Lightning Component for attaching files using input file component

A rough markup of this component using input type file component. Please refer the previous article to get an idea of how the helper JS and the apex class is formed.

<div class="slds-form-element">
    <span class="slds-form-element__label" id="file-selector-id">Attachment</span>
    <div class="slds-form-element__control">
        <div class="slds-file-selector slds-file-selector_files">
            <div class="slds-file-selector__dropzone">
                <input type="file" class="slds-file-selector__input slds-assistive-text" accept="image/png" id="file-upload-input-01" aria-describedby="file-selector-id" aura:id="file" onchange="{!c.showfile}"/>
                <label class="slds-file-selector__body" for="file-upload-input-01">
                    <span class="slds-file-selector__button slds-button slds-button_neutral">
                        <c:svgIcon class="slds-button__icon slds-button__icon_left" xlinkHref="/resource/slds232/assets/icons/utility-sprite/svg/symbols.svg#upload" />
                        Upload Files
                    </span>
                    <span class="slds-file-selector__text slds-medium-show">or Drop Files</span>
                </label>
            </div>
        </div>
    </div>
</div>

showfile:function(component,event,helper){
    helper.show(component,event);
    
    var f = event.target.files[0]; 
    var fileInput = component.find("file").getElement();
    var file = fileInput.files[0];
    
    var reader = new FileReader();
    reader.onloadend = function(e) {
        var contents = e.target.result;
        var base64Mark = 'base64,';
        var dataStart = contents.indexOf(base64Mark) + base64Mark.length;
        var fileContents = contents.substring(dataStart);
        
        helper.upload(component, file, encodeURIComponent(fileContents), function(answer) {
            if (answer) {
                helper.hide(component,event);
            }
            else{
            }
        });
    }
    reader.readAsDataURL(file);
}