<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="description" content="">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title></title>
<script>
function getOrientation(file, callback) {
var reader = new FileReader();
reader.onload = function(e) {
var view = new DataView(e.target.result);
if (view.getUint16(0, false) != 0xFFD8)
{
return callback(-2);
}
var length = view.byteLength, offset = 2;
while (offset < length)
{
if (view.getUint16(offset+2, false) <= 8) return callback(-1);
var marker = view.getUint16(offset, false);
offset += 2;
if (marker == 0xFFE1)
{
if (view.getUint32(offset += 2, false) != 0x45786966)
{
return callback(-1);
}
var little = view.getUint16(offset += 6, false) == 0x4949;
offset += view.getUint32(offset + 4, little);
var tags = view.getUint16(offset, little);
offset += 2;
for (var i = 0; i < tags; i++)
{
if (view.getUint16(offset + (i * 12), little) == 0x0112)
{
return callback(view.getUint16(offset + (i * 12) + 8, little));
}
}
}
else if ((marker & 0xFF00) != 0xFF00)
{
break;
}
else
{
offset += view.getUint16(offset, false);
}
}
return callback(-1);
};
reader.readAsArrayBuffer(file);
}
window.onload = function(){
var input = document.getElementById('input');
input.onchange = function(e) {
getOrientation(input.files[0], function(orientation) {
alert('orientation: ' + orientation);
});
}
};
</script>
</head>
<body>
<input id='input' type='file' />
</body>
</html>
