HTML Canvas 涂鸦
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HTML Canvas 涂鸦一
<!doctype html><head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>javascript结合html5 canvas实现的涂鸦板 - 分享JavaScript-sharejs.com</title> <meta name="Copyright" content="JavaScript分享网 http://www.sharejs.com/" /> <meta name="description" content="javascript结合html5 canvas实现的涂鸦板,JavaScript分享网，js脚本，网页特效，网页模板，png图标，矢量图下载" /> <meta content="JavaScript,分享,JavaScript代码,Ajax,jQuery,网页模板,PNG图标，矢量图" name="keywords" /></head><body> <style> * { margin: 0; padding: 0; } .fa { width: 740px; margin: 0 auto; } .top { margin: 20px 0; } .top input { width: 25px; height: 25px; border: 1px solid #fff; border-radius: 4px; background: #ddd; } .top .i1 { background: #000000; } .top .i2 { background: #FF0000; } .top .i3 { background: #80FF00; } .top .i4 { background: #00FFFF; } .top .i5 { background: #808080; } .top .i6 { background: #FF8000; } .top .i7 { background: #408080; } .top .i8 { background: #8000FF; } .top .i9 { background: #CCCC00; } #canvas { background: #eee; cursor: default; } .font input { font-size: 14px; } .top .grea { background: #aaa; } </style> </head> <body> <div class="fa"> <div class="top"> <div id="color"> 请选择画笔颜色： <input class="i1" type="button" value="" /> <input class="i2" type="button" value="" /> <input class="i3" type="button" value="" /> <input class="i4" type="button" value="" /> <input class="i5" type="button" value="" /> <input class="i6" type="button" value="" /> <input class="i7" type="button" value="" /> <input class="i8" type="button" value="" /> <input class="i9" type="button" value="" /> </div> <div class="font" id="font"> 请选择画笔的宽度： <input type="button" value="细" /> <input type="button" value="中" class="grea" /> <input type="button" value="粗" /> </div> <div> <span id="error">如果有错误，请使用橡皮擦：</span> <input id="eraser" style="width:60px;font-size:14px;" type="button" value="橡皮擦" /> </div> <input id="clear" type="button" value="清除画布" style="width:80px;" /> <input id="revocation" type="button" value="撤销" style="width:80px;" /> <input id="imgurl" type="button" value="导出图片路径" style="width:80px;" /> </div> <canvas id="canvas" width="740" height="420">您的浏览器不支持 canvas 标签</canvas> <div id="div1"></div> </div> <div id="html"> </div> <script> (function() { var paint = { init: function() { this.load(); }, load: function() { this.x = []; //记录鼠标移动是的X坐标 this.y = []; //记录鼠标移动是的Y坐标 this.clickDrag = []; this.lock = false; //鼠标移动前，判断鼠标是否按下 this.isEraser = false; //this.Timer=null;//橡皮擦启动计时器 //this.radius=5; this.storageColor = "#000000"; this.eraserRadius = 15; //擦除半径值 this.color = ["#000000", "#FF0000", "#80FF00", "#00FFFF", "#808080", "#FF8000", "#408080", "#8000FF", "#CCCC00"]; //画笔颜色值 this.fontWeight = [2, 5, 8]; this.$ = function(id) { return typeof id == "string" ? document.getElementById(id) : id; }; this.canvas = this.$("canvas"); if (this.canvas.getContext) {} else { alert("您的浏览器不支持 canvas 标签"); return; } this.cxt = this.canvas.getContext('2d'); this.cxt.lineJoin = "round"; //context.lineJoin - 指定两条线段的连接方式 this.cxt.lineWidth = 5; //线条的宽度 this.iptClear = this.$("clear"); this.revocation = this.$("revocation"); this.imgurl = this.$("imgurl"); //图片路径按钮 this.w = this.canvas.width; //取画布的宽 this.h = this.canvas.height; //取画布的高 this.touch = ("createTouch" in document); //判定是否为手持设备 this.StartEvent = this.touch ? "touchstart" : "mousedown"; //支持触摸式使用相应的事件替代 this.MoveEvent = this.touch ? "touchmove" : "mousemove"; this.EndEvent = this.touch ? "touchend" : "mouseup"; this.bind(); }, bind: function() { var t = this; /*清除画布*/ this.iptClear.onclick = function() { t.clear(); }; /*鼠标按下事件，记录鼠标位置，并绘制，解锁lock，打开mousemove事件*/ this.canvas['on' + t.StartEvent] = function(e) { var touch = t.touch ? e.touches[0] : e; var _x = touch.clientX - touch.target.offsetLeft; //鼠标在画布上的x坐标，以画布左上角为起点 var _y = touch.clientY - touch.target.offsetTop; //鼠标在画布上的y坐标，以画布左上角为起点 if (t.isEraser) { /* t.cxt.globalCompositeOperation = "destination-out"; t.cxt.beginPath(); t.cxt.arc(_x, _y,t.eraserRadius, 0, Math.PI * 2); t.cxt.strokeStyle = "rgba(250,250,250,0)"; t.cxt.fill(); t.cxt.globalCompositeOperation = "source-over"; */ t.resetEraser(_x, _y, touch); } else { t.movePoint(_x, _y); //记录鼠标位置 t.drawPoint(); //绘制路线 } t.lock = true; }; /*鼠标移动事件*/ this.canvas['on' + t.MoveEvent] = function(e) { var touch = t.touch ? e.touches[0] : e; if (t.lock) //t.lock为true则执行 { var _x = touch.clientX - touch.target.offsetLeft; //鼠标在画布上的x坐标，以画布左上角为起点 var _y = touch.clientY - touch.target.offsetTop; //鼠标在画布上的y坐标，以画布左上角为起点 if (t.isEraser) { //if(t.Timer)clearInterval(t.Timer); //t.Timer=setInterval(function(){ t.resetEraser(_x, _y, touch); //},10); } else { t.saveDraw(); t.movePoint(_x, _y, true); //记录鼠标位置 t.drawPoint(); //绘制路线 } } }; this.canvas['on' + t.EndEvent] = function(e) { /*重置数据*/ t.lock = false; t.x = []; t.y = []; t.clickDrag = []; clearInterval(t.Timer); t.Timer = null; }; this.revocation.onclick = function() { t.redraw(); }; this.changeColor(); this.imgurl.onclick = function() { t.getUrl(); }; /*橡皮擦*/ this.$("eraser").onclick = function(e) { t.isEraser = true; t.$("error").style.color = "red"; t.$("error").innerHTML = "您已使用橡皮擦！"; }; }, movePoint: function(x, y, dragging) { /*将鼠标坐标添加到各自对应的数组里*/ this.x.push(x); this.y.push(y); this.clickDrag.push(y); }, drawPoint: function(x, y, radius) { for (var i = 0; i < this.x.length; i++) //循环数组 { this.cxt.beginPath(); //context.beginPath() , 准备绘制一条路径 if (this.clickDrag[i] && i) { //当是拖动而且i!=0时，从上一个点开始画线。 this.cxt.moveTo(this.x[i - 1], this.y[i - 1]); //context.moveTo(x, y) , 新开一个路径，并指定路径的起点 } else { this.cxt.moveTo(this.x[i] - 1, this.y[i]); } this.cxt.lineTo(this.x[i], this.y[i]); //context.lineTo(x, y) , 将当前点与指定的点用一条笔直的路径连接起来 this.cxt.closePath(); //context.closePath() , 如果当前路径是打开的则关闭它 this.cxt.stroke(); //context.stroke() , 绘制当前路径 } }, clear: function() { this.cxt.clearRect(0, 0, this.w, this.h); //清除画布，左上角为起点 }, redraw: function() { /*撤销*/ this.cxt.restore(); }, preventDefault: function(e) { /*阻止默认*/ var touch = this.touch ? e.touches[0] : e; if (this.touch) touch.preventDefault(); else window.event.returnValue = false; }, changeColor: function() { /*为按钮添加事件*/ var t = this, iptNum = this.$("color").getElementsByTagName("input"), fontIptNum = this.$("font").getElementsByTagName("input"); for (var i = 0, l = iptNum.length; i < l; i++) { iptNum[i].index = i; iptNum[i].onclick = function() { t.cxt.save(); t.cxt.strokeStyle = t.color[this.index]; t.storageColor = t.color[this.index]; t.$("error").style.color = "#000"; t.$("error").innerHTML = "如果有错误，请使用橡皮擦："; t.cxt.strokeStyle = t.storageColor; t.isEraser = false; } } for (var i = 0, l = fontIptNum.length; i < l; i++) { t.cxt.save(); fontIptNum[i].index = i; fontIptNum[i].onclick = function() { t.changeBackground(this.index); t.cxt.lineWidth = t.fontWeight[this.index]; t.$("error").style.color = "#000"; t.$("error").innerHTML = "如果有错误，请使用橡皮擦："; t.isEraser = false; t.cxt.strokeStyle = t.storageColor; } } }, changeBackground: function(num) { /*添加画笔粗细的提示背景颜色切换，灰色为当前*/ var fontIptNum = this.$("font").getElementsByTagName("input"); for (var j = 0, m = fontIptNum.length; j < m; j++) { fontIptNum[j].className = ""; if (j == num) fontIptNum[j].className = "grea"; } }, getUrl: function() { this.$("html").innerHTML = this.canvas.toDataURL(); }, resetEraser: function(_x, _y, touch) { /*使用橡皮擦-提醒*/ var t = this; //this.cxt.lineWidth = 30; /*source-over 默认,相交部分由后绘制图形的填充(颜色,渐变,纹理)覆盖,全部浏览器通过*/ t.cxt.globalCompositeOperation = "destination-out"; t.cxt.beginPath(); t.cxt.arc(_x, _y, t.eraserRadius, 0, Math.PI * 2); t.cxt.strokeStyle = "rgba(250,250,250,0)"; t.cxt.fill(); t.cxt.globalCompositeOperation = "source-over" } }; paint.init(); })(); </script> <div style="clear:both"></div> <br> <br> <div align="center"> <script language="javascript" src="http://www.sharejs.com/js/720.js"></script> <br> <br> 获取更多JavaScript代码，请登录JavaScript分享网 <a href="http://www.sharejs.com">http://www.sharejs.com</a> <br> 转载请注明出处，本代码仅供学习交流，不可用于任何商业用途！ </div> </body> </html>涂鸦二
<div align="center"> <canvas id="myCanvas" width="500" height="200" style="border:2px solid #6699cc"></canvas> <div class="control-ops"> <button type="button" class="btn btn-primary" onclick="javascript:clearArea();return false;">清空画板</button> Line width : <select id="selWidth"> <option value="1">1</option> <option value="3">3</option> <option value="5">5</option> <option value="7">7</option> <option value="9" selected="selected">9</option> <option value="11">11</option> </select> Color : <select id="selColor"> <option value="black">black</option> <option value="blue" selected="selected">blue</option> <option value="red">red</option> <option value="green">green</option> <option value="yellow">yellow</option> <option value="gray">gray</option> </select> </div></div>
var mousePressed = false;var lastX, lastY;var ctx; function InitThis() { ctx = document.getElementById('myCanvas').getContext("2d"); $('#myCanvas').mousedown(function (e) { mousePressed = true; Draw(e.pageX - $(this).offset().left, e.pageY - $(this).offset().top, false); }); $('#myCanvas').mousemove(function (e) { if (mousePressed) { Draw(e.pageX - $(this).offset().left, e.pageY - $(this).offset().top, true); } }); $('#myCanvas').mouseup(function (e) { mousePressed = false; }); $('#myCanvas').mouseleave(function (e) { mousePressed = false; });} function Draw(x, y, isDown) { if (isDown) { ctx.beginPath(); ctx.strokeStyle = $('#selColor').val(); ctx.lineWidth = $('#selWidth').val(); ctx.lineJoin = "round"; ctx.moveTo(lastX, lastY); ctx.lineTo(x, y); ctx.closePath(); ctx.stroke(); } lastX = x; lastY = y;} function clearArea() { // Use the identity matrix while clearing the canvas ctx.setTransform(1, 0, 0, 1, 0, 0); ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height);} 上传
我们需要在html页面上创建3个元素：
- 一个canvas元素，用于绘制图片，实际绘图在js文件中完成。
- 一个用于触发绘图操作的按钮。
- 一个用于上传在canvas中绘制好的图片的按钮。
<formid="form1"runat="server"> <divalign="center"class="i-canvas"> <canvasid="myCanvas"width="500"height="300"></canvas> <ul> <li><buttononclick="javascript:DrawPic();return false;">开始画图</button></li> <li><buttononclick="javascript:UploadPic();return false;">上传到服务器</button></li> </ul> </div></form> JAVASCRIPT
在js代码中要完成两项工作：在canvas画布中绘制图像和使用ajax来上传图片。我们写两个函数来分别完成这两项工作。一个hisDrawPic()函数，用于绘图。一个是UploadPic()函数，用于上传图片。
functionDrawPic() { // Get the canvas element and its 2d context varCnv = document.getElementById('myCanvas'); varCntx = Cnv.getContext('2d'); // Create gradient varGrd = Cntx.createRadialGradient(100, 100, 20, 140, 100, 230); Grd.addColorStop(0,"red"); Grd.addColorStop(1,"black"); // Fill with gradient Cntx.fillStyle = Grd; Cntx.fillRect(0, 0, 300, 200); // Write some text for(i=1; i<10 ; i++) { Cntx.fillStyle = "white"; Cntx.font = "36px Verdana"; Cntx.globalAlpha = (i-1) / 9; Cntx.fillText("Codicode.com", i * 3 , i * 20); }} functionUploadPic() { // Generate the image data varPic = document.getElementById("myCanvas").toDataURL("image/png"); Pic = Pic.replace(/^data:image\/(png|jpg);base64,/, "") // Sending the image data to Server $.ajax({ type:'POST', url:'Save_Picture.aspx/UploadPic', data:'{ "imageData" : "' + Pic + '" }', contentType:'application/json; charset=utf-8', dataType:'json', success:function(msg) { alert("Done, Picture Uploaded."); } });} 0 0
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