Create a Mobile App Using Famo.us and Angular

Admin 2016-05-03 19:40:50

I love high-performance JavaScript, and I love sharing what I believe is its true potential. In this tutorial, I want to focus on Famo.us, which can allow you to maintain a silky-smooth 60 frames per second while having fluid animations on screen. 

Famo.us does this by utilizing the CSS3 primitive -webkit-transform: matrix3d, which lets the framework compute the composite matrix and skip the browser’s renderer. No plug-in, no download, no hack. By appending this to each DIV, developers can render the composite matrix and go straight to the GPU.

I go more in-depth when discussing the ins and outs of Famo.us in this blogpost. Thanks to Zack Brown for all of his assistance with this! Let’s get started.

By the end of this project you will be able to:

  • understand how Angular works within the context of a Famo.us application
  • harness the true power of JavaScript and the good parts of HTML5
  • create smooth animations

My goal for this project is to illustrate how easily you can create HTML5 and JavaScript projects that work at near-native speeds on mobile applications.

Features

  • The mobile application runs on iOS and Android via Cordova.
  • The Windows 10 universal app runs natively on, well, Windows 10.
  • This project can also be run as a hosted website, although I have it scaled which is best for mobile devices.

Requirements

  • PC or Mac
  • Web server
  • Cross-platform test matrix (like a BrowserStack, IDE, or free virtual machines for EdgeHTML, the rendering engine for Microsoft Edge and hosted web app content on Windows 10)

Setup

  1. Download the source from GitHub.
  2. Download and install a web server (I use MAMP on OS X, or the built-in IIS server with Visual Studio on Windows).

Open the Project

  1. Start your web server.
  2. Navigate to famous-angular-Pokemon/app/.

The project is designed to work on mobile devices, so use the mobile emulator in your browser to get the correct view. Here's what it would look like on an iPhone 6 inside the emulator via the Chrome desktop browser (375x667):

Mobile app were creating displayed on iPhone 6 emulator

How It Works

Hitting the Database

I pull all of the information from the PokeAPI, which has a well-documented API, but it's missing images for each of the Pokémon. For the images, I just pull the name of the currently chosen Pokémon and append it to the end of this URL: http://img.pokemondb.net/artwork/. For example: http://img.pokemondb.net/artwork/venusaur.jpg will lead you to an image of Vanosaur. Nifty, right? Sadly, they do not have an API available.

Each time the user presses the Next button, a random number is generated between a min/max value that I've defined (say, 1 to 20), and it pulls a Pokémon from the database that matches that number. Here's what it looks like:

http://pokeapi.co/api/v1/pokemon/1/ returns a JSON object for Bulbasaur. You can play with their API.

Looping Through the Data

I then loop through that JSON object and set the properties I find to variables in Angular, using the $Scope object.

Here's an example:

/*
   * Grab Pokemon from the DB
   */
  $scope.getPokemon = function () {  

    // Generate a random num and use it for the next pokemon
    getRandomInt($scope.minVal, $scope.maxVal);

    // Retrieve data from DB and draw it to screen
    $http.get($scope.dbURL + $scope.pokemonNum + "/")
      .success(function(data) {
        $scope.name       = data.name;
        $scope.imageUrl   = $scope.imgDbURL + $scope.name.toLowerCase() + '.jpg';

        /* 1) Empty out the current array to store the new items in there
         * 2) Capitalize the first character for each ability from the database
         * 3) Store that ability in a new abilityObj & add it into the abilities array
         */
        $scope.abilities.length = 0;
        for (var i = 0; i < data.abilities.length; i++){
         var capitalizedString = capitalizeFirstLetter(data.abilities[i].name);
         var abilityObj        = {name: capitalizedString };
          $scope.abilities.push(abilityObj);
        }

        $scope.hitPoints  = data. hp;
        var firstType     = data.types[0].name;
        $scope.types.name = capitalizeFirstLetter(firstType);
        determineNewBgColor();
      })
      .error(function(status){
        console.log(status);
        $scope.name = "Couldn't get Pokemon from the DB";
      });
  };

You may notice that I also have a few other functions here, such as capitalizeFirstLetter, which does exactly that. I wanted the abilities and type (e.g. poison, grass, flying) to have the first letter capitalized, since they come back from the database in all lowercase characters.

I also loop through the abilities and push them to an ability object, which looks like this:

   $scope.abilities       = [
    { name: "Sleep"},
    { name: "Eat"  }
  ];

The database also returns multiple types for certain Pokémon, such as Charizard, who is flying as well as fire. To keep things simple, though, I only wanted to return one from the database.

  $scope.types      = { name: "Grass" };

  var firstType     = data.types[0].name;

Drawing It to the Screen

Famo.us has two waves of drawing content to the screen by creating surfaces, which are the elements that contain your text, images, etc.:

  • JavaScript
  • FA-Directives (HTML)

I didn't use JavaScript to draw the surfaces in this app. Instead I chose to use only FA (Famous-Angular) Directives, such as:

<!-- Name-->
<fa-modifier
    fa-origin    ="origin.center"
    fa-align     ="align.frontName"
    fa-size      ="size.frontName"
    fa-translate ="trans.topLayer">
    <fa-surface
        class    ="front-name-text">
        {{name}}
    </fa-surface>
</fa-modifier>

This is for the name above the Pokémon on the front screen.

You'll notice that the surface is wrapped by a fa-modifier. You can read about those in the Famo.us documentation, but they essentially adjust the properties of a surface, such as alignment, size, and origin. It took me a while to wrap my head around the difference between alignment and origin, so here's how I came to understand it.

Origin 

This is the reference point on any surface. If I want to draw a rectangle and move it around the screen, I need to decide which point on that rectangle will be my starting point. The Famo.us docs explain it well. The values are laid out as follows:

  $scope.origin          = {
                         // X    Y 
   topLeft:                [0,   0  ],
   topRight:               [1,   0  ],
   center:                 [0.5, 0.5],
   bottomLeft:             [0,   1  ],
   bottomRight:            [1,   1  ]
  };

Alignment

This is a surface's location on the screen. When you make changes to the alignment, it is using the origin as the reference point to start from.

  $scope.align          =  {
                          // X        Y 
    frontName:             [0.50,    0.10],
    frontImg:              [0.50,    0.40],
    backImg:               [0.5,     0.38],
    center:                [0.50,    0.50]
  };

Where Angular Finally Comes In

Now here's where you can put all of your Angular skills and data binding to work with the Angular implementation. If you're already experienced with Angular, then it's not radically different here.

<!-- Next button -->
<fa-modifier
    fa-origin    ="origin.center"
    fa-align     ="align.nextBtn"
    fa-size      ="size.btn"
    fa-scale     ="scale.nextBtn.get()"
    fa-translate ="trans.topLayer">
    <fa-surface
        class    ="one-edge-shadow center-align next-btn"
        ng-click ="getPokemon(); nextBtnPressAnim(); frontImgAnim()">
        {{nextBtn}}
    </fa-surface>
</fa-modifier>

This button appears on the first screen and simply pulls another Pokémon from the database. All of the ng (Angular) directives you are familiar with are here, such as ng-click. I have multiple functions here. Notice that they are not comma-separated.

I am also binding the value of $scope.nextBtn to {{nextBTn}} in HTML.

To allow Famo.us and Angular to work together, we need to include $Famo.us at the top of our JavaScript file. Here's how you do it:

angular.module('famousAngularStarter')
  .controller('PokemonCtrl', ['$scope', '$http', '$famous', function ($scope, $http, $famous) {

    /* Inject famo.us to DOM */
    var View           = $famous['famous/core/View'                 ];
    var Modifier       = $famous['famous/core/Modifier'             ];
    var Surface        = $famous['famous/core/Surface'              ];
    var Transform      = $famous['famous/core/Transform'            ];
    var Transitionable = $famous['famous/transitions/Transitionable'];
    var Timer          = $famous['famous/utilities/Timer'           ];

Animations

What would a high-performance app be without animations? Famo.us is packed with them, which makes it easy to get started. Here's one for animating the image on the front.

  /*
   * @OnClick: Sets the opacity and scale for the front image when user clicks "Next" btn
   * 1) Turns opacity invisible quickly before returning to original opacity, revealing new Pokemon
   * 2) Turns scale down before quickly turning it back up to original size
   */
  $scope.frontImgAnim = function() {
    var hideDuration   =  200;
    var returnDuration = 1300;

    $scope.opac.imgFront.    set(0,           {duration: hideDuration,   curve: "easeIn"},
      function returnToOrigOpacity() {
        $scope.opac.imgFront.set(1,           {duration: returnDuration, curve: "easeIn"})
      }
    );
    $scope.scale.imgFront    .set([0.5, 0.5], {duration: hideDuration,   curve: "easeIn"},
      function returnToOrigSize() {
        $scope.scale.imgFront.set([0.8, 0.8], {duration: returnDuration, curve: "easeIn"})
      }
    )
  };

There are several curve types you can use here. Checkout the docs for more info. I'm also using a callback function, returnToOrigSize, to have the image grow and then shrink back to the original size.

Points of Frustration

I ran into a few issues along the way.

FA-Directives Have Their Properties Set as Strings

 fa-origin    ="origin.center"

If you have a spelling error, the app will just use the default values for that property. This snagged me several times, which is why you see I set all of my properties as an object, such as align.frontName, to make it easier to read.

Adding Classes

In FA-Directives you add multiple classes as strings and they are not comma-separated.

<fa-surface
    class    ="one-edge-shadow center-align next-btn"
    ng-click ="infoBtnPressAnim(); flip()">
    {{infoBtnText}}
</fa-surface>

If you try to add classes by creating surfaces in JavaScript, you pass in an array of strings.

var logo = new Surface({
    properties: {
         ...
    },
    classes: ['backfaceVisibility, class-two'] 
});

It took me a while to understand that, as I only found the solution in thisthread.

Famo.us + Angular Seems to Be Deprecated (For Now)

Midway through this project, I saw that Famo.us was working on an improved version of the framework that includes Mixed Mode. Famo.us + Angular doesn't take advantage of these additions (yet) at least. That doesn't mean FA is going anywhere, as it works perfectly fine—it's just that you won't be getting the latest features.

Resources

More Hands-On With JavaScript

This article is part of the web development series from Microsoft tech evangelists on practical JavaScript learning, open-source projects, and interoperability best practices, including Microsoft Edge browser and the new EdgeHTML rendering engine. 

We encourage you to test across browsers and devices including Microsoft Edge—the default browser for Windows 10—with free tools on dev.modern.IE:

In-depth tech learning on Microsoft Edge and the Web Platform from our engineers and evangelists:

More free cross-platform tools and resources for the web platform:

Tags:

Comments

Related Articles

Creating a Web App From Scratch Using AngularJS and Firebase: Part 4

Creating a Web App From Scratch Using AngularJS an...

Working With IndexedDB - Part 3

Working With IndexedDB - Part 3

Rewriting History with Git Rebase

Rewriting History with Git Rebase

Data Validation With Core Data: Common Constraints

Data Validation With Core Data: Common Constraints

SpriteKit From Scratch: Visual and Audio Effects

SpriteKit From Scratch: Visual and Audio Effects

iOS 6 SDK: Displaying App Store Products In-App

iOS 6 SDK: Displaying App Store Products In-App