resize.js

function OnClientFileSelected(sender, args) {
    
    var fileInput = sender;
    //get the file from the input field
    var file = args.get_fileInputField().files[0];
    var imageType = /image.*/;
    //stop the image from uploading to the temp storage on the server
    if (file.type === 'image/jpeg') {
        sender.pauseUpload();
        $('.ruUploadProgress').addClass('ruUploadSuccess');
        $('.ruFileProgressWrap').css('display', 'none');
    }
        
    if (file.type.match(imageType)) {
        var reader = new FileReader();

        reader.onload = function (e) {
            
            var img = new Image();
            img.src = reader.result;
            img.onload = function () {
                var MAX_HEIGHT = 800;
                var MAX_WIDTH = 600;

                var width = img.width;
                var height = img.height;

                if (width > height) {
                    if (width > MAX_WIDTH) {
                        height *= MAX_WIDTH / width;
                        width = MAX_WIDTH;
                    }
                } else {
                    if (height > MAX_HEIGHT) {
                        width *= MAX_HEIGHT / height;
                        height = MAX_HEIGHT;
                    }
                }

                var canvas = document.createElement('canvas');
                canvas.width = width;
                canvas.height = height;

                var ctx = canvas.getContext("2d");
                ctx.drawImage(img, 0, 0, width, height);
                var mpImg = new MegaPixImage(img);

                getImageOrientation(file, function (imgOrientation) {
                    mpImg.render(canvas, { width: width, height: height, orientation: imgOrientation });
                    var dataurl = canvas.toDataURL("image/jpeg");
                    $('#MainContent_hiddenFile').val(dataurl);
                });
            }
        }
        reader.readAsDataURL(file);
    } 
}
function getImageOrientation(file, callBack) {
    EXIF.getData(file, function () {
        return callBack(EXIF.getAllTags(file).Orientation);
    });
}