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- 'use strict';
- var instances = require('../instances')
- , updateGeometry = require('../update-geometry')
- , updateScroll = require('../update-scroll');
- function bindMouseWheelHandler(element, i) {
- var shouldPrevent = false;
- function shouldPreventDefault(deltaX, deltaY) {
- var scrollTop = element.scrollTop;
- if (deltaX === 0) {
- if (!i.scrollbarYActive) {
- return false;
- }
- if ((scrollTop === 0 && deltaY > 0) || (scrollTop >= i.contentHeight - i.containerHeight && deltaY < 0)) {
- return !i.settings.wheelPropagation;
- }
- }
- var scrollLeft = element.scrollLeft;
- if (deltaY === 0) {
- if (!i.scrollbarXActive) {
- return false;
- }
- if ((scrollLeft === 0 && deltaX < 0) || (scrollLeft >= i.contentWidth - i.containerWidth && deltaX > 0)) {
- return !i.settings.wheelPropagation;
- }
- }
- return true;
- }
- function getDeltaFromEvent(e) {
- var deltaX = e.deltaX;
- var deltaY = -1 * e.deltaY;
- if (typeof deltaX === "undefined" || typeof deltaY === "undefined") {
- // OS X Safari
- deltaX = -1 * e.wheelDeltaX / 6;
- deltaY = e.wheelDeltaY / 6;
- }
- if (e.deltaMode && e.deltaMode === 1) {
- // Firefox in deltaMode 1: Line scrolling
- deltaX *= 10;
- deltaY *= 10;
- }
- if (deltaX !== deltaX && deltaY !== deltaY/* NaN checks */) {
- // IE in some mouse drivers
- deltaX = 0;
- deltaY = e.wheelDelta;
- }
- return [deltaX, deltaY];
- }
- function shouldBeConsumedByTextarea(deltaX, deltaY) {
- var hoveredTextarea = element.querySelector('textarea:hover');
- if (hoveredTextarea) {
- var maxScrollTop = hoveredTextarea.scrollHeight - hoveredTextarea.clientHeight;
- if (maxScrollTop > 0) {
- if (!(hoveredTextarea.scrollTop === 0 && deltaY > 0) &&
- !(hoveredTextarea.scrollTop === maxScrollTop && deltaY < 0)) {
- return true;
- }
- }
- var maxScrollLeft = hoveredTextarea.scrollLeft - hoveredTextarea.clientWidth;
- if (maxScrollLeft > 0) {
- if (!(hoveredTextarea.scrollLeft === 0 && deltaX < 0) &&
- !(hoveredTextarea.scrollLeft === maxScrollLeft && deltaX > 0)) {
- return true;
- }
- }
- }
- return false;
- }
- function mousewheelHandler(e) {
- var delta = getDeltaFromEvent(e);
- var deltaX = delta[0];
- var deltaY = delta[1];
- if (shouldBeConsumedByTextarea(deltaX, deltaY)) {
- return;
- }
- shouldPrevent = false;
- if (!i.settings.useBothWheelAxes) {
- // deltaX will only be used for horizontal scrolling and deltaY will
- // only be used for vertical scrolling - this is the default
- updateScroll(element, 'top', element.scrollTop - (deltaY * i.settings.wheelSpeed));
- updateScroll(element, 'left', element.scrollLeft + (deltaX * i.settings.wheelSpeed));
- } else if (i.scrollbarYActive && !i.scrollbarXActive) {
- // only vertical scrollbar is active and useBothWheelAxes option is
- // active, so let's scroll vertical bar using both mouse wheel axes
- if (deltaY) {
- updateScroll(element, 'top', element.scrollTop - (deltaY * i.settings.wheelSpeed));
- } else {
- updateScroll(element, 'top', element.scrollTop + (deltaX * i.settings.wheelSpeed));
- }
- shouldPrevent = true;
- } else if (i.scrollbarXActive && !i.scrollbarYActive) {
- // useBothWheelAxes and only horizontal bar is active, so use both
- // wheel axes for horizontal bar
- if (deltaX) {
- updateScroll(element, 'left', element.scrollLeft + (deltaX * i.settings.wheelSpeed));
- } else {
- updateScroll(element, 'left', element.scrollLeft - (deltaY * i.settings.wheelSpeed));
- }
- shouldPrevent = true;
- }
- updateGeometry(element);
- shouldPrevent = (shouldPrevent || shouldPreventDefault(deltaX, deltaY));
- if (shouldPrevent) {
- e.stopPropagation();
- e.preventDefault();
- }
- }
- if (typeof window.onwheel !== "undefined") {
- i.event.bind(element, 'wheel', mousewheelHandler);
- } else if (typeof window.onmousewheel !== "undefined") {
- i.event.bind(element, 'mousewheel', mousewheelHandler);
- }
- }
- module.exports = function (element) {
- var i = instances.get(element);
- bindMouseWheelHandler(element, i);
- };
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