JavaScript 手势解锁

朱雀 2022-03-25 07:48 197阅读 0赞

![在这里插入图片描述][20190119145847758.gif]

<!DOCTYPE html>
    <html>
    <head>
    <meta charset="utf8">
    <style>
    * {
    	margin: 0;
    	padding: 0;
    }
    #canvas {
    	width: 100%;
    	height: 100%;
    	/*! 要想让元素铺满全屏，要么用absolute的100%，要么用100vh */
    	position: absolute;
    }
    </style>
    <script>
    class GestureUnlock {
    	
    	constructor(canvas) {
    		//圆圈直径/画布比例
    		this.circleSizeRatio = 0.1;
    		//圆圈内部镂空直径/圆圈半径
    		this.circleHollowRatio = 0.5;
    		//圆圈边框线宽/圆圈半径
    		this.circleLineWidthRatio = 0.1;
    		//画笔线宽/圆圈内部镂空半径
    		this.lineWidthRatio = 1;
    		//线条颜色
    		this.color = "RoyalBlue";
    		//行数
    		this.numRow = 3;
    		//列数
    		this.numColumn = 5;
    		//圆圈的坐标数组(x,y)
    		this.pointPos = [];
    		//已经选中的圈编号(i)，规则：先横后竖。保存手势的时候只要保存该变量即可
    		this.points = [];
    		//起始按下是否在某个圆圈的范围
    		this.isDownOnPoint = false;
    		
    		this.doublePI = 2*Math.PI;
    		this.canvas = canvas;
    
    		this.initListener();
    		this.setData();
    		this.draw();
    	}
    	
    	setData() {
    		//必须要设置canvas的宽高，而不能用style的宽高，否则默认会按300×150缩放
    		//注意：当canvas的大小改变时，ctx就会重置，包括之前设置的样式会全部被重置
    		this.canvas.width = this.canvas.clientWidth;
    		this.canvas.height = this.canvas.clientHeight;
    		const size = Math.min(this.canvas.clientWidth, this.canvas.clientHeight);
    		//圆圈的直径
    		const circleWidth = size * this.circleSizeRatio;
    		this.circleR = circleWidth/2;
    		//连接线可填充的孔洞半径
    		this.circleHollowR = this.circleR * this.circleHollowRatio;
    		//圆圈外径和中间可填充的孔洞中间的半径
    		this.circleMiddleR = (this.circleR + this.circleHollowR) / 2;
    		//圆圈的边框线条宽度
    		this.circleLineWidth = this.circleR * this.circleLineWidthRatio;
    		//圆圈填充白色的宽度
    		this.circlePadWidth = this.circleR - this.circleHollowR;
    		//连接线宽度
    		this.lineWidth = this.circleHollowR * this.lineWidthRatio;
    		//行的一个间隔长度
    		this.rowPad = this.canvas.clientHeight/(this.numRow*2);
    		//列的一个间隔长度
    		this.columnPad = this.canvas.clientWidth/(this.numColumn*2);
    		//console.log(this.rowPad, this.columnPad, this.circleR);
    		
    		this.ctx = canvas.getContext("2d");
    		this.ctx.strokeStyle = "RoyalBlue";
    		this.ctx.fillStyle = this.color;
    		//线条两端的笔帽(lineCap)支持butt(默认)、round、square，但是默认的拐点会突出
    		this.ctx.lineCap = "round";
    		//两条线条交汇处的样式(lineJoin)支持miter(默认，尖角)、round、bevel(斜角或缺角)
    		this.ctx.lineJoin = "bevel"
    	}
    	
    	drawCircle() {
    		this.pointPos = [];
    		for(let i=0;i<this.numRow;i++) {	
    			for(let j=0;j<this.numColumn;j++) {	
    				const x = (2*j+1)*this.columnPad;
    				const y = (2*i+1)*this.rowPad;
    				this.pointPos.push([x, y]);
    				//console.log(x, y)
    				this.ctx.beginPath();
    				this.ctx.strokeStyle = "white";
    				this.ctx.lineWidth = this.circlePadWidth;
    				this.ctx.arc(x, y, this.circleMiddleR, 0, this.doublePI);
    				this.ctx.stroke();
    				
    				this.ctx.beginPath();
    				this.ctx.strokeStyle = this.color;
    				this.ctx.lineWidth = this.circleLineWidth;
    				this.ctx.arc(x, y, this.circleR, 0, this.doublePI);
    				this.ctx.stroke();			
    			}
    		}
    	}
    	
    	drawLine(x, y) {
    		const that = this;
    		function getPointPos(i) {
    			return that.pointPos[that.points[i]];
    		}
    	
    		if(this.points.length == 0) return;
    		for(let i=0;i<this.points.length;i++) {
    			//ES6的自动拆包
    			this.ctx.beginPath();
    			this.ctx.arc(...getPointPos(i), this.circleHollowR, 0, this.doublePI);
    			this.ctx.fill();
    		}
    		
    		this.ctx.beginPath();
    		this.ctx.lineWidth = this.lineWidth;
    		//ES6的自动拆包
    		this.ctx.moveTo(...getPointPos(0));
    		for(let i=1;i<this.points.length;i++) {
    			this.ctx.lineTo(...getPointPos(i));
    		}
    		
    		if(x != undefined && y != undefined) {
    			this.ctx.lineTo(x, y);
    		}
    		this.ctx.stroke();
    	}
    	
    	draw(x, y) {
    		this.ctx.clearRect(0,0,this.canvas.width, this.canvas.height);
    		this.drawLine(x, y);
    		this.drawCircle();
    	}
    	
    	indexOfPoint(x,y) {
    		if(this.pointPos.length == 0) throw new Error("未找到圆圈坐标数组");
    		//为了减少计算量，将每个圆当作正方形来看
    		for(let i=0;i<this.pointPos.length;i++) {
    			if((Math.abs(x - this.pointPos[i][0]) < this.circleR) && 
    				(Math.abs(y - this.pointPos[i][1]) < this.circleR)) {
    				return i;
    			}
    		}
    		return -1;
    	}
    	
    	pushToPoints(index) {
    		if(index == -1 || this.points.includes(index)) return false;
    		this.points.push(index);
    		return true;
    	}
    	
    	initListener() {
    		//内嵌箭头函数(即匿名函数)是为了继续使用this
    		this.canvas.addEventListener("mousedown", (e)=>{this.touchStart(e);});
    		this.canvas.addEventListener("mousemove", (e)=>{this.touchMove(e);});
    		this.canvas.addEventListener("mouseup", (e)=>{this.touchEnd(e);});
    		this.canvas.addEventListener("touchstart", (e)=>{this.touchStart(e);});
    		this.canvas.addEventListener("touchmove", (e)=>{this.touchMove(e);});
    		this.canvas.addEventListener("touchend", (e)=>{this.touchEnd(e);});
    		
    		window.addEventListener("resize", ()=>{	this.setData(); this.draw(); });
    	}
    	
    	//兼容PC端和手机端的获取单击点坐标
    	getEventPos(event) {
    		const x = event.clientX || event.touches[0].clientX;
    		const y = event.clientY || event.touches[0].clientY;
    		return [x,y];
    	}
    	
    	touchStart(e) {
    		const [x,y] = this.getEventPos(e);
    		this.points = [];
    		const index = this.indexOfPoint(x, y);
    		this.isDownOnPoint = this.pushToPoints(index);
    	}
    	
    	touchMove(e) {
    		if(!this.isDownOnPoint) return;
    		const [x,y] = this.getEventPos(e);
    		const index = this.indexOfPoint(x, y);
    		this.pushToPoints(index);
    		this.draw(x, y);
    	}
    	
    	touchEnd(e) {
    		if(!this.isDownOnPoint) return;
    		this.isDownOnPoint = false;
    		this.draw();
    		if(this.points.length > 1) {
    			/*
    			浏览器中弹出的对话框都是模态对话框（Modal Dialogue Box，又叫做模式对话框）
    			是指在用户想要对对话框以外的应用程序进行操作时，必须首先对该对话框进行响应。
    			*/
    			//conform 遵守；confirm 确认
    			//const ret = confirm("点击的顺序是：" + this.points.join(" -> "));
    			alert("点击的顺序是：" + this.points.join(" -> "));
    			this.points = [];
    			this.draw();
    		}
    	}
    }
    window.()=>{
    	const canvas = document.getElementById("canvas");
    	const gestureUnlock = new GestureUnlock(canvas);
    	
    }
    
    </script>
    </head>
    <body>
    <canvas id="canvas"></canvas>
    </body>
    </html>

[20190119145847758.gif]: /images/20220325/393704ff2afb4f68bb9e560e7563b2db.png