AngularJS Tutorial — a simple UI to control elements

Angular in practice! Today we have a small AngularJS tutorial, about creating small UI connected with dynamically created (refreshed) graphical object.

AngularJS Tutorial — control an element with Angular

In the basic course of Angular, we focused on information. Now it’s time to see it in a real example. Today’s simple tutorial in small steps will help us with this.

Step 1.

Let’s create HTML5 document and include AngularJS library.

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Step 2.

Define an element, on which we will operate from the level of UI. In our example we will create a simple element using CSS:

.my-elem {
  background: #00c;
  border-radius: 10%;
  position: absolute;
  width: 200px;
  height: 200px;
  max-width: 500px;
  max-height: 500px;

  /* speed */
  transition: 0.8s;
  -webkit-transition: 0.8s;

  /* init pos*/
  left: 100px;
  top: 200px;
}

Step 3.

With the help of HTML5 we will create “range” inputs, which will be bind-ed with our element through Angular:

…
  <body ng-app="app">
    <div class="ng-scope" ng-controller="TutController">

      <label>dX:</label>
      <input value="10" ng-model="object.pos.x"
        ng-change="changeStyle(object)"
        min="1" max="500" type="range"><br>

      <label>dY:</label>
      <input value="10" ng-model="object.pos.y"
        ng-change="changeStyle(object)" min="1"
        max="200" type="range"><br>

      <label>Size:</label>
      <input value="150" ng-model="object.size"
        ng-change="changeStyle(object)"
        min="1" max="500" type="range"><br>

      <p class="ng-binding" debug-position="">Adjust the ranges</p>

      <div id="container">
          <div id="my-elem" class="my-elem"
            ng-style="style(object)">
          </div>
      </div>

    </div>
  </body>
…

There are 3 inputs to control following parameters:

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– position X

– position Y

– the size of an element

Step 4.

Now let’s write little bit of JavaScript code. We should know it well: define an application and controller. In the controller’s scope we define two methods:

– returning current style of an element

– changing the style of an element depending on the UI changes.

Everything of course connected and handled thanks to AngularJS.

var app = angular.module('app', []);

app.controller("TutController", function ($scope) {
    $scope.object = {
      pos: {
        x: 5,
        y: 5
      },
      size: 150,
      style: {}
    };

    // return the object with current styles
    $scope.style = function (object) {
      return object.style;
    };

    // update styles depending on UI inputs state
    $scope.changeStyle = function (object) {
      object.style = {
        'width': object.size + 'px',
        'height': object.size + 'px',
        'left': object.pos.x + 'px',
        'top': parseInt(object.pos.y) + 200 + 'px'
      };
    };

    // …
});

Actually that’s all! Data binding will handle of updating the appearance of an element depending on UI elements state.

Additionally, we can write a simple directive, wich will show us some debug info:

// …
app.directive('debugPosition', function () {
  return {
    template: '<strong>Debug:</strong><br> dX: {{object.pos.x}}
    <br>
    dY: {{object.pos.y}}
    <br>
    Size: {{object.size}}',
    };
});

Please pay attention on using this directive (name) in HTML code:

<p class="ng-binding" debug-position="">Adjust the ranges</p>

A sample view:

AngularJS tutorial — an example

Source available on GitHub:

https://github.com/dominik-w/angularjs/tree/master/angular-ui-tutorial

AngularJS Tutorial — Summary

Few small steps: adding UI input elements and little bit of JS code and Angular directives, and our small application is ready.

Happy coding!

Posted in AngularJS, HTML5, JavaScript Frameworks, Practice, Tutorials

Tags: AngularJS, html5, JavaScript, tutorial, UI

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