将画布图像作为多部分/表单数据类型的Blob上传到facebook

Question

我正在尝试使用facebook api从保存在页面上的画布上传图像：

var file = dataURItoBlob(canvas.toDataURL('image/jpeg', 1.0))

FB.api('/me/photos', 'POST', {
  source: file,
  message: 'photo description'
}, function (response) {
    console.log(response)
  }
)

这是blob转换器：

function dataURItoBlob(dataURI) {
  var byteString = atob(dataURI.split(',')[1]);
  var ab = new ArrayBuffer(byteString.length);
  var ia = new Uint8Array(ab);
  for (var i = 0; i < byteString.length; i++) {
    ia[i] = byteString.charCodeAt(i);
  }
  return new Blob([ab], { type: 'image/jpeg' });
}

我收到一个错误：消息：（#324）需要上传文件“，因此上传者似乎无法识别该blob为有效文件。

更新1：

我发了这篇帖子：将数据URI转换为文件，然后将其附加到FormData关于将blob转换为FormData，尝试如下：

var dataURL = canvas.toDataURL('image/jpeg', 1.0)
var blob = dataURItoBlob(dataURL)
var fd = new FormData(document.forms[0])
fd.append("canvasImage", blob)

FB.api('/me/photos', 'POST', {
  source: fd .....

但还是一样的错误。

更新2：

甚至尝试过这个XHR post解决方案，使用Facebooks javascript api发布多部分/表单数据编码的图像，但仍然收到文件问题“无法上传照片。照片应小于4 MB，并保存为JPG、PNG、GIF或TIFF文件。”

function postImageToFacebook(access_token) {
  var filename = "samplepic.png",
    mimeType = "image/png",
    message = "test comment",
    data = canvas.toDataURL("image/png"),
    encodedPng = data.substring(data.indexOf(',') + 1, data.length),
    imageData = atob(encodedPng);

  // build the multipart/form-data
  var boundary = '----ThisIsTheBoundary1234567890';
  var formData = '--' + boundary + '\r\n'
  formData += 'Content-Disposition: form-data; name="source"; filename="' + filename + '"\r\n';
  formData += 'Content-Type: ' + mimeType + '\r\n\r\n';
  for (var i = 0; i < imageData.length; ++i) {
    formData += String.fromCharCode(imageData[i] & 0xff);
  }
  formData += '\r\n';
  formData += '--' + boundary + '\r\n';
  formData += 'Content-Disposition: form-data; name="message"\r\n\r\n';
  formData += message + '\r\n'
  formData += '--' + boundary + '--\r\n';

  var xhr = new XMLHttpRequest();
  xhr.open( 'POST', 'https://graph.facebook.com/v2.5/me/photos?access_token=' + access_token, true );
  xhr.onload = xhr.onerror = function() {
    console.log( xhr.responseText );
  };
  xhr.setRequestHeader( "Content-Type", "multipart/form-data; boundary=" + boundary );
  xhr.send( formData );
}




Answer 1

要直接从画布上传到Facebook照片，这对我来说很有用：

function postImageToFacebook(token, imageData, message, successCallback, errorCallback) {
  var fd = new FormData();
  fd.append("access_token", token);
  fd.append("source", imageData);
  fd.append("caption", message);

  $.ajax({
      url: "https://graph.facebook.com/me/photos?access_token=" + token,
      type: "POST",
      data: fd,
      processData: false,
      contentType: false,
      cache: false,
      success: function (data) {
        successCallback(data);
      },
      error: function (shr, status, data) {
        errorCallback(data);
      },
      complete: function (data) {
        console.log('Completed');
      }
  });
}

function dataURItoBlob(dataURI) {
  var byteString = atob(dataURI.split(',')[1]);
  var ab = new ArrayBuffer(byteString.length);
  var ia = new Uint8Array(ab);
  for (var i = 0; i < byteString.length; i++) {
      ia[i] = byteString.charCodeAt(i);
  }
  return new Blob([ab], {type: 'image/jpeg'});
}

使用它

// *IMPORTANT*
var FBLoginScope = 'publish_actions'; // or sth like 'user_photos,publish_actions' if you also use other scopes.

var caption = "Hello Facebook!";
var successCallback = ...;
var errorCallback = ...;

var data = $('#your_canvas_id')[0].toDataURL("image/jpeg");
try {
  imageData = dataURItoBlob(data);
} catch (e) {
  console.log(e);
}

FB.getLoginStatus(function (response) {
  if (response.status === "connected") {
    postImageToFacebook(response.authResponse.accessToken, imageData, caption, successCallback, errorCallback);
  } else if (response.status === "not_authorized") {
    FB.login(function (response) {
        postImageToFacebook(response.authResponse.accessToken, imageData, caption, successCallback, errorCallback);
    }, {scope: FBLoginScope});
  } else {
    FB.login(function (response) {
        postImageToFacebook(response.authResponse.accessToken, imageData, caption, successCallback, errorCallback);
    }, {scope: FBLoginScope});
  }
});

修改自：http://gorigins.com/posting-a-canvas-image-to-facebook-and-twitter/

Answer 2

出于某种原因，我发现这些问题是我试图应用的标题，作为以前问题的解决方案...这是一个工作解决方案：https://jsfiddle.net/ilyador/vyne7oh2/8/

function fbUpload(token){
  var dataURL = canvas.toDataURL('image/jpeg', 1.0)
  var blob = dataURItoBlob(dataURL)
  var formData = new FormData()
  formData.append('token', token)
  formData.append('source', blob)

  var xhr = new XMLHttpRequest();
  xhr.open( 'POST', 'https://graph.facebook.com/me/photos', true )
  xhr.onload = xhr.onerror = function() {
    console.log( xhr.responseText )
  };
  xhr.send( formData )
}

function dataURItoBlob(dataURI) {
  var byteString = atob(dataURI.split(',')[1]);
  var ab = new ArrayBuffer(byteString.length);
  var ia = new Uint8Array(ab);
  for (var i = 0; i < byteString.length; i++) { ia[i] = byteString.charCodeAt(i); }
  return new Blob([ab], { type: 'image/jpeg' });
}