105 lines
2.8 KiB
Plaintext
105 lines
2.8 KiB
Plaintext
/**
|
|
* Copyright (c) 2013-present, Facebook, Inc.
|
|
*
|
|
* This source code is licensed under the MIT license found in the
|
|
* LICENSE file in the root directory of this source tree.
|
|
*
|
|
* This is utility that hanlds onWheel events and calls provided wheel
|
|
* callback with correct frame rate.
|
|
*
|
|
* @providesModule ReactWheelHandler
|
|
* @typechecks
|
|
*/
|
|
'use strict';
|
|
|
|
const emptyFunction = require("./emptyFunction");
|
|
|
|
const normalizeWheel = require("./normalizeWheel");
|
|
|
|
const requestAnimationFramePolyfill = require("./requestAnimationFramePolyfill");
|
|
|
|
class ReactWheelHandler {
|
|
/**
|
|
* onWheel is the callback that will be called with right frame rate if
|
|
* any wheel events happened
|
|
* onWheel should is to be called with two arguments: deltaX and deltaY in
|
|
* this order
|
|
*/
|
|
constructor(
|
|
/*function*/
|
|
onWheel,
|
|
/*boolean|function*/
|
|
handleScrollX,
|
|
/*boolean|function*/
|
|
handleScrollY,
|
|
/*?boolean|?function*/
|
|
stopPropagation) {
|
|
this._animationFrameID = null;
|
|
this._deltaX = 0;
|
|
this._deltaY = 0;
|
|
this._didWheel = this._didWheel.bind(this);
|
|
|
|
if (typeof handleScrollX !== 'function') {
|
|
handleScrollX = handleScrollX ? emptyFunction.thatReturnsTrue : emptyFunction.thatReturnsFalse;
|
|
}
|
|
|
|
if (typeof handleScrollY !== 'function') {
|
|
handleScrollY = handleScrollY ? emptyFunction.thatReturnsTrue : emptyFunction.thatReturnsFalse;
|
|
}
|
|
|
|
if (typeof stopPropagation !== 'function') {
|
|
stopPropagation = stopPropagation ? emptyFunction.thatReturnsTrue : emptyFunction.thatReturnsFalse;
|
|
}
|
|
|
|
this._handleScrollX = handleScrollX;
|
|
this._handleScrollY = handleScrollY;
|
|
this._stopPropagation = stopPropagation;
|
|
this._onWheelCallback = onWheel;
|
|
this.onWheel = this.onWheel.bind(this);
|
|
}
|
|
|
|
onWheel(
|
|
/*object*/
|
|
event) {
|
|
const normalizedEvent = normalizeWheel(event);
|
|
const deltaX = this._deltaX + normalizedEvent.pixelX;
|
|
const deltaY = this._deltaY + normalizedEvent.pixelY;
|
|
|
|
const handleScrollX = this._handleScrollX(deltaX, deltaY);
|
|
|
|
const handleScrollY = this._handleScrollY(deltaY, deltaX);
|
|
|
|
if (!handleScrollX && !handleScrollY) {
|
|
return;
|
|
}
|
|
|
|
this._deltaX += handleScrollX ? normalizedEvent.pixelX : 0;
|
|
this._deltaY += handleScrollY ? normalizedEvent.pixelY : 0;
|
|
event.preventDefault();
|
|
let changed;
|
|
|
|
if (this._deltaX !== 0 || this._deltaY !== 0) {
|
|
if (this._stopPropagation()) {
|
|
event.stopPropagation();
|
|
}
|
|
|
|
changed = true;
|
|
}
|
|
|
|
if (changed === true && this._animationFrameID === null) {
|
|
this._animationFrameID = requestAnimationFramePolyfill(this._didWheel);
|
|
}
|
|
}
|
|
|
|
_didWheel() {
|
|
this._animationFrameID = null;
|
|
|
|
this._onWheelCallback(this._deltaX, this._deltaY);
|
|
|
|
this._deltaX = 0;
|
|
this._deltaY = 0;
|
|
}
|
|
|
|
}
|
|
|
|
module.exports = ReactWheelHandler; |