js+cavans实现图片滑块验证

 

 
 
 
 
 

 

 

 

 

 

 
 
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(function(){
 function slider(params){
 var obj={
 el:params.el,
 w:params.w || 280, //canvas的宽度
 h:params.h || 150, //canvas的高度
 range:params.range || 5, //相差多少像素内触发成功
 imgArr:params.imgArr || [], //图片数组
 sliderW:36, //slider的边长
 sliderIcon:params.sliderIcon || '',
 refresh:params.refresh, //刷新回调
 finish:params.finish , //完成回调
 
 };
 
 //创建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"
 //创建大小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();
 //创建标题和刷新按钮
 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="图形验证";
 refreshDom.innerHTML="刷新";
 
 //创建拖拽区域
 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="拖动左边滑块完成上方拼图";
 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:随机生成占位块canvas的x轴位置
 startDownX://鼠标按下时x轴位置
 smartCanvasBL: 可移动canvas的left初始值
 sliderMaxRange：slider可移动的最大距离
 */
 
 //生成canvas图案
 function creatCanvas(){
 //重置初始值
 canvasCoverL=0;startDownX=0;smartCanvasBL=0; 
 slider.style.left = sliderCover.style.width = 0;
 
 var l= 40, //滑块的正方形边长，不包括小圆点
 r = 10, //小圆点半径
 PI = Math.PI,
 sliderW=l+2*r, //滑块边长
 rand=canvasSize(sliderW,r), //获取随机生成的x,y,left值
 x = canvasCoverL= rand.x, //占位块x轴
 y = rand.y; //占位块y轴
 
 smartCanvasBL=rand.left;
 //先清空画布
 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里调用，否则canvas里不能放进图片
 bcxt.drawImage(img,0,0,obj.w,obj.h);
 scxt.drawImage(img,0,0,obj.w,obj.h);
 //裁剪滑块长度
 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();
 }
 
 //随机生成canvas滑块和占位块，到左边的距离和到顶部的距离
 function canvasSize(cw,r){
 // cw为占位块和的宽度，r为绘制圆点的半径
 var random =Math.random();
 var x=Math.floor(obj.w/2 + random*(obj.w/2 - cw)); //x为占位块x坐标位置，保证占位块始终在画布的右半区域
 var y=Math.floor(r*2+random*(obj.h - cw - r*2)); //y为占位块y坐标位置,（值至少为小圆半径的2倍才能完全显示，因为绘制的原点是小正方形的左上角）
 var left =Math.floor(random*(obj.w/2 - cw)); //canvas滑块的left值，这里的值范围保证它始终在画布的左半区域
 return {x:x,y:y,left:left}
 }
 
 //绘制canvas滑块和占位块
 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'
 }
 
 
 
 
 //滑块被按下
 function moveStart(e){
 var ev = e || window.event;
 startDownX = ev.touches!=undefined&＃63; ev.touches[0].clientX : ev.clientX; 
 }
 //滑块移动
 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