I have a remote server which has profile data and an image and when I retrieve it, I get the image url, which I can display using the <img> tag, by using the url.
When I have to modify the details, I send a new image, for which I upload a new image using a small AngularJS function and send the whole data using formData and http request.
But, out of curiosity, I was wondering whether there is any way to send an object of the same image using the url I received from the server.
Another reason I thought of it was that I was thinking of maybe changing its dimensions,etc.
Just in case if I ever needed to generate a thumbnail of the image of a smaller size in future.
Solved it myself by looking around and generating a canvas from the url, through dataURI by using the function :
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);
}
var blob= new Blob([ab], { type: 'image/jpeg' });
to create a blob to send the image back after scaling(was required).
Related
I would like to upload local image file and extract text from it. I followed the below link and it works as expected when I pass URL. https://learn.microsoft.com/en-us/azure/developer/javascript/tutorial/static-web-app/add-computer-vision-react-app
I managed to configure for local image and get the base64 encoded dataURL of the uploaded image. But when I pass base64 encoded dataURL to Computer Vision API , it says "Input data is not a valid image" (POST 400 status code). I am getting error in the line that is shown below:
const analysis = await computerVisionClient.analyzeImage(urlToAnalyze, { visualFeatures });
The code I have included for handling local image:
const handleChange = (e) => {
var file = e.target.files[0];
var reader = new FileReader();
reader.onloadend = function()
{
setFileSelected(reader.result) // this is the base64 encoded dataurl
}
reader.readAsDataURL(file);
}
In computerVision.js file, I have changed the 'contentType' in header as below.
const computerVisionClient = new ComputerVisionClient(
new ApiKeyCredentials({ inHeader: {'Ocp-Apim-Subscription-Key': key, 'Content-Type': 'application/octet-stream'} }), endpoint);
I tried replacing client.read() with readTextInStream() as per docs in computerVision.js (please refer above link), but still throws error.
May I know why I get the error "Input data is not a valid image" ? Thanks.
Here is the link for input requirements.
There is a brand new online portal provided by Microsoft https://preview.vision.azure.com/demo/OCR
The advantage is that it will directly list your available resources so you just have to pick the right one, then you test, and there are also some samples.
Supabase is wonderful !! I am trying to upload an image to the public bucket using POST request to <SUPABASE_URL>/storage/v1/object/<BUCKET_NAME>/<IMAGE_NAME>.
The difficult is I have only base64 encoded image string and I am not able to make a successful request to above endpoint. Have tried numerous iterations of setting Content-type but no luck.
I am trying to upload my image from Appsmith which provides base64 format for the image from where I will have to hit the above endpoint.
Please help me out here.
I'm glad to be able to find another Supabase fan like me!
I hear your pain. Could you try this technique to convert base 64 string to a blob object?
const byteCharacters = atob(b64Data);
const byteNumbers = new Array(byteCharacters.length);
for (let i = 0; i < byteCharacters.length; i++) {
byteNumbers[i] = byteCharacters.charCodeAt(i);
}
const byteArray = new Uint8Array(byteNumbers);
const blob = new Blob([byteArray], {type: contentType});
The blob variable at the end is the variable you can use to upload to Supabase.
Also, have you considered using the Supabase-js SDK? It will make your life a lot easier as they provide better API's to interact with Supabase.
You can get the supabase-js package here:
https://www.npmjs.com/package/#supabase/supabase-js
And you can find some sample code here:
https://supabase.io/docs/reference/javascript/storage-from-upload
In your case, you could do something like this to upload your file:
const { data, error } = await supabase
.storage
.from('avatars')
.upload('public/sample.png', blob, {
cacheControl: 3600,
upsert: false
})
I am trying to append the recorded video which is blob object into quill editor but the video which is appended in the editor is not playable.
Able to see only the blob object getting printed in the quill editor. If i try to open the contents in the browser it is working fine. Any suggestions?
enter image description here
well,according to this issue,
I think you maybe need to overwrite the video module's sanitize method to make it work,for image it can work like this:
var Image = Quill.import('formats/image')
Image.sanitize = function(url) {
return url
}
so as I guess, following things maybe useful:
var Video = Quill.import('formats/video')
Video.sanitize = function(url) {
return url
}
and you may need provide blob url to make it work
I'm implementing file download using AngularJS and WCF. My back-end is a .NET project hosted in IIS. The file is serialized as an array of bytes and then on the client side I utilize the File API to save the content.
To simplify the problem, back-end is like:
[WebInvoke(Method = "GET", UriTemplate = "FileService?path={path}")]
[OperationContract]
public byte[] DownloadFileBaseOnPath(string path)
{
using (var memoryStream = new MemoryStream())
{
var fileStream = File.OpenRead(path);
fileStream.CopyTo(memoryStream);
fileStream.Close();
WebOperationContext.Current.OutgoingResponse.Headers["Content-Disposition"] = "attachment; filename=\"Whatever\"";
WebOperationContext.Current.OutgoingResponse.ContentType = "application/octet-stream"; // treat all files as binary file
return memoryStream.ToArray();
}
}
And on client side, it just sends a GET request to get those bytes, converts in into a blob and save it.
function sendGetReq(url, config) {
return $http.get(url, config).then(function(response) {
return response.data;
});
}
Save the file then:
function SaveFile(url) {
var downloadRequest = sendGetReq(url);
downloadRequest.then(function(data){
var aLink = document.createElement('a');
var byteArray = new Uint8Array(data);
var blob = new Blob([byteArray], { type: 'application/octet-stream'});
var downloadUrl = URL.createObjectURL(blob);
aLink.setAttribute('href', downloadUrl);
aLink.setAttribute('download', fileNameDoesNotMatter);
if (document.createEvent) {
var event = document.createEvent('MouseEvents');
event.initEvent('click', false, false);
aLink.dispatchEvent(event);
}
else {
aLink.click();
}
setTimeout(function () {
URL.revokeObjectURL(downloadUrl);
}, 1000); // cleanup
});
}
This approach works fine with small files. I could successfully download files up to 64MB. But when I try to download a file larger than 64MB, the response.body is empty in Chrome. I also used Fiddler to capture the traffic. According to Fiddler, Back-end has successfully serialized the byte array and returned it. Please refer to the screenshot below.
In this example, I was trying to download a 70MB file:
And the response.data is empty:
Any idea why this is empty for file over 70MB? Though the response itself is more than 200MB, I do have enough memory for that.
Regarding to the WCF back-end, I know I should use Stream Mode when it comes to large files. But the typical use of my application is to download files less than 10MB. So I hope to figure this out first.
Thanks
Answer my own question.
Honestly I don't know what's going wrong. The issue still persists if I transfer it as a byte array. I eventually gave up this approach by returning a stream instead. Then on the client side, adding the following configuration
{responseType : blob}
and save it as a blob.
A server side application requires authorization on file download links. This means a normal <a ng-href="{{createLinkToFile()}}"> is no longer sufficient to get enough parameters passed to the server.
When trying to use a programmatic call to the file download, I get the response data back to Dart client application. Using a simple http GET:
var url = "http://example.com/file";
headers.putIfAbsent("Authorization", () => "bearer " + token;
_http.get(url: url, headers : headers);
The future returned by the GET will hold the data, but how do I instruct the browser to download it as a file, instead of just trying to keep it in memory?
Or is there a way to just do it in a normal link?
After downloading the data from the server like shown in Using Dart to Download a PNG File (Binary File) and displaying it not working you can create a download link like shown at http://blog.butlermatt.me/2014/03/dynamically-generating-download-files/
import 'dart:html';
void main() {
List body = [ 'Some test data ...\n'];
// Create a new blob from the data.
Blob blob = new Blob(body, 'text/plain', 'native');
// Create a data:url which points to that data.
String url = Url.createObjectUrlFromBlob(blob);
// Create a link to navigate to that data and download it.
AnchorElement link = new AnchorElement()
..href = url
..download = 'random_file.txt'
..text = 'Download Now!';
// Insert the link into the DOM.
var p = querySelector('#text');
p.append(link);
}
The code of Seth solves indeed part of the problem. To make it a bit more complete, I'm now using the following:
void doPdfFileRequest(String url) {
var request = new HttpRequest();
request.open('GET', url);
request.responseType = "blob";
request.withCredentials = false;
request.setRequestHeader("Accept", _httpAcceptHeader);
request.setRequestHeader("Authorization", "bearer " + token);
request.onReadyStateChange
.listen((r) => onData(request, "filename.pdf"));
request.send();
}
void onData(HttpRequest request, String filename) {
if (request.readyState == HttpRequest.DONE && request.status == 200) {
if (!isIE()) {
var contentType = request.getResponseHeader("content-type");
AnchorElement downloadLink = new AnchorElement(
href: Url.createObjectUrlFromBlob(request.response));
downloadLink.rel = contentType;
downloadLink.download = filename;
var event = new MouseEvent("click", view: window, cancelable: false);
downloadLink.dispatchEvent(event);
} else {
var href = Url.createObjectUrlFromBlob(request.response);
window.open(href, "_self");
}
}
}
A few things to notice. Instead of using the downloadLink.click(), a mouse event is constructed to ensure that it works on Firefox as well as on Safari and Chrome. Firefox seems not to handle the click() otherwise. Binding it to the DOM as is done in the code of Seth isn't necessary.
Internet Explorer doesn't understand the download attribute, so nothing will happen, therefore a window.open is used to at least have it work (though not ideal) on IE, it's redirecting to self to avoid being hit by the pop up blocker.
There are solutions that convert the result download result to Base64 first and put it in a data:mimetype href, using the blob this isn't necessary.
A nice way to set the filename on the file to download would be through the content disposition header, but this header is marked as unsafe, so cannot be used. The filename is now set in the code.
Another note, notice that a HttpRequest is used instead http.get(), The HttpRequest allows you to set the responseType, in this case blob, which can be transformed into a object url.