java 教你如何给你的头像添加一个好看的国旗

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
  })
}