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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>For Akkartik & Konrad</title>
<style>
body {
font-family: Arial, sans-serif;
max-width: 800px;
margin: 0 auto;
padding: 20px;
background-color: beige;
}
#imagePreview {
max-width: 100%;
margin: 20px 0;
}
.controls {
margin: 20px 0;
}
button {
padding: 10px 20px;
margin: 5px;
}
button:hover {
cursor: pointer;
}
</style>
</head>
<body>
<h1>For Akkartik & Konrad</h1>
<p>A demo of how to edit a file in place using the <a href="https://developer.mozilla.org/en-US/docs/Web/API/File_System_Access_API">File System Access API</a>.</p>
<p>At a quick glance, it doesn't seem to be available in Firefox or WebKit, just Chromium browsers.</p>
<div class="controls">
<button id="selectFile">Select a png</button>
<button id="saveChanges" disabled>Save changes</button>
<input type="file" id="fileInput" accept=".png" style="display: none;">
</div>
<img id="imagePreview" alt="Preview">
<div class="controls">
<button id="invertColors" disabled>Invert colors</button>
<button id="grayscale" disabled>Convert to greyscale</button>
</div>
<script>
// Store the file handle for later
let fileHandle = null;
let currentImageData = null;
// Get DOM elements
const selectButton = document.getElementById('selectFile');
const saveButton = document.getElementById('saveChanges');
const invertButton = document.getElementById('invertColors');
const grayscaleButton = document.getElementById('grayscale');
const imagePreview = document.getElementById('imagePreview');
selectButton.addEventListener('click', async () => {
try {
if ('showOpenFilePicker' in window) {
// Modern File System Access API approach for browsers that support it
// This will open a file picker and return a file handle
fileHandle = await window.showOpenFilePicker({
types: [{
description: 'PNG Files',
accept: {
'image/png': ['.png']
}
}]
});
// Get the file object from the handle
const file = await fileHandle[0].getFile();
handleSelectedFile(file);
} else {
// Fallback for browsers that don't support the API
document.getElementById('fileInput').click();
}
} catch (err) {
console.error('Error selecting file:', err);
}
});
// Event listener for the fallback file input
document.getElementById('fileInput').addEventListener('change', async (e) => {
const file = e.target.files[0];
if (file) {
handleSelectedFile(file);
// When in fallback mode, we download a new file, rather than saving in place
saveButton.textContent = 'Download edited image';
}
});
async function handleSelectedFile(file) {
// Create a URL for the image preview
const imageUrl = URL.createObjectURL(file);
imagePreview.src = imageUrl;
// Load the image data into a canvas for editing
await loadImageData(file);
// Enable the editing buttons
invertButton.disabled = false;
grayscaleButton.disabled = false;
saveButton.disabled = false;
}
// Load image data into canvas
async function loadImageData(file) {
return new Promise((resolve) => {
const img = new Image();
img.onload = () => {
const canvas = document.createElement('canvas');
canvas.width = img.width;
canvas.height = img.height;
const ctx = canvas.getContext('2d');
ctx.drawImage(img, 0, 0);
currentImageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
resolve();
};
img.src = URL.createObjectURL(file);
});
}
// Invert colors
invertButton.addEventListener('click', () => {
const data = currentImageData.data;
for (let i = 0; i < data.length; i += 4) {
data[i] = 255 - data[i]; // Red
data[i + 1] = 255 - data[i + 1]; // Green
data[i + 2] = 255 - data[i + 2]; // Blue
}
updatePreview();
});
// Convert to grayscale
grayscaleButton.addEventListener('click', () => {
const data = currentImageData.data;
for (let i = 0; i < data.length; i += 4) {
const avg = (data[i] + data[i + 1] + data[i + 2]) / 3;
data[i] = avg;
data[i + 1] = avg;
data[i + 2] = avg;
}
updatePreview();
});
function updatePreview() {
const canvas = document.createElement('canvas');
canvas.width = currentImageData.width;
canvas.height = currentImageData.height;
const ctx = canvas.getContext('2d');
ctx.putImageData(currentImageData, 0, 0);
imagePreview.src = canvas.toDataURL('image/png');
}
saveButton.addEventListener('click', async () => {
try {
if (fileHandle) {
// Using the File System Access API
const writable = await fileHandle[0].createWritable();
const blob = await getImageBlob();
await writable.write(blob);
await writable.close();
alert('Changes saved successfully!');
} else {
// Download the edited image as a new file, if the API is not supported
const blob = await getImageBlob();
const downloadUrl = URL.createObjectURL(blob);
const a = document.createElement('a');
a.href = downloadUrl;
a.download = 'edited-image.png';
document.body.appendChild(a);
a.click();
document.body.removeChild(a);
URL.revokeObjectURL(downloadUrl);
}
} catch (err) {
console.error('Error saving the file:', err);
}
});
async function getImageBlob() {
const canvas = document.createElement('canvas');
canvas.width = currentImageData.width;
canvas.height = currentImageData.height;
const ctx = canvas.getContext('2d');
ctx.putImageData(currentImageData, 0, 0);
return new Promise(resolve => {
canvas.toBlob(resolve, 'image/png');
});
}
</script>
</body>
</html>
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