How to draw a smiling expression using canvas (code example)

The content of this article is about how to use canvas to draw a smiling expression (code example). It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

During my internship, I was asked to use canvas to draw an expression. It was relatively simple, so I went straight to the code without saying much:

<div>
    <canvas>
        你的浏览器居然不支持Canvas!
    </canvas>
</div>
<script>
    window.onload = function () {
        var canvas = document.getElementById("canvas");
        canvas.width = 400;
        canvas.height = 400;
        //获取上下文
        var context = canvas.getContext("2d");
        //用于画有填充色圆的函数  参数分别为圆心坐标 ，半径，起始与终止位置，线颜色，填充颜色
        function drawCircle(x2, y2, r2, a2, b2, lineColor, FillColor) {
            context.beginPath();
            context.arc(x2, y2, r2, a2, b2 * Math.PI);
            context.strokeStyle = lineColor;
            context.fillStyle = FillColor;
            context.fill(); //确认填充
            context.stroke();
        };
        //用于画圆弧函数 默认线条为黑色 无填充 参数分别为：圆心x坐标，圆心y坐标，半径，开始位置，终止位置
        function drawsArc(x, y, r, l1, l2) {
            context.beginPath();
            context.arc(x, y, r, l1 * Math.PI, l2 * Math.PI);
            context.strokeStyle = "black";
            context.stroke();
        };
        //用于画眼睛的函数
        function darwEyes(x1, y1, a1, b1) { //参数分别为椭圆圆心位置 长轴  短轴
            context.strokeStyle = "#754924"
            ParamEllipse(context, x1, y1, a1, b1); //椭圆
            function ParamEllipse(context, x, y, a, b) {
                //使每次循环所绘制的路径（弧线）接近1像素
                var step = (a > b) ? 1 / a : 1 / b;
                context.beginPath();
                context.moveTo(x + a, y); //从椭圆的左端点开始绘制
                for (var i = 0; i < 2 * Math.PI; i += step) {
                    //参数为i，表示度数（弧度）
                    context.lineTo(x + a * Math.cos(i), y + b * Math.sin(i));
                }
                context.closePath();
                context.fillStyle = "#754924";
                context.fill(); 
                context.stroke();
            };
        };
        //脸
        drawCircle(200, 200, 200, 0, 2, "#EEE685", "#FCF200");
        //左眼
        context.strokeStyle = "#754924"
        darwEyes(116, 130, 18, 25);
        drawCircle(110, 127, 12, 0, 2, "#754924", "#F5F5F5");
        //右眼
        darwEyes(296, 130, 18, 25);
        drawCircle(290, 127, 12, 0, 2, "#754924", "#F5F5F5");
        //左眉毛
        drawsArc(100, 100, 50, 1.3, 1.7);
        //右眉毛
        drawsArc(300, 100, 50, 1.3, 1.7);
        //嘴巴
        drawsArc(200, 120, 180, 0.3, 0.7);
    }
</script>

The above is the detailed content of How to draw a smiling expression using canvas (code example). For more information, please follow other related articles on the PHP Chinese website!