Other Components

• ActivityStarter
• BarcodeScanner
• BluetoothClient
• BluetoothServer
• Notifier
• SpeechRecognizer
• TextToSpeech
• TinyWebDB
• Web

ActivityStarter

A component that can launch another activity from your application.

You communicate with the activity starter by setting properties of the component to pass information related to the activity, including the action and activity class. See Using the Activity Starter Component for details and examples.

Activities that can be launched include:

• Starting another App Inventor for Android app. To do so, first determine class of the other application by downloading the source code and using a file explorer or unzip utility to find a file named "youngandroidproject/project.properties". The first line of the file will start with "main=" and be followed by the class name; for example,

  main=com.gmail.Bitdiddle.Ben.HelloPurr.Screen1

  To make your ActivityStarter launch this application, set the following properties:

  • ActivityPackage to the class name, dropping the last component (for example, com.gmail.Bitdiddle.Ben.HelloPurr)
  • ActivityClass to the entire class name (for example, com.gmail.Bitdiddle.Ben.HelloPurr.Screen1)
• Starting an activity that is built in to the Android OS, such as using the camera, or performing a web search. You can start camera by setting the following properties:
  • Action: android.intent.action.MAIN
  • ActivityPackage: com.android.camera
  • ActivityClass: com.android.camera.Camera
• Performing web search: Assuming the term you want to search for is "vampire" (feel free to substitute your own choice), set the properties to:
  • Action: android.intent.action.WEB_SEARCH
  • ExtraKey: query
  • ExtraValue: vampire
  • ActivityPackage: com.google.android.providers.enhancedgooglesearch
  • ActivityClass: com.google.android.providers.enhancedgooglesearch.Launcher
• Opening a browser to a specified web page. Assuming the page you want to go to is "www.facebook.com" (feel free to substitute your own choice), set the properties to:
  • Action: android.intent.action.VIEW
  • DataUri: http://www.facebook.com

You can also launch third-party applications installed on the phone, provided you know the appropriate intents to invoke them, and you can also launch activities that produce text results and get them back to use in your application. The way this data is extracted depends on how the application has been implemented.

Properties

Action: text

Action of the activity to be launched.

ActivityClass: text

Class name of the activity to be launched.

ActivityPackage: text

Package name of the activity to be launched.

DataUri: text

URI passed to activity to be launched.

ExtraKey: text

Key name of text passed to the activity.

ExtraValue: text

Value of text passed to the activity.

Result: text

Value returned by the activity being started.

ResultName: text

The name used to extract the result returned from the activity being started.

ResultType: text

Type information returned from the activity being started.

ResultUri: text

URI (or Data) information returned from the activity being started.

Events

ActivityError(text message)>

Indicates that an error occurred while using this ActivityStarter.

AfterActivity(text result)

Called after activity ends.

Methods

text ResolveActivity()

Returns the name of the activity that corresponds to this ActivityStarter, or an empty string if no corresponding activity can be found. You can use this before starting an external application to ensure that the application is installed on the phone.

StartActivity()

Start the activity associated with this component.

BarcodeScanner

This non-visible component uses the phone's camera to read a 1-dimensional barcode or 2-dimensional barcode (QR code). In order for this component to work, the Barcode scanner app from ZXing must be installed on the phone. This app is available for free in the Android Market.

Properties

Result

The text result of the last successful scan. This becomes available after AfterScan has been signaled. This value is also returned as the result value.

Methods

DoScan()

Start a scan

Events

AfterScan(text result)

Called after scanning ends.

BluetoothClient

Bluetooth client component

Properties

AddressesAndNames

A list of the addresses and names of paired Bluetooth devices.

Available

Tell whether Bluetooth is available on the Android device.

CharacterEncoding

The character encoding to use when sending and receiving text.

DelimiterByte

The delimiter byte to use when passing a negative number for the numberOfBytes parameter when calling ReceiveText, ReceiveSignedBytes, or ReceiveUnsignedBytes.

Enabled

Tell whether Bluetooth is enabled.

HighByteFirst

Whether 2 and 4 byte numbers should be sent and received with the high (or most significant) byte first. Check the documentation for the device with which your app will be communicating for the appropriate setting. This is also known as big-endian.

IsConnected

Tell whether a Bluetooth connection has been made.

Events

none

Methods

number BytesAvailableToReceive()

Returns an estimate of the number of bytes that can be received without blocking

boolean Connect(text address)

Connect to the Bluetooth device with the specified address and the Serial Port Profile (SPP). Returns true if the connection was successful. The address parameter can contain extra characters after the MAC address if there is a space immediately after the MAC address. This means that you may pass an item from the list returned from the AddressesAndNames property without splitting apart the address and the name.

boolean ConnectWithUUID(text address, text uuid)

Connect to the Bluetooth device with the specified address and UUID. Returns true if the connection was successful. The address parameter can contain extra characters after the MAC address if there is a space immediately after the MAC address. This means that you may pass an item from the list returned from the AddressesAndNames property without splitting apart the address and the name.

Disconnect()

Disconnect from the connected Bluetooth device.

boolean IsDevicePaired(text address)

Checks whether the Bluetooth device with the specified address is paired.

number ReceiveSigned1ByteNumber()

Receive a signed 1-byte number from the connected Bluetooth device.

number ReceiveSigned2ByteNumber()

Receive a signed 2-byte number from the connected Bluetooth device.

number ReceiveSigned4ByteNumber()

Receive a signed 4-byte number from the connected Bluetooth device.

list ReceiveSignedBytes(number numberOfBytes)

Receive multiple signed byte values from the connected Bluetooth device. If numberOfBytes is less than 0, read until a delimiter byte value is received.

text ReceiveText(number numberOfBytes)

Receive text from the connected Bluetooth device. If numberOfBytes is less than 0, read until a delimiter byte value is received.

number ReceiveUnsigned1ByteNumber()

Receive an unsigned 1-byte number from the connected Bluetooth device.

number ReceiveUnsigned2ByteNumber()

Receive a unsigned 2-byte number from the connected Bluetooth device.

number ReceiveUnsigned4ByteNumber()

Receive a unsigned 4-byte number from the connected Bluetooth device.

list ReceiveUnsignedBytes(number numberOfBytes)

Receive multiple unsigned byte values from the connected Bluetooth device. If numberOfBytes is less than 0, read until a delimiter byte value is received.

Send1ByteNumber(text number)

Send a 1-byte number to the connected Bluetooth device.

Send2ByteNumber(text number)

Send a 2-byte number to the connected Bluetooth device.

Send4ByteNumber(text number)

Send a 4-byte number to the connected Bluetooth device.

SendBytes(list list)

Send a list of byte values to the connected Bluetooth device.

SendText(text text)

Send text to the connected Bluetooth device.

BluetoothServer

Bluetooth server component

Properties

Available: boolean

Tell whether Bluetooth is available on the Android device.

CharacterEncoding: text

The character encoding to use when sending and receiving text.

DelimiterByte: number

The delimiter byte to use when passing a negative number for the numberOfBytes parameter when calling ReceiveText, ReceiveSignedBytes, or ReceiveUnsignedBytes.

Enabled: boolean

Tell whether Bluetooth is enabled.

HighByteFirst: boolean

Whether 2 and 4 byte numbers should be sent and received with the high (or most significant) byte first. Check the documentation for the device with which your app will be communicating for the appropriate setting. This is also known as big-endian.

IsAccepting: boolean

Tell whether this BluetoothServer component is accepting an incoming connection.

IsConnected: boolean

Tell whether a Bluetooth connection has been made.

Events

ConnectionAccepted()

Indicates that a bluetooth connection has been accepted.

Methods

AcceptConnection(text serviceName)

Accept an incoming connection with the Serial Port Profile (SPP).

AcceptConnectionWithUUID(text serviceName, text uuid)

Accept an incoming connection with a specific UUID.

number BytesAvailableToReceive()

Returns an estimate of the number of bytes that can be received without blocking

Disconnect()

Disconnect from the connected Bluetooth device.

number ReceiveSigned1ByteNumber()

Receive a signed 1-byte number from the connected Bluetooth device.

number ReceiveSigned2ByteNumber()

Receive a signed 2-byte number from the connected Bluetooth device.

number ReceiveSigned4ByteNumber()

Receive a signed 4-byte number from the connected Bluetooth device.

list ReceiveSignedBytes(number numberOfBytes)

Receive multiple signed byte values from the connected Bluetooth device. If numberOfBytes is less than 0, read until a delimiter byte value is received.

text ReceiveText(number numberOfBytes)

Receive text from the connected Bluetooth device. If numberOfBytes is less than 0, read until a delimiter byte value is received.

number ReceiveUnsigned1ByteNumber()

Receive an unsigned 1-byte number from the connected Bluetooth device.

number ReceiveUnsigned2ByteNumber()

Receive a unsigned 2-byte number from the connected Bluetooth device.

number ReceiveUnsigned4ByteNumber()

Receive a unsigned 4-byte number from the connected Bluetooth device.

list ReceiveUnsignedBytes(number numberOfBytes)

Receive multiple unsigned byte values from the connected Bluetooth device. If numberOfBytes is less than 0, read until a delimiter byte value is received.

Send1ByteNumber(text number)

Send a 1-byte number to the connected Bluetooth device.

Send2ByteNumber(text number)

Send a 2-byte number to the connected Bluetooth device.

Send4ByteNumber(text number)

Send a 4-byte number to the connected Bluetooth device.

SendBytes(list list)

Send a list of byte values to the connected Bluetooth device.

SendText(text text)

Send text to the connected Bluetooth device.

StopAccepting()

Stop accepting an incoming connection.

Notifier

A notifier is a non-visible component that can show verious kinds of alerts and can log information. Use a notifier to display notices and alerts to users of your app, and also to log information that can help you debug your app.

Methods

ShowMessageDialog(Text message, Text title, Text buttonText)

Pops up a notice that remains until the user taps a button with the given text. The arguments are the message to be shown, the title of the notice, and the label on the button.

ShowChooseDialog(Text message, Text title, Text button1Text, Text button2Text)

Pops up a notice the user must respond to by tapping one of two buttons with the given text. The arguments are the message to be shown, the title of the notice, and the labels on the left and right buttons, respectively. The AfterChoosing event is signalled after the user taps one of the buttons.

ShowTextDialog(Text message, Text title)

Pops up a notice which the user must respond to by entering some text. The arguments are the message to be shown and the title of the notice. The AfterTextInput event is signalled after the user enters the text.

ShowAlert(Text message

Pops up a temporary notice, which vanishes after a few seconds. The argument is the text of the notice.

LogError(Text message)

LogError(Text message)

LogError(Text message)

These methods are for use in debugging. They write messages to the various logs on the Android device. The logs can be read with the use of Android debugging tools, like the Android Debug Bridge (ADB).

Events

AfterChoosing(Text choice)

Signaled after the user has made a choice in response to ShowChooseDialog. The argument is the text on the button that the user tapped.

AfterTextInput(Text response)

Signaled after the user has responded to ShowTextDialog. The argument is the text on the button that the user entered.

SpeechRecognizer

Use a speech recognizer component to listen to the user speaking and convert the spoken sound into text using Android's speech recognition feature.

Properties

Result

The last text produced by the recognizer.

Methods

GetText()

Asks the user to speak, and converts the speech to text. Signals the AfterGettingText event when the result is available.

Events

AfterGetting(Text result)

Signaled after the recognizer has produced text. The argument is the text result that was produced.

BeforeGettingText()

Signaled just before the recognizer is called.

TextToSpeech

Use a text-to-speech component to have the device speak text audibly.

In order for this component to work, the device must have the TTS Extended Service app by Eyes-Free Project installed. You can download this from http://code.google.com/p/eyes-free/downloads/list

The text-to-speech component has properties you can set to guide the pronunciation of the text to be spoken. These properties use three-letter codes to specify the language and the country in which the language is spoken. For example, you can specify British English or US English. For British English, the language code is eng and the country code is GBR, while for US English, the language code is eng and the country code is USA. The complete list is below.

Properties

Country

The country code for speech production.

Language

The language code for speech production.

Result

Details to come.

Methods

Speak(Text message)

Speaks the given text.

Events

AfterSpeaking(Text result)

Signaled after the text is spoken. The argument is the text result that was produced.

BeforeSpeaking()

Signaled just before the text is spoken.

Here are the language and country codes you can use. The codes are organized first by language; then, in each language section are a list of possible country codes:

• ces (Czech)
  • CZE
• 
  
• spa (Spanish)
  • ESP
  • USA
• 
  
• deu (German)
  • AUT
  • BEL
  • CHE
  • DEU
  • LIE
  • LUX
• 
  
• fra (French)
• • BEL
  • CAN
  • CHE
  • FRA
  • LUX
• 
  
• nld (Dutch)
  • BEL
  • NLD
• 
  
• ita (Italian)
• • CHE
  • ITA
• 
  
• pol (Polish)
• • POL
• 
  
• eng (English)
• • AUS
  • BEL
  • BWA
  • BLZ
  • CAN
  • GBR
  • HKG
  • IRL
  • IND
  • JAM
  • MHL
  • MLT
  • NAM
  • NZL
  • PHL
  • PAK
  • SGP
  • TTO
  • USA
  • VIR
  • ZAF
  • ZWE

TinyWebDB

Non-visible component that communicates with a Web service to store and retrieve information.

See Creating a Custom TinyWebDB Service.

Properties

ServiceURL

Events

GotValue(text tagFromWebDB, any valueFromWebDB)

Indicates that a GetValue server request has succeeded.

ValueStored()

Event indicating that a StoreValue server request has succeeded.

WebServiceError(text message)

Indicates that the communication with the Web service signaled an error

Methods

GetValue(text tag)

GetValue asks the Web service to get the value stored under the given tag. It is up to the Web service what to return if there is no value stored under the tag. This component just accepts whatever is returned.

StoreValue(text tag, any valueToStore)

Asks the Web service to store the given value under the given tag

Web

Non-visible component that provides functions for HTTP GET and POST requests.

Properties

AllowCookies

Whether the cookies from a response should be saved and used in subsequent requests. Cookies are only supported on Android version 2.3 or greater.

RequestHeaders

The request headers, as a list of two-element sublists. The first element of each sublist represents the request header field name. The second element of each sublist represents the request header field values, either a single value or a list containing multiple values.

ResponseFileName

The name of the file where the response should be saved. If SaveResponse is true and ResponseFileName is empty, then a new file name will be generated.

SaveResponse

Whether the response should be saved in a file.

Url

The URL for the web request.

Events

GotFile(text url, number responseCode, text responseType, text fileName)

Event indicating that a request has finished.

GotText(text url, number responseCode, text responseType, text responseContent)

Event indicating that a request has finished.

Methods

text BuildPostData(list list)

Converts a list of two-element sublists, representing name and value pairs, to a string formatted as application/x-www-form-urlencoded media type, suitable to pass to PostText.

ClearCookies()

Clears all cookies for this Web component.

Get()

Performs an HTTP GET request using the Url property and retrieves the response.
If the SaveResponse property is true, the response will be saved in a file and the GotFile event will be triggered. The ResponseFileName property can be used to specify the name of the file.
If the SaveResponse property is false, the GotText event will be triggered.

text HtmlTextDecode(text htmlText)

Decodes the given HTML text value. HTML character entities such as &amp;, &lt;, &gt;, &apos;, and &quot; are changed to &, <, >, ', and ". Entities such as &#xhhhh, and &#nnnn are changed to the appropriate characters.

text JsonTextDecode(text jsonText)

Decodes the given JSON text value. If the given JSON text is surrounded by quotes, the quotes will be removed.

PostFile(text path)

Performs an HTTP POST request using the Url property and data from the specified file.
If the SaveResponse property is true, the response will be saved in a file and the GotFile event will be triggered. The ResponseFileName property can be used to specify the name of the file.
If the SaveResponse property is false, the GotText event will be triggered.

PostText(text text)

Performs an HTTP POST request using the Url property and the specified text.
The characters of the text are encoded using UTF-8 encoding.
If the SaveResponse property is true, the response will be saved in a file and the GotFile event will be triggered. The responseFileName property can be used to specify the name of the file.
If the SaveResponse property is false, the GotText event will be triggered.

PostTextWithEncoding(text text, text encoding)

Performs an HTTP POST request using the Url property and the specified text.
The characters of the text are encoded using the given encoding.
If the SaveResponse property is true, the response will be saved in a file and the GotFile event will be triggered. The ResponseFileName property can be used to specify the name of the file.
If the SaveResponse property is false, the GotText event will be triggered.

text UriEncode(text text)

Encodes the given text value so that it can be used in a URL.