalDeltaY === totalDeltaY &&
newTotalDeltaZ === totalDeltaZ
) {
return;
}
totalDeltaX = newTotalDeltaX;
totalDeltaY = newTotalDeltaY;
totalDeltaZ = newTotalDeltaZ;
const direction = fragment.direction;
const intent = fragment.intent;
const time =
eventQueueCopy[MH.lengthOf(eventQueueCopy) - 1]?.timeStamp -
eventQueueCopy[0]?.timeStamp || 0;
const data = {
device,
direction,
intent,
deltaX,
deltaY,
deltaZ,
time,
totalDeltaX,
totalDeltaY,
totalDeltaZ,
};
if (
direction !== MC.S_NONE &&
(!directions || MH.includes(directions, direction)) &&
(!intents || MH.includes(intents, intent))
) {
callback.invoke(target, data, eventQueueCopy).catch(logError);
} else {
debug: logger?.debug7(
`[${id}] Directions or intents not matching for callback`,
);
}
},
);
// This wrapper is NOT debounced and adds the events to the queue, prevents
// default action if needed, and indicates whether the gesture is terminated.
const wrapper = (
target: EventTarget,
device: GestureDevice,
event: Event,
preventDefault: boolean,
) => {
eventQueue.push(event);
const fragment = fragmentGetters[device](eventQueue, {
angleDiffThreshold,
deltaThreshold,
reverseScroll,
dragHoldTime,
dragNumFingers,
});
debug: logger?.debug8(
`[${id}] Got fragment for ${device} (${event.type})`,
fragment,
[...eventQueue].map((e) => e.type),
);
if (preventDefault) {
preventDefaultActionFor(
event,
!!fragment || (event.type === MC.S_CLICK && preventNextClick),
);
}
if (fragment === false) {
// not enough events in the queue, pass
debug: logger?.debug9(`[${id}] Not enough events for gesture ${device}`);
return false;
} else if (fragment === null) {
// consider the gesture terminated
clearEventQueue(device, eventQueue);
debug: logger?.debug9(`[${id}] Gesture for ${device} terminated`);
return true;
}
if (device === MC.S_POINTER) {
// If we're here, there's been a drag, expect a click immediately
// afterwards and prevent default action.
preventNextClick = true;
MH.setTimer(() => {
preventNextClick = false;
}, 10);
}
debouncedWrapper(
target,
fragment,
[...eventQueue], // copy
);
return false;
};
return { _callback: callback, _wrapper: wrapper };
};
const clearEventQueue = (device: GestureDevice, queue: Event[]) => {
const keepLastEvent = device === MC.S_POINTER || device === MC.S_TOUCH;
queue.splice(0, MH.lengthOf(queue) - (keepLastEvent ? 1 : 0));
};
const preventDefaultActionFor = (event: Event, isActualGesture: boolean) => {
const target = event.currentTarget;
const eventType = event.type;
const isPointerDown =
eventType === MC.S_POINTERDOWN || eventType === MC.S_MOUSEDOWN;
if (
eventType === MC.S_TOUCHMOVE ||
eventType === MC.S_WHEEL ||
((eventType === MC.S_CLICK || eventType === MC.S_KEYDOWN) &&
isActualGesture) ||
(isPointerDown && (event as MouseEvent).buttons === 1)
) {
MH.preventDefault(event);
if (isPointerDown && MH.isHTMLElement(target)) {
// Otherwise capturing key events won't work
target.focus({ preventScroll: true });
}
}
};
const setGestureCssProps = (
target: EventTarget,
data: Partial<GestureData>,
) => {
const intent = data.intent;
if (!MH.isElement(target) || !intent || intent === MC.S_UNKNOWN) {
return;
}
const prefix = `${intent}-`;
if (intent === MC.S_ZOOM) {
setNumericStyleJsVars(
target,
{
deltaZ: data.totalDeltaZ,
},
{
_prefix: prefix,
_numDecimal: 2,
},
); // don't await here
} else {
setNumericStyleJsVars(
target,
{
deltaX: data.totalDeltaX,
deltaY: data.totalDeltaY,
},
{
_prefix: prefix,
},
); // don't await here
}
};
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