How should I read an image as a byte array?

Question

I'm trying to read an image as a byte array through a openAsync()

 

pageData.photofile.openAsync(Windows.Storage.FileAccessMode.read).then(function (stream) {

                var inputStream = stream.getInputStreamAt(0);

                var reader = new Windows.Storage.Streams.DataReader(inputStream);

                var size = stream.size;

                if (size > 0) {

                    reader.loadAsync(size).then(function () {

                        var fileContent = new Array(size);

                        reader.readBuffer(fileContent); //.readString(size);



                        displayDebugMessage(fileContent.toString());

 

I overrided toString method of Array:

 

Array.prototype.toString = function () {

        var retStr = "[";

        for (var x in this) {

            if (isNaN(x)) {

                val = (typeof(this[x]) == 'string') ? "'" + this[x] + "'" : this[x];

                retStr += x + ":" + val + ", ";

            } else {

                val = (typeof(this[x]) == 'string') ? "'" + this[x] + "'" : this[x];

                retStr += val + ", ";

            }

        }

        return retStr + "]";

    }

But it returned nothing. It looks like I have made some mistakes in reading the byte array. How should I do?

Answer 1

In addition, when I seen the fileContent variable in Watch window, the "fileContent.length" is correctly set and when I put "fileContent[0]", it shows "undefined".

Answer 2

Hi Sungsoo,

 

Try something like this:

var reader = new Windows.Storage.Streams.DataReader(inputStream);
reader.loadAsync(size).then(
function (readsize) {
var array = new Array(readsize);
reader.readBytes(array);

 

-Jeff

---

Jeff Sanders (MSFT)

Answer 3

Thanks Jeff!

The method is the answer :)