<template>
 <div class="fullPage" ref="fullPage">
 <div
  class="fullPageContainer"
  ref="fullPageContainer"
  @mousewheel="mouseWheelHandle" //監聽鼠標事件
  @DOMMouseScroll="mouseWheelHandle" // 監聽鼠標事件
 >
  <div class="section section1">1</div>
  <div class="section section2">2</div>
  <div class="section section3">3</div>
  <div class="section section4">4</div>
 </div>
 </div>
</template>

<script>
export default {
 name: "Home",
 data() {
 return {
  fullpage: {
  current: 1, // 當前的頁面編號
  isScrolling: false, // 是否在滾動,是為了防止滾動多頁，需要通過一個變量來控制是否滾動
  deltaY: 0 // 返回鼠標滾輪的垂直滾動量，保存的鼠標滾動事件的deleteY,用來判斷是往下還是往上滾
  }
 };
 },
 methods: {
 next() { // 往下切換
  let len = 4; // 頁面的個數
  if (this.fullpage.current + 1 <= len) { // 如果當前頁面編號+1 小于總個數，則可以執行向下滑動
  this.fullpage.current += 1; // 頁面+1
  this.move(this.fullpage.current); // 執行切換
  }
 },
 pre() {// 往上切換
  if (this.fullpage.current - 1 > 0) { // 如果當前頁面編號-1 大于0，則可以執行向下滑動
  this.fullpage.current -= 1;// 頁面+1
  this.move(this.fullpage.current);// 執行切換
  }
 },
 move(index) {
  this.fullpage.isScrolling = true; // 為了防止滾動多頁，需要通過一個變量來控制是否滾動
  this.directToMove(index); //執行滾動
  setTimeout(() => {  //這里的動畫是1s執行完，使用setTimeout延遲1s后解鎖
  this.fullpage.isScrolling = false;
  }, 1010);
 },
 directToMove(index) {
  let height = this.$refs["fullPage"].clientHeight; //獲取屏幕的寬度
  let scrollPage = this.$refs["fullPageContainer"]; // 獲取執行tarnsform的元素
  let scrollHeight; // 計算滾動的告訴，是往上滾還往下滾
  scrollHeight= -(index - 1) * height + "px";
  scrollPage.style.transform = `translateY(${scrollHeight})`;
  this.fullpage.current = index;
 },
 mouseWheelHandle(event) { // 監聽鼠標監聽
  // 添加冒泡阻止
  let evt = event || window.event;
  if (evt.stopPropagation) {
  evt.stopPropagation();
  } else {
  evt.returnValue = false;
  }
  if (this.fullpage.isScrolling) { // 判斷是否可以滾動
  return false;
  }
  let e = event.originalEvent || event;
  this.fullpage.deltaY = e.deltaY || e.detail; // Firefox使用detail
  if (this.fullpage.deltaY > 0) {
  this.next();
  } else if (this.fullpage.deltaY < 0) {
  this.pre();
  }
 }
 }
};
</script>

<style scoped>
.fullPage{
 height: 100%;//一定要設置，保證占滿
 overflow: hidden;//一定要設置，多余的先隱藏
 background-color: rgb(189, 211, 186);
}
.fullPageContainer{
 width: 100%;
 height: 100%;
 transition: all linear 0.5s;
}
.section {
 width: 100%;
 height: 100%;
 background-position: center center;
 background-repeat: no-repeat;
}
.section1 {
 background-color: rgb(189, 211, 186);
 background: url("./assets/intro-bg.jpg");
}
.section1 .secction1-content {
 color: #fff;
 text-align: center;
 position: absolute;
 top: 40%;
 right: 0;
 left: 0;
}
.secction1-content h2 {
 font-size: 40px;
 padding-bottom: 30px;
}
.secction1-content p {
 font-size: 20px;
}
.section2 {
 background-color: rgb(44, 48, 43);
}
.section3 {
 background-color: rgb(116, 104, 109);
}
.section4 {
 background-color: rgb(201, 202, 157);
}
</style>