.animation{
  width: 800px;
  height: 800px;
  border: 1px solid #000;
}
#canvas{
  animation: rotate 6s linear infinite;  
}
/* 給太極圖設置旋轉(zhuǎn)動畫 */
@keyframes rotate{
  0%{
    transform: none;
  }
  100%{
    transform: rotate(360deg);
  }
}

//文檔加載完畢后執(zhí)行函數(shù)
window.onload = function(){
  //獲取畫布對象
  var canvas = document.getElementById('canvas');
  //獲取上下文對象
  var context = canvas.getContext('2d');
  //圓開始路徑
  context.beginPath();
  //繪制最外層的大圓(黑色)
  context.arc(400, 400, 300, Math.PI / 180 * 0, Math.PI / 180 * 360);
  //將大圓填充為黑色
  context.fillStyle = '#000';
  context.fill();
  //繪制左半圓(白色)
  context.beginPath();
  context.arc(400, 400, 300, Math.PI / 180 * 90, Math.PI / 180 * 270);
  context.fillStyle = '#fff';
  context.fill(); 
  //繪制右半圓(黑色)，會覆蓋外層大圓，顏色一樣。所以寫不寫都可以
  /* context.beginPath();
  context.arc(400, 400, 300, Math.PI / 180 * 270, Math.PI / 180 * 90);
  context.fillStyle = '#000';
  context.fill(); */
  //繪制左上半圓(黑色)
  context.beginPath();
  context.arc(400, 250, 150, Math.PI / 180 * 90, Math.PI / 180 * 270);
  context.fillStyle = '#000';
  context.fill(); 
  //繪制右下半圓(白色)
  context.beginPath();
  context.arc(400, 550, 150, Math.PI / 180 * 270, Math.PI / 180 * 90);
  context.fillStyle = '#fff';
  context.fill(); 
  //繪制左上小半圓(白色)
  context.beginPath();
  context.arc(400, 250, 35, Math.PI / 180 * 0, Math.PI / 180 * 360);
  context.fillStyle = '#fff';
  context.fill(); 
  //繪制右下小半圓(黑色)
  context.beginPath();
  context.arc(400, 550, 35, Math.PI / 180 * 0, Math.PI / 180 * 360);
  context.fillStyle = '#000';
  context.fill(); 
}

<div class="animation">
    <canvas id="canvas" width="800" height="800"></canvas>
  </div>