熬夜总结了 “HTML5画布” 的知识点（共10条）

var img = new Image();
img.src = 'logo.png';
img.onload = function() {
    ctx.drawImage(img,0,0,40,40,0,0,80,80);
}

var imageData = ctx.getImageData(x,y,w,h)

返回的是一维数组：[r1,g1,b1,a1,r2,g2,b2,a2...]

ctx.putImageData(imageData,x,y)
把imageData放在(x,y)处

ctx.putImageData(imageData, x, y, dirtyX, dirtyY, dirtyW, dirtyH)

只显示（dirtyX,dirtyY）处的宽dirtyW,dirtyH的区域

context.arc(x,y,radius, starAngle,endAngle, anticlockwise)

圆心(x,y)  半径radius
从starAngle到endAngle
anticlockwise代表是否逆时针方向

context.quadraticCurveTo(qcpx,qcpy, qx,qy)

context.bezierCurveTo(cp1x,cp1y, cp2x, cp2y, x,y)

ctx.drawImage(canvas,x,y),该方法把canvas绘制在(x,y)处

ctx.drawImage(canvas,x,y, w,h),该方法把canvas绘制在(x,y)处，并缩放为宽w,高h

ctx.drawImage(canvas, sx, sy, sw, sh, dx, dy, dw, dh)，该方法把canvas中（sx, sy）处的宽sw,高sh的区域，绘制到(dx,dy)处，并缩放为宽dw, 高dh

<style>
#canva {
    border: 1px solid red;
}
</style>
<div>
<canvas id="canva" width="200" height="200"></canvas>
// 绘制宽高200的canvas
</div>

var canvas = document.getElementById("canvas")

可以使用通过标签名称来获取对象的getElementsByTagName方法

var context  = canvas.getContext("2d")

context.font="98px 黑体"; // 文字样式
context.fillStyle="red"; // 文字颜色
context.textAlign = "center"; // 文字对齐方式
// 绘制文字
context.fillText("达达前端"，100, 123, 234);

drawImage(image, x, y) 
// 在画布上定位图像
// 方法在画布上绘制图像、画布或视频。
// 方法也能够绘制图像的某些部分，以及/或者增加或减少图像的尺寸。

drawImage(image, x, y, width, height)
// 在画布上定位图像，并规定图像的宽度和高度

drawImage(image, sourceX, sourceY, sourceWidth, sourceHeight, destX, destY, destWidth, destHeight)
// 剪切图像，并在画布上定位被剪切的部分

function Draw() {
    // 获取canvas对象
    var canvas = document.getElementById("canvas"); 
    // 获取2d上下文绘图对象
    var context = canvas.getContext("2d"); 
    // 使用Image()构造函数创建图像对象
    var newImg = new Image(); 
    // 指定图像的文件地址
    newImg.src = "../images/dadaqianduan.jpg"; 
    newImg.onload = function () {
        // 左上角开始绘制图像
        context.drawImage(newImg, 0, 0); 
        context.drawImage(newImg, 250, 100, 150, 200); 
        context.drawImage(newImg, 90, 80, 100, 100, 0, 0, 120, 120);
    }
}

// canvas 宽高200
<canvas id="canvas" width="200" height="200"></canvas>
<style type="text/css">
canvas {
    border: 2px solid #ccc;
}
</style>
<script>
    // 获取canvas
    var canvas = document.getElementById("canvas");
    var context = canvas.getContext("2d");
    // 设置字体
    context.font="98px 黑体";
    // 填充
    context.fillStyle="#036";
    // 文本水平位置
    context.textAlign="center";
    // 执行绘制
    context.fillText("达达前端",100, 120, 200);
</script>

// 绘制矩形边框
strokeRect(x,y, width, height);

// 填充矩形区域
fillRect(x,y,width,height);

// 绘制矩形
function drawRect() {
    var canvas = document.getElementById("canvas");
    var context = canvas.getContext("2d");
    // 描边
    context.strokeStyle = "#000";
    // 线条宽度
    context.lineWidth = 1;
    // 矩形边框
    context.strokeRect(50,50, 150, 100);
    // 填充
    context.fillStyle="#f90";
    // 矩形
    context.fillRect(50,50,150,100);
}
window.addEventListener("load",DrawRect,true);

// 擦除指定的矩形区域
context.clearRect(x,y,width,height)

// 为画布设置边框
canvas {
    border: 1px solid #ccc;
}
// 准备画布，默认是300*150
// 设置画布的大小
<canvas width="1200" height="800"></canvas>
// 准备绘制工具
<script>
// 获取元素
var myCanvas = document.querySelector('canvas');
// 获取上下文，绘制工具箱
var ctx = myCanvas.getContext('2d');
// 移动画笔
ctx.moveTo(100,100);
// 绘制直线，轨迹
ctx.lineTo(200,100);
// 描边
ctx.stroke()

// 规定元素的 id、宽度和高度
<canvas id="myCanvas" width="200" height="100"></canvas>

var grid = 10;
// 画多少条x轴方向的线，横向的条数，画布的高度
var canvasHeight = myCanvas.height
var canvasWidth = myCanvas.width
// 画布宽高
ctx.canvas.width
ctx.canvas.height
// 网格大小
var gridSize = 10;
var canvasHeight = ctx.canvas.height;
var xLineTotal = canvasHeight / gridSize
// 总线条
var xLineTotal = Math.floor(canvasHeight / gridSize);
for (var i=0; i<=xLineTotal; i++) {
    ctx.beginPath();
    ctx.moveTo(0, i*gridSize-0.5);
    ctx.lineTo(canvasWidth, i*gridSize-0.5);
    ctx.strokeStyle='#eee';
    ctx.stroke();
}
// 画多少条y轴方向的线
var yLineTotal = canvasWidth / gridSize
var yLineTotal = Math.floor(canvasWidth / gridSize);
for (var i=0; i <= yLineTotal; i++) {
    ctx.beginPath();
    ctx.moveTo(i*gridSize-0.5,0);
    ctx.lineTo(i*gridSize-0.5,canvasHeight);
    ctx.strokeStyle='#eee';
    ctx.stroke();
}

// 绘制坐标系
var space = 20;
var arrowSize = 10;
// 画布宽高
var canvasWidth = ctx.canvas.width;
var canvasHeight = ctx.canvas.height;
// 坐标系
var x0 = space;
var y0 = canvasHeight - space;
// 绘制x轴
ctx.moveTo(x0,y0);
ctx.lineTo(canvasWidth-space, y0);
ctx.stroke();
// 箭头
ctx.lineTo(canvasWidth-space-arrowSize, y0 + arrowSize/2);
ctx.lineTo(canvasWidth-space-arrowSize, y0 - arrowSize/2);
ctx.lineTo(canvasWidth-space, y0);
ctx.fill();
ctx.stroke();
// 绘制y轴
ctx.beginPath();
ctx.moveTo(x0, y0);
ctx.lineTo(space, space);
ctx.stroke();
// 箭头
ctx.lineTo(space+space-arrowSize/2, space + arrowSize);
ctx.lineTo(space-space-arrowSize/2, space - arrowSize);
ctx.lineTo(space, space);
ctx.fill();
ctx.stroke();
// 绘制点
var coordinate = {
    x: 146,
    y: 356
}
// 点尺寸
var dottedSize = 6;
ctx.moveTo(coordinate.x - dottedSize/2, coordinate.y - dottedSize/2);
ctx.lineTo(coordinate.x + dottedSize/2, coordinate.y - dottedSize/2);
ctx.lineTo(coordinate.x + dottedSize/2, coordinate.y + dottedSize/2);
ctx.lineTo(coordinate.x - dottedSize/2, coordinate.y + dottedSize/2);
ctx.closePath();
ctx.fill();

// 圆形
context.arc(100,100,30,0,Math.PI*2,true);

function DrawLine() {
    var canvas = document.getElementById("canvas");
    var context = canvas.getContext("2d");
    // 创建绘制过程
    context.beginPath();
    context.moveTo(50,50);
    context.lineTo(120,120);
    context.lineTo(120,60);
    context.closePath();
    context.strokeStyle="#000";
    // 执行绘制
    context.stroke();
}

// 圆形，曲线
arc(x, y, radius, startAngle, endAngle, counterclockwise);

<style>
// 画布背景颜色
#canvas {
    background: #000;
}
</style>
// 画布宽度400
<canvas id="canvas" width="400" height="400">
<script>
 var canvas = document.getElementById('canvas');
 var context= canvas.getContext('2d')
 // 开始
 context.beginPath();
 // 绘制圆形
 context.arc(100, 100, 50, 0, Math.PI*2, true);
 // 关闭
 context.closePath();
 // 填充颜色
 context.fillStyle = 'rgb(255,255,255)';
 context.fill();
</script>

// 设置画布宽度
var cx = canvas.width = 400;
var cy = canvas.height = 400;

// 获取这个canvas的上下文对象
var canvas = document.getElementById('canvas');
var context = canvas.getContext('2d');

// 辅助线绘制弧线
arcTo(x1, y1, x2, y2, radius)

// 绘制一条弧线
function draw() {
    var canvas = document.getElementById('canvas');
    var context = canvas.getContext('2d');
    // 开始绘制
    context.beginPath();
    // 移动点
    context.moveTo(80, 120);
    // 绘制线条
    context.lineTo(150, 60);
    context.lineTo(180, 130);
    // 描边
    context.strokeStyle="rgba(0,0,0,0.4)";
    context.lineWidth=2;
    context.stroke();
    context.beginPath();
    context.moveTo(80,120);
    context.arcTo(150,60,180,130,50);
    context.strolkeStyle="rgba(255,135,0,1)";
    context.stroke();
}

quadraticCurveTo(cpX, cpY, x, y);
// cpX, cpY描述了控制点的坐标，x, y描述了曲线的终点坐标

bezierCurveTo(cp1X, cp1Y, cp2X, cp2Y, x, y);
// cp1X, cp1Y 表示第一个控制点的坐标 
// cp2X, cp2Y 表示第二个控制点的坐标 
// x, y表示曲线的终点坐标

function draw() {
    // 绘制曲线
    var canvas = document..getElementById('canvas');
    var context = canvas.getContext('2d');
    // 开始绘制
    context.beginPath();
    // 移动
    context.moveTo(100,180);
    // 连线
    context.lineTo(110,80);
    context.moveTo(260,100);
    context.lineTo(300,200);
    // 描边
    context.strokeStyle="rgba(0,0,0,0.4)";
    // 设置宽度
    context.lineWidth=3;
    context.stroke();
    context.beginPath();
    context.moveTo(100,180);
    // 绘制贝济埃曲线
    context.bezierCurveTo(110,80,260,100,300,200);
    // 设置宽度
    context.lineWidth = 3;
    context.strokeStyle="rgba(255,135,0,1)";
    context.stroke();
}

var canvas = document.getElementById('canvas');
var context = canvas.getContext('2d');
// 画布宽度200
var canX = canvas.width = 200
var canY = canvas.height = 200;
// 开始绘制
context.beginPath();
// 四分之一圆
context.arc(100, 100, 50, 0, Math.PI*0.5, false);
context.strokeStyle="white"
context.stroke();

context.beginPath();
context.lineTo(200, 200);
context.lineTo(200, 100);
context.lineTo(100,50);
context.strokeStyle = '#fff';
context.stroke();

gradient.addColorStop(stop,color)

function draw() {
    var canvas = document.getElementById('canvas');
    var context = canvas.getContext('2d');
    // image实例
    var newImg = new Image();
    newImg.src='../images/dada.jpg' // 指定图像的文件地址
    newImg.onload = function(){
        // 绘图
        context.drawImage(newImg, 0, 0);
        context.drawImage(newImg, 250,100, 150,200);
        context.drawImage(newImg, 90,80,100,100,0,0,120,120);
    }
}

// 创建线性渐变
createLinearGradient()方法

// 创建径向渐变
createRadialGradient()方法

addColorStop(offset, color);

function draw() {
    var canvas = document.getElementById('canvas')
    var context = canvas.getContext('2d')
    // 创建渐变对象，线性渐变
    var grd = context.createLinearGradient(0,0,300,0)
    // 设置渐变颜色
    grd.addColorStop(0, '#xxx'); // 设置颜色
    grd.addColorStop(1, '#xxx'); // 设置颜色
    // 将填充样式设置为线性渐变对象
    context.fillStyle = grd;
    context.fillRect(0,0,300,80);
}

function draw() {
    var canvas = document.getElementById('canvas')
    var context = canvas.getContext('2d')
    // 径向渐变
    var grd = context.createRadialGradient(50,50,0,100,100,90);
    // 设置渐变颜色以及方式
    grd.addColorStop(0,'#xxx');
    grd.addColorStop(1,'#xxx');
    context.fillStyle = grd;
    context.beginPath();
    // 圆形
    context.arc(100,100,90,0,Math.PI*2,true);
    context.fill();
}

butt
// 定义了线段没有线帽
round
// 定义了线段的末端为一个半圆形的线帽
square
// 定义了线段的末端为一个矩形的线帽

lineJoin = [value];

round 
// 两条线段的外边缘应该和一个填充的弧结合
bevel 
// 两条线段的外边缘应该和一个填充的三角形相交

createPattern(image, repetitionStyle)

function draw() {
    var canvas = document.getElementById('canvas')
    var context = canvas.getContext('2d')
    var img = new Image(); 
    // 使用Image()构造函数创建图像对象
    img.src='../images/xxx' 
    // 指定图像的文件地址
    img.onload = function() {
        // 绘图模式
        var ptrn = context.createPattern(img, 'repeat');
        // 填充样式
        context.fillStyle = ptrn;
        // 填充矩形
        context.fillReat(0,0,500,200);
    }
}

// 移动
translate(dx,dy);
// 绘制
function draw() {
    var canvas = document.getElementById('canvas')
    var context = canvas.getContext('2d')
    // 设置移动偏移量
    context.translate(200, 200);
    // 绘制一个圆形
    ArcFace(context);
}
// 绘制一个圆形
function ArcFace(context) {
    // 绘制一个圆形边框
    context.beginPath();
    // 绘制圆形
    context.arc(0,0,90,0,Math.PI*2,true);
    // 线宽
    context.lineWidth=5;
    // 描边
    context.strokeStyle='#f90';
    context.stroke();
    // 绘制
    context.beginPath();
    context.moveTo(-30, -30);
    context.lineTo(-30, -20);
    context.moveTo(30, -30);
    context.lineTo(30, -20);
    context.moveTo(-20, 30);
    // 曲线
    context.bezierCurveTo(-20, 44, 20, 30, 30, 20);
    context.strokeStyle='#000';
    context.lineWidth=10;
    context.lineCap = 'round';
    // 笑脸?
    context.stroke();
}

scale(sx, sy);
// sx为水平方向上的缩放因子，sy为垂直方向上的缩放因子

// 示例
function draw() {
    var canvas = document.getElementById('canvas')
    var context = canvas.getContent('2d')
    // 移动
    context.translate(200,200);
    // 缩放
    context.scale(0.5,0.5);
    ArcFace(context);
}

rotate(angle)

// 旋转例子
function draw() {
    var canvas = document.getElementById('canvas');
    var context = canvas.getContext('2d')
    context.translate(200,200);
    // 旋转
    context.rotate(Math.PI/6);
    context.scale(0.5, 0.5)
    ArcFace(context)
}

transform(m1x,m1y,m2x,m2y,dx,dy); // 移动，缩放，旋转

1. 移动translate (dx, dy)
2. 缩放scale (sx,sy)
3. 旋转rotate (A)

// 绘制文本示例
function draw() {
    var canvas = document.getElementById('canvas')
    var context = canvas.getContext('2d')
    // 填充颜色
    context.fillStyle = '#000';
    context.font = 'bold 12px impact';
    // 绘制文本
    context..fillText('达达前端，魔王哪吒', 10, 10);
    context.strokeStyle = '#000';
    context.font = 'bold italic 12px impact';
    // 绘制文本
    context.strokeText('jeskson', 10, 10);
}

measureText(text)

function draw() {
    var canvas = document.getElementById('canvas');
    var context = canvas.getContext('2d');
    context.fillStyle='#000';
    context.font='bold 10px impact';
    // 测量文本的宽度
    var tm = context.measureText(txt);
    context.fillText(txt,10,10);
    context.fillText(tm.width, tm.width+10, 50);
    context.strokeStyle = '#000';
    context.font = 'bold italic 10px impact';
    // 测量文本的宽度
    tm = context.measureText(txt);
    context.strokeText(txt,10,10);
    context.strokeText(tm.width, tm.width+10, 100);
}

<template>
	<view class="backgroundColor">
	    // 画布
		<canvas class="isCan" canvas-id="dadaPoster" :style="{ width: cansWh.cansWidth + 'px', height: cansWh.cansHeight + 'px' }"></canvas>
		// 效果图
		<image class="showImg" mode="aspectFit" v-if="tempImgShow" @longpress="longpress" :src="tempImg"></image>
		// 按钮
		<view v-if="tempImgShow" class="fixedBox flex flex-direction">
			<view class="boxTop text-white">长按图片发送给朋友</view>
			<view class="boxDown">
				<button class="flexBtn" hover-class="btnHover" @click="closeCans">关闭</button>
			</view>
		</view>
	</view>
</template>
data() {
	return {
		tempImgShow: false,
		tempImg: '',
		cansWh: { // 画布宽高
			cansWidth: 800,
			cansHeight: 900,
		},
		qrcode: { // 举例二维码
			top: 0.85,
			left: 0.035,
			width: 0.23,
			qrHeight: null,
		},
		...
		productImg: { // 产品图
			top: 0.1,
			left: 0.03,
			width: 1,
			height: 0.5,
		},
	};
},

// 绘制图
drawImg(method,param){
	return new Promise((resolve, reject)=>{
		if(param.url.indexOf('http') === 0){
			uni.downloadFile({
				url: param.url,
				success(res) {
					param.url = res.tempFilePath
					method(param).then(res=>{
						resolve(res)
					}).catch(err=>{
						reject(err)
					})
				},
				fail(error) {
					console.log(error)
				}
			})
		}else{
			method(param).then(res=>{
				resolve(res)
			}).catch(err=>{
				reject(err)
			})
		}
	})
}

// 绘制圆形
drawCircle(param) {
var that = this,x = param.x,y = param.y,r = param.r,url = param.url;
return new Promise((resolve, reject) => {
	x = Math.ceil(that.cansWh.cansWidth * x);
	y = Math.ceil(that.cansWh.cansHeight * y);
	r = r > 1 ? r : Math.ceil(that.cansWh.cansWidth * r);
	that.ctx.save();
	var d = 2 * r;
	var cx = x + r;
	var cy = y + r;
	that.ctx.arc(cx, cy, r, 0, 2 * Math.PI);
	that.ctx.clip();
	that.ctx.drawImage(url, x, y, d, d);
	that.ctx.restore();
	that.ctx.draw(true, res=>{
		resolve();
	});
});
}

// 绘制图
drawPic(item) {
return new Promise((resolve, reject) => {
	let x, y, w, h, r;
	y = item.sTop <= 1 ? this.cansWh.cansHeight * item.sTop : item.sTop;
	w = item.sWidth <= 1 ? this.cansWh.cansWidth * item.sWidth : item.sWidth;
	h = item.sHeight <= 1 ? this.cansWh.cansHeight * item.sHeight : item.sHeight;
	if (item.sLeft == 'center') {
		x = item.sWidth <= 1 ? this.cansWh.cansWidth * (0.5 - item.sWidth / 2) : this.cansWh.cansWidth * 0.5 - item.sWidth /
			2;
	} else {
		x = this.cansWh.cansWidth * item.sLeft;
	}
	if (item.r) {
		r = item.r;
		this.ctx.save();
		if (w < 2 * r) r = w / 2;
		if (h < 2 * r) r = h / 2;
		this.ctx.beginPath();
		this.ctx.moveTo(x + r, y);
		this.ctx.arcTo(x + w, y, x + w, y + h, r);
		this.ctx.arcTo(x + w, y + h, x, y + h, r);
		this.ctx.arcTo(x, y + h, x, y, r);
		this.ctx.arcTo(x, y, x + w, y, r);
		this.ctx.closePath();
		this.ctx.clip();
		this.ctx.drawImage(item.url, x, y, w, h);
		this.ctx.restore(); // 返回上一状态
	} else {
		this.ctx.drawImage(item.url, x, y, w, h);
	}
	this.ctx.draw(true, res=>{
		resolve();
	});
});
}

// 保存
saveCans() {
let tempRatio = 1;
uni.canvasToTempFilePath({
x: 0,
y: 0,
width: this.cansWh.cansWidth * tempRatio,
height: this.cansWh.cansHeight * tempRatio,
destWidth: this.cansWh.cansWidth * tempRatio * 2,
destHeight: this.cansWh.cansHeight * tempRatio * 2,
canvasId: 'dadaPoster',
success: (res) => {
	this.tempImg = res.tempFilePath;
	setTimeout(() => {
		this.tempImgShow = true;
	}, 100);
	uni.hideLoading();
},
fail: (res) => {
	console.log(res);
	uni.hideLoading();
}
},
);
}

// canvas标签的使用
<canvas width="100" height="100"></canvas>
// 获取canvas
var canvas = document.getElementById('target')
if(canvas.getContext) {
    var ctx = canvas.getContext('2d');
}else {
    alert('该浏览器版本过低，请更换')
}

// 矩形
fillRect( x , y , width , height) // 填充
strokeRect( x , y , width , height) // 空心
clearRect( x, y , width , height ) // 清除透明 
var grd = ctx.createLinearGradient( x1 ,y1 ,x2 ,y2); //线性渐变
var grd = ctx.createRadialGradient(x1 ,y1 ,r1 ,x2 ,y2 ,r2);//径向渐变

<body>
    <img src="img/bg.png" id="img1" style="display: block" width="1200" height="800" />
    <img src="img/dada.png" id="img2" style="display: block" width="100" height="100" />
    <img id="img3" />
    <button onclick="draw()" id="btn">点击下载</button>
    
    <script>
        function draw() {
            var img1 = document.getElementById("img1"),
            var img2 = document.getElementById("img2"),
            var img3 = document.getElementById("img3");
            
            var img1.width = 1200;
            var img1.height = 800;
            var img2.width = 100;
            var img2.height = 100;
            
            var canvas = document.createElement("canvas"),
                context = canvas.getContext("2d");
            // 绘制宽度
            canvas.width = img1.width;
            // 绘制高度
            canvas.height = img1.height; 
            /**
             * context.drawImage(image,x,y,w,h)
             * var img=new Image(); img.src="url(...)";
             * x:绘制图像的x坐标
             * y:绘制图像的y坐标
             * w:绘制图像的宽度
             * h:绘制图像的高度
             */
             
            context.drawImage(img1, 0, 0, img1.width, img1.height);
            // 将 img2 加入画布
            context.drawImage(img2, 100, 100, img2.width, img2.height);
            // 文字填充颜色
            context.fillStyle = '#333';
            // 文字字体
            context.font = 'bold 45px 黑体';
            // 设置文字
            var name_text = '达达前端，魔王哪吒';
            // 获取文字的宽度
            var name_width = context.measureText(name_text).width;
            // 获取除去文本后的一半的宽度
            var x = (canvas.width - name_width) / 2;
            
            /**
             * context.font:设置字体样式
             * context.textAlign:水平对齐方式
             * context.textBaseline:垂直对齐方式
             * context.measureText(text):计算字体长度(px)
             */
            context.fillText(name_text, x, 450);
            context.fillStyle = '#333'; // 文字填充颜色
            context.font = '25px bold 黑体';
            var con_1 = 'dadaqianduan';
            var con_2 = '达达';
            /**
             * text:要绘制的文字
             * x:文字起点的x坐标轴
             * y:文字起点的y坐标轴
             */
            context.fillText(con_1, x, 400);
            var con_width_2 = context.measureText(con_2).width;
            context.fillText(con_2, canvas.width - x - con_width_2, 400);
            context.stroke();
            // 将画布内容导出
            var src = canvas.toDataURL();
            img3.src = src;
            const a = document.createElement("a");
            a.href = src;
            a.download = '自定义.png';
            a.click();
        }
    </script>
</body>

script引入文件

html2canvas(content, { //content是将要截图的div元素
    scale: 2,
    logging: false,  //在console中输出信息
    useCORS: true  //允许跨域
    //proxy: string,   //代理地址
    //timeout: number   //超时时间
}).then(function(canvas) {
    let dataUrl = canvas.toDataURL()
    console.log(dataUrl)
})

<script>
var code_model = '<div id="qrcode" style="position: fixed; opacity: 0;"></div>', // 放置二维码
    canvas_model = '<canvas width="1200" height="800" style="position: fixed;opacity:0;" id="myCanvas"></canvas>', // 放置canvas
    poster_model = '<div class="poster_container"><div class="poster"><img src="" alt="" class="poster_img"><p class="save_poster">长按保存图片至手机相册</p><p style="margin-top: 0.5rem" class="aaaa"></p></div></div>';
    //poster_model为效果图
$("body").append(code_model, canvas_model, poster_model);
$.ajax({
    url: "/photo/dada",
    data: {
        id: id
    },
    success: function (res) {
        $.hideLoading();
        if (res.e = "1111") {
            if (!res.data.is_buy) {
                location.href = res.data.jump_url;
                return false;
            }
            $(".poster").show();
            
            var data_base = res.data.poster_info;
            new QRCode('qrcode', {
                text: data_base.url,
                width: 100,
                height: 100,
                colorDark: '#000000',
                colorLight: '#ffffff',
                correctLevel: QRCode.CorrectLevel.H
            });
            var c = document.getElementById("myCanvas"), 
            cxt = c.getContext("2d");
            var img = new Image(), imgUrl, personName = data_base.name;
            //跨域问题
            img.crossOrigin = 'anonymous';
            img.src = data_base.image;
            img.onload = function () {
                //图片加载为异步加载
                cxt.drawImage(img, 0, 0);
                cxt.save();
                cxt.beginPath();
                cxt.arc(100, 200, 33, 0, 2 * Math.PI, true);
                cxt.strokeStyle = '#fff';
                cxt.stroke();
                cxt.clip();
                var img_head = new Image();
                img_head.crossOrigin = 'anonymous';
                var avatar_height = data_base.avatar_height, avatar_width = data_base.avatar_width;
                img_head.src = data_base.avatar;
                img_head.onload = function () {
                    cxt.drawImage(img_head, 0, 0, avatar_height, avatar_width, 54, 520, 80, 80);
                    cxt.restore();
                    var img_code = new Image();
                    img_code.crossOrigin = 'anonymous';
                    cxt.lineWidth = "4";
                    cxt.strokeStyle = '#FFF';
                    cxt.rect(80, 80, 400, 400);
                    cxt.stroke();
                    setTimeout(function () {
                        img_code.src = $("#qrcode").find("img").attr("src");
                        img_code.onload = function () {
                            cxt.drawImage(img_code, 0, 0, 100, 100, 450, 450, 80, 80);
                            cxt.font = '21px 黑体';
                            cxt.fillStyle = "#000";
                            cxt.fillText(personName, 250, 520);
                            imgUrl = c.toDataURL("image/png", 1);
                            $(".poster_img").attr("src", imgUrl);
                            $(".poster_container").show();
                        };
                    }, 0);
                };
            };
        } else {
            $.toast(res.m, "text");
        }
    }
});
</script>

<view class="photoCan">
  <canvas style="width: 375px; height: 612px; position:fixed; top:9999px; left:0; z-index:223;" canvas-id="mycanvas"></canvas>
  <image src="{{imagePath}}" mode="widthFix"></image>
</view>

const app = getApp()
const setText = (context, fs, color, x, y, c) => {
  context.setFontSize(fs);
  context.setFillStyle(color);
  context.setTextAlign('left');
  context.fillText(c, x, y);
  context.restore();
};

Page({
  data: {
    imagePath:''
  },
  onLoad(){
    var that=this;
    wx.downloadFile({
       url: 'https://xxxx.com/image',
       success: function (res) {
           that.setData({
              path: res.tempFilePath
           })
        }
     })
    var ctx = wx.createCanvasContext('mycanvas');
    var c_avatar = '../image/timg2.jpg';
    var wechat = '../image/wechat.png';
    var path = that.data.path;
    ctx.fillStyle = "#ffe200";
    ctx.fillRect(0, 0, 375, 612);
    setText(ctx, 16, '#xxx', 90, 45, '达达);
    // 绘制画报背景图
    ctx.drawImage(path, 30, 95, 400, 500);
    //头像
    ctx.arc(45, 45, 25, 0, 2 * Math.PI)
    ctx.strokeStyle = "#fff";
    ctx.clip();
    ctx.drawImage(c_avatar, 20, 20, 50, 50);
    // 绘制生成画报
    ctx.draw(true, setTimeout(function () {
      // 保存
      wx.canvasToTempFilePath({
        canvasId: 'mycanvas',
        success: function (res) {
          console.log(res)
          var tempFilePath = res.tempFilePath;
          that.setData({
            imagePath: tempFilePath
          });
        },
        fail: function (res) {
          console.log(res);
        }
      })
    }, 1000));
  }
})