使用zrender绘制基本图形 - vue - 前端 - 技术设计

基于 zrender 实现在 canvas 中绘制基本图形

	<!DOCTYPE html>
	<html>
	<head>
	<meta charset="utf-8">
	<title>demo1</title>
	<script type="text/javascript" src="js/echarts.js"></script>
	</head>
	<body>
	<div id="main" style="height:600px;width:600px;"></div>
	<script type="text/javascript">
	var main = echarts.init(document.getElementById('main'));
	var option = {
	title:{
	text:'ECharts demo'
	},
	legend:{
	data:['销量']
	},
	xAxis:{
	data:["衬衫","羊毛衫","雪纺衫","裤子","高跟鞋","袜子"]
	},
	yAxis:{},
	series:[{
	name:'销量',
	type:'bar',
	data:[5,20,36,10,10,20]
	}]
	};
	main.setOption(option);
	</script>
	<input type="text" id="text"placeholder="请输入文字"/><br/><br/>
	<input type="button" name="" value="写入文字" id="btn"/><br/><br/>
	<input type="file" id="file"placeholder="请输入图片"/><br/><br/>
	<input type="button" name="" value="导入图片" id="btn1"/><br/><br/>
	<canvas id="mycv" width="600px" height="600px" style="border:1px solid black">
	您的浏览器不支持canvas
	</canvas>
	<script text="text/javascript">
	var canvas1 = document.getElementById("mycv");
	var text= document.getElementById("text");
	var btn = document.getElementById("btn");
	var arr=[];
	var imgs=[];//canvas 中的所有图像
	var img;// 当前操作的图像
	btn.onclick = function(){
	var value = text.value;
	if(canvas1.getContext){
	var ctx = canvas1.getContext("2d");
	ctx.font = "bold 30px arial";
	ctx.fillStyle="black";
	ctx.fillText(value,150,150);
	}
	}
	var btn1 = document.getElementById("btn1");
	btn1.onclick = function(){
	let reader = new FileReader();
	reader.readAsDataURL(document.querySelector("#file").files[0]);
	reader.onload = function (e) {
	let result = e.target.result; //base64 格式图片地址
	img = new Image();
	img.src = result; // 设置 image 的地址为 base64 的地址
	img.onload = function () {
	if(canvas1.getContext){
	var ctx = canvas1.getContext("2d");
	ctx.drawImage(img, 0, 0, 100, 100);
	arr.push(ctx.getImageData(0, 0, canvas1.width, canvas1.height));
	imgs.push([img,0,0,100,100]);
	}

	}
	};
	}
	canvas1.onmousedown = function (e) {
	let ax, ay, x, y;

	canvas1.onmousemove = function (e) {
	x = e.clientX;
	y = e.clientY;
	arr.pop();
	imgs.pop();
	ctx = canvas1.getContext("2d");
	//// 先清除之前的然后重新绘制
	ctx.clearRect(0, 0, canvas1.width, canvas1.height);
	// if (arr.length != 0) {
	// ctx.putImageData(arr[arr.length - 1], 0, 0, 0, 0, canvas1.width, canvas1.height);
	// }
	imgs.forEach(function(item, index){
	ctx.drawImage(item[0], item[1], item[2],item[3],item[4]);
	});
	ctx.drawImage(img, x-50, y-250, 100, 100);
	arr.push(ctx.getImageData(0, 0, canvas1.width, canvas1.height));
	imgs.push([img,x-50, y-250, 100, 100]);
	};
	canvas1.onmouseup = function () {
	canvas1.onmousemove = null;
	canvas1.onmouseup = null;
	};
	}
	</script>
	</body>
	</html>

	var type = "pen";// 当前画图的类型
	// 用于保存所有画出的图形，包括图片
	var objs = [];
	var canvas;
	var zr;
	// 设置类型
	function setType(t){
	type=t;
	// 界面展示当前操作名称
	var operate = document.getElementById("operate");
	switch(t){
	case "img":
	operate.innerText="导入图片";
	break;
	case "pen":
	operate.innerText="铅笔";
	break;
	case "line":
	operate.innerText="直线";
	break;
	case "circle":
	operate.innerText="圆";
	break;
	case "rect":
	operate.innerText="矩形";
	break;
	case "isogon":
	operate.innerText="正多边形";
	break;
	case "":
	operate.innerText="移动";
	break;
	}
	// 类型为空代表移动，其他时候设置图形不可移动防止画新图形时改变原有图形的位置
	objs = zr.storage._displayList;
	if(type == ""){
	for (let index = 0; index < objs.length; index++) {
	var tmpobj = objs[index];
	objs[index].attr({"draggable":true})
	}
	} else{
	for (let index = 0; index < objs.length; index++) {
	var tmpobj = objs[index];
	objs[index].attr({"draggable":false})
	}
	}
	zr.refresh();
	}

	window.onload = function() {
	var btn1 = document.getElementById("btn1");
	var saveAndClear = document.getElementById("saveAndClear");
	var clear = document.getElementById("clear");
	var load = document.getElementById("load");
	var undo = document.getElementById("undo");
	canvas = document.getElementById('mycv');
	zr = zrender.init(canvas);

	var obj;// 当前画图的对象
	var penline=[];
	var objParam =[];// 保存已画图形的关键元素
	var s;// 将当前对象序列化后的内容
	// 保存历史记录，用于撤销绘图
	var objsHistory=[];
	// 清除画布但保留已画对象
	saveAndClear.onclick = function(){
	objs = zr.storage._displayList;// 获取当前画布上的所有内容
	for (let index = 0; index < objs.length; index++) {
	var elementParam = [];
	var element = objs[index];
	var elementType = element.__proto__.type;// 类型
	var transform = element.transform;// 平移

	elementParam.push(elementType);
	switch(elementType){
	case "polyline"://曲线
	var elementPoints = element.shape.points;
	var elementSmooth = element.shape.smooth;
	var elementStroke = element.style.stroke;
	var elementLineWidth = element.style.lineWidth;
	var opts = {
	rectHover:true,
	shape: {
	points:elementPoints,
	smooth:elementSmooth
	},
	style:{
	stroke:elementStroke,
	lineWidth:elementLineWidth
	},
	position:[transform == null ? 0 : transform[4], transform == null ? 0 : transform[5]]
	}
	elementParam.push(opts);
	break;
	case "line":
	var x1 = element.shape.x1;
	var x2 = element.shape.x2;
	var y1 = element.shape.y1;
	var y2 = element.shape.y2;
	var elementStroke = element.style.stroke;
	var elementLineWidth = element.style.lineWidth;
	var opts = {
	rectHover:true,
	shape: {
	x1: x1,
	y1: y1,
	x2: x2,
	y2: y2,
	percent:1
	},
	style:{
	stroke:elementStroke,
	lineWidth:elementLineWidth
	},
	position:[transform == null ? 0 : transform[4], transform == null ? 0 : transform[5]]
	}
	elementParam.push(opts);
	break;
	case "circle":
	var cx = element.shape.cx;
	var cy = element.shape.cy;
	var r = element.shape.r;
	var elementStroke = element.style.stroke;
	var elementLineWidth = element.style.lineWidth;
	var opts = {
	rectHover:true,
	shape: {
	cx: cx,
	cy: cy,
	r: r,
	},
	style:{
	fill:"rgba(255,255,255,0",
	stroke:elementStroke,
	lineWidth:elementLineWidth
	},
	position:[transform == null ? 0 : transform[4], transform == null ? 0 : transform[5]]
	}
	elementParam.push(opts);
	break;
	case "rect":
	var x = element.shape.x;
	var y = element.shape.y;
	var width = element.shape.width;
	var height = element.shape.height;
	var elementStroke = element.style.stroke;
	var elementLineWidth = element.style.lineWidth;
	var opts = {
	rectHover:true,
	shape: {
	x: x,
	y: y,
	width:width,
	height:height
	},
	style:{
	fill:"rgba(255,255,255,0",
	stroke:elementStroke,
	lineWidth:elementLineWidth
	},
	position:[transform == null ? 0 : transform[4], transform == null ? 0 : transform[5]]
	}
	elementParam.push(opts);
	break;
	case "isogon":
	var x = element.shape.x;
	var y = element.shape.y;
	var r = element.shape.r;
	var n = element.shape.n;
	var elementStroke = element.style.stroke;
	var elementLineWidth = element.style.lineWidth;
	var opts = {
	rectHover:true,
	shape: {
	x:x,
	y:y,
	r:r,
	n:n
	},
	style:{
	fill:"rgba(255,255,255,0",
	stroke:elementStroke,
	lineWidth:elementLineWidth
	},
	position:[transform == null ? 0 : transform[4], transform == null ? 0 : transform[5]]
	}
	elementParam.push(opts);
	break;
	case "image":
	var x = element.style.x;
	var y = element.style.y;
	var width = element.style.width;
	var height = element.style.height;
	var image = element.style.image;
	var opts = {
	style: {
	image:image,
	x:100,
	y:100,
	width:200,
	height:200
	},
	position:[transform == null ? 0 : transform[4], transform == null ? 0 : transform[5]]
	}
	elementParam.push(opts);
	break;
	}

	objParam.push(elementParam);
	}
	s = JSON.stringify(objParam)
	console.log(s);
	zr.clear();
	objs=[];
	}

	// 清除画布，不保留已画对象
	clear.onclick = function(){
	zr.clear();
	objs = [];
	objsHistory=[];
	}
	// 加载最后一次绘画
	load.onclick = function(){
	zr = zrender.init(canvas);
	objParam = eval('('+s+')');
	for (let index = 0; index < objParam.length; index++) {
	var element = objParam[index];
	var elementType = element[0];
	var elementParam = element[1];
	switch(elementType){
	case "polyline":
	obj = new zrender.Polyline(elementParam);
	zr.add(obj);
	break;
	case "line":
	obj = new zrender.Line(elementParam);
	zr.add(obj);
	break;
	case "circle":
	obj = new zrender.Circle(elementParam);
	zr.add(obj);
	break;
	case "rect":
	obj = new zrender.Rect(elementParam);
	zr.add(obj);
	break;
	case "isogon":
	obj = new zrender.Isogon(elementParam);
	zr.add(obj);
	break;
	case "image":
	obj = new zrender.Image(elementParam);
	obj.on("mousewheel", function(params){
	var shape = params.target;
	var event = params.event;
	var delta = event.wheelDelta;
	if(delta>0){
	img.attr("height",shape.style.height += 10);
	img.attr("width",shape.style.width += 10);
	} else{
	img.attr("height",shape.style.height -= 10);
	img.attr("width",shape.style.width -= 10);
	}
	zr.refresh();
	});
	zr.add(obj);
	break;
	}
	// 添加鼠标双击事件，修改线的宽及颜色
	obj.on("dblclick",function(){
	var lineWidth = document.getElementById("input2").value;
	var color = document.getElementById("input3").value;
	this.attr({
	style:{
	stroke:color,
	lineWidth:lineWidth
	}
	});
	});
	}
	objParam=[]
	}
	// 撤销
	undo.onclick = function(){
	zr.clear();
	objsHistory.pop();
	objs = objsHistory[objsHistory.length-1];
	if(objs != undefined){
	zr = zrender.init(canvas);
	for (let index = 0; index < objs.length; index++) {
	zr.add(objs[index]);
	}
	}else{
	objs=[];
	}
	}
	// 导入图片
	btn1.onclick = function(){
	type="image";
	let reader = new FileReader();
	reader.readAsDataURL(document.querySelector("#file").files[0]);
	reader.onload = function (e) {
	let result = e.target.result; //base64 格式图片地址
	var img = new zrender.Image({
	style: {
	image:result,
	x:100,
	y:100,
	width:200,
	height:200
	}
	});
	// 圖片支持縮放
	img.on("mousewheel", function(params){
	var shape = params.target;
	var event = params.event;
	var delta = event.wheelDelta;
	if(delta>0){
	img.attr("height",shape.style.height += 10);
	img.attr("width",shape.style.width += 10);
	} else{
	img.attr("height",shape.style.height -= 10);
	img.attr("width",shape.style.width -= 10);
	}
	zr.refresh();
	});
	zr.add(img);
	// 历史记录中保存当前所有元素的集合，用于撤销操作
	objs = zr.storage._displayList;
	objsHistory.push(new Array().concat(objs));
	};
	}

	// 繪製圖形
	canvas.onmousedown = function(e){
	var x0, y0;
	x0 = e.offsetX;
	y0 = e.offsetY;
	var lineWidth = document.getElementById("input2").value;
	var color = document.getElementById("input3").value;
	// 圆
	if(type == "circle"){
	var r=10;
	obj = new zrender.Circle({
	shape: {
	cx: x0,
	cy: y0,
	r: r
	},
	style:{
	fill:"rgba(255,255,255,0",
	stroke:color,
	lineWidth:lineWidth
	}
	});

	zr.add(obj);
	}
	// 矩形
	if(type == "rect"){
	obj = new zrender.Rect({
	shape: {
	x: x0,
	y: y0,
	width: 10,
	height:10
	},
	style:{
	fill:"rgba(255,255,255,0",
	stroke:color,
	lineWidth:lineWidth
	}
	});
	zr.add(obj);
	}
	// 正多边形
	if(type == "isogon"){
	var n = document.getElementById("input1").value;
	obj = new zrender.Isogon({
	shape: {
	x: x0,
	y: y0,
	r: 10,
	n: n
	},
	style:{
	fill:"rgba(255,255,255,0",
	stroke:color,
	lineWidth:lineWidth
	}
	});
	zr.add(obj);
	}
	// 直线
	if(type == "line"){
	obj = new zrender.Line({
	rectHover:true,
	shape: {
	x1: x0,
	y1: y0,
	x2: x0,
	y2: y0,
	percent:1
	},
	style:{
	stroke:color,
	lineWidth:lineWidth
	}
	});
	zr.add(obj);
	}
	// 曲线
	if(type == "pen"){
	penline.push([x0,y0]);
	obj = new zrender.Polyline({
	rectHover:true,
	shape: {
	points:penline,
	smooth:0.5
	},
	style:{
	stroke:color,
	lineWidth:lineWidth
	}
	});
	zr.add(obj);
	}
	// 定义鼠标移动事件，用于画图
	canvas.onmousemove = function(e){
	x1 = e.offsetX;
	y1 = e.offsetY;
	// 移动鼠标修改圆的半径
	if(type == "circle"){
	zr.remove(obj);
	var r=Math.sqrt(Math.pow(x0-x1,2)+Math.pow(y0-y1,2));
	obj = new zrender.Circle({
	shape: {
	cx: x0,
	cy: y0,
	r: r
	},
	style:{
	fill:"rgba(255,255,255,0)",
	stroke:color,
	lineWidth:lineWidth
	}
	});
	zr.add(obj);
	}
	// 移动鼠标修改矩形长宽
	if(type == "rect"){
	zr.remove(obj);
	obj = new zrender.Rect({
	shape: {
	x: x0,
	y: y0,
	width: x1-x0,
	height:y1-y0
	},
	style:{
	fill:"rgba(255,255,255,0",
	stroke:color,
	lineWidth:lineWidth
	}
	});
	zr.add(obj);
	}
	// 修改正多边形大小
	if(type == "isogon"){
	zr.remove(obj);
	var n = document.getElementById("input1").value;
	var r=Math.sqrt(Math.pow(x0-x1,2)+Math.pow(y0-y1,2));
	obj = new zrender.Isogon({
	shape: {
	x: x0,
	y: y0,
	r: r,
	n: n
	},
	style:{
	fill:"rgba(255,255,255,0",
	stroke:color,
	lineWidth:lineWidth
	}
	});
	zr.add(obj);
	}
	// 修改直线的长度及方向
	if(type == "line"){
	zr.remove(obj);
	obj = new zrender.Line({
	rectHover:true,
	shape: {
	x1: x0,
	y1: y0,
	x2: x1,
	y2: y1,
	percent:1
	},
	style:{
	stroke:color,
	lineWidth:lineWidth
	}
	});
	zr.add(obj);
	}
	// 画曲线
	if(type == "pen"){
	zr.remove(obj);
	penline.push([x1,y1]);
	obj = new zrender.Polyline({
	rectHover:true,
	shape: {
	points:penline,
	smooth:0.5
	},
	style:{
	stroke:color,
	lineWidth:lineWidth
	}

	});
	zr.add(obj);
	}
	}
	// 鼠标松开后为元素添加双击事件，历史记录中保存数据方便撤销
	canvas.onmouseup = function(e){
	canvas.onmousemove = null;
	// 保存绘画的对象
	if(obj != undefined){
	// 支持修改线宽度
	obj.on("dblclick",function(){
	var lineWidth = document.getElementById("input2").value;
	var color = document.getElementById("input3").value;
	this.attr({
	style:{
	stroke:color,
	lineWidth:lineWidth
	}
	});
	});
	objs = zr.storage._displayList;
	// 历史记录中保存当前所有元素的集合，用于撤销操作
	objsHistory.push(new Array().concat(objs));
	}

	// 清空铅笔画线的点集
	penline=[];
	obj = null;
	}
	}
	}

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