摘要：那便是極好的自定義字體不過可能會發(fā)現(xiàn)這是因為版本的沒有這個函數(shù)。

為什么要在服務(wù)端裝canvas？ 因為并不是所有的客戶端都能很好的支持canvas（比如微信小程序不能修改自定義字體），所以我們需要一個
能夠在服務(wù)端生成圖片的，然后將圖片傳輸

sudo apt-get install libcairo2-dev libjpeg8-dev libpango1.0-dev libgif-dev build-essential g++ -y

npm install -g canvas

var Canvas = require("canvas"),
    canvas = new Canvas(300, 200),
    ctx = canvas.getContext("2d"),
    fs = require("fs");
 
var out = fs.createWriteStream(__dirname + "/image.png")
  , stream = canvas.createPNGStream();
 
stream.on("data", function(chunk){
  out.write(chunk);
});
 
//在左邊畫正方形
ctx.fillStyle = "#A00"    
ctx.fillRect(0, 30,50,50);   
  
 
//在右邊畫正方形
ctx.fillStyle = "#aaa"    
ctx.fillRect(50, 30, 50, 50);
 
//畫文字
ctx.fillStyle = "#000";
ctx.font = "20px Arial";
ctx.fillText("Hello World", 0, 20);
 
//畫一個圓
ctx.beginPath();
ctx.arc(30, 110, 20, 0, 2*Math.PI);
ctx.stroke();
ctx.fillStyle = "green";                                                                                                                          
ctx.fill();
ctx.save();  

如果你按上述方法操作，并且運行成功了。那便是極好的

// You need to call it before the Canvas is created
Canvas.registerFont("comicsans.ttf", {family: "Comic Sans"});

var canvas = new Canvas(500, 500),
  ctx = canvas.getContext("2d");

ctx.font = "12px "Comic Sans"";
ctx.fillText(250, 10, "Everyone hates this font :(");

不過可能會發(fā)現(xiàn)Canvas.registerFont is not a function這是因為npm版本的沒有這個函數(shù)。

所以你需要去找另一個github版https://github.com/chearon/node-canvas#12971f64a66b

git clone 下來

然后將Canvas = require("canvas")改成require("./node-canvas")，
將var canvas = new Canvas(300, 200)改成var canvas = new Canvas.Canvas(300, 200)

如果遇到這個問題，請cd進你的node-canvas目錄執(zhí)行npm install
如果還是不行，請執(zhí)行npm install -g node-gyp

然后再cd項目目錄執(zhí)行node-gyp rebuild，then cd 進node-canvas同樣執(zhí)行node-gyp rebuild

如果成功則會出現(xiàn)

.
├── 1.html
├── composer.json
├── font
├── fz.ttf
├── img
├── index.js
├── node-canvas
├── node_modules
├── package.json
└── package-lock.json

var fs = require("fs"),path = require("path");
var http = require("http"),url = require("url");
var Canvas = require("./node-canvas"),Image = Canvas.Image;
var Fonts = [];
var filePath = path.resolve("./font");

let promise = new Promise(function(resolve, reject) {
  let i=0;
  fs.readdir(filePath,function(err,files){  
    if(err){  
      console.warn(err)  
    }else{
      files.forEach(function(filename){
        Canvas.registerFont(filePath + "/" + filename, {family: "font" + i});
        console.log(i);
        i++;
      });
    }
  });
  
});

promise.then(function() {
  console.log("ASDF");
  Fonts.forEach((Element) =>{
    console.log(Element);
  });
});

console.log("Hi!");


http.createServer(function (req, res) {
  var params = url.parse(req.url, true).query;
  var str = params.str + "
",site = params.site;
  var row =  1,col = 15,width = 1500;
  row = str.length / 15 + 1;
  var fontsize = width/col;
  var height = fontsize * row + 200;
  if(height < 1000){height = 1000}
  var canvas = new Canvas.Canvas(width, height), ctx = canvas.getContext("2d")
  res.writeHead(200,{"Content-Type": "image/png"});
  ctx.fillStyle = "#FFF";
  ctx.fillRect(0,0,canvas.width, canvas.height);
  ctx.fillStyle = "#000";
  if(row < 2){
    let num = str.length
    fontsize = 1200 / num;
    ctx.font = fontsize + "px "font"+ site +""";
    ctx.fillText(str,( width - num * fontsize ) / 2, (height-fontsize)/2 -200 + fontsize);
  }
  else{
    ctx.font = fontsize + "px "font"+ site +""";
    for(let i = 0;i < row ; i++){
      ctx.fillText(str.substring(i*15,(i+1)*15), 0, fontsize*(i+1));
    }
  }
  
  fs.readFile(__dirname + "/img/brand.png", function(err, squid){
    if (err) throw err;
    img = new Image;
    img.src = squid;
    ctx.fillStyle = "#42b983";
    ctx.fillRect(0,canvas.height - 230,canvas.width, 230);
    ctx.drawImage(img, canvas.width - img.width / 2 - 50, canvas.height - img.height / 2 - 50, img.width / 2, img.height / 2);
    res.end(canvas.toBuffer());
  });
}).listen(8080);