Android How to Program Presented by Thomas Bucag, Rob Goodfellowe, Samantha Tomeï © by Pearson Education, Inc. All Rights Reserved.

 Objectives  Demo of the app/GUI design  Technology Overview  UML Diagrams  BitmapFactory  TransitionDrawable  MediaPlayer  Intents

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 Launching Intents that use built-in content providers  Specifying the GUI for an AlertDialog  Customizing the Layout for a ListActivity  Launch an Intent that returns a result  ArrayAdapter for a ListView  View-Holder Pattern  Notifying a ListView when its data source changes  Adding data to a GUI component for use in an event handler  Playing Music with a MediaPlayer  Loading Images with BitmapFactory  Cross fading between images with TransitionDrawable and BitmapDrawable Technology Overview

Class Overview Diagrams Generated by ObjectAid UML Explorer for Eclipse

Slideshow Class Diagrams Generated by ObjectAid UML Explorer for Eclipse

Slideshow Editor Class Class SlideshowEditor is-a ListActivity (List View) is-an Activity Diagrams Generated by ObjectAid UML Explorer for Eclipse Load BitmapFactory

Class SlideshowInfo, SlideshowPlayer SlideshowInfo is used by Slideshow Stores data for a single slideshow Diagrams Generated by ObjectAid UML Explorer for Eclipse

TransitionDrawable Class PictureTaker, MediaItem Diagrams Generated by ObjectAid UML Explorer for Eclipse

Bitmap Factory Used to create bitmap objects Used in this app to load from the device for use as thumbnails Package: android.graphics Extends: java.lang.Object.android.graphics.BitmapFactory Nested Class: BitmapFactory.Options Used in this case to configure the bitmaps, and downsample the images to save memory Helps prevent out of memory errors common with bitmaps Public Constructor: BitmapFactory() Public Methods: public static BitmapdecodeFile(String pathName) Since: API Level 1 Decode a file path into a bitmap. If the specified file name is null, or cannot be decoded into a bitmap, the function returns null. Parameters: pathName - complete path name for the file to be decoded. Returns the resulting decoded bitmap, or null if it could not be decoded. BitmapFactory.Options() - Create a default Options object, which if left unchanged will give the same result from the decoder as if null were passed. Source: android.developer.com retrieved 30 July 2012

TransitionDrawable extends LayerDrawable implements Drawable.Callback Hierarchy java.lang.Object android.graphics.drawable.Drawable android.graphics.drawable.LayerDrawable android.graphics.drawable.TransitionDrawable An extension of LayerDrawables that is intended to cross-fade between the first and second layer. To start the transition, call startTransition(int). To display just the first layer, call resetTransition(). It can be defined in an XML file with the element. Each Drawable in the transition is defined in a nested. For more information, see the guide to Drawable Resources. Source: android.developer.com retrieved 30 July 2012

TransitionDrawable Public Constructor: TransitionDrawable(Drawable[] layers) Create a new transition drawable with the specified list of layers (at least 2). Public Methods: draw(Canvas canvas): Draw in its bounds (set via setBounds) respecting optional effects such as alpha (set via setAlpha) and color filter (set via setColorFilter). setCrossFadeEnabled(boolean enabled): Enables or disables the cross fade of the drawables. isCrossFadeEnabled(): Indicates whether the cross fade is enabled for this transition. startTransition(int durationMillis): Begin the second layer on top of the first layer. XML Attributes android:top, :left, :right, :bottom - coordinate of the layer’s side. android:drawable - Drawable used to render the layer. android:id - Identifier of the layer. This can be used to retrieve the layer from a drawbable container. Source: android.developer.com retrieved 30 July 2012

Ability to play music and videos within an application  Import android.media.MediaPlayer  MediaPlayer vs SoundPool  Methods associated with MediaPlayer ◦ MediaPlayer//create new object ◦ setDataSource//obtain file location ◦ Prepare//prepares player ◦ seekTo//passes a time ◦ start//starts media player ◦ pause //pauses playback ◦ reset//resets media player ◦ release//releases resources ◦ setLooping//loop playback  Developer.android.com/reference/android/media/MediaPlayer.html MediaPlayer

Launching Intents that use built-in content providers  Specify the MIME type of data ◦ Activity that shows specified type of data (Fig. 12.4a) ◦ Activity-chooser dialog to select Activity to use (Fig. 12.5) Launch an Intent that returns a result  startActivity to launch Activity associated with each Intent ◦ Favorite Twitter Searches app returns from Browser ◦ Address Book app automatically returns to main Activity  startActivityForResult ◦ Refresh the Slideshow Activity’s ListView after the user edits a slideshow ◦ Refresh the SlideshowEditor Activity’s ListView after the user adds a new image to the slideshow ◦ Get the location of an image of music track the user added to a slideshow Intents

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Is a ListActivity Is an Activity

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