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