30. Custom Views and Touch Events
by Kristin Marsicano, Chris Stewart, Bill Phillips
Android Programming: The Big Nerd Ranch Guide, 4th Edition
- Title Page
- Dedication
- Acknowledgments
- Table of Contents
- Learning Android
- The Necessary Tools
- 1. Your First Android Application
- 2. Android and Model-View-Controller
- 3. The Activity Lifecycle
- Rotating GeoQuiz
- Activity States and Lifecycle Callbacks
- Logging the Activity Lifecycle
- Exploring How the Activity Lifecycle Responds to User Actions
- Device Configuration Changes and the Activity Lifecycle
- For the More Curious: UI Updates and Multi-Window Mode
- For the More Curious: Log Levels
- Challenge: Preventing Repeat Answers
- Challenge: Graded Quiz
- 4. Persisting UI State
- 5. Debugging Android Apps
- 6. Your Second Activity
- 7. Android SDK Versions and Compatibility
- 8. UI Fragments and the Fragment Manager
- 9. Displaying Lists with RecyclerView
- Adding a New Fragment and ViewModel
- Adding a RecyclerView
- Creating an Item View Layout
- Implementing a ViewHolder
- Implementing an Adapter to Populate the RecyclerView
- Recycling Views
- Cleaning Up Binding List Items
- Responding to Presses
- For the More Curious: ListView and GridView
- Challenge: RecyclerView ViewTypes
- 10. Creating User Interfaces with Layouts and Widgets
- 11. Databases and the Room Library
- 12. Fragment Navigation
- 13. Dialogs
- 14. The App Bar
- 15. Implicit Intents
- 16. Taking Pictures with Intents
- 17. Localization
- 18. Accessibility
- 19. Data Binding and MVVM
- 20. Unit Testing and Audio Playback
- Creating a SoundPool
- Accessing Assets
- Loading Sounds
- Playing Sounds
- Test Dependencies
- Creating a Test Class
- Setting Up Your Test
- Writing Tests
- Data Binding Callbacks
- Unloading Sounds
- For the More Curious: Integration Testing
- For the More Curious: Mocks and Testing
- Challenge: Playback Speed Control
- Challenge: Play Sound Across Rotation
- 21. Styles and Themes
- 22. XML Drawables
- 23. More About Intents and Tasks
- 24. HTTP and Background Tasks
- Creating PhotoGallery
- Networking Basics with Retrofit
- Fetching JSON from Flickr
- Networking Across Configuration Changes
- Displaying Results in RecyclerView
- For the More Curious: Alternate Parsers and Data Formats
- For the More Curious: Canceling Requests
- For the More Curious: Managing Dependencies
- Challenge: Adding a Custom Gson Deserializer
- Challenge: Paging
- Challenge: Dynamically Adjusting the Number of Columns
- 25. Loopers, Handlers, and HandlerThread
- Preparing RecyclerView to Display Images
- Preparing to Download Bytes from a URL
- Downloading Lots of Small Things
- Assembling a Background Thread
- Messages and Message Handlers
- Listening to the View Lifecycle
- Retained Fragments
- For the More Curious: Solving the Image Downloading Problem
- For the More Curious: StrictMode
- Challenge: Observing View LifecycleOwner LiveData
- Challenge: Improving ThumbnailDownloader’s Lifecycle Awareness
- Challenge: Preloading and Caching
- 26. SearchView and SharedPreferences
- 27. WorkManager
- 28. Broadcast Intents
- 29. Browsing the Web and WebView
- One Last Bit of Flickr Data
- The Easy Way: Implicit Intents
- The Harder Way: WebView
- Proper Rotation with WebView
- WebView vs a Custom UI
- For the More Curious: Injecting JavaScript Objects
- For the More Curious: WebView Updates
- For the More Curious: Chrome Custom Tabs (Another Easy Way)
- Challenge: Using the Back Button for Browser History
- 30. Custom Views and Touch Events
- 31. Property Animation
- 32. Afterword
- Index
In this chapter, you will learn how to handle touch events by writing a custom subclass of View named BoxDrawingView. The BoxDrawingView class will be the star of a new project named DragAndDraw and will draw boxes in response to the user touching the screen and dragging. The finished product will look like Figure 30.1.
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