Visage Android Hands-on Lab (OSCON)

Lab session given at OSCON Java 2011:
Visage is the successor to the JavaFX Script Language, a domain-specific language for writing UIs. It excels at rapid application design and can be used on any platform that supports Java. In this lab you will have an opportunity to write Visage applications that deploy to and run on Android mobile devices. No prior experience with Android or Visage development is required.

1. Visage Android
Hands-on Lab
Stephen Chin
Chief Agile Methodologist – GXS
OSCON Java Program Chair

http://steveonjava.com/
Tweet: @steveonjava

2. How This Session Works
Team A
Team B
Team C

3. The Visage Language
3!
! Statically Compiled Language
! Based on F3 / JavaFX Script
! Planning Support for Different
Platforms:
- JavaFX 2.0
- Android
- Apache Pivot
- Flex
- JSF
> “Visage is a domain specific
language (DSL) designed for the
express purpose of writing user
interfaces.”

4. What Does Visage Look Like?
Stage {
var input:TextBox;
title: bind input.text
Scene {
input = TextBox {
color: #DDCC33
}
}
}!
4!

5. UI Focused Language Features
! Declarative Object Construction
- Code looks like the UI it is representing.
! Data Binding
- Variables can be bound to UI state, allowing automatic updates and
behavior to be triggered.
! UI Definition Literals
- Built-in literal syntax for colors, angles, lengths, and durations
! Null Safety
- Application logic will proceed even if intermediate variables are undefined
or null.
5!

6. Visage on Android
6!
! Visage Runs as a Native App on Android
! Full Access to all the Android APIs
! Declarative Layer on Top of Android APIs

7. HELLO WORLD, VISAGE
Module 1
7!

8. Exercise 1.A – Android Setup
! Setup and run the VirtualBox image
! Create an emulator instance
! Create a new Android project from the command line
! Run the project in the emulator
8!

9. Setting Up Your Machine
1. Copy these files off the USB stick
(or from http://projavafx.com/VisageLab/):
- VirtualBox for your platform (Mac, Windows, or Linux)
- VisageLab folder
1. Decompress
VisageLab/Visage Dev2.vdi.zip
2. Install VirtualBox
3. Open Visage Dev.vbox
9!

10. Set Up Your Device for Debugging
! And mount it from:
- Devices > USB Devices > (your-device-name)
10!
10

11. Or Create a Virtual Android Device
11!
! Launch the AVD Manager by typing: android

12. Setting Up Your Project
! Project creation command:
- android create project –t 1 –p HelloVisage –k org.test –a HelloVisage
! Arguments:
- n : Project name (optional)
- t : Target ID of the new project (required)
- p : Project directory (required)
- k : Package name for the application (required)
- a : Name of the default Activity (required)
12!

13. Android XML Code
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Hello World, HelloVisage"
/>
</LinearLayout>
13!

14. Plus some more Java…
public class HelloVisage extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedIS) {
super.onCreate(savedIS);
setContentView(R.layout.main);
}
}
14!

15. Run Your Project
! cd HelloVisage
! ant install
! Open it in the applications menu
15!

16. Exercise 1.B – All Java Conversion
! Make sure you have the basic project running first
! Convert the XML Code to Java
! Run the all Java project
! You should get identical results
16!

17. Converted XML Code (simplified)
public class HelloVisage extends Activity {
@Override public void onCreate(Bundle savedIS) {
super.onCreate(savedIS);
Context context = getApplicationContext();
LinearLayout layout = new LinearLayout(context);
layout.setOrientation(LinearLayout.VERTICAL);
TextView text = new TextView(context);
text.setText("Hello World, Java Only");
layout.addView(text);
setContentView(layout);
}
}
17!

18. (and here are the imports…)
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.widget.LinearLayout;
import android.widget.TextView;
18!

19. Exercise 1.C – DDMS Debugging
! So you made a mistake in your code… the compiler can’t catch
everything
- (even if you didn’t make a mistake, force one… a beautiful
NullPointerException will do)
! Launch DDMS and select your emulator/device
19!

20. Break the code (change in bold)
public class HelloVisage extends Activity {
@Override public void onCreate(Bundle savedIS) {
super.onCreate(savedIS);
Context context = getApplicationContext();
LinearLayout layout = null;//new LinearLayout(context);
layout.setOrientation(LinearLayout.VERTICAL);
TextView text = new TextView(context);
text.setText("Hello World, HelloVisage");
layout.addView(text);
setContentView(layout);
}
}
20!

21. DDMS Displaying a Stack Trace
21!

22. Exercise 1.D – Visage Port
! Modify the build script to compile Visage
! Copy the Visage Runtime libraries
! Convert the Java code to Visage
! Run on device/emulator
22!

23. Modify the Build Script (1)
<target name="-post-compile">
<path id="android.classpath">
<fileset dir="./libs" includes="*.jar" />
<path refid="android.target.classpath"/>
<pathelement location="${out.classes.absolute.dir}"/>
</path>
<pathconvert refid="android.classpath" property="androidcpath"/>
<path id="visage.sources">
<fileset dir="${source.absolute.dir}" includes="**/*.fx"/>
</path>
23!

24. Modify the Build Script (2)
<pathconvert refid="visage.sources" property="visagepath" pathsep=" "/>
<exec executable="${visagehome}/bin/javafxc${binary.extension}"
failonerror="true" logerror="true">
<arg value="-d"/>
<arg value="${out.classes.absolute.dir}"/>
<arg value="-cp"/>
<arg value="${androidcpath}"/>
<arg line="${visagepath}"/>
</exec>
</target>
24!

25. Add Some Properties…
! local.properties:
- visagehome=/home/visage/visage-sdk
- binary.extension=
25!

26. Copy Over the Runtime JAR
! Copy:
- javafxrt.jar
! From:
- $visagehome/lib/shared/
! To:
- $projectdir/libs
26!

27. Straight JavaFX Conversion...
public class Test extends Activity {
override function onCreate(savedInstanceState:Bundle) {
super.onCreate(savedInstanceState);
def context = getApplicationContext();
def layout = new LinearLayout(context);
layout.setOrientation(LinearLayout.VERTICAL);
def text = new TextView(context);
text.setText("Hello World, Hello Long Visage");
layout.addView(text);
setContentView(layout);
}
}
27!

28. Rename your source file
! *.java -> *.fx
28!

29. Exercise 1.E – Simplified Visage
! Include the visage-android jar
! Modify the Visage code to use the new APIs
! Run on device/emulator
29!

30. Copy the visage-android JAR
! Copy:
visage-android.jar
! From:
/home/visage/visage-android/dist/
! To:
$projectdir/libs
30!

31. Android JavaFX Code
public class HelloVisage extends Activity {
override var view = LinearLayout {
orientation: Orientation.VERTICAL
view: TextView {
text: "Hello World, Beautified Visage"
}
}
}

31!

32. And change the imports…
! org.visage.android.app.Activity;
! org.visage.android.widget.LinearLayout;
! org.visage.android.widget.Orientation;
! org.visage.android.widget.TextView;
32!

33. Working Hello Visage Application
33!

34. 34!
JAVA VS. VISAGE
Lesson 1

35. Language Similarities
Java is…
! Statically typed
! Compiled to bytecodes
! Runs on the JVM
! Has a large library
Visage is…
! Statically typed
! Compiled to bytecodes
! Runs on the JVM
! Can call Java libraries
35!

36. Language Differences
36!
Visage
• Type Inferencing
• Closures
• Binding
• Sequences
• Animation Syntax
Java
• Annotations
• Generics
• Multi-Threading

37. Integrating Visage and Java
! Calling Java from Visage
- Can call Java interface or classes directly
- Automatic conversion to and from Arrays and Collections
- Can even extend Java interfaces and classes
! Calling Visage from Java
- Easiest way is to create a Java interface that Visage extends
- Can invoke Visage as a script and get results back
37!

38. VISAGE LANGUAGE FUNDAMENTALS
Lesson 2
38!

39. Datatype Support
DataType! Java Equivalent! Range! Examples!
Boolean! boolean! true or false! true, false!
Integer! int! -2147483648 to 2147483647! 2009, 03731, 0x07d9!
Number! Float! 1.40×10
-45
and 3.40×10
38
! 3.14, 3e8, 1.380E-23!
String! String! N/A! "java's", 'in"side"er'!
Duration! <None>! -2
63
to 2
63
-1 milliseconds! 1h, 5m, 30s, 500ms!
Length <None> dp, sp, em, %, mm, cm, in 2mm, 5sp, 1in
Angle <None> rad, deg, turn 1rad, 30deg
Color <None> #RRGGBB, #RGB,
#RRGGBB|AA, #RGB|A
#CCCCCC, #202020|D0
Character! char! 0 to 65535! 0, 20, 32!
Byte! byte! -128 to 127! -5, 0, 5!
Short! short! -32768 to 32767! -300, 0, 521!
Long! long! -2
63
to 2
63
-1! 2009, 03731, 0x07d9!
Float! float! 1.40×10
-45
and 3.40×10
38
! 3.14, 3e8, 1.380E-23!
Double! double! 4.94×10
-324
and 1.80×10
308
! 3.14, 3e231, 1.380E-123!
39!

40. Visage Operators
Operator ! Meaning ! Precedence ! Examples !
++ ! Pre/post increment ! 1! ++i, i++ !
-- ! Pre/post decrement ! 1! --i, i-- !
not ! Boolean negation ! 2! not (cond) !
* ! Multiply ! 3! 2 * 5, 1h * 4 !
/ ! Divide ! 3! 9 / 3, 1m / 3 !
mod ! Modulo ! 3! 20 mod 3 !
+ ! Add ! 4! 0 + 2, 1m + 20s !
- ! Subtract (or negate) ! 4 (2) ! -2, 32 -3, 1h -5m !
40!
> Multiplication and division of two durations is allowed, but not meaningful
> Underflows/Overflows will fail silently, producing inaccurate results
> Divide by zero will throw a runtime exception

41. Visage Operators (continued)
Operator ! Meaning ! Precedence ! Examples !
== ! Equal ! 5! value1 == value2, 4 == 4 !
!= ! Not equal ! 5! value1 != value2, 5 != 4 !
< ! Lessthan ! 5! value1 < value2, 4 < 5 !
<= ! Lessthanorequal ! 5! value1 <= value2, 5 <= 5 !
> ! Greater than ! 5! value1 > value2, 6 > 5 !
>= ! Greater than or equal ! 5! value1 >= value2, 6 >= 6 !
instanceof ! Is instance of class ! 6! node instanceof Text !
as ! Typecast to class ! 6! node as Text !
and ! Boolean and ! 7! cond1 and cond2 !
or ! Boolean or ! 8! cond1 or cond2 !
+= ! Add and assign ! 9! value += 5 !
-= ! Subtract and assign ! 9! value -= 3 !
*= ! Multiply and assign ! 9! value *= 2 !
/= ! Divide and assign ! 9! value /=4 !
= ! Assign ! 9! value = 7 !
41!

42. Access Modifiers
Modifier! Name! Description!
<default>! Script only access! Only accessible within the same script file!
package! Package access! Only accessible within the same package!
protected! Protected access! Only accessible within the same package or by subclasses.!
public! Public access! Can be accessed anywhere.!
public-read! Read access modifier! Var/def modifier to allow a variable to be read anywhere!
public-init! Init access modifier! Var/def modifier to allow a variable to be initialized or read anywhere!
42!

43. Data Binding
! A variable or a constant can be bound to an expression
- var x = bind a + b;
! The bound expression is remembered
! The dependencies of the expression is watched
! Variable is updated lazily when possible
43!

44. CONTROLS AND SETTINGS
Module 2
44!

45. Exercise 2.A – NetBeans Integration
! Create a new JavaFX NetBeans project
! Merge in build scripts from Android project
! Start coding!
45!

46. Create a new JavaFX Project
! File > New Project…
! Name the project “ConfigReporter”
! In package "org.test"
46!

47. Merging Project Folders
! Copy these files over:
- *.properties
- AndroidManifest.xml
- res/
- libs/
- proguard.cfg
- build.xml [replace]
47!

48. Merging Build Scripts
! Update the build.xml file:
Set the project name to “ConfigReporter”
! Update the strings.xml file:
Set the app_name to “ConfigReporter”
! Load the NetBeans property files (in build.xml):
<property file="nbproject/private/config.properties"/>
<property file="nbproject/private/configs/${config}.properties"/>
<property file="nbproject/private/private.properties"/>
<property file="${user.properties.file}"/>
<property file="nbproject/configs/${config}.properties"/>
<property file="nbproject/project.properties"/>
48!

49. Alias NetBeans Targets:
<target name="launch" depends="install”>
<exec executable="${adb}" failonerror="true">
<arg line="${adb.device.arg}"/>
<arg value="shell"/>
<arg value="am"/>
<arg value="start"/>
<arg value="-n"/>
<arg value=”org.test/.ConfigReporter"/>
<arg value="-a"/>
<arg value="android.intent.action.MAIN"/>
</exec>
</target>
<target name="jar" depends="compile"/>
<target name="run" depends="launch"/>
49!

50. Update AndroidManifest.xml
! Change project name to "ConfigReporter"
50!

51. Modify Project Properties
! Set JavaFX Platform to “Visage_SDK”
! Add Libraries:
- “libs” folder
- android.jar
51!

52. Update ConfigReporter.fx
! Make it extend the visage Activity class
! For now, you can copy the logic from HelloVisage
52!

53. Exercise 2.C – Android Controls
! Create a Text Field
! Create an Edit Box
! Wire them up using Binding
53!

54. Bound Controls (1)
override var view = LinearLayout {
orientation: Orientation.VERTICAL
var secret:String;
view: [
EditText {
hint: "Super Secret Text”
password: true
text: bind secret with inverse
54!

55. Bound Controls (2)
}
TextView {
text: "Is Revealed!!!”
}
TextView {
text: bind secret
}
]
}
55!

56. Exercise 2.D – Button Handler
! Create a Button Control
! Add an onClick handler
! Make something happen (maybe a bind)
56!

57. Button onClick handler
Button {
text: "Launch Settings"
onClick: function() {
startActivity(new Intent(this, Settings.class));
setting = "Launching...";
}
}
TextView {
text: "Setting is:"
}
TextView {
text: bind setting
}
57!

58. Exercise 2.E – Android Settings
! Create a Settings Activity
! Populate it with the following preferences:
- Text
- Password
- List
! Launch it from the Button control
58!

59. Settings Class
public class Settings extends PreferenceActivity {
var usernamePref:EditTextPreference;
var passwordPref:EditTextPreference;
var pollingPref:ListPreference;

override var screen = PreferenceScreen {
preferences: [
…
59!

60. Text Preference
PreferenceCategory {
title: "Preferences"
preferences: [
usernamePref = EditTextPreference {
title: "Username"
key: "usernamePref"
summary: bind if (usernamePref.text == "") "Currently
undefined" else "Current value: {usernamePref.text}"
}
60!

61. Password Preference
passwordPref = EditTextPreference {
title: "Password”
key: "passwordPref”
summary: bind passwordPref.text.replaceAll(".", "*");
}
61!

62. List Preference
pollingPref = ListPreference {
title: "Polling Interval"
key: "pollingPref"
defaultValue: "60000"
entries: ["30 seconds", "1 minute", "5 minutes", "10 minutes", "15
minutes", "30 minutes", "1 hour"]
entryValues: ["30000", "60000", "300000", "600000", "900000",
"1800000", "3600000"]
summary: bind pollingPref.entry
}
62!

63. Service Metadata
! Update AndroidManifest.xml:
<activity android:name=".Settings”
android:label="@string/settings_label"/>
! Update string.xml:
<string name="settings_label">Settings</string>
63!

64. Invoke the new service
! In the onClick handler:
startActivity(new Intent(this, Settings.class));
64!

65. Working Settings Panel
65!

66. ADVANCED JAVAFX SEQUENCES
Lesson 3
66!

67. What Bind Updates
var x = bind if(a) then b else c
! x is updated if a or b or c changes
var x = bind for (i in [a..b]) { i * i }
! Not everything is recalculated
! If a = 1 and b = 2, x is [1, 4]
! If b changes to 3, only the added element is calculated
67!
1 4 9

68. Binding to Expressions
! Binding to a block
! Bound block may contain any number of defs followed by one
expression
! Dependencies of block is backtraced from the expression
! Binding to function invocation expression
- Regular function: dependencies are parameters
- Bound function: backtraced from final expression inside function
68!

69. Binding to Object Literals
var a = 3; var b = 4;
var p = bind Point { x: a, y: b };
var q = bind Point { x: bind a, y: b };
var r = bind Point { x: bind a, y: bind b };

! When a changes:
- p gets a new instance of Point
- q and r keep the old instance with a new x value
- r will never get a new instance of Point
- (the outer bind in r is useless)
69!

70. Visage Sequences
! Represents collections of homogeneous data
! A fundamental container data type
! Rich set of language facilities
! Contributor to declarative syntax
! Automatic conversion to and from Java Arrays and Collections
70!

71. Creating Sequences
! Explicit sequence expression
- [1, 3, 5, 7, 9]
! Elements are separated by commas
! Comma may be omitted if element ends with brace
71!
1 3 5 7 9

72. Creating Sequences
! Numeric sequence with range expressions:
- [1..10]
! Can have a step:
- [1..10 step 2]
- [0.0..0.9 step 0.1]
! Can be decreasing:
- [10..1 step -3]
! Beware of step that goes opposite direction:
- [10..1] is []
! Exclusive right end
- [1..<5]
1 2 3 4 5 6 7 8 9 10
1 3 5 7 9
0 .1 .2 .3 .4 .5 .6 .7 .8 .9
10 7 4 1
1 2 3 4

73. Getting Info from Sequences
ints = [1, 3, 5, 7, 9]

! sizeof ints is 5
! ints[0] is 1, ints[1] is 3, ..., ints[4] is 9
! ints[-1] is 0 (default value of Integer), so is ints[5]
! For a sequence of objects, the default is null
73!
1 3 5 7 9
[0] [1] [2] [3] [4]

74. Getting Slices from Sequences
ints = [1, 3, 5, 7, 9]
! ints[0..2] is [1, 3, 5]
! ints[0..<2] is [1, 3]
! ints[2..] is [5, 7, 9]
! ints[2..<] is [5, 7]
! ints[2..0], ints[-2..-1], ints[5..6] are all []s
74!
1 3 5 7 9
[0] [1] [2] [3] [4]

75. Getting Subsets from Sequences
ints = [1, 3, 5, 7, 9]
! ints[k | k > 6] is:
- [7, 9] (k > 6 is a condition)
! ints[k | indexof k < 2] is:
- [1, 3]
! ints[k | k > 10] is:
- []
75!
1 3 5 7 9
[0] [1] [2] [3] [4]

76. Inserting into Sequences
ints = [1, 3, 5, 7, 9]
insert 20 into ints
insert 30 before ints[2]
insert 40 after ints[4]
insert [50, 60] into ints
1 3 5 7 9
1 3 5 7 9
1 3 5 7 9
20
20 30
1 3 5 7 9 20 30 40
1 3 5 7 9 20 30 40 50 60

77. Deleting from Sequences
! ints = [1, 3, 5, 7, 9]
! delete 7 from ints
! delete ints[0]
! delete ints[0..1]
! delete ints: ints becomes []
1 3 5 7 9
1 3 5 9
3 5 9
9
1 3 5 7 9

78. Sequence Puzzlers
What is the size of this sequence:
! [1..10 step -1]

What does this evaluate to:
! [10..<20 step 2][k|k>17]

What is the size of this sequence:
! sizeof [20..1 step -3]

79. How Did I Do?

80. Thank You!
Stephen Chin
http://steveonjava.com
Tweet: @steveonjava
80!