Section 1.1: The quadraticCurveTo Method

A useful approach for creating curves in the HTML5 canvas is through the quadraticCurveTo method associated with the canvas context object. To begin, you will first need to set up the HTML structure. Here’s an example:

<canvas width="200" height="200"></canvas>

Next, you can implement the following JavaScript code:

const points = [

{ x: 1, y: 1 },

{ x: 20, y: 30 },

{ x: 30, y: 40 },

{ x: 40, y: 20 },

{ x: 50, y: 60 }

];

const canvas = document.querySelector('canvas');

const ctx = canvas.getContext("2d");

ctx.beginPath();

ctx.moveTo(points[0].x, points[0].y);

for (const point of points) {

const xMid = (point.x + point.x) / 2;

const yMid = (point.y + point.y) / 2;

const cpX1 = (xMid + point.x) / 2;

const cpX2 = (xMid + point.x) / 2;

ctx.quadraticCurveTo(cpX1, point.y, xMid, yMid);

ctx.quadraticCurveTo(cpX2, point.y, point.x, point.y);

}

ctx.stroke();

This code snippet defines an array of points with their respective x and y coordinates. After selecting the canvas element with document.querySelector, we retrieve its context using getContext. We initiate the drawing process with beginPath, move to the starting point using moveTo, and subsequently draw the curve using quadraticCurveTo.

Finally, we use stroke to render the line on the canvas.

Section 1.2: Conclusion

In summary, the quadraticCurveTo method provided by the canvas context object is instrumental in drawing smooth curves that connect multiple points.