Need help in Posting pasted image to PHP via Javascript

I'm a total Javascript-illiterate, but I need your help in modifying the following code so that it can

allow users to paste their clipboard image (via Chrome), and
upload the image along with other user input to my PHP script via POST.

I'd much appreciate it if you could help....

<!DOCTYPE html>
<html>
<head>

<title>Paste-able Canvas</title>
<script type="text/javascript">

function enablePasteForCanvas(canvas) {
  var pasteEvent = function(e) {
    (function() {
      var i;
      // Search image data in the clipboard 
      var items = e.clipboardData.items;
      var imageItem = null;
      for(i = 0; i < items.length; i++) {
        if(items[i].type.indexOf("image/") != -1) {
          imageItem = items[i];
          break;
        }
      }
      if(! imageItem) {
        console.log("clipboard does not contain an image.");
        return;
      }
      
      //convert:  clipboardData.items -> Blob -> Image 
      var blob = imageItem.getAsFile();
      var blobUrl = window.URL.createObjectURL(blob);
      var img = new Image();
      img.onload = function() {
        //Draw the image on canvas
        var context = canvas.getContext("2d");
        context.drawImage(img, 0, 0);
		
      };
      img.src = blobUrl;
    }());
    e.preventDefault();
  };
  
  canvas.addEventListener("focus", function(e){
    document.addEventListener("paste", pasteEvent, false);
  }, false);
  canvas.addEventListener("blur", function(e){
    document.removeEventListener("paste", pasteEvent, false);
  }, false);
}

window.addEventListener("load",function(e){
  enablePasteForCanvas(document.getElementById("my_canvas"));
}, false);


</script>

</head>
<body>

  <h2>Paste an image below</h2>(use Cntl + V)
  <br><br>Browswer:  Chrome only.<br>
  <table border=1 width=640><tr><td>
  
     <canvas id="my_canvas" width="640" height="280" tabindex="2"></canvas>

  </table>
  <br><br>
  

  <form type=POST action=drag.php>

     Text:  <input type=textbox name=text_1 width=10><br><br>
     Color: <input type=radio name=radio_1 value=blue> Blue  
	          <input type=radio name=radio_1 value=red> Red  <br><br><br>

   <input type=submit name=submit value=submit>

</form>
  
  
</body>
</html>

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JavaScriptPHPAJAXGoogle Chrome OSjQuery

Last Comment

Julian Hansen

8/22/2022 - Mon

Julian Hansen

9/11/2016

You need to do to things
1. Add a hidden input to your form to store the data in
2. Either in your paste event handler or onsubmit handler put the contents of the canvas into the control

The following sample adds an onsubmit handler to add the image on submit
HTML

	<h2>Paste an image below</h2>(use Cntl + V)
	<br><br>Browswer:  Chrome only.<br>

	<div style="margin: 0 auto">
	     <canvas id="my_canvas" width="640" height="280" tabindex="2"></canvas>
	</div>

	<form method="POST" action="reflect.php" onsubmit="canvastoimage()">
		<input type="hidden" id="canvasimg" name="canvasimg" />
		<input class="btn btn-default" type="submit" />
	</form>

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JavaScript

...
function canvastoimage()
{
	var canvas = document.getElementById('my_canvas');
	document.getElementById('canvasimg').value = canvas.toDataURL();
}

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PHP

<?php
echo "POST\n";
echo "<pre>" . print_r($_POST, true) . "</pre>";
if (isset($_POST['canvasimg'])) {
  $img = $_POST['canvasimg'];
  $img = str_replace('data:image/png;base64,', '', $img);
  $img = str_replace(' ', '+', $img);
  $data = base64_decode($img);
  file_put_contents('images/canvasimg.png', $data);
  if (exif_imagetype('images/canvasimg.png') != IMAGETYPE_PNG) {
    unlink('images/canvasimg.png');
  }
  else {
    echo '<img src="images/canvasimg.png" />';
  }
}

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Working sample here

Ray Paseur

9/11/2016

This is a very cool idea, but I wonder about the efficacy of an application that doesn't work for the majority of browsers. It might be worth triggering some kind of alternate event to prompt / redirect the client to save the clipboard if a non-Chrome browser encounters the application. I don't know how to do that -- just a thought...
https://upload.wikimedia.org/wikipedia/commons/e/e9/Web-browser_usage_on_Wikimedia.png

golgo

9/11/2016

ASKER

Dear Julian,

I'm blown away by your codes (including the php script) !!
Thank you so much!

...but going hidden inputs would make it a two-step process (requiring two pages)...
I apologize for being greedy while I'm being helped so much, is there any way that we could send the image and the user texts (via <input> tags) at the same time...?

And Ray, thank you for the stats, too! That's a good point, and thank you again, Julian, for adding the filter too!

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Julian Hansen

9/11/2016

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golgo

9/12/2016

ASKER

Sorry Julian,
I must have misunderstood what you meant.

Wow....
Thank you so much for your quick help.
You have no idea how thankful I am to you after having pulled out my hair over this for a week and almost gave up.
Thank you SO MUCH, Julian!

Elpmet

Julian Hansen

9/12/2016

You are most welcome.