Android gui framework

The Android GUI Framework
Android experience day
December 2008

Markus Pilz
Peter Wlodarczak

Agenda
1. Introduction
2. Anatomy
3. A real word example
4. Life cycle
5. Trends
6. Findings

Why Android
 Android was designed as a platform for
software development
 Android is open
 Android is free
 Community support
 Tool support

Anatomy I
 Android is Linux based
 GUI is fully written in Java
 Java 1.5 support
 Widget toolkit
 XML based GUI
 Single Touch screen

Anatomy II
 Activity
 Intent, IntentFilter, IntertReceiver
 View
 Service
 Content provider

Anatomy III
 Storage
 AIDL
 Security
 Life cycle management
 Native calls (not officially)

 NLS support

A real word example I
 A translator for Android
 If you are in a country where no one
understands your language

 You cannot read anything
 You have your mobile
phone always with you
 No additional device needed

A real word example II
 Uses the Google translator
 Uses XMPP for data transmission
 Can be extended with new languages
 Adaptive GUI
 GUI fully defined in XML

A real word example III

Lets see it

A real word example IV
 Used Eclipse for development
 ANT script and make for build
 Uses persistence of user data
 Uses touch screen and keyboard input

A real word example V
The AndroidManifest.xml
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.greenliff.translator">
<application android:icon="@drawable/logo">
<activity android:label="@string/settings" android:name="Settings">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
</intent-filter>
</activity>
<activity android:label="@string/app_name" android:name="Translate">
<intent-filter>
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:label="@string/ocr" android:name="OCR">
<intent-filter>
</intent-filter>
</activity>
</application>
</manifest>

A real word example V
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.greenliff.translator">
<application android:icon="@drawable/logo">
<activity android:label="@string/settings" android:name="Settings">
<intent-filter>
</intent-filter>
</activity>
<activity android:label="@string/app_name" android:name="Translate">
<intent-filter>
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:label="@string/ocr" android:name="OCR">
<intent-filter>
</intent-filter>
</activity>
</application>
</manifest>

Launch

A real word example VI

 Used for security
 Define permissions, e. g.
<uses-permission android:name="android.permission.RECEIVE_SMS" />

 Give other Activities access

A real word example VII
An XML snipped of the main Activity
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:scrollbars="vertical">
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/linLayout"
android:orientation="vertical"
android:layout_height="wrap_content">
<TextView
Text reference
android:background="@drawable/blue"
android:text="@string/translate_to_1"/>
<EditText
android:id="@+id/toTranslate"
android:background="@android:drawable/editbox_background"
android:layout_below="@id/linLayout“
android:hint="Type here..." />
.....

A real word example VIII
 Could also be developed purely in Java
 XML cannot be debugged
 Not all the attributes can be defined in XML

A real word example IX
A code snipped of the Translate Activity
@Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
Window wp = getWindow();
mContext = wp.getContext();
setTheme(android.R.style.Theme_Light);
setContentView(R.layout.main);
mLayout = (LinearLayout) this.findViewById(R.id.linLayout);
mToTranslate = (EditText) this.findViewById(R.id.toTranslate);
setShowLanguages();
mEnge = (LinearLayout) this.findViewById(R.id.enge);
LANGUAGE_LAYOUT[0] = mEnge;
de2en = (Button) this.findViewById(R.id.de2en);
de2en.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
if(!connect()) {
notLoggedInAlert();
} else {
doConnect("de2en@bot.talk.google.com");
rearrange(mEnge);
}
}
});
....


Set layout

@Override
setShowLanguages();
if(!connect()) {
notLoggedInAlert();
} else {
rearrange(mEnge);
}
}
});
....


Set layout

@Override
Find
setShowLanguages();
if(!connect()) {
notLoggedInAlert();
} else {
rearrange(mEnge);
}
}
});
....

elements


Set layout

@Override
Find
setShowLanguages();
if(!connect()) {
notLoggedInAlert();
} else {
rearrange(mEnge);
}
}
});

Add behavior

....

elements

A real word example X
Call an other Activity

@Override
public boolean onOptionsItemSelected(Menu.Item item) {
switch (item.getId()) {
case 0:
showLogin();
break;
case 1:
Intent intent = new Intent(Translate.this, Settings.class);
intent.putExtras(mShownLanguages);
startSubActivity(intent, SETTINGS);
break;
} // switch
return true;
}


Start an Activity

@Override
case 0:
showLogin();
break;
case 1:
break;
} // switch
return true;
}


Start an Activity

@Override
case 0:
showLogin();
break;
case 1:
break;
} // switch
Pass data to
return true;
}

new Activity

A real word example XI
Store user data

@Override
protected void onPause() {
Persistent store
super.onPause();
SharedPreferences.Editor ed = mPrefs.edit();
for(int i = 0; i < SUPPORTED_LANGUAGES.length; i++) {
ed.putBoolean(SUPPORTED_LANGUAGES[i],
mShownLanguages.getBoolean(SUPPORTED_LANGUAGES[i]));
}
ed.commit();
}

A real word example XII
Store user data
 Preferences
 Database
 Files

 Content provider
 Network

Life cycle
 Life cycle not directly controlled by application
 System can kill an application to free up
memory

 Controll through onCreate(), onPause(),
onStop() ... methods
 Android has different types of processes,
visible processes, service processes,
background processes ...

 Services can be used for long-lived
background processes

Trends I
 Eyes-free user interfaces
 Other user interfaces like tones, vibrant alarm,
sensors, actuators
 Leverage hearing and touch
 Camera input


Ubiquitous computing technologies

Trends II
 Speech recognition
 Accelerometer
 Magnetic compass
 Location self-awareness


Locating others



Sensing the environment

Findings
 Android uses proven technology like Java,
XML and Linux
 It offers a rich API for application development
 There is an initial learning effort
 Android doesn‘t have many of the limitations
other mobile platforms have
 Trend towards eyes-free user interfaces

Some figures
 Q4 2007 more than 3 billion mobile subscribers
(world population 6.7 billion)
 1.14 billion handsets delivered in 2007
(computers 271.2 million)

 118 million where smart phones
 Currently more than 30 mobile platforms
 Symbian leads with 65% share, ahead of
Microsoft on 12%, RIM on 11%, Apple on 7%, and
Linux at 5%

Thank you for the attention

Questions?

Find out more at:
http://code.google.com/android

Android gui framework

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