前言效果展示(初始版)
Demo代碼
HTML
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="stylesheet" href="style.css">
<title>Document</title>
</head>
<body>
<section><span></span></section>
</body>
</html>
CSS
html, body {
margin: 0;
height: 100%;
}
body {
display: flex;
justify-content: center;
align-items: center;
background: #ed556a;
/* background-color: #82466e; */
animation: backColor 4s infinite;
}
section {
width: 650px;
height: 300px;
padding: 10px;
position: relative;
display: flex;
align-items: center;
justify-content: center;
border: 2px solid white;
}
span {
width: 12px;
height: 64px;
border-radius: 4px;
display: inline-block;
position: relative;
background: currentColor;
color: white;
/* background-color: red; */
animation: animloader61m 1s 1s linear infinite alternate;
}
span::before, span::after {
content: '';
width: 12px;
height: 64px;
border-radius: 4px;
background: currentColor;
position: absolute;
bottom: 0;
left: 20px;
animation: animloader61 1s 1.5s linear infinite alternate;
}
span::after {
left: -20px;
animation-delay: 0s;
}
@keyframes animloader61 {
0% {
height: 64px;
}
100% {
height: 5px;
}
}
@keyframes animloader61m {
0% {
height: 64px;
transform: translateY(0);
}
100% {
height: 15px;
transform: translateY(30px)
}
}
仔細觀察效果圖,其實可以明顯發現整個白色部分整體也在上下移動,隻是移動距離較小。
感覺要是下方可以固定住就行了,為此,在源代碼基礎上修改了一下,得到改進後的效果,如下:
效果展示(改進版)
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="stylesheet" href="style.css">
<title>Document</title>
</head>
<body>
<section><span></span></section>
</body>
</html>
html, body {
margin: 0;
height: 100%;
}
body {
display: flex;
justify-content: center;
align-items: center;
background: #ed556a;
/* background-color: #82466e; */
animation: backColor 4s infinite;
}
section {
width: 650px;
height: 300px;
padding: 10px;
position: relative;
display: flex;
align-items: center;
justify-content: center;
border: 2px solid white;
}
span {
width: 12px;
height: 64px;
border-radius: 4px;
display: inline-block;
position: relative;
background: white;
color: white;
animation: loading 1s 1s linear infinite alternate;
}
span::before, span::after {
/* content: ''; */
width: 12px;
height: 64px;
border-radius: 4px;
background: currentColor;
position: absolute;
bottom: 0;
left: 20px;
animation: loadingx 1s 1.5s linear infinite alternate;
}
span::after {
left: -20px;
animation-delay: 0s;
}
@keyframes loadingx {
0% {
height: 64px;
}
100% {
height: 14px;
}
}
@keyframes loading {
0% {
height: 64px;
transform: translateY(0);
}
100% {
height: 14px;
transform: translateY(25px)
}
}
原理詳解
步驟1
使用span标簽,設定為
- 相對定位
- 寬度:12px 高度:64px
- border-radius: 4px
- 背景色:白色
- colore:白色
span {
width: 12px;
height: 64px;
border-radius: 4px;
position: relative;
background: white;
color: white;
}
效果圖如下
步驟2
為span添加動畫
效果簡單描述為:長度由長變短,再變短,依次循環
如果隻是簡單的設定height屬性的變化
- 初始狀态:height=64px
- 末尾狀态:heigth=14px
代碼為:
span {
animation: loading 1s linear infinite alternate;
}
@keyframes loading {
0% {
height: 64px;
}
100% {
height: 14px;
}
}
産生的效果如下
這是因為海轟事先将span設定為水準、豎直均位于頁面中間的,是以僅長度變化産生的效果圖如上
如何實作span一頭固定、一頭延伸呢?
這裡就需要利用translateY屬性了,不清楚的可以查查,其實就是二維平面y軸變換
- 初始狀态:height=64px transform: translateY(0)
- 末尾狀态:height=14px transform: translateY(25px)
注: 25px=(64-14)/2 px
span {
animation: loading 1s linear infinite alternate;
}
@keyframes loading {
0% {
height: 64px;
transform: translateY(0);
}
100% {
height: 14px;
transform: translateY(25px)
}
}
span動畫效果如下
步驟3
在使用span::before和span::after僞元素
設定為
- 絕對定位( bottom: 0 left: 20px,固定在底部)
- 寬度為12px 高度為64px
- 背景色:currentColor(這裡其實之間設定白色也行)
span::before, span::after {
content: '';
width: 12px;
height: 64px;
border-radius: 4px;
background: currentColor;
position: absolute;
bottom: 0;
left: 20px;
}
span與span::before位置關系如下
步驟4
分離span::before和span::after
将span::after位置移動至span左邊
span::after {
left: -20px;
}
位置關系如下
步驟5
為span::before、span::after添加動畫
隻涉及長度改變
span::before, span::after {
animation: loadingx 1s linear infinite alternate;
}
@keyframes loadingx {
0% {
height: 64px;
}
100% {
height: 14px;
}
}
span::before和span::after動畫如下(span動畫不生效時)
為什麼這裡就不需要使用translateY屬性了呢?
海轟的了解:因為span::before、span::after的位置是同span一樣的,span已經設定了,那麼before和after就不需要設定了
如果再設定translateY
産生的效果圖如下
步驟6
同時開啟span、span::before、span::after動畫
同時分别設定動畫開始延時
- span:延時1s
- span::before:延時1.5s
- span::after:延時0s
注:具體資料依據自己喜好設定即可,隻需要保障各部分動畫開始時有時間間隔就行
最後代碼如下:
span {
animation: loading 1s 1s linear infinite alternate;
}
span::before, span::after {
animation: loadingx 1s 1.5s linear infinite alternate;
}
span::after {
animation-delay: 0s;
}
@keyframes loadingx {
0% {
height: 64px;
}
100% {
height: 14px;
}
}
@keyframes loading {
0% {
height: 64px;
transform: translateY(0);
}
100% {
height: 14px;
transform: translateY(25px)
}
}
得到最終效果: