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使用js+cavans實(shí)現(xiàn)一個(gè)圖片滑塊驗(yàn)證效果

發(fā)布時(shí)間：2020-10-29 18:16:50 來源：億速云 閱讀：213 作者：Leah 欄目：開發(fā)技術(shù)

使用js+cavans實(shí)現(xiàn)一個(gè)圖片滑塊驗(yàn)證效果？很多新手對此不是很清楚，為了幫助大家解決這個(gè)難題，下面小編將為大家詳細(xì)講解，有這方面需求的人可以來學(xué)習(xí)下，希望你能有所收獲。

代碼：html

<!DOCTYPE html>
<html lang="en">
 
<head>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <meta http-equiv="X-UA-Compatible" content="ie=edge">
 <title>Document</title>
 <style>
 * {
 margin: 0;
 padding: 0;
 }
 
 
 .sliderModel {
 position: fixed;
 left: 0;
 top: 0;
 width: 100%;
 height: 100%;
 background: rgba(0, 0, 0, 0.5);
 display: flex;
 justify-content: center;
 align-items: center;
 display: none;
 
 }
 .sliderModel .cont{padding: 20px; width: 280px; background: #fff;border-radius: 6px;margin: 50px auto;}
 .showMessage {
 text-align: center;
 font-size: 14px;
 height: 30px;
 line-height: 30px;
 }
 
 #canvas_wrap{
 width: 280px;
 }
 #canvas_wrap canvas{
 display: block; 
 }
 
 </style>
</head>
 
<body>
 <div class="sliderModel">
 <div class="cont">
 <div id="canvas_wrap"></div>
 <div class="showMessage"></div>
 </div>
 <div id="close">關(guān)閉</div>
 </div>
 <div id="open">打開</div>
</body>
<script src="newSlider.js"></script>
<script>
 function showMessage(msg,color){
 var showMessage = document.querySelector('.showMessage');
 showMessage.innerHTML=msg;
 showMessage.style.color=color;
 }
 var obj={
 el:'#canvas_wrap',
 w:280,
 h:150,
 imgArr:['images/sliderz/1.jpg','images/sliderz/2.jpg','images/sliderz/3.jpg','images/sliderz/4.jpg'],
 sliderIcon:'images/sliderz/sangangy.png',
 refresh:function(){
 showMessage('','#333')
 },
 finish:function(e){ 
 e&#63; showMessage('驗(yàn)證成功!','green') : showMessage('驗(yàn)證失敗,請重試','red');
 }
 }
 
 
 document.querySelector('#open').onclick=function(){ //打開
 document.querySelector('.sliderModel').style.display="block";
 new window.$newSlider(obj);
 
 }
 
 document.querySelector('#close').onclick=function(){ //關(guān)閉
 document.querySelector('.sliderModel').style.display="none";
 }
</script>
 
</html>

newSlider.js:

(function(){
 function slider(params){
 var obj={
 el:params.el,
 w:params.w || 280, //canvas的寬度
 h:params.h || 150, //canvas的高度
 range:params.range || 5, //相差多少像素內(nèi)觸發(fā)成功
 imgArr:params.imgArr || [], //圖片數(shù)組
 sliderW:36, //slider的邊長
 sliderIcon:params.sliderIcon || '',
 refresh:params.refresh, //刷新回調(diào)
 finish:params.finish , //完成回調(diào)
 
 };
 
 //創(chuàng)建canvas的父元素
 var container=document.querySelector(obj.el);
 container.innerHTML='';
 var canvas_wrap=document.createElement('div');
 canvas_wrap.className="canvas_wrap";
 canvas_wrap.style.cssText="position:relative;overflow:hidden;border-radius:4px;width:"+obj.w+"px;height:"+obj.h+"px;background:#fff"
 //創(chuàng)建大小canvas元素
 var bigCanvas=document.createElement('canvas');
 var smartCanvas=bigCanvas.cloneNode(true);
 bigCanvas.width=smartCanvas.width=obj.w;
 bigCanvas.height=smartCanvas.height=obj.h;
 bigCanvas.style.cssText=smartCanvas.style.cssText="position:absolute;left:0;top:0";
 var bcxt=bigCanvas.getContext('2d'),scxt=smartCanvas.getContext('2d'),img=new Image();
 //創(chuàng)建標(biāo)題和刷新按鈕
 var titleDom=document.createElement('div');
 var refreshDom=document.createElement('div');
 titleDom.className="slider_title";
 refreshDom.className="slider_refresh";
 titleDom.style.cssText="position:relative;width:"+obj.w+"+px;height:60px;text-align:center;font-size:18px; line-height:60px";
 refreshDom.style.cssText="position:absolute;top:0;right:14px;font-size:14px;color:green;cursor: pointer";
 titleDom.innerHTML="圖形驗(yàn)證";
 refreshDom.innerHTML="刷新";
 
 //創(chuàng)建拖拽區(qū)域
 var slider_wrap=document.createElement('div'),slider=document.createElement('div'),sliderCover=document.createElement('div');
 slider_wrap.className="slider_wrap";
 slider.className="canvas_slider";
 sliderCover.className="sliderCover";
 slider_wrap.innerText="拖動(dòng)左邊滑塊完成上方拼圖";
 slider_wrap.style.cssText="width:"+obj.w+"px;height:30px; border-radius:30px;line-height:30px; position:relative;margin-top:10px;text-align:center;box-shadow: inset 0 0 4px #ccc;font-size: 14px;color:#999";
 slider.style.cssText="cursor: pointer;position: absolute;left: 0;top: 50%;z-index: 2;height: "+obj.sliderW+"px;width: "+obj.sliderW+"px;background:rgb(0, 124, 255) url("+obj.sliderIcon+") no-repeat center;background-size: 60% 60%;border-radius: "+obj.sliderW+"px;line-height:"+obj.sliderW+"px;text-align:center;transform: translateY(-50%);";
 sliderCover.style.cssText="position: absolute;left: 0;top:0;width:0;height:100%;background:#eee;border-radius:30px;"
 
 slider_wrap.appendChild(slider);
 slider_wrap.appendChild(sliderCover);
 canvas_wrap.appendChild(bigCanvas);
 canvas_wrap.appendChild(smartCanvas);
 titleDom.appendChild(refreshDom);
 container.appendChild(titleDom);
 container.appendChild(canvas_wrap);
 container.appendChild(slider_wrap);
 
 
 var canvasCoverL=0,startDownX=0,smartCanvasBL=0,sliderMaxRange=obj.w-obj.sliderW; 
 /*
 canvasCoverL:隨機(jī)生成占位塊canvas的x軸位置
 startDownX://鼠標(biāo)按下時(shí)x軸位置
 smartCanvasBL: 可移動(dòng)canvas的left初始值
 sliderMaxRange：slider可移動(dòng)的最大距離
 */
 
 //生成canvas圖案
 function creatCanvas(){
 //重置初始值
 canvasCoverL=0;startDownX=0;smartCanvasBL=0; 
 slider.style.left = sliderCover.style.width = 0;
 
 var l= 40, //滑塊的正方形邊長，不包括小圓點(diǎn)
 r = 10, //小圓點(diǎn)半徑
 PI = Math.PI,
 sliderW=l+2*r, //滑塊邊長
 rand=canvasSize(sliderW,r), //獲取隨機(jī)生成的x,y,left值
 x = canvasCoverL= rand.x, //占位塊x軸
 y = rand.y; //占位塊y軸
 
 smartCanvasBL=rand.left;
 //先清空畫布
 bcxt.clearRect(0, 0, obj.w, obj.h)
 scxt.clearRect(0, 0, obj.w, obj.h)
 smartCanvas.width=obj.w;
 
 var srcIndex=Math.floor(Math.random()*(obj.imgArr.length-1));
 img.src=obj.imgArr[srcIndex];
 draw(scxt,x,y,l,r,PI,'clip');
 draw(bcxt,x,y,l,r,PI,'fill');
 img.onload = function() { //一定要在onload里調(diào)用，否則canvas里不能放進(jìn)圖片
 bcxt.drawImage(img,0,0,obj.w,obj.h);
 scxt.drawImage(img,0,0,obj.w,obj.h);
 //裁剪滑塊長度
 var ImageData = scxt.getImageData(x, y-2*r, sliderW, sliderW)
 smartCanvas.width = sliderW;
 smartCanvas.style.left=rand.left+"px";
 scxt.putImageData(ImageData, 0, y-2*r)
 } 
 obj.refresh && obj.refresh();
 }
 
 //隨機(jī)生成canvas滑塊和占位塊，到左邊的距離和到頂部的距離
 function canvasSize(cw,r){
 // cw為占位塊和的寬度，r為繪制圓點(diǎn)的半徑
 var random =Math.random();
 var x=Math.floor(obj.w/2 + random*(obj.w/2 - cw)); //x為占位塊x坐標(biāo)位置，保證占位塊始終在畫布的右半?yún)^(qū)域
 var y=Math.floor(r*2+random*(obj.h - cw - r*2)); //y為占位塊y坐標(biāo)位置,（值至少為小圓半徑的2倍才能完全顯示，因?yàn)槔L制的原點(diǎn)是小正方形的左上角）
 var left =Math.floor(random*(obj.w/2 - cw)); //canvas滑塊的left值，這里的值范圍保證它始終在畫布的左半?yún)^(qū)域
 return {x:x,y:y,left:left}
 }
 
 //繪制canvas滑塊和占位塊
 function draw(ctx,x,y,l,r,PI,operation) {
 ctx.beginPath()
 ctx.moveTo(x, y)
 ctx.arc(x + l / 2, y - r + 2, r, 0.72 * PI, 2.26 * PI)
 ctx.lineTo(x + l, y)
 ctx.arc(x + l + r - 2, y + l / 2, r, 1.21 * PI, 2.78 * PI)
 ctx.lineTo(x + l, y + l)
 ctx.lineTo(x, y + l)
 ctx.arc(x + r - 2, y + l / 2, r + 0.4, 2.76 * PI, 1.24 * PI, true)
 ctx.lineTo(x, y)
 ctx.lineWidth = 1
 ctx.fillStyle = 'rgba(200, 200, 200, 1)'
 ctx.strokeStyle = 'rgba(255, 255, 255, 0.7)'
 ctx.stroke()
 ctx[operation]()
 ctx.globalCompositeOperation = 'destination-over'
 }
 
 
 
 
 //滑塊被按下
 function moveStart(e){
 var ev = e || window.event;
 startDownX = ev.touches!=undefined&#63; ev.touches[0].clientX : ev.clientX; 
 }
 //滑塊移動(dòng)
 function moveProcess(e){
 var ev = e || window.event,downX = (ev.touches!=undefined)&#63; ev.touches[0].clientX : (startDownX!=0&#63; ev.clientX : 0),range=downX-startDownX;
 console.log(downX)
 var sliderRange= range<=0&#63; 0 : (range<sliderMaxRange &#63; range : sliderMaxRange);
 slider.style.left=sliderRange+"px";
 sliderCover.style.width=obj.sliderW/2 + sliderRange +"px";
 smartCanvas.style.left=smartCanvasBL+sliderRange+"px";
 }
 
 //停止滑動(dòng)
 function moveEnd(e){
 var ev = e || window.event;
 ev.touches!=undefined&#63; slider.ontouchmove=null : slider.onmousemove=null;
 var smartCanvasL= parseInt(smartCanvas.style.left);
 if(Math.abs(canvasCoverL - smartCanvasL) < obj.range){
 obj.finish && obj.finish(true);
 }else{
 obj.finish && obj.finish(false);
 var timer = null,step = 10;
 var sliderL = parseInt(slider.style.left)
 timer = setInterval(function () {
  sliderL -= step;
  step += 5;
  if (sliderL <= 0) {
  clearInterval(timer);
  sliderL = 0;
  slider.style.left = sliderCover.style.width = 0;
  smartCanvas.style.left = smartCanvasBL + "px"
  }
  slider.style.left = sliderL + "px";
  sliderCover.style.width = sliderL+obj.sliderW/2 +"px";
  smartCanvas.style.left = sliderL + smartCanvasBL+ "px";
 }, 20)
 }
 
 }
 
 
 //事件調(diào)用
 creatCanvas();
 refreshDom.onclick=refreshDom.ontouchstart=creatCanvas;
 slider.ontouchstart=function(){
 moveStart();
 this.ontouchmove=moveProcess;
 this.ontouchend=moveEnd;
 };
 slider.onmousedown=function(){
 moveStart();
 this.onmousemove=moveProcess;
 this.onmouseup=moveEnd;
 };
 
 }
 
 window.$newSlider=slider
})()

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