iscroll/src/wheel/wheel.js

Smooth scrolling for the web

	_initWheel: function () {
		utils.addEvent(this.wrapper, 'wheel', this);
		utils.addEvent(this.wrapper, 'mousewheel', this);
		utils.addEvent(this.wrapper, 'DOMMouseScroll', this);

		this.on('destroy', function () {
			clearTimeout(this.wheelTimeout);
			this.wheelTimeout = null;
			utils.removeEvent(this.wrapper, 'wheel', this);
			utils.removeEvent(this.wrapper, 'mousewheel', this);
			utils.removeEvent(this.wrapper, 'DOMMouseScroll', this);
		});
	},

	_wheel: function (e) {
		if ( !this.enabled ) {
			return;
		}

		e.preventDefault();

		var wheelDeltaX, wheelDeltaY,
			newX, newY,
			that = this;

		if ( this.wheelTimeout === undefined ) {
			that._execEvent('scrollStart');
		}

		// Execute the scrollEnd event after 400ms the wheel stopped scrolling
		clearTimeout(this.wheelTimeout);
		this.wheelTimeout = setTimeout(function () {
			if(!that.options.snap) {
				that._execEvent('scrollEnd');
			}
			that.wheelTimeout = undefined;
		}, 400);

		if ( 'deltaX' in e ) {
			if (e.deltaMode === 1) {
				wheelDeltaX = -e.deltaX * this.options.mouseWheelSpeed;
				wheelDeltaY = -e.deltaY * this.options.mouseWheelSpeed;
			} else {
				wheelDeltaX = -e.deltaX;
				wheelDeltaY = -e.deltaY;
			}
		} else if ( 'wheelDeltaX' in e ) {
			wheelDeltaX = e.wheelDeltaX / 120 * this.options.mouseWheelSpeed;
			wheelDeltaY = e.wheelDeltaY / 120 * this.options.mouseWheelSpeed;
		} else if ( 'wheelDelta' in e ) {
			wheelDeltaX = wheelDeltaY = e.wheelDelta / 120 * this.options.mouseWheelSpeed;
		} else if ( 'detail' in e ) {
			wheelDeltaX = wheelDeltaY = -e.detail / 3 * this.options.mouseWheelSpeed;
		} else {
			return;
		}

		wheelDeltaX *= this.options.invertWheelDirection;
		wheelDeltaY *= this.options.invertWheelDirection;

		if ( !this.hasVerticalScroll ) {
			wheelDeltaX = wheelDeltaY;
			wheelDeltaY = 0;
		}

		if ( this.options.snap ) {
			newX = this.currentPage.pageX;
			newY = this.currentPage.pageY;

			if ( wheelDeltaX > 0 ) {
				newX--;
			} else if ( wheelDeltaX < 0 ) {
				newX++;
			}

			if ( wheelDeltaY > 0 ) {
				newY--;
			} else if ( wheelDeltaY < 0 ) {
				newY++;
			}

			this.goToPage(newX, newY);

			return;
		}

		newX = this.x + Math.round(this.hasHorizontalScroll ? wheelDeltaX : 0);
		newY = this.y + Math.round(this.hasVerticalScroll ? wheelDeltaY : 0);

		this.directionX = wheelDeltaX > 0 ? -1 : wheelDeltaX < 0 ? 1 : 0;
		this.directionY = wheelDeltaY > 0 ? -1 : wheelDeltaY < 0 ? 1 : 0;

		if ( newX > 0 ) {
			newX = 0;
		} else if ( newX < this.maxScrollX ) {
			newX = this.maxScrollX;
		}

		if ( newY > 0 ) {
			newY = 0;
		} else if ( newY < this.maxScrollY ) {
			newY = this.maxScrollY;
		}

		this.scrollTo(newX, newY, 0);

// INSERT POINT: _wheel
	},