java 教你如何给你的头像添加一个好看的国旗

今天朋友圈又火了，听说原因是 @腾讯官网 就能得到一顶绿色的帽子，啊呸，是一个好看的国庆节头像，可是听说没一会就502了，那么我们自己动手实现一个吧

由于代码比较简单就不一一介绍了。

var cvs = document.getElementById("cvs");
var ctx = cvs.getContext("2d");
var exportImage = document.getElementById("export");
var img = document.getElementById("img");
var hat = "hat6";
var canvasFabric;
var hatInstance;
var screenWidth = window.screen.width < 500 ? window.screen.width : 300;

function viewer() {
 var file = document.getElementById("upload").files[0];
 console.log(file);
 var reader = new FileReader;
 if (file) {
   reader.readAsDataURL(file);
   reader.onload = function(e) {
     img.src = reader.result;
     img.onload = function() {
       img2Cvs(img)
     }
   }
 } else {
   img.src = ""
 }
}

function img2Cvs(img) {
 cvs.width = img.width;
 cvs.height = img.height;
 cvs.style.display = "block";
 canvasFabric = new fabric.Canvas("cvs", {
   width: screenWidth,
   height: screenWidth,
   backgroundImage: new fabric.Image(img, {
     scaleX: screenWidth / img.width,
     scaleY: screenWidth / img.height
   })
 });
 changeHat();
 document.getElementById("uploadContainer").style.display = "none";
 document.getElementById("uploadText").style.display = "none";
 document.getElementById("upload").style.display = "none";
 document.getElementById("change").style.display = "block";
 document.getElementById("exportBtn").style.display = "block";
 document.getElementById("tip").style.opacity = 1
}

function changeHat() {
 document.getElementById(hat).style.display = "none";
 var hats = document.getElementsByClassName("hide");
 hat = "hat" + (+hat.replace("hat", "") + 1) ％ hats.length;
 var hatImage = document.getElementById(hat);
 hatImage.style.display = "block";
 if (hatInstance) {
   canvasFabric.remove(hatInstance)
 }
 hatInstance = new fabric.Image(hatImage, {
   top: 40,
   left: screenWidth / 3,
   scaleX: 100 / hatImage.width,
   scaleY: 100 / hatImage.height,
   cornerColor: "#0b3a42",
   cornerStrokeColor: "#fff",
   cornerStyle: "circle",
   transparentCorners: false,
   rotatingPointOffset: 30
 });
 hatInstance.setControlVisible("bl", false);
 hatInstance.setControlVisible("tr", false);
 hatInstance.setControlVisible("tl", false);
 hatInstance.setControlVisible("mr", false);
 hatInstance.setControlVisible("mt", false);
 canvasFabric.add(hatInstance)
}

function exportFunc() {
 document.getElementsByClassName("canvas-container")[0].style.display = "none";
 document.getElementById("exportBtn").style.display = "none";
 document.getElementById("tip").innerHTML = "长按图片保存或分享";
 document.getElementById("change").style.display = "none";
 cvs.style.display = "none";
 exportImage.style.display = "block";
 exportImage.src = canvasFabric.toDataURL({
   width: screenWidth,
   height: screenWidth
 })
}

最后效果

拖动图片可见已经拼合成一张完整图片了

右键查看源代码

所有图片素材均来自腾讯官网

源码地址：https://gitee.com/alterem/avatar

演示地址：http://alterem.gitee.io/avatar/

来源：https://segmentfault.com/a/1190000020482505