canvas仿写贝塞尔曲线图的示例编码

2021-02-23 15:55 jianzhan

天正在等烟雨,而我在等你,啦啦啦,欢迎关心我的简书,今日共享的是原創的canvas仿写贝塞尔曲线图方式。实际以下:

实际效果图:

html

<canvas id="mycanvas" width="500" height="500">您的访问器不适用canvas</canvas>

css

canvas{ border: 1px solid black;}

js

var canvas = document.getElementById("mycanvas");
        var context = canvas.getContext("2d");
        var x1 = 100;
        var y1 = 100;
        var x2 = 400;
        var y2 = 400;
        draw();
        function draw(){
            //画半全透明的线
            context.beginPath();
            context.moveTo(500,0);
            context.lineTo(0,500);
            context.strokeStyle = "rgba(0,0,0,0.3)";
            context.lineWidth = 10;
            context.stroke();
            //画联接线
            context.beginPath();
            context.moveTo(0,500);
            context.lineTo(x1,y1);
            context.lineWidth = 2;
            context.strokeStyle = "black";
            context.stroke();
            context.beginPath();
            context.moveTo(500,0);
            context.lineTo(x2,y2);
            context.lineWidth = 2;
            context.strokeStyle = "black";
            context.stroke();
            //画红球
            context.beginPath();
            context.arc(x1,y1,10,0,Math.PI*2);
            context.fillStyle = "orange";
            context.fill();
            //画蓝球
            context.beginPath();
            context.arc(x2,y2,10,0,Math.PI*2);
            context.fillStyle = "blue";
            context.fill();
            //画贝塞尔曲线图
            context.beginPath();
            context.moveTo(0,500);
            context.bezierCurveTo(x1,y1,x2,y2,500,0);
            context.lineWidth = 5;
            context.stroke();
        }
        //拖拽小球做动漫
        //分辨是不是拖拽小球
        //假如在小球上就做动漫
        canvas.onmousedown = function(e){
            var ev = e || window.event;
            var x = ev.offsetX;
            var y = ev.offsetY;
            //分辨是不是在红球上
            var dis = Math.pow((x-x1),2) + Math.pow((y-y1),2);
            if(dis<100){
                console.log("电脑鼠标在红球上");
                canvas.onmousemove = function(e){
                    var ev = e || window.event;
                    var xx = ev.offsetX;
                    var yy = ev.offsetY;
                    //消除画布
                    context.clearRect(0,0,canvas.width,canvas.height);
                    x1 = xx;
                    y1 = yy;
                    //重绘图
                    draw();
                }
            }
            //分辨电脑鼠标是不是在蓝球上
            var dis = Math.pow((x-x2),2) + Math.pow((y-y2),2);
            if(dis<100){
                canvas.onmousemove = function(e){
                    var ev = e || window.event;
                    var xx1 = ev.offsetX;
                    var yy1 = ev.offsetY;
                    //消除画布
                    context.clearRect(0,0,canvas.width,canvas.height);
                    x2 = xx1;
                    y2 = yy1;
                    //重绘图
                    draw();
                }
            }
        }
        document.onmouseup =function(){
            canvas.onmousemove = " ";
        }

以上便是本文的所有內容,期待对大伙儿的学习培训有一定的协助,也期待大伙儿多多适用脚本制作之家。