主要的邏輯代碼:
// 繪制二次方貝塞爾曲線
var context = document.getElementById('canvas').getContext('2d');
context.fillStyle = 'cornflowerblue';
context.strokeStyle = 'yellow';
context.shadowColor = 'rgba(50, 50, 50, 1)';
context.shadowOffsetX = 2;
context.shadowOffsetY = 2;
context.shadowBlur = 4;
context.lineWidth = 20;
context.lineCap = 'round';
context.beginPath();
context.moveTo(120.5, 130);
context.quadraticCurveTo(150.8, 130, 160.6, 150.5);
context.quadraticCurveTo(190,250,210.5, 160.5);
context.quadraticCurveTo(240,100.5,290,70.5);
context.stroke();
二次方的公式為:
效果圖如下: