I have some client-side JavaScript which will output a jpeg file based on HTML5 canvas manipulation, if the user performs an action such as clicking the "OK" button.
I would like the jpeg output to be automatically loaded into the "Upload Front Side" field in a form, as if the user uploaded the file from his or her own hard drive.
However, I can't seem to get it to work.
Here is the form:
<div class="property-wrapper">
<label for="upload-front">Upload Front Side</label>
<input id="upload" class="file" type="file" enctype="multipart/form-data" id="Front-Side" name="properties[Front Side]" onchange="readURL(this);" accept="image/*" />
</div>
<script>
document.getElementById('upload').value="http://upload.wikimedia.org/wikipedia/commons/thumb/2/22/Turkish_Van_Cat.jpg/353px-Turkish_Van_Cat.jpg"
</script>
The problem is browsers have several restrictions on what can be done programatically with file upload due to security reasons, have a look at this answer.
The file upload functionality is potentially exploitable, and some browsers will for example not open the explorer box if for example the file upload input field is hidden with display:none.
Most browsers will not allow programatic clicks to a file upload element and require the user to click them instead, to prevent attacks where someone sends a link to a page that immediately steals content from the user's hard drive.
So the functionality you mention does not seem to be feasible due to common browser security restrictions. There are usually no error messages or warnings, it just doesn't work.
An alternative to using the file upload browser input component could be to encode the contents of the file in Base64 and send in the body of an ajax POST for example.
Are you asking how to upload to a server, via a form, the graphic image you extracted from the canvas of your page? This would be useful, I hope to see this answered.
I would start by enabling the user to download/export the image. This might be done with a blob. Ive done this for text data exports, works nicely.
Maybe there is a way to apply the same tricks, just feed the blob/buffer to the server.
Another path might be to "PUT" the file at the server.
Hope this helps.
I would ajax POST a base64 encoded string of the image and forget the whole file upload thingy. You can upload the canvas code directly and reconvert it server side if you need a preview or something or see what other outputs are available from your canvas/image converter code.
I am assuming you are uploading to same server so you would not have cross domain issue but otherwise you can setup your server to accept cross domain ajax request very easily.
Related
<img class='preview' src='preview.png'>
This is an input for image upload:
<input type='file' class='img-upload' accept='image/*'>
When I clicked on the preview image(<img class='preview' src='preview.png'>), I have to change the value of the file input (<input type='file' class='img-upload' accept='image/*'>). The value of the file input should be the preview image.
Short answer: you cannot.
Long answer: The problem is that the file inputs are very sandbox'ed and will not allow user scripts to change their value. The goal is to make sure the user needs to click and acknowledge that he is sending a file from his computer.
Now, the user cannot send the image he clicked on mostly because it is not on his computer (well, technically yes, but even then he would need to know where it is stored and choose it by manually going over the folder). Another thing is, why would you want him to send over a file that you have served him? You could simply get the name of the file or an ID of any sort and use that internally.
Let's take the example of an user avatar. The user gets the possibility to pick between 10 different "preset" pictures, or to upload his own. What you'd do is have 2 form fields, one for the uploaded picture and one for the chosen preset. On server side you would see if the user uploaded a picture, and use that one. If not, use the picture he chose from your server.
I hope I got your question right...
EDIT: If you really, really, really needed to upload the displayed picture, you could get the image data (with ajax I guess), store it into a Blob and send it for upload.
But that has some serious drawbacks. And I think you'll be limited by crossdomain policies so basically you'll only be able to access files that your server can access directly...
Even if you got all that covered, it would be a painfully slow process for the user while all that is required is just sending the name of the picture and the server does the rest.
input type="file" can only be set by the user. Not by a script (not HTML, nor javascript, ...).
Every exe on a windows pc has the capacity to access your files. Including renaming, deleting, encrypting, ... them. For example that's what Wannacry (randsomware) does.
(similar for Mac and Linux, I guess)
A webbrowser is an executable, thus has all those capacities. For security reasons most of these features are turned off, on purpose.
Long ago I wrote a program in C++ (or C#, not sure), with Visual Studio. VS has a webbrowser component. The purpose was to upload multiple albums of photos to a website, but the exe on my pc did have the capacity to use a script to set the input type="file".
So my program could read all subfolders, find all images, automatically upload them, and then the php server saved the albums/images.
In order to stop people like you and me from doing these kind of things, real webbrowsers disabled all these abilities.
I am trying to allow users to upload pictures to the server.
I am trying to create a similar system to any website that has an 'attach' file or 'upload image' feature. All I need is to get the full path of the file select by the file dialog.
I tried using this for the file dialog with no success:
<input type="file">
This method does not provide the full file path, due to security reasons. My question is how can I create a similar input dialog to websites like tinypic, photobucket, etc.. that can help users input the full file path of a given image, into an input field?
I am aware that this cannot be done using the method above for security reasons, however, I have seen this done before on various websites without any problems, I was wondering what I had to do to implement a similar file dialog that helps fill in the text, which is a full file path, of an input field?
It is not possible to get the file full path on local machine using browser and javascript.
However, as you would like to upload the file to the server, the easy possibility I see is to use html form with input type file. You will receive the file on your http server when the form is submitted.
Here is a very good url http://www.cs.tut.fi/~jkorpela/forms/file.html that explains the whole process nicely.
I've a very small doubt. I've a html tag to browse the file. and as soon as I browse the file from the local server, I want to set that path to the source of image tag. Is it possible to implement?
I've code something like this.
<form name="image" id="image" enctype="multipart/form-data" action="" method="post">
<input type="file" name="img" />
<img src=""></img>
</file>
So as soon as I browse and select the file from the local server,that path should be set to image tag.My intention is to browse the image and display it in that page itself. Any help will be appreciated. Thanks in advance.
Browsers have now allowed you to access the path of a file from the input[type=file] tag for a long time. You can't simply do it like you're trying to. In order to accomplish your goal of showing the file after the user selects it, you actually need to upload it to your server. This typically requires a page-refresh, but there are plenty of javascript libraries that are available in order to make it happen without refreshing the page. Once the file is uploaded, you can "ping back" a URL to view the image, and load that in your image tag.
The jQuery library I've been using recently to do inline file uploads is jQuery File Upload
What you need is the full path to the file on the client side - which is not allowed (see also this thread).
Sorry mate, but without sending the file to the server you can't do anything with it other than getting the file name (not the path), the file type and the file size.
Is there any way I can do that? For example, I have an
<input type="file" id="upload_file" />
Obviously I can't just
$('#upload_file').val('http://www.site.com/path/to/image.jpg').parent().submit();
You can't do it.
Javascript won't let you read from other domains (for security reasons).
File inputs don't accept URL inputs (or for that matter paths) AFAIK.
I can't see how you will get this to work. What server side language are you using? Would it not be better to just make a direct request for the remote file from the server?
IF that site supports what are you trying to do it should work.
Most of file uploads are very strict, as you can't just upload a file wherever you want even if you know the upload script.
If host supports sending a link to the picture and he knows what to do with it ... I don't see why your script should not work.
<form method="post" action="http://www.example.org/">
<input type="text" name="upload_file" id="upload_file" value="" />
<input type="submit" onclick="$('#upload_file').val('http://www.example.org/example.jpg');">
</form>
Te begin with, you cannot do file uploads without a server-side tool. Sending a file to the server is pointless if there isn't anything on the side other to receive it.
Said that, if you already have a server-side language available and a file that's publicly reachable at a URL, the server-side language is perfectly capable of fetching the file by its own means. There's no need to use the browser as intermediary. You just need to send the URL in a regular <input type="text"> element.
If the file is not publicly reachable, e.g., it belongs to an intranet or is password-protected, it's probably simpler to instruct the user to type the URL in the browser's "Open file" dialoque. In many cases, the browser will download the file and fill the <input type="file"> control with the temporary downloaded file.
is there a way to load the full binary of an image in javascript?
what i want to do is to allow the user to preview an image before uploading it.
ie the user selects an image on his local drive (C:\image.jpg) , view it, and decides to upload or cancel.
i tried to set the source to the image path, but it didn't work since it is outside the webapplication project folder.
any help?
thx for your posts, but i ended up creating a temp folder on the server that stores the uploaded image using ajax. and when the user saves the data, the image is moved to another location, and the temp folder is deleted.
You can do something like this:
<img id="preview" src="" style="display:none;" />
<form>
....
<input type="file" id="file" />
....
</form>
<script type="text/javascript">
var file = document.getElementById("file");
var img = document.getElementById("preview");
file.onchange = function(){
img.src = file.value;
img.style.display = 'block';
};
</script>
There is no easy way, what You could do:
Preload image with some ajax file uploader to temp area and then let user decide
Use some third party written solution (f.ex. some flash component)
Here there is also similar question:
is it possible to preview local images before uploading them via a form?
You need server cooperation to access the image binary data. You won't be able to use the "Upload Form" to access the file info without uploading it to a server.
You could however do something like tell the user to paste the source binary data of the image in a textarea or something, then you can use JavaScript to load that binary data and display the actual image.
This is available in some browsers via the HTML5 file access API. Here is the Firefox documentation for file access.
As answered several times, you can't do this with plain HTML/JavaScript due to security restrictions. You need to send the image anyway. You can however handle this using a Java Applet since it runs entirely at the client machine and offers more control than HTML/JS. There are several free and ready-to-use ones. JumpLoader looks good and some major sites also uses it. With Flash it should also be possible, but I am not sure which ones offers this functionality. Check/tryout some Flash Multi File Uploaders.