Chrome应用未在iframe中显示Base64编码的PDF

Question

我正在开发一个Chrome应用，它是webview中主要应用的包装。 Webview将Base64编码的PDF作为消息发送给应用程序，并且该应用程序创建一个隐藏的iframe，将PDF加载到框架中并调用该框架上的print。

所有这些都可以在我的开发计算机（Win10，Chrome Beta v47）上使用，但在我尝试过的任何其他计算机或Chrome版本上都无法使用。 iframe不显示PDF，因此在打印预览中显示空白页。

是什么原因造成的？ 我的机器上是否启用了某些设置或权限？

这是我用来重现此问题的简化的Chrome应用。

的manifest.json

{
  "manifest_version": 2,
  "version": "2",
  "name": "Print PDF test",
  "app": {
    "background": {
      "scripts": ["main.js"]
    }
  },
  "permissions": [

  ]
}

main.js

chrome.app.runtime.onLaunched.addListener(function() {
  chrome.app.window.create('index.html', {
    innerBounds: {
      width: 768,
      height: 1024
    }
  });
});

的index.html

<!DOCTYPE html>
<html style="height: 100%">
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
  <title>Print PDF</title>
</head>
<body style="height: 100%">
</body>
    <script src="app.js"></script>
</html>

app.js

function showPDF() {
  var base64pdf = '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';

  var blobPdf = new Blob([base64ToUint8(base64pdf)], {
    type: 'application/pdf;base64'
  });

  var pdfFrame = document.createElement('iframe');
  pdfFrame.id = 'pdfFrame';
  pdfFrame.style.width = "100%";
  pdfFrame.style.height = "100%";
  pdfFrame.src = URL.createObjectURL(blobPdf);

  document.body.appendChild(pdfFrame);
}

function base64ToUint8(base64str) {

  var binary = atob(base64str.replace(/\s/g, ''));
  var len = binary.length;
  var buffer = new ArrayBuffer(len);
  var view = new Uint8Array(buffer);

  for (var i = 0; i < len; i++) {
    view[i] = binary.charCodeAt(i);
  }
  return view;
}

document.addEventListener('DOMContentLoaded', function() {
  showPDF();
});

Answer 1

我终于找到了我问题的答案。

我在开发机器上的chrome：// plugins /中选中了Chrome PDF Viewer的“始终允许”复选框。 这就是为什么它不能在其他计算机上运行的原因。