Monday, August 4, 2014

Introduction to AngularJS NitinShrivastava

Microsoft Angular JS Introduction Microsoft Virtual Academy
Introduction to AngularJS Jump Start
Recordings on MVA!

Stacey and Christopher (and the rest of us in MVA, MSL and DPE) had such a great
time delivering the Introduction to AngularJS Jump Start on January 21st!  What a
fantastic audience!  We send our thanks to you for investing a valuable day with us!

For those who wish to view the session or couldn’t attend the video recordings are now
posted to MVA  - enjoy!
Recently I started learning AngularJS, it was very difficult for me to find some good detailed articles or beginner tutorials on AngularJS. I have to read from many different articles, books and tutorials. So I decided to put step by step help for beginners like me, so that they get complete required help from one single channel. Since AngularJS is a very rich framework so I decided to write in a series of post that will help beginners who want to learn or work on SPA(Single Page Application) using AngularJS. I am assuming that people reading this article are aware of html and javascript/jquery. So lets start with a short but detailed AngularJS tutorial where you will be able to quickly understand the power of AngularJS in the world of web.


You may have heard people talking about MVC/MVVM/MV*/ MVW (Model View Whatever) or have ever worked with, in some other programming languages. Though MV*/MVW is not a concept specific to AngularJS, but rather an approach to program architecture which is implemented in variety of programming languages and environments. It depends on the architect to architect that how he wants the architecture of the software and AngularJS provides facilty to design application in Model View and Whatever you want to have(lets say mvc,mvvm etc..).  There are bunch of topics to cover which we will be looking into one by one in the later part of tutorial, but still I will try to make you familiar with atleast some of the terminologies that I have used here in this part of tutorial.
So first lets try to understand MV* concept relative to AngularJS.


View in an application actually is a part which is rendered in a browser through which user can interact or see whatever data has been requested. In an AngularJS application view is composed of directives, filters and data-bindings. But to make view simple and maintainable we do not put all of our code into the View. This helps us to separate code from view and also makes it easy to write tests for the business logic.


Controller holds all of our application logic in AngularJS. The Controller controls and prepares the data into the form so that it can be rendered at the View. Functionally what controller actually does is, it collects all of data into the representational form and also takes from view and set into the Model after validating it. The controller is responsible for communicating the server code to fetch the data from a server using Ajax requests and send the data to back-end server from Views.

Model / View Model / $Scope

The most important and head part of the MV* architecture is Model or View Model or $Scope.  $Scope is a term which is introduced in AngularJS and we will discuss more on this in the later part of the article. Model is the bridge standing between Controllers and Views . There can be a controller which we can bind to two or more views. Lets suppose we have a controller assigned for a registration of users, for thispurpose you can have a different view for desktop and another view for mobile.
In reality the Controller is blank about views and has no information about the views and similarly View is independent of logic implemented or data present in the Controller. $scope acts as the communication tunnel between the Views and Controller.
Picture above is actually related to the sample application that we are going to create in the later part of the article. But for now from this picture atleast you can get an idea to MV* pattern.

What Exactly AngularJS Is?

In my terms AngularJS is nothing different to plain HTML but simply an extension to HTML with new attributes. AngularJS is a JavaScript MV* or MVW structured framework for dynamic web applications. It is maintained by Google to allow you to develop well architectured and easily maintainable web-applications. AngularJS makes use of declarative programming for building UI. AngularJS is client-sided so all these things are happening in browsers and you get the elegance of standalone application. 

Why To Use AngularJS?

There are a lot many front-end frameworks available in the web world like BackboneKnockoutEmberSpline etc. and all of them have some pros and cons. But as the tutorial is all about AngularJS so the question arises that What is so peculiar about AngularJS ? So here is the answer to all your question.
With AngularJS you need to write lesser code as it allows you to reuse components. Also, it provides an easy way of two-way bindings and dependency injection (we will discuss more on next part of the tutorials). As AngularJS is client-sided so all these things are happening in browsers, which gives you feel of standalone applications(Desktop application).
Some of the reasons why I would prefer AngularJS or rather I say why AngularJS has become choice for the modern application architectures are described below:
1) You can create a template and reuse it in application multiple times.
2) You can bind data to any element in two ways, where two-way actually means changing data will automatically change element and changing element will change the data.
3) You can directly call the code-behind code in your html.
4) You can validate forms and input fields before submitting it without writing a single line of code.
5) Allows you to control complete dom structure show/hide, changing everything with AngularJS properties.
6) AngularJS allows you to write basic flow end-to-end testing, unit-testing, ui mocks.
In short, AngularJS provides all the features you need to build a CRUD application like data-binding, data validation, url routing, reusable HTML components and most importantly dependency injection.
<contined at link at top> 

Friday, June 20, 2014

Advanced C# Concepts - Nullable Types ?

Advanced C# Concepts - Nullable Types ?

From MS documentation:

Nullable Types (C# Programming Guide)

Visual Studio 2013
Nullable types are instances of the System.Nullable<T> struct. A nullable type can represent the correct range of values for its underlying value type, plus an additional null value. For example, a Nullable<Int32>, pronounced "Nullable of Int32," can be assigned any value from -2147483648 to 2147483647, or it can be assigned the nullvalue. A Nullable<bool> can be assigned the values true false, or null. The ability to assign null to numeric and Boolean types is especially useful when you are dealing with databases and other data types that contain elements that may not be assigned a value. For example, a Boolean field in a database can store the values true or false, or it may be undefined.
class NullableExample
    static void Main()
        int? num = null;

        // Is the HasValue property true? 
        if (num.HasValue)
            System.Console.WriteLine("num = " + num.Value);
            System.Console.WriteLine("num = Null");

        // y is set to zero 
        int y = num.GetValueOrDefault();

        // num.Value throws an InvalidOperationException if num.HasValue is false 
            y = num.Value;
        catch (System.InvalidOperationException e)
The example will display the output:
num = Null
Nullable object must have a value.

Nullable Types Overview

Nullable types have the following characteristics:
  • Nullable types represent value-type variables that can be assigned the value of null. You cannot create a nullable type based on a reference type. (Reference types already support the null value.)
  • The syntax T? is shorthand for Nullable<T>, where T is a value type. The two forms are interchangeable.
  • Assign a value to a nullable type just as you would for an ordinary value type, for example int? x = 10;or double? d = 4.108. A nullable type can also be assigned the value null: int? x = null.
  • Use the Nullable<T>.GetValueOrDefault method to return either the assigned value, or the default value for the underlying type if the value is null, for example int j = x.GetValueOrDefault();
  • Use the HasValue and Value read-only properties to test for null and retrieve the value, as shown in the following example: if(x.HasValue) j = x.Value;
    • The HasValue property returns true if the variable contains a value, or false if it is null.
    • The Value property returns a value if one is assigned. Otherwise, aSystem.InvalidOperationException is thrown.
    • The default value for HasValue is false. The Value property has no default value.
    • You can also use the == and != operators with a nullable type, as shown in the following example:if (x != null) y = x;
  • Use the ?? operator to assign a default value that will be applied when a nullable type whose current value is null is assigned to a non-nullable type, for example int? x = null; int y = x ?? -1;
  • Nested nullable types are not allowed. The following line will not compile: Nullable<Nullable<int>> n;

Thursday, May 29, 2014

CodeProject: Flappy Bird in 100 lines of Jquery Javascript

shared from open source:
CodeProject: Flappy Bird in 100 lines of Jquery Javascript

Build Flappy Bird with jQuery and 100 lines of Javascript

By 29 May 2014


Build Flappy Bird with jQuery and 100 lines of Javascript
Play online at Gasp Mobile Games


So Flappy bird became a big news: the developer walked away from $50,000 a day. I downloaded a game and played it - it did look simplistic and silly. I put it aside. Then my friends brough up the same topic and jokingly asked "you can probably build it in a couple of days. $50,000 in a couple of days - not a bad business." I though I should, but then I was busy at work. Some other things came up, and finally when the Apple started to reject Flappy Bird clones because there were soo many, I thought - "I got to get me some of this. With the right timing and a little bit of luck - those $50,000/day can be mine."
The version I'm presenting here took me a whooping 2 hours to build and under a 100 lines of my javascript.

For those who don't know the game - get out of your caves. You tap on the bird to give it some initial up speed. Then it start falling (under gravity). You need to keep it in the air and avoid the obstacles it can run into. To simplify the objective, the bird is only moves up and down, perception of horisontal motion is acheived by scrolling background. This is it - get it done and $50,000 a day is yours.


The game needs only 5 images : the bird, background grass, background sky, obstacles and instuction tap-to-start.
As you can see, to save myself some headace I'm skimping out on frame animation by using an animated gif file. This way browser can use it much more efficiently. Also it's something that prevented me from publishing it on Windows Phone - since browser control there doesn't support animated GIF files.

The base html is also pretty simple:
        <div id='board' style='position:absolute; left:50px; top:50px; width:478px; 
                height:300px; overflow:hidden;'>
            <div id='score' style='position:absolute; left:400px; top:0px; height:25px; 
                    z-index:5; color:red; font-weight:900'></div>
            <img class="c" id='bird' src="b2.gif" style="z-index:5"/>
            <img id='instr' src='instr.png' class='c' style="left:205px; top:75px; 
                    z-index:100" />
            <div class="bg" id='bGrnd' style="top:-20px; height:320px; 
                    background-image:url(bg1.png) "/>
            <div class="bg" id='fGrnd' style="top:235px; height:85px; z-index:4; 
                    background-image:url(bg2.png) "/>
I also include latest jQuery from

Global variables and Initialization

The game uses following global variables:
birdjQuery object to hold our bird
boardjQuery object to hold the board - container object
dimPipeObstacle dimentions
cPosCurrent bird position (only Y coordinate can change)
gravityConfigurable gravity constant - how fast the bird falls
iniSpeedConfigurable initial speed
curSpeedCurrent vertical bird's speed
scoreCurrent Score
noClrnumber of obstacles cleared
tmStepStep timer to position a bird and launch obstacles
stateGame state : 0 - not started; 1 - in play; 2 - game over
The game is initialized in 2 steps: usual jQuery $.ready and reusable start() that we can call every time the game is restarted:
    $(document).ready(function() {
        bird = $('#bird');
        var evt = (typeof(bird[0].ontouchend) == "function") 
                ? "touchstart" : "mousedown";
        board = $('#board').bind(evt, onTap);
    function start() {
        state = noClr = score = 0;                    // not started
        cPos = { x: 80, y:100, h:40, w:50 };
        bird.css({left:cPos.x, top:cPos.y, width:cPos.w, height:cPos.h, rotate:0});
As you can see in $.ready we are initializing bird and board global variables, attaching tap event handler to the board and calling start() function. One word about tap: on Android devices mouseDown event comes quite a bit after the actual tap happens, so in the code above, we are checking if element has onTouchEnd element and using that as an indication of the touch support.
In the start() function I'm resetting all the variables, removing any obstacles still on the board and showing instructions image prompting to tap/click.

Click/Tap handling

So the game is ready to go. The missing part is what happen when you click on the board. The game at this point starts main timer (BirdStep) (if needed) and sets bird's initial up speed:
    function onTap() {
        if (state > 1) return;
        if (state == 0) {
            state = 1;
            tmStep = window.setInterval(BirdStep, 30);
        curSpeed = iniSpeed;
Thing to consider is that the program uses 3 states -
  • 0 - not running
  • 1 - play mode
  • 2 - die mode - no input is accepted.
So here we are checking - if we are in die mode - just get out. If we are not playing, then go into play mode - change state, hide intro image and start timer. Aside from that we want to give our bird initial up speed.

The main logic however is done in the BirdStep timer function:
    function BirdStep() {
        // update bird position
        curSpeed += gravity;                                
        cPos.y = Math.max(cPos.y + curSpeed, 0);
        var mh = board.height()-cPos.h, m = -12, lo = 0, actPipe = $('.obs');
        bird.css({top: cPos.y});
        // check if we hit the floor or other obstacles
        if (cPos.y > mh)
            return gameOver();
        for (var i = actPipe.length-1; i >= 0; i--) {
            var s = actPipe[i].style, x = parseInt(s.left), y = parseInt(;
            lo = Math.max(lo, x);
            if (x+dimPipe.width +m < cPos.x || x > cPos.x+cPos.w+m)    continue;
            if (y+dimPipe.height+m < cPos.y || y > cPos.y+cPos.h+m) continue;
            return gameOver();
        // check if can launch more obstacles
        if (actPipe.length > 3 || lo > 300 || Math.random() >= 0.05 * (1+noClr))
        var og = cPos.h * 2;
        var oh = og + Math.floor(Math.random() * (mh-og+1));
        var obs = $("<img /><img />").addClass('c obs').css({left:480, zIndex:3}).css(dimPipe).attr('src', 'vine.png')
            .appendTo(board).animate({left:-50}, 3000, 'linear', function() { 
                $('#score').text(' Score: ' + (score += 1 + Math.floor(++noClr/10)));
        obs[0] = oh + 'px';
        obs[1] = (oh - og - dimPipe.height) + "px";
As you can see this function tries to do 3 major things:

Update bird position

Every time the BirdStep timer executed, the current bird speed get's increased by gravity and added to current bird Y position. Also at this point I'm checking to make sure bird doesn't fly above ceiling (negative Y).

Hit Testing

Here we are testing if bird didn't fall too low (Y exceeds board height) or we hitting any obstacles - loop that checks if bird's position (stored in cPos and reduced by some fudge margin - m = 12px) intersects with any of the obstacles - any objects with class of .obs. If so then the game is lost - we can just get out.

Launch new obstacles

First thing we check if new obstacles can be launched:
  • Less then 4 obstacles already on thescreen
  • Last obstacles travel some distance
  • add some random factor
If conditions are satisfied, we can launch 2 more obstacles, one on top of the other, with the gap of 2 bird sizes between randomly positioned along Y coordinate, right after right edge of the board (left = 480px).
After they are created they are animated to move off the left edge of the screen (left = -50px), at which point the score is increased and obstacles are removed. To do the animation we are using plain and simple jQuery linear animation.

Bells and wistles: parallax scrolling effect

That's pretty much a game. But so far it looks too plain. To add some umpf lets add parallax scrolling effect. Actually we are adding 2 parallax layers - the sky and the grass. We are also need to add a depth perception - in this implementation - the sky will just move slower then the grass - it should suffice. To create a parallax layer, I will create a very wide div element (16,000px) with background-repeat: repeat-x; and set desired image as a background. The browser will horisontally replicate the image. The only thing I need to do is just to add animation - set left position of the div using very handy jQuery animate:
    function Parallax(elm, tmo) {
        elm.css('left', 0).animate({left:-15360}, {
                duration:tmo*1000, easing:'linear', 
                complete : function() { Parallax(elm, tmo); } 
    function onTap() {
        if (state == 0) {
            Parallax($('#bGrnd'), 240);
            Parallax($('#fGrnd'), 80);
As you can see the code is surprisingly simple : the left position of the div is set to 0px and then linearly animated to -15,360px (the largest common denominator less then 16,000 of all the background images width - just so I don't have to add extra parameter to the function) after which the whole process repeats. The supplied argument is a time to animate - the foreground (grass) supposed to scroll for 80 seconds and background (sky) - 240 sec - 3 times slower.

Bells and wistles: rotation

Aside from parallax, it would be nice to rotate the bird - tilt it up when it flies up, and down when it falls. Also when the game is over, to show bird roll over. To do that i created simple jquery css hook. Please check jQuery documentation on detail about CSS Hooks.
    $.cssNumber.rotate = true;
    $.cssHooks.rotate = {
        set : function(el, v) {
                if (typeof v === 'string') 
                v = (v.indexOf("rad") != -1) ? parseInt(v) * 180 / Math.PI : parseInt(v);
            v = (~~v);
            if (v == ($.data(el, 'rotate') || 0)) return;
  ["MozTransform"] =["MozTransform"] =["-webkit-transform"]
                =["transform"] = " rotate(" + (v % 360) + "deg)"; 
            $.data(el, 'rotate', v);
        get : function(el, computed) {
            return $.data(el, 'rotate') || 0;
As you can see over here we are storing current rotation value in $.data("rotate") and setting element's browser specific CSS attributes to set current rotation.
To use newly acquired capability let's change our BirdStep function to rotate a bird with the angle of 5 times the speed. If bird flies up and speed negative, the bird tilts up, if bird is falling and speed is positive, the bird tilts down. On top of that we want to limit the tilt between -20 and 90 degrees - completely arbitrary:
        function BirdStep() {
            var ang = curSpeed * 5;
            bird.css({top: cPos.y, rotate:(ang < -20) ? -20 : (ang > 90) ? 90 : ang});
Also we can introduce a nice animation when the bird dies - it will fall to the ground and rotate 540 degrees for one second and then wait for another half a second :
        function gameOver() {
            state = 2;
            if (tmStep) tmStep = window.clearInterval(tmStep);
            bird.animate({ top:board.height()-cPos.h, rotate:540}, 1000)
                .animate({ top:board.height()-cPos.h}, 500, function() {
                    $('#score').text(' Score: ' + score);
Beside that as you can see we are setting our game state to the 'die' mode so we don't check for any clicks while we are showing the animation, stop all the animations (think parallax scrolling and moving obstacles), stop the bird timer. After that we can play 'die sequence' and once done move back to the start screen.

Points of Interest

Just as I mentioned in the begining this was an initial version of the game that took me 2 hours to put together. Added a PhoneGap, threw onto the Galaxy and got completely bummed out: while working just fine on the slowest laptop, it would completely choke even on the best smart phone, so I had to spend next 2 days trying to improve performance - caching jQuery obstacles objects, accounting for time between timer executions not being as requested, ... Even with all those improvements, depending on the model of your smartphone performance may be somewhat disappointing - check it for yourself at:
As far as $50,000/day - that didn't quite materialize - in a last 3 month on the market I made a cool $20 off that game - or about $1/hr for the time I spend. Once again I attribute my success to the perfect timing and a little bit of luck. Good thing I already had Google developer account (one time $25), Apple Developer account ($99/year), Microsoft Store ($99/year) and Web Publishing ($49/year) - otherwise it could of been really expensive excersize. But since I already paid for those - it's a $20 I didn't have before - the glass is half full!



This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

United States United States
Writing code since 1987 using whatever language/environment you can imagine. Recently got into the mobile games. Feel free to check them out at

Wednesday, May 28, 2014

Next ASP.Net Uses Mono and Xamarin to Run On Linux, Apple OsX iOs and Android

Next ASP.Net Uses Mono and Xamarin to Run On Linux, Apple OsX iOs and Android


Microsoft delivered a preview of the next version of its ASP.NET Web development framework at its TechEd 2014 conference, and now that software is able to run on OS X and Linux. Graeme Christie, a .NET developer, wrote a blog post on how he has enabled Microsoft's open-source, cross-platform ASP.NET vNext to run on OS X and Linux - See more at:

Last November, Microsoft announced a partnership with Xamarin to enable C# and Visual Studio developers to target additional mobile devices, including iOS and Android. Visual Studio and .NET provide developer productivity for application developers targeting the Windows family of devices. With Xamarin, developers can take this productivity to iOS and Android as well. Xamarin is working closely with Microsoft on the newly formed .NET Foundation. Xamarin's co-founder and chief technical officer, Miguel de Icaza, is the founder of the Mono project and also sits on the board of the .NET Foundation. "ASP.NET vNext is an evolution of ASP.NET. Everything you know today about ASP.NET will apply to ASP.NET vNext," - See more at: