Views
Many classes have shortcut names used when creating (instantiating) a class with a
configuration object. The shortcut name is referred to as an alias (or xtype if the
class extends Ext.Component). The alias/xtype is listed next to the class name of
applicable classes for quick reference.
Framework classes or their members may be specified as private or protected. Else,
the class / member is public. Public, protected, and private are access
descriptors used to convey how and when the class or class member should be used.
Public classes and class members are available for use by any other class or application code and may be relied upon as a stable and persistent within major product versions. Public classes and members may safely be extended via a subclass.
Protected class members are stable public members intended to be used by the
owning class or its subclasses. Protected members may safely be extended via a subclass.
Private classes and class members are used internally by the framework and are not intended to be used by application developers. Private classes and members may change or be omitted from the framework at any time without notice and should not be relied upon in application logic.
static label next to the
method name. *See Static below.Below is an example class member that we can disect to show the syntax of a class member (the lookupComponent method as viewed from the Ext.button.Button class in this case).
Let's look at each part of the member row:
lookupComponent in this example)( item ) in this example)Ext.Component in this case). This may be omitted for methods that do not
return anything other than undefined or may display as multiple possible values
separated by a forward slash / signifying that what is returned may depend on the
results of the method call (i.e. a method may return a Component if a get method calls is
successful or false if unsuccessful which would be displayed as
Ext.Component/Boolean).PROTECTED in
this example - see the Flags section below)Ext.container.Container in this example). The source
class will be displayed as a blue link if the member originates from the current class
and gray if it is inherited from an ancestor or mixed-in class.view source in the example)item : Object in the example).undefined a "Returns" section
will note the type of class or object returned and a description (Ext.Component in the
example)Available since 3.4.0 - not pictured in
the example) just after the member descriptionDefaults to: false)The API documentation uses a number of flags to further commnicate the class member's function and intent. The label may be represented by a text label, an abbreviation, or an icon.
classInstance.method1().method2().etc();false is returned from
an event handler- Indicates a framework class
- A singleton framework class. *See the singleton flag for more information
- A component-type framework class (any class within the Ext JS framework that extends Ext.Component)
- Indicates that the class, member, or guide is new in the currently viewed version
- Indicates a class member of type config
- Indicates a class member of type property
- Indicates a class member of type
method
- Indicates a class member of type event
- Indicates a class member of type
theme variable
- Indicates a class member of type
theme mixin
- Indicates that the class, member, or guide is new in the currently viewed version
Just below the class name on an API doc page is a row of buttons corresponding to the types of members owned by the current class. Each button shows a count of members by type (this count is updated as filters are applied). Clicking the button will navigate you to that member section. Hovering over the member-type button will reveal a popup menu of all members of that type for quick navigation.
Getting and setter methods that correlate to a class config option will show up in the methods section as well as in the configs section of both the API doc and the member-type menus just beneath the config they work with. The getter and setter method documentation will be found in the config row for easy reference.
Your page history is kept in localstorage and displayed (using the available real estate) just below the top title bar. By default, the only search results shown are the pages matching the product / version you're currently viewing. You can expand what is displayed by clicking on the button on the right-hand side of the history bar and choosing the "All" radio option. This will show all recent pages in the history bar for all products / versions.
Within the history config menu you will also see a listing of your recent page visits. The results are filtered by the "Current Product / Version" and "All" radio options. Clicking on the button will clear the history bar as well as the history kept in local storage.
If "All" is selected in the history config menu the checkbox option for "Show product details in the history bar" will be enabled. When checked, the product/version for each historic page will show alongside the page name in the history bar. Hovering the cursor over the page names in the history bar will also show the product/version as a tooltip.
Both API docs and guides can be searched for using the search field at the top of the page.
On API doc pages there is also a filter input field that filters the member rows using the filter string. In addition to filtering by string you can filter the class members by access level, inheritance, and read only. This is done using the checkboxes at the top of the page.
The checkbox at the bottom of the API class navigation tree filters the class list to include or exclude private classes.
Clicking on an empty search field will show your last 10 searches for quick navigation.
Each API doc page (with the exception of Javascript primitives pages) has a menu view of metadata relating to that class. This metadata view will have one or more of the following:
Ext.button.Button class has an alternate class name of Ext.Button). Alternate class
names are commonly maintained for backward compatibility.Runnable examples (Fiddles) are expanded on a page by default. You can collapse and expand example code blocks individually using the arrow on the top-left of the code block. You can also toggle the collapse state of all examples using the toggle button on the top-right of the page. The toggle-all state will be remembered between page loads.
Class members are collapsed on a page by default. You can expand and collapse members using the arrow icon on the left of the member row or globally using the expand / collapse all toggle button top-right.
Viewing the docs on narrower screens or browsers will result in a view optimized for a smaller form factor. The primary differences between the desktop and "mobile" view are:
The class source can be viewed by clicking on the class name at the top of an API doc page. The source for class members can be viewed by clicking on the "view source" link on the right-hand side of the member row.
From a user's point of view, your application is simply a collection of views. Although much of the value of the app is in the Models and Controllers, users directly interact with the Views. In this guide we are going to look at how to create the views that build your application.
The easiest way to create a view is to use Ext.create with an existing Component. For example, if we wanted to create a simple Panel with some HTML inside, we can use the following code:
Ext.create('Ext.Panel', {
html: 'Welcome to my app',
fullscreen: true
});
This example creates a Panel with some html content and makes it fill the screen. Although you can create any of the built-in components this way, the best practice is to create a subclass with your specializations and then instantiate that class as follows:
Ext.define('MyApp.view.Welcome', {
extend: 'Ext.Panel',
config: {
html: 'Welcome to my app',
fullscreen: true
}
});
Ext.create('MyApp.view.Welcome');
The outcome is the same, but this time we have a new component that we can create any number of times. This is the pattern we normally want to follow when building our app - create a subclass of an existing component, then create an instance of it later. Let us take a look at the changes:
Any of the config options available on Ext.Panel can be specified in either our new class's config block or when we come to create the class instance. When defining a subclass make sure to use the config object, when creating just pass in an object.
For example, the following code is based on the previous code, but with additional configuration passed in with the Ext.create call:
Ext.define('MyApp.view.Welcome', {
extend: 'Ext.Panel',
config: {
html: 'Welcome to my app',
fullscreen: true
}
});
Ext.create('MyApp.view.Welcome', {
styleHtmlContent: true
});
The following example illustrates one of the View classes from our Twitter app:
Ext.define('Twitter.view.SearchBar', {
extend: 'Ext.Toolbar',
xtype : 'searchbar',
requires: ['Ext.field.Search'],
config: {
ui: 'searchbar',
layout: 'vbox',
cls: 'big',
items: [
{
xtype: 'title',
title: 'Twitter Search'
},
{
xtype: 'searchfield',
placeHolder: 'Search...'
}
]
}
});
This code sample follows the same pattern as before - we created a new class called Twitter.view.SearchBar, which extends the framework's Ext.Toolbar class. We also passed in some configuration options, including a layout and an items array.
In this example we used the following new options:
requires - because we use a searchfield in our items array, we indicate the new view to require the Ext.field.Search class. At the moment the dynamic loading system does not recognize classes specified by xtype, so we need to define the dependency manually
xtype - gives our new class its own xtype, allowing us to easily create it in a configuration object, which is similar to the approach taken with the searchfield
This allows us to create instances of our new view class in a couple of ways:
//creates a standalone instance
Ext.create('Twitter.view.SearchBar');
//alternatively, use xtype to create our new class inside a Panel
Ext.create('Ext.Panel', {
html: 'Welcome to my app',
items: [
{
xtype: 'searchbar',
docked: 'top'
}
]
});
Sencha Touch makes extensive use of the configuration system to provide predictable APIs and keep the code clean and easily testable. We strongly suggest you do the same in your own classes.
Let us assume that you want to create an image viewer that pops up information about the image when you tap on it. Our design goal is to create a reusable view that can be configured with the image url, its title and its description, and that displays the title and description when you tap on it.
Most of the work around displaying images is taken care of for us by the Ext.Img component, so we subclass that as follows:
Ext.define('MyApp.view.Image', {
extend: 'Ext.Img',
config: {
title: null,
description: null
},
//sets up our tap event listener
initialize: function() {
this.callParent(arguments);
this.element.on('tap', this.onTap, this);
},
//this function is called whenever you tap on the image
onTap: function() {
Ext.Msg.alert(this.getTitle(), this.getDescription());
}
});
//creates a full screen tappable image
Ext.create('MyApp.view.Image', {
title: 'Orion Nebula',
description: 'The Orion Nebula is rather pretty',
src: 'http://apod.nasa.gov/apod/image/1202/oriondeep_andreo_960.jpg',
fullscreen: true
});
In this example, we have added two additional configurations to our class - title and description - which both start off as null. When we create an instance of our new class, we pass in the title and the description configs like any other configuration.
The new behavior occurs in the initialize and onTap functions. Since the initialize function is called whenever any component is instantiated, it is a good place to set up behavior such as event listeners. First we use this.callParent(arguments) to make sure the superclass' initialize function is called. This is very important, omitting this line may cause your components not to behave correctly.
After callParent, we add a tap listener to the component's element, which calls the onTap function whenever the element is tapped. All components in Sencha Touch have an element property that you can use in this way to listen to events on the DOM objects, to add or remove styling, or to do anything else you would normally do to an Ext.dom.Element.
The onTap function itself uses Ext.Msg.alert to pop up some information about the image. Note that our two new configs - title and description - both receive generated getter functions (getTitle and getDescription respectively), as well as generated setter functions (setTitle and setDescription).
When you create a new configuration option to a class, the getter and setter functions are generated for you. For example, the config called 'border' in the following example is automatically given getBorder and setBorder functions:
Ext.define('MyApp.view.MyView', {
extend: 'Ext.Panel',
config: {
border: 10
}
});
var view = Ext.create('MyApp.view.MyView');
alert(view.getBorder()); //alerts 10
view.setBorder(15);
alert(view.getBorder()); //now alerts 15
The getter and setter are not the only generated functions, there are a couple more that make life as a component author much simpler - applyBorder and updateBorder:
Ext.define('MyApp.view.MyView', {
extend: 'Ext.Panel',
config: {
border: 0
},
applyBorder: function(value) {
return value + "px solid red";
},
updateBorder: function(newValue, oldValue) {
this.element.setStyle('border', newValue);
}
});
The applyBorder function is called internally any time the border configuration is set or changed, including when the component is first instantiated. This is the best place to put any code that transforms an input value. In this case we take the border width passed in and return a CSS border specification string.
This means that when we set the view's border config to 10, our applyBorder function will make sure that we transform that value to '10px solid red'. The apply function is optional, but note that you must return a value from it or nothing will happen.
The updateBorder function is called after the applyBorder function has transformed the value, and is usually used to modify the DOM, to send AJAX requests, or to perform any other kind of processing. In our case we are getting the view's element and updating the border style using setStyle. This means that every time setBorder is called, the DOM is immediately updated to reflect the new style.
The following code is an example of the new view in action. Click the Code Editor button to see the source - basically we created an instance of the new view and docked a spinner at the top, allowing us to change the border width by tapping the spinner buttons. We then hooked into the Spinner's spin event and called our view's new setBorder function from there:
//as before
Ext.define('MyApp.view.MyView', {
extend: 'Ext.Panel',
config: {
border: 0
},
applyBorder: function(value) {
return value + "px solid red";
},
updateBorder: function(newValue, oldValue) {
this.element.setStyle('border', newValue);
}
});
//create an instance of MyView with a spinner field that updates the border config
var view = Ext.create('MyApp.view.MyView', {
border: 5,
fullscreen: true,
styleHtmlContent: true,
html: 'Tap the spinner to change the border config option',
items: {
xtype: 'spinnerfield',
label: 'Border size',
docked: 'top',
value: 5,
minValue: 0,
maxValue: 100,
increment: 1,
listeners: {
spin: function(spinner, value) {
view.setBorder(value);
}
}
}
});
We recommend that most Sencha Touch applications follow the MVC conventions so that your code remains well organized and reusable. As the "V" in MVC, Views also fit into this structure. The conventions around Views in MVC are very simple and follow directly from the naming convention we used throughout the previous examples.
The MyApp.view.MyView class should be defined inside a file called app/view/MyView.js
this allows the Application to find and load it automatically. If you are not already familiar with the file structure for MVC-based Sencha Touch apps, it is pretty simple - an app is just an html file, an app.js file, and a collection of models, views and controllers stored inside the app/model, app/view and app/controller directories:
index.html app.js app/
controller/
model/
view/
MyView.js
You can create as many views as you want and organize them inside your app/view directory. By specifying your application's Views inside your app.js file, they are loaded automatically:
//contents of app.js
Ext.application({
name: 'MyApp',
views: ['MyView'],
launch: function() {
Ext.create('MyApp.view.MyView');
}
});
By following the simple View naming conventions, you can easily load and create instances of View classes inside your application. The previous example does exactly that - it loads the MyView class and creates an instance of it in the application launch function. To find out more about writing MVC apps in Sencha Touch please see the intro to apps guide.
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