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orientation.html
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orientation.html
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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, minimum-scale=1.0, initial-scale=1"/>
<title>Exifr orientation example</title>
<link rel="stylesheet" type="text/css" href="../homepage/app.css">
<style>
table {
border-spacing: 8px;
border-collapse: separate;
}
table,
table tr,
table td {
text-align: center;
vertical-align: middle;
white-space: pre-wrap;
margin: 0 !important;
padding: 0 !important;
}
table tr td:first-child {
min-width: 140px;
max-width: 160px;
}
.name {
font-size: 14px;
margin: 2px 0;
font-weight: 700;
}
.subtitle {
font-size: 11px;
margin: 2px 0;
font-style: italic;
opacity: 0.6;
}
.code {
font-size: 10px;
}
</style>
</head>
<body>
<p><strong>Warning:</strong> Some modern browsers automatically rotate images based on their exif. They're changing default value of the css property <code>image-orientation</code> from <code>'none'</code> to <code>'from-image'</code> on <code><img></code> elements and <code>background-image</code>. However they can also pass rotated photo to <code><canvas></code> through <code>ctx.drawImage()</code>. Though this behavior is quirky and differs from browser to browser, especially in Safari on iOs 13.4 and newer.</p>
<p>Use <code>exifr.rotation()</code> if you want to manipulate the image and avoid afore mentioned problems.</p>
<p>If <code>canvas</code> property is <code>true</code>, you need to rotate the image yourself in <code><canvas></code> using <code>ctx.rotate(...)</code>.</p>
<p>If <code>css</code> property is <code>true</code>, you need to rotate the image yourself with CSS using <code>transform:rotate(...)</code>.</p>
<table></table>
<script src="../dist/mini.umd.js"></script>
<script>
let table = document.querySelector('table')
function createElement(name) {
return document.createElement(name)
}
function createRow(name, subtitle, array) {
let tr = createElement('tr')
let head = createElement('td')
head.innerHTML = `<p class="name">${name}</p>`
if (subtitle) head.innerHTML += `<p class="subtitle">${subtitle}</p>`
tr.append(head)
for (let item of array) {
let td = createElement('td')
td.append(item)
tr.append(td)
}
table.append(tr)
}
function createImg(url) {
let img = createElement('img')
img.src = url
return img
}
let urls = [
'../test/fixtures/orientation/f1t.jpg',
'../test/fixtures/orientation/f2t.jpg',
'../test/fixtures/orientation/f3t.jpg',
'../test/fixtures/orientation/f4t.jpg',
'../test/fixtures/orientation/f5t.jpg',
'../test/fixtures/orientation/f6t.jpg',
'../test/fixtures/orientation/f7t.jpg',
'../test/fixtures/orientation/f8t.jpg',
]
let rawTransforms = [
{deg: 0, scaleX: 1, scaleY: 1},
{deg: 0, scaleX: -1, scaleY: 1},
{deg: 0, scaleX: -1, scaleY: -1},
{deg: 0, scaleX: 1, scaleY: -1},
{deg: 90, scaleX: 1, scaleY: -1},
{deg: 90, scaleX: -1, scaleY: -1},
{deg: 90, scaleX: -1, scaleY: 1},
{deg: 90, scaleX: 1, scaleY: 1},
]
;(async function() {
let orientationsPromises = urls.map(exifr.orientation)
let rotationsPromises = urls.map(exifr.rotation)
let orientations = await Promise.all(orientationsPromises)
let rotations = await Promise.all(rotationsPromises)
let images = urls.map(createImg)
await Promise.all(images.map(img => new Promise(resolve => img.onload = resolve)))
let raw = rawTransforms.map(rot => createRaw(urls[0], rot))
let rotated1 = images.map((img, i) => createRotatedCanvas(img, rotations[i]))
let rotated2 = urls.map((url, i) => createRotatedImg(url, rotations[i]))
createRow('orientation', 'standardized EXIF number', orientations)
createRow('raw image', 'The way it looks in basic photo viewers or old browsers.', raw)
createRow('unmodified <img>', 'The way browser renders it. May be autorotated in modern browsers.', images)
createRow('rotated <canvas>', 'Using <code>ctx.rotate()</code> with <code>ctx.drawImage()</code> if <code>rotation.canvas===true</code>', rotated1)
createRow('rotated with css', 'Using property <code>transform:rotate()</code> if <code>rotation.css===true</code>', rotated2)
createRow('exifr.rotation()', 'Output of exifr describing if and how rotation should be handled depending on current browser.', rotations.map(rot => {
rot = JSON.parse(JSON.stringify(rot))
rot.rad = Number(rot.rad.toFixed(3))
let json = Object.entries(rot).map(([key, val]) => `${key}: ${val}`).join('\n')
let div = document.createElement('div')
div.style.textAlign = 'left'
div.style.whiteSpace = 'pre-wrap'
div.style.fontSize = '10px'
div.innerHTML = json
return div
}))
})();
function createRaw(url, rot) {
let img = createImg(url)
img.style.transform = `rotate(${rot.deg}deg) scale(${rot.scaleX}, ${rot.scaleY})`
return img
}
function createRotatedCanvas(img, rot) {
let w = img.width
let h = img.height
// only swap width and height if the image is rotated 90 or 270 degrees
// and if the browser doesn't do autorotation already
if (rot.canvas && rot.dimensionSwapped) {
w = img.height
h = img.width
}
let canvas = document.createElement('canvas')
canvas.width = w
canvas.height = h
let ctx = canvas.getContext('2d')
// only rotate the image using canvas if browser doesn't do autorotation already
if (rot.canvas) {
ctx.translate(w / 2, h / 2)
ctx.rotate(rot.rad)
ctx.scale(rot.scaleX, rot.scaleY)
ctx.drawImage(img, -img.width / 2, -img.height / 2, img.width, img.height)
} else {
ctx.drawImage(img, 0, 0)
}
return canvas
}
function createRotatedImg(url, rot) {
let img = createImg(url)
// only rotate the image using css if browser doesn't do autorotation already
if (rot.css) img.style.transform = `rotate(${rot.deg}deg) scale(${rot.scaleX}, ${rot.scaleY})`
return img
}
</script>
</body>
</html>