How to use common drawing methods in Canvas API

The draw (drawing) method in JavaScript is a technology used to draw graphics in web pages. It allows developers to create animations, interactive graphics, and other visual elements in the browser to make web pages richer and more engaging.

In JavaScript, the Canvas API is generally used to create a canvas, and then JavaScript is used to write code to draw graphics or graphics sequences. The Canvas API provides various drawing methods, such as drawing lines, rectangles, circles, paths, etc. Through the Canvas API, we can control the color, thickness, transparency and other properties of the drawing.

In the following examples, we demonstrate how to use common drawing methods in the Canvas API.

//创建画布canvas
var canvas = document.getElementById('myCanvas');
var context = canvas.getContext('2d');

//绘制矩形
context.fillStyle = '#FF0000'; //设置填充颜色为红色
context.fillRect(10, 10, 50, 50); //绘制矩形，起点坐标为10,10，长宽为50

//绘制圆形
context.beginPath();
context.fillStyle = '#00FF00'; //设置填充颜色为绿色
context.arc(100, 100, 30, 0, 2 * Math.PI); //绘制圆形，圆心坐标为100,100，半径为30
context.fill();

//绘制线条
context.beginPath();
context.moveTo(200, 200); //设置线条起点坐标为200,200
context.lineTo(300, 200); //设置线条终点坐标为300,200
context.strokeStyle = '#0000FF'; //设置线条颜色为蓝色
context.stroke(); //绘制线条

//绘制文本
context.font = '30px Arial'; //设置文字样式和大小
context.fillStyle = '#000000'; //设置文字颜色为黑色
context.fillText('Hello World', 400, 400); //绘制文本，起点坐标为400,400

In the above code, we first use JavaScript to create a canvas element and obtain its 2D context (i.e. CanvasRenderingContext2D object). Then, we use fillRect, arc, stroke and other methods to draw rectangles, circles, lines and other graphics. Finally, we use the fillText method to draw the text.

Of course, in actual use, we usually combine other technologies such as CSS, DOM, events, etc. to achieve more complex effects. For example, we can use CSS to control the size and position of the canvas, use DOM to dynamically create elements to achieve interactive effects, use event listeners to respond to user operations, and so on.

Through the drawing method, we can add vivid graphics and animation effects to the web page, making the web page more vivid, interesting and practical. At the same time, the programmability and flexibility of JavaScript also allow us to be creative and provide users with a richer and better browsing experience.

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