css3 - 為什么運(yùn)行動(dòng)畫后，原本居中的位置卻發(fā)生了偏移？
問(wèn)題描述
為什么運(yùn)行動(dòng)畫后，原本居中的位置卻發(fā)生了偏移？
<!DOCTYPE html><html> <head><meta charset='utf-8'><title></title><style type='text/css'>*{padding: 0px;margin: 0px; } .box1{width: 600px;height: 200px;background: orange;position: relative; } .box1 span{position: absolute;border: 8px solid #fff;border-top: 8px solid transparent;border-radius: 999px;top: 50%;left: 50%;transform: translate(-50%,-50%); } .box1 span:nth-child(1){width: 80px;height: 80px;/*animation: span1 2s linear infinite ;*/ } .box1 span:nth-child(2){width: 40px;height: 40px;/*animation: span2 1s linear infinite ;*/ }@-webkit-keyframes span1{0%{transform: rotate(360deg); opacity: 1;}50%{transform: rotate(180deg); opacity: .5;}100%{transform: rotate(0deg); opacity: 0;} } @-webkit-keyframes span2{0%{transform: rotate(0deg); opacity: .5;}50%{transform: rotate(180deg); opacity: 1;}100%{transform: rotate(360deg); opacity: .5;} } </style> </head> <body><p class='box1'> <span></span> <span></span></p></body>
</html>
問(wèn)題解答
回答1：.box1 span:nth-child(1){ width: 80px; height: 80px; animation: span1 2s linear infinite ; margin: -40px 0 0 -40px;}.box1 span:nth-child(2){ width: 40px; height: 40px; animation: span2 1s linear infinite ; margin: -20px 0 0 -20px;}回答2：
這個(gè)坑我碰到過(guò)，你的定位轉(zhuǎn)換別用transfrom,改成margin-left:-50%width;用了transfrom他會(huì)把初始位置定位到left:50%的地方。
回答3：transform-origin: center;回答4：
.box1 span{
position: absolute;border: 8px solid #fff;border-top: 8px solid transparent;border-radius: 999px;top: 50%;left: 50%;transform: translate(-50%,-50%);**transform-origin: 0 0;**
}@-webkit-keyframes span1{
0%{transform: rotate(360deg) **translate(-50%,-50%);** opacity: 1;}50%{transform: rotate(180deg) **translate(-50%,-50%);** opacity: .5;}100%{transform: rotate(0deg) **translate(-50%,-50%);** opacity: 0;}
}@-webkit-keyframes span2{
0%{transform: rotate(0deg) **translate(-50%,-50%);** opacity: .5;}50%{transform: rotate(180deg) **translate(-50%,-50%);** opacity: 1;}100%{transform: rotate(360deg) **translate(-50%,-50%);** opacity: .5;}
}
回答5：原因是樓上說(shuō)的，因?yàn)橛昧薱ss3動(dòng)畫，所上面設(shè)置偏移的時(shí)候不要用transfrom,順手把具體的代碼寫出來(lái)：
<!DOCTYPE html><html><head> <meta charset='utf-8'> <title></title> <style type='text/css'>* { padding: 0px; margin: 0px;}.box1 { width: 600px; height: 200px; background: orange; position: relative;}.box1 span { position: absolute; border: 8px solid #fff; border-top: 8px solid transparent; border-radius: 999px; top: 50%; left: 50%; /*移除這里定位*/}.box1 span:nth-child(1) { width: 80px; height: 80px; /*新增*/ margin-left: -40px; margin-top: -40px; animation: span1 2s linear infinite ;}.box1 span:nth-child(2) { width: 40px; height: 40px; /*新增*/ margin-left: -20px; margin-top: -20px; animation: span2 1s linear infinite ;}@keyframes span1 { 0% {transform: rotate(360deg);opacity: 1; } 50% {transform: rotate(180deg);opacity: .5; } 100% {transform: rotate(0deg);opacity: 0; }}@-webkit-keyframes span1 { 0% {transform: rotate(360deg);opacity: 1; } 50% {transform: rotate(180deg);opacity: .5; } 100% {transform: rotate(0deg);opacity: 0; }}@-webkit-keyframes span2 { 0% {transform: rotate(0deg);opacity: .5; } 50% {transform: rotate(180deg);opacity: 1; } 100% {transform: rotate(360deg);opacity: .5; }} </style></head><body> <p class='box1'><span></span><span></span> </p></body></html>回答6：
你需要用絕對(duì)定位將要旋轉(zhuǎn)的元素的初始點(diǎn)定位到元素的中心，正常的初始點(diǎn)是在左上用left:50%;top:50%;margin-left:-20px/元素的二分之一/;margin-top:-20px/元素的二分之一/;這樣元素的旋轉(zhuǎn)就不會(huì)出現(xiàn)交錯(cuò)了。
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