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

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

7. Module 1
HELLO WORLD, VISAGE
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
§ Launch the AVD Manager by typing: android
11

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. Lesson 1
JAVA VS. VISAGE
34

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

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

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. Lesson 2
VISAGE LANGUAGE FUNDAMENTALS
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 3.40×1038
3.14, 3e8, 1.380E-23
String
String
N/A
"java's", 'in"side"er'
Duration
<None>
-263 to 263-1 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, #CCCCCC, #202020|D0
#RRGGBB|AA, #RGB|A
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
-263 to 263-1
2009, 03731, 0x07d9
Float
float
1.40×10-45 and 3.40×1038
3.14, 3e8, 1.380E-23
Double
double
4.94×10-324 and 1.80×10308
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
> 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
40

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. Module 2
CONTROLS AND SETTINGS
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. Lesson 3
ADVANCED JAVAFX SEQUENCES
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
1 4 9
67

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
1 3 5 7 9
71

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

73. Getting Info from Sequences
ints = [1, 3, 5, 7, 9]
1 3 5 7 9
[0] [1] [2] [3] [4]
§ 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

74. Getting Slices from Sequences
ints = [1, 3, 5, 7, 9]
1 3 5 7 9
[0] [1] [2] [3] [4]
§ 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

75. Getting Subsets from Sequences
ints = [1, 3, 5, 7, 9]
1 3 5 7 9
[0] [1] [2] [3] [4]
§ 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

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

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