Utilize images inputted via an HTML DOM file uploader within p5.js

Question

Utilize images inputted via an HTML DOM file uploader within p5.js

I'm facing a challenge with allowing users to upload their image file through a DOM file uploader (

<input type="file"></input>

). Once the image is uploaded, I'm unsure of how to transfer it to JavaScript and process it using p5.js. How can I convert an HTML file to a p5.js file or an array of pixels that I can manipulate in JavaScript?

Initially, I set restrictions on the element to only accept .png and .jpg files.

I attempted to use the .file[0] syntax and load the image by its path using the .value within the loadImage() function.

Unfortunately, neither method worked for me, and I'm feeling lost about what steps to take next.

<div id="uploadMenu">
  <h4>Please select your image file:</h4>
  <input accept=".png, .jpg, .jpeg" type="file" id="imageUpload">
  <button onclick="fileToGrid()">Done</button>
  <script>
  </script>
  <script>
  let thisWindow = document.getElementById("uploadMenu");
  let windowWidth = thisWindow.style.width;
  console.log(windowWidth);
  thisWindow.style.left = `${innerWidth/2 - 100}px`
  thisWindow.style.top = `${innerHeight/2 - 50}px`
  </script>
</div>

function fileToGrid() {
  let uploadFromHTML = document.getElementById("imageUpload");
  let uploadedImage = loadImage(uploadFromHTML.value);
  let imageW = uploadedImage.width;
  let imageH = uploadedImage.height;
  console.log(imageW, imageH); 
// My ultimate goal is to convert this image into an array of pixel values.
}

javascript html css p5.js

Answer 1

Answer №1

It's been a little while since I originally posted this, but I finally figured it out.

First, we need to locate the upload element in the DOM. In my example, the id was simply "upload".

const selectedFile = document.getElementById('upload');

Next, we retrieve the uploaded file.

const myImageFile = selectedFile.files[0];

We can then generate a URL for the image using the following code.

let urlOfImageFile = URL.createObjectURL(myImageFile);

If you're working with p5.js, you can use the following code snippet to create a p5.Image object.

let imageObject = loadImage(urlOfImageFile);

I suggest setting up a callback function when working with images, as they may not load instantaneously. The complete process looks like this:

const selectedFile = document.getElementById('upload');
const myImageFile = selectedFile.files[0];
let urlOfImageFile = URL.createObjectURL(myImageFile);
let imageObject = loadImage(urlOfImageFile, () => {image(imageObject, 0, 0)});

Alternatively, you can also use the same URL as the src attribute for an image element in the DOM.

Answer 2

It's been a little while since I originally posted this, but I finally figured it out.

First, we need to locate the upload element in the DOM. In my example, the id was simply "upload".

const selectedFile = document.getElementById('upload');

Next, we retrieve the uploaded file.

const myImageFile = selectedFile.files[0];

We can then generate a URL for the image using the following code.

let urlOfImageFile = URL.createObjectURL(myImageFile);

If you're working with p5.js, you can use the following code snippet to create a p5.Image object.

let imageObject = loadImage(urlOfImageFile);

I suggest setting up a callback function when working with images, as they may not load instantaneously. The complete process looks like this:

const selectedFile = document.getElementById('upload');
const myImageFile = selectedFile.files[0];
let urlOfImageFile = URL.createObjectURL(myImageFile);
let imageObject = loadImage(urlOfImageFile, () => {image(imageObject, 0, 0)});

Alternatively, you can also use the same URL as the src attribute for an image element in the DOM.

Answer 3

Answer №2

Take a look at the createFileInput() function. You can find more information about it here.

Here's an example from the page:

let img;

function setup() {
  input = createFileInput(handleFile);
  input.position(0, 0);
}

function draw() {
  background(255);
  if (img) {
    image(img, 0, 0, width, height);
  }
}

function handleFile(file) {
  print(file);
  if (file.type === 'image') {
    img = createImg(file.data);
    img.hide();
  } else {
    img = null;
  }
}

This demonstration illustrates how to implement a file input in P5.js and extract an image from it.

You might be able to achieve similar results with an existing file input in the DOM.

Answer 4

Take a look at the createFileInput() function. You can find more information about it here.

Here's an example from the page:

let img;

function setup() {
  input = createFileInput(handleFile);
  input.position(0, 0);
}

function draw() {
  background(255);
  if (img) {
    image(img, 0, 0, width, height);
  }
}

function handleFile(file) {
  print(file);
  if (file.type === 'image') {
    img = createImg(file.data);
    img.hide();
  } else {
    img = null;
  }
}

This demonstration illustrates how to implement a file input in P5.js and extract an image from it.

You might be able to achieve similar results with an existing file input in the DOM.

Utilize images inputted via an HTML DOM file uploader within p5.js

Answer №1

Answer №2

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