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- <!doctype html>
- <html lang="en">
- <head>
- <meta charset="UTF-8" />
- <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1" />
- <title> canvas 手写毛笔字效果 </title>
- <style type="text/css">
- #canvasId {
- background-color: #FFFFcc;
- }
- </style>
- </head>
- <body>
- <canvas id="canvasId" width="700" height="500"></canvas><br />
- <input type="button" value="clear" οnclick="hw.clear();" />
- <script type="text/javascript">
- function Handwriting(id) {
- this.canvas = document.getElementById(id);
- this.ctx = this.canvas.getContext("2d");
- this.ctx.fillStyle = "rgba(0,0,0,0.25)";
- var _this = this;
- this.canvas.onmousedown = function (e) { _this.downEvent(e)};
- this.canvas.onmousemove = function (e) { _this.moveEvent(e)};
- this.canvas.onmouseup = function (e) { _this.upEvent(e)};
- this.canvas.onmouseout = function (e) { _this.upEvent(e)};
- this.moveFlag = false;
- this.upof = {};
- this.radius = 0;
- this.has = [];
- this.lineMax = 30;
- this.lineMin = 3;
- this.linePressure = 1;
- this.smoothness = 80;
- }
- Handwriting.prototype.clear = function () {
- this.ctx.clearRect(0,0,this.canvas.width,this.canvas.height);
- }
- Handwriting.prototype.downEvent = function (e) {
- this.moveFlag = true;
- this.has = [];
- this.upof = this.getXY(e);
- }
- Handwriting.prototype.moveEvent = function (e) {
- if (!this.moveFlag)
- return;
- var of = this.getXY(e);
- var up = this.upof;
- var ur = this.radius;
- this.has.unshift({time:new Date().getTime() ,dis:this.distance(up,of)});
- var dis = 0;
- var time = 0;
- for (var n = 0; n < this.has.length-1; n++) {
- dis += this.has[n].dis;
- time += this.has[n].time-this.has[n+1].time;
- if (dis>this.smoothness)
- break;
- }
- var or = Math.min(time/dis*this.linePressure+this.lineMin , this.lineMax) / 2;
- this.radius = or;
- this.upof = of;
- if (this.has.length<=4)
- return;
- var len = Math.round(this.has[0].dis/2)+1;
- for (var i = 0; i < len; i++) {
- var x = up.x + (of.x-up.x)/len*i;
- var y = up.y + (of.y-up.y)/len*i;
- var r = ur + (or-ur)/len*i;
- this.ctx.beginPath();
- this.ctx.arc(x,y,r,0,2*Math.PI,true);
- this.ctx.fill();
- }
- }
- Handwriting.prototype.upEvent = function (e) {
- this.moveFlag = false;
- }
- Handwriting.prototype.getXY = function (e)
- {
- return {
- x : e.clientX - this.canvas.offsetLeft + (document.body.scrollLeft || document.documentElement.scrollLeft),
- y : e.clientY - this.canvas.offsetTop + (document.body.scrollTop || document.documentElement.scrollTop)
- }
- }
- Handwriting.prototype.distance = function (a,b)
- {
- var x = b.x-a.x , y = b.y-a.y;
- return Math.sqrt(x*x+y*y);
- }
- var hw = new Handwriting("canvasId");
- hw.lineMax = 40;
- hw.lineMin = 5;
- hw.linePressure = 2.5;
- hw.smoothness = 100;
- </script>
- </body>
- </html>
-
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