创建模因并存储到本地答案

【问题标题】：Creating a meme and storing into local创建模因并存储到本地
【发布时间】：2021-03-18 03:21:57
【问题描述】：

我正在尝试通过获取用户的输入在浏览器中创建 meme 图像。

用户还应该能够在创建 meme 后下载图像。

下面给出的代码，其中下载/保存按钮不起作用

function textChangeListener(evt) {
  var id = evt.target.id;
  var text = evt.target.value;

  if (id == "topLineText") {
    window.topLineText = text;
  } else {
    window.bottomLineText = text;
  }

  redrawMeme(window.imageSrc, window.topLineText, window.bottomLineText);
}
//------
function redrawMeme(image, topLine, bottomLine) {
  // Get Canvas2DContext
  var canvas = document.querySelector('canvas');
  var ctx = canvas.getContext("2d");
  if (image != null)
    ctx.drawImage(image, 0, 0, canvas.width, canvas.height);

  // clear previous
  ctx.clearRect(0, 0, canvas.width, canvas.height);

  if (image != null)
    ctx.drawImage(image, 0, 0, canvas.width, canvas.height);

  // Text attributes
  ctx.font = '30pt Impact';
  ctx.textAlign = 'center';
  ctx.strokeStyle = 'black';
  ctx.lineWidth = 3;
  ctx.fillStyle = 'white';

  if (topLine != null) {
    ctx.fillText(topLine, canvas.width / 2, 40);
    ctx.strokeText(topLine, canvas.width / 2, 40);
  }

  if (bottomLine != null) {
    ctx.fillText(bottomLine, canvas.width / 2, canvas.height - 20);
    ctx.strokeText(bottomLine, canvas.width / 2, canvas.height - 20);
  }
}

function saveFile() {

  window.open(document.querySelector('canvas').toDataURL());
}
//--------

function handleFileSelect(evt) {
  //make canvas
  var canvasWidth = 500;
  var canvasHeight = 500;
  var file = evt.target.files[0];

  //image upload
  var reader = new FileReader();
  reader.onload = function(fileObject) {
    var data = fileObject.target.result;

    // Create an image object
    var image = new Image();
    image.onload = function() {

      window.imageSrc = this;
      redrawMeme(window.imageSrc, null, null);
    }

    // Set image data to background image.
    image.src = data;
    console.log(fileObject.target.result);
  };
  reader.readAsDataURL(file)
}
window.imageSRC = null;
window.topLineText = "";
window.bottomLineText = "";
window.imageSRC = null;
window.topLineText = null;
window.bottomLineText = null;

var file = document.querySelector("#file");
file.onchange = handleFileSelect;

var input1 = document.getElementById('topLineText');
var input2 = document.getElementById('bottomLineText');
input1.oninput = textChangeListener;
input2.oninput = textChangeListener;
document.getElementById('file').addEventListener('change', handleFileSelect, false);
document.querySelector('button').addEventListener('click', saveFile, false);

<!DOCTYPE html>
<html>

<head>
  <title>html2canvas</title>
  <link href="style.css" rel="stylesheet" type="text/css">
</head>

<body>

  <div class="container">
    <h1>CREATE YOUR OWN MEME</h1>
    <p>Upload an image, type in some lines and save</p>
    <input type="file" id="file" />
  </div>
  <div id="image-container">
    <canvas width="500" height="500" id="canvas"></canvas>
    <div class="inputs">
      <br/>
      <input id="topLineText" type="text" placeholder="TOP LINE"><br/>
      <br/>
      <input id="bottomLineText" type="text" placeholder="BOTTOM LINE"><br/>
      <button id="saveBtn" onclick="saveFile()">Save</button>
    </div>
  </div>


</body>

</html>

我认为 saveFile() 中应该有一些修复，谁能帮我修复这段代码？我试图在没有角度支持的情况下做到这一点

【问题讨论】：

为什么saveFile会打开一个窗口（很可能是被浏览器屏蔽了）？请改用 Blob API，例如使用toBlob 方法和动态添加的<a download> 元素。

标签： javascript html css html2canvas

【解决方案1】：

似乎在新窗口中打开画布数据 url 不起作用。下载图像的更好方法是创建一个链接标签并分配您的画布 URL，然后打开链接试试这个小提琴https://jsfiddle.net/gd3a7hLn/

var link = document.createElement('a');
link.download = 'filename.png';
link.href = document.getElementById('canvas').toDataURL()
link.click();

【讨论】：