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/**
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* 签名版，钢笔效果
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* 源参考：https://www.cnblogs.com/fangsmile/p/14324460.html
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*/
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class Point {
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constructor(x, y, time) {
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this.x = x;
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this.y = y;
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this.isControl = false;
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this.time = Date.now();
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this.lineWidth = 0;
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this.isAdd = false;
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}
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}
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class Line {
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constructor() {
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this.points = new Array();
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this.changeWidthCount = 0;
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this.lineWidth = 10;
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}
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}
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class HandwritingSelf {
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constructor(canvas,w,h,line_w=8,line_color='#ff0000') {
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this.canvas = {width:w,height:h};
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this.ctx = canvas
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var context = this.ctx;
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this.ctx.ellipse = function( x, y, a, b){
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// ----
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}
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// this.points = new Array();
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this.line = new Line();
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this.pointLines = new Array();//Line数组
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this.k = 0.5;
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this.begin = null;
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this.middle = null;
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this.end = null;
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this.preTime = null;
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this.lineWidth = line_w;
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this.lineColor = line_color;
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this.isDown = false;
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}
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down(x, y) {
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this.isDown = true;
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this.line = new Line();
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this.line.lineWidth = this.lineWidth;
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let currentPoint = new Point(x, y, Date.now());
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this.addPoint(currentPoint);
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this.preTime = Date.now();
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}
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move(x, y) {
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// console.log("move:",x,y)
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if (this.isDown) {
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let currentPoint = new Point(x, y, Date.now())
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this.addPoint(currentPoint);
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this.draw();
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}
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}
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up(x, y) {
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// if (e.touches.length > 0) {
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let currentPoint = new Point(x, y, Date.now())
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this.addPoint(currentPoint);
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// }
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this.draw(true);
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this.pointLines.push(this.line);
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this.begin = null;
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this.middle = null;
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this.end = null;
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this.isDown = false;
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}
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draw(isUp = false) {
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// this.ctx.clearRect(0, 0, this.canvas.width, this.canvas.height);
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this.ctx.setStrokeStyle(this.lineColor)
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//绘制不包含this.line的线条
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this.pointLines.forEach((line, index) => {
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let points = line.points;
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this.ctx.beginPath();
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this.ctx.ellipse(points[0].x - 1.5, points[0].y, 6, 3, Math.PI / 4, 0, Math.PI * 2);
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this.ctx.fill();
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this.ctx.beginPath();
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this.ctx.moveTo(points[0].x, points[0].y);
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let lastW = line.lineWidth;
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this.ctx.setLineWidth(line.lineWidth);
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this.ctx.setLineJoin("round");
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this.ctx.setLineCap( "round");
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let minLineW = line.lineWidth / 4;
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let isChangeW = false;
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let changeWidthCount = line.changeWidthCount;
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for (let i = 1; i <= points.length; i++) {
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if (i == points.length) {
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this.ctx.stroke();
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break;
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}
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if (i > points.length - changeWidthCount) {
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if (!isChangeW) {
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this.ctx.stroke();//将之前的线条不变的path绘制完
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isChangeW = true;
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if (i > 1 && points[i - 1].isControl)
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continue;
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}
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let w = (lastW - minLineW) / changeWidthCount * (points.length - i) + minLineW;
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points[i - 1].lineWidth = w;
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this.ctx.beginPath();//为了开启新的路径 否则每次stroke 都会把之前的路径在描一遍
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// this.ctx.strokeStyle = "rgba("+Math.random()*255+","+Math.random()*255+","+Math.random()*255+",1)";
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this.ctx.setLineWidth(w);
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this.ctx.moveTo(points[i - 1].x, points[i - 1].y);//移动到之前的点
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this.ctx.lineTo(points[i].x, points[i].y);
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this.ctx.stroke();//将之前的线条不变的path绘制完
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} else {
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if (points[i].isControl && points[i + 1]) {
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this.ctx.quadraticCurveTo(points[i].x, points[i].y, points[i + 1].x, points[i + 1].y);
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} else if (i >= 1 && points[i - 1].isControl) {//上一个是控制点 当前点已经被绘制
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} else
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this.ctx.lineTo(points[i].x, points[i].y);
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}
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}
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})
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//绘制this.line线条
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let points;
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if (isUp)
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points = this.line.points;
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else
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points = [...this.line.points];
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//当前绘制的线条最后几个补点 贝塞尔方式增加点
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let count = 0;
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let insertCount = 0;
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let i = points.length - 1;
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let endPoint = points[i];
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let controlPoint;
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let startPoint;
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while (i >= 0) {
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if (points[i].isControl == true) {
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controlPoint = points[i];
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count++;
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} else {
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startPoint = points[i];
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}
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if (startPoint && controlPoint && endPoint) {//使用贝塞尔计算补点
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let dis = this.z_distance(startPoint, controlPoint) + this.z_distance(controlPoint, endPoint);
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let insertPoints = this.BezierCalculate([startPoint, controlPoint, endPoint], Math.floor(dis / 6) + 1);
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insertCount += insertPoints.length;
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var index = i;//插入位置
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// 把insertPoints 变成一个适合splice的数组（包含splice前2个参数的数组）
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insertPoints.unshift(index, 1);
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Array.prototype.splice.apply(points, insertPoints);
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//补完点后
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endPoint = startPoint;
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startPoint = null;
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}
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if (count >= 6)
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break;
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i--;
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}
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//确定最后线宽变化的点数
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let changeWidthCount = count + insertCount;
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if (isUp)
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this.line.changeWidthCount = changeWidthCount;
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//制造椭圆头
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this.ctx.fillStyle = "rgba(255,20,87,1)"
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this.ctx.beginPath();
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this.ctx.ellipse(points[0].x - 1.5, points[0].y, 6, 3, Math.PI / 4, 0, Math.PI * 2);
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this.ctx.fill();
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this.ctx.draw(true);
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this.ctx.beginPath();
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this.ctx.moveTo(points[0].x, points[0].y);
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let lastW = this.line.lineWidth;
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this.ctx.setLineWidth(this.line.lineWidth);
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this.ctx.setLineJoin("round");
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this.ctx.setLineCap( "round");
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let minLineW = this.line.lineWidth / 4;
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let isChangeW = false;
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for (let i = 1; i <= points.length; i++) {
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if (i == points.length) {
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this.ctx.stroke();
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break;
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}
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//最后的一些点线宽变细
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if (i > points.length - changeWidthCount) {
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if (!isChangeW) {
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this.ctx.stroke();//将之前的线条不变的path绘制完
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isChangeW = true;
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if (i > 1 && points[i - 1].isControl)
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continue;
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}
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//计算线宽
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let w = (lastW - minLineW) / changeWidthCount * (points.length - i) + minLineW;
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points[i - 1].lineWidth = w;
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this.ctx.beginPath();//为了开启新的路径 否则每次stroke 都会把之前的路径在描一遍
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// this.ctx.strokeStyle = "rgba(" + Math.random() * 255 + "," + Math.random() * 255 + "," + Math.random() * 255 + ",0.5)";
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this.ctx.setLineWidth(w);
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this.ctx.moveTo(points[i - 1].x, points[i - 1].y);//移动到之前的点
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this.ctx.lineTo(points[i].x, points[i].y);
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this.ctx.stroke();//将之前的线条不变的path绘制完
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} else {
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if (points[i].isControl && points[i + 1]) {
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this.ctx.quadraticCurveTo(points[i].x, points[i].y, points[i + 1].x, points[i + 1].y);
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} else if (i >= 1 && points[i - 1].isControl) {//上一个是控制点 当前点已经被绘制
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} else
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this.ctx.lineTo(points[i].x, points[i].y);
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}
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}
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this.ctx.draw(true);
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}
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addPoint(p) {
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if (this.line.points.length >= 1) {
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let last_point = this.line.points[this.line.points.length - 1]
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let distance = this.z_distance(p, last_point);
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if (distance < 10) {
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return;
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}
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}
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if (this.line.points.length == 0) {
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this.begin = p;
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p.isControl = true;
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this.pushPoint(p);
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} else {
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this.middle = p;
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let controlPs = this.computeControlPoints(this.k, this.begin, this.middle, null);
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this.pushPoint(controlPs.first);
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this.pushPoint(p);
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p.isControl = true;
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this.begin = this.middle;
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}
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}
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addOtherPoint(p1, p2, w1, w2) {
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let otherPoints = new Array();
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let dis = this.z_distance(p1, p2);
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if (dis >= 25) {
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otherPoints.push(p1);
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let insertPCount = Math.floor(dis / 20);
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for (let j = 0; j < insertPCount; j++) {
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let insertP = new Point(p1.x + (j + 1) / (insertPCount + 1) * (p2.x - p1.x), p1.y + (j + 1) / (insertPCount + 1) * (p2.y - p1.y))
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insertP.isAdd = true;
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otherPoints.push(insertP);
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}
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otherPoints.push(p2);
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}
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let count = otherPoints.length;
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if (count > 0) {
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console.log("addOtherPoint")
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debugger
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let diffW = (w2 - w1) / (count - 1);
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for (let i = 1; i < count; i++) {
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let w = w1 + diffW * i;
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this.ctx.beginPath();
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this.ctx.setLineWidth(w);
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this.ctx.moveTo(otherPoints[i - 1].x, otherPoints[i - 1].y);
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this.ctx.lineTo(otherPoints[i].x, otherPoints[i].y)
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this.ctx.stroke();
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}
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}
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return otherPoints
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}
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pushPoint(p) {
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//排除重复点
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if (this.line.points.length >= 1 && this.line.points[this.line.points.length - 1].x == p.x && this.line.points[this.line.points.length - 1].y == p.y)
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return;
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this.line.points.push(p);
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}
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computeControlPoints(k, begin, middle, end) {
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if (k > 0.5 || k <= 0)
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return;
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let diff1 = new Point(middle.x - begin.x, middle.y - begin.y)
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let diff2 = null;
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if (end)
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diff2 = new Point(end.x - middle.x, end.y - middle.y)
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// let l1 = (diff1.x ** 2 + diff1.y ** 2) ** (1 / 2)
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// let l2 = (diff2.x ** 2 + diff2.y ** 2) ** (1 / 2)
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let first = new Point(middle.x - (k * diff1.x), middle.y - (k * diff1.y))
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let second = null;
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if (diff2)
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second = new Point(middle.x + (k * diff2.x), middle.y + (k * diff2.y))
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return { first: first, second: second }
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}
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// W_current =
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// W_previous + min( abs(k*s - W_previous), distance * K_width_unit_change) (k * s-W_previous) >= 0
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// W_previous - min( abs(k*s - W_previous), distance * K_width_unit_change) (k * s-W_previous) < 0
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// W_current 当前线段的宽度
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// W_previous 与当前线条相邻的前一条线段的宽度
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// distance 当前线条的长度
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// w_k 设定的一个固定阈值,表示:单位距离内, 笔迹的线条宽度可以变化的最大量.
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// distance * w_k 即为当前线段的长度内, 笔宽可以相对于前一条线段笔宽的基础上, 最多能够变宽或者可以变窄多少.
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z_linewidth(b, e, bwidth, step) {
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if (e.time == b.time)
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return bwidth;
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let max_speed = 2.0;
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let d = this.z_distance(b, e);
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let s = d / (e.time - b.time);//计算速度
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console.log("s", e.time - b.time, s)
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s = s > max_speed ? max_speed : s;
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// let w = (max_speed - s) / max_speed;
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let w = 0.5 / s;
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let max_dif = d * step;
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console.log(w, bwidth, max_dif)
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if (w < 0.05) w = 0.05;
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if (Math.abs(w - bwidth) > max_dif) {
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if (w > bwidth)
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w = bwidth + max_dif;
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else
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w = bwidth - max_dif;
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}
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// printf("d:%.4f, time_diff:%lld, speed:%.4f, width:%.4f\n", d, e.t-b.t, s, w);
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return w;
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}
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z_distance(b, e) {
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return Math.sqrt(Math.pow(e.x - b.x, 2) + Math.pow(e.y - b.y, 2));
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}
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BezierCalculate(poss, precision) {
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//维度，坐标轴数（二维坐标，三维坐标...）
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let dimersion = 2;
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//贝塞尔曲线控制点数（阶数）
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let number = poss.length;
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//控制点数不小于 2 ，至少为二维坐标系
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if (number < 2 || dimersion < 2)
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return null;
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let result = new Array();
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//计算杨辉三角
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let mi = new Array();
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mi[0] = mi[1] = 1;
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for (let i = 3; i <= number; i++) {
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let t = new Array();
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for (let j = 0; j < i - 1; j++) {
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t[j] = mi[j];
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}
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mi[0] = mi[i - 1] = 1;
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for (let j = 0; j < i - 2; j++) {
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mi[j + 1] = t[j] + t[j + 1];
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}
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}
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//计算坐标点
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for (let i = 0; i < precision; i++) {
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let t = i / precision;
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let p = new Point(0, 0);
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p.isAdd = true;
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result.push(p);
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for (let j = 0; j < dimersion; j++) {
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let temp = 0.0;
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for (let k = 0; k < number; k++) {
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temp += Math.pow(1 - t, number - k - 1) * (j == 0 ? poss[k].x : poss[k].y) * Math.pow(t, k) * mi[k];
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}
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j == 0 ? p.x = temp : p.y = temp;
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}
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}
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return result;
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}
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}
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export default HandwritingSelf; |