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Android Open Source Project
  • Docs
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    • What's New?
    • Getting Started
    • Security
    • Core Topics
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  • Android Code Search
  • Overview
  • Architecture
    • Overview
    • Hardware abstraction layer (HAL)
      • Overview
      • HIDL (deprecated)
        • Overview
        • Interfaces and packages
        • Interface hashing
        • Services and data transfer
        • Fast Message Queue
        • Use Binder IPC
        • Use MemoryBlock
        • Network stack configuration tools
        • Model threading
        • Convert HAL modules
        • Data types
        • Safe union
        • Interface versioning
        • Code style guide
        • HIDL C++
        • Overview
        • Packages
        • Interfaces
        • Data types
        • Functions
        • HIDL Java
        • Overview
        • Data types
        • Interface methods and errors
        • Export constants
        • Other
        • HIDL framework backward compatibility verification
        • Dynamically available HALs
      • Legacy HALs (AOSP <=v7)
    • Kernel
      • Overview
      • Kernel release notes
      • Stable kernel releases and updates
      • Android common kernels
      • GKI project
      • GKI development
      • GKI versioning scheme
      • GKI release builds
        • Overview
        • android12-5.10 release builds
        • android13-5.10 release builds
        • android13-5.15 release builds
        • android14-5.15 release builds
        • android14-6.1 release builds
        • android15-6.6 release builds
        • android16-6.12 release builds
      • GKI deprecated builds
        • android12-5.10 deprecated builds
        • android13-5.10 deprecated builds
        • android13-5.15 deprecated builds
        • android14-5.15 deprecated builds
        • android14-6.1 deprecated builds
        • android15-6.6 deprecated builds
        • android16-6.12 deprecated builds
      • GKI release process
      • GKI 16-6.12 android-mainline errata
      • Maintain a stable KMI
      • Kernel ABI monitoring
        • Overview
        • Run ABI monitoring
        • Work with symbol lists
      • Modules
        • Overview
        • Configure kernel features as GKI modules
        • Vendor module guidelines
        • Loadable kernel modules
        • Kernel module support
        • Test GKI modules
      • Boot time optimization
      • Debug features
      • Develop kernel code for GKI
      • Android kernel file system support
      • Extend the kernel with eBPF
      • Use DebugFS in Android 12
      • FIPS 140-3 certifiable GKI crypto module
      • EROFS
      • Android kernel FAQ
      • Kernel networking unit tests
      • Transition from ION to DMA-BUF heaps (5.4 kernel)
      • Incremental file system
    • Configuration
      • Overview
      • Implement system properties as APIs
      • Add system properties
      • Implement Config File Schema API
      • Archive
        • Overview
        • ConfigStore
        • Create the HAL interface
        • Implement the service
        • Client-side use
        • Add ConfigStore classes and items
    • Device tree overlays
      • Overview
      • Implement DTOs
      • DTO syntax
      • Compile and verify
      • Use multiple DTs
      • DTB and DTBO partitions
      • Optimize DTO
    • Vendor NDK (<=AOSP 14)
      • Overview
      • Enable VNDK
      • VNDK build system support
      • VNDK extensions
      • VNDK snapshot design
      • Generate VNDK snapshots
      • Generate vendor snapshots
      • Linker namespace
      • Directories, rules, and sepolicy
      • RenderScript
      • ABI stability
      • Prebuilt ABI usages checker
    • Vendor interface object
      • Overview
      • Manifests
      • Compatibility matrixes
      • FCM lifecycle
      • Device manifest development
      • Match rules
      • Additional resources
    • AIDL
      • Overview
      • AIDL language
      • AIDL backends
      • Stable AIDL
      • AIDL for HALs
      • Run AIDL services dynamically
      • Annotations in AIDL
      • FMQ with AIDL
      • AIDL fuzzing
      • AIDL style guide
    • Interprocess communication with Binder
      • Overview
      • Handle threads
      • Priority inheritance
    • Bootloader
      • Overview
      • Canonical boot reason
      • Boot image header
      • Implement bootconfig
      • Recovery images
      • DTB images
      • Implement OTA updates
      • Lock and unlock the bootloader
      • Version information in AVB properties
      • Move fastboot to userspace
      • Generic Bootloader
        • Overview
        • Deploy GBL
    • Partitions
      • Overview
      • Partition layout
      • Vendor boot partitions
      • Vendor and ODM DLKM partitions
      • Android shared system image
      • Ramdisk partitions
      • Generic boot partition
      • ODM partitions
      • Product partitions
      • Implement a GKI module partition
      • Enforce product partition interfaces
      • Trusty OS partitions
    • 16 KB page size
      • Overview
      • Use Cuttlefish with 16 KB page size on ARM64
      • Simulate Cuttlefish with 16 KB page size on x86-64
      • Build and Flash Pixel 8 devices with 16 KB support
      • Flash Pixel with 16 KB page size support
      • Get the page size
      • Optimize performance for 16 KB mode
      • 16 KB system properties
      • Enable 16 KB toggle
      • Enable 16 KB backcompat option
    • Vendor API level
  • Audio
    • Overview
    • Terminology
    • Implementation
      • Audio HAL
      • AIDL Audio HAL
      • Configurable Audio Policy support in AIDL HAL
      • AIDL and HIDL Audio HAL comparison
      • HIDL
        • HIDL Audio HAL
        • Configure audio policies
        • Configure a shared library
      • Configure preprocessing effects
    • Data formats
    • Attributes
    • Effects
    • High-resolution audio
    • Device type limit
    • AAudio and MMAP
    • Audio warmup
    • Latency
      • Overview
      • Contributors
      • Design for reduced latency
      • Measure audio latency
      • Audio loopback dongle
      • Measurements
      • For app developers
    • Avoid priority inversion
    • Sample rate conversion
    • Debugging
    • MIDI
      • Overview
      • MIDI architecture
      • MIDI test procedure
    • USB
      • USB digital audio
      • Preferred mixer attributes on USB devices
    • TV audio
    • Concurrent capture
    • Sound Trigger
    • Combined audio device routing
    • Spatial audio
      • Spatial audio and head tracking
      • Implementation
      • Head tracking over LE audio
    • Sound dose
    • Dynamic soundbar mode
  • Camera
    • Overview
    • Architecture
    • Camera HAL
    • HAL subsystem
    • Core concepts
    • 3A modes and state transition
    • Camera debugging
    • Error and stream handling
    • Metadata and controls
    • Output streams, cropping, and zoom
    • Request creation and submission
    • Stream configurations
    • Performance
    • Camera HAL3 buffer management APIs
    • Session parameters
    • Single producer, multiple consumer
    • Camera features
    • 10-bit camera output
    • Camera bokeh
    • Concurrent camera streaming
    • Camera extensions
    • Camera extensions validation tool
    • Camera preview stabilization
    • External USB cameras
    • High dynamic range modes
    • HEIF imaging
    • Monochrome cameras
    • Motion tracking
    • Multi-camera support
    • System cameras
    • Torch strength control
    • Ultra HDR
    • Use a device as a webcam
    • Wide gamut capture
    • Versioning
    • Camera version support
  • Connectivity
    • Overview
    • Bluetooth
      • Overview
      • Bluetooth services
      • Bluetooth Low Energy
      • Hearing aid audio support using BLE
      • BLE advertising
      • Verify and debug
      • HCI requirements
      • Presence calibration
      • Android OS identification
    • NFC
      • Host card emulation of FeliCa
      • NFC off-host payment synchronization
      • Secure NFC
      • Quick Access Wallet
      • Android proprietary NCI commands
    • Calling and messaging
      • 5G non-standalone (NSA)
      • Implement phone number blocking
      • Call notifications
      • Domain selection service
      • Implement Emergency Affordance
      • Android emergency number database
      • Emergency numbers and emergency calling
      • Implement IMS
      • IMS service entitlement
      • IMS single registration
      • Phone account suggestion
      • Implement RTT
      • Support third-party calling apps
      • Visual voicemail
    • Carrier
      • Overview
      • 5G network slicing
      • APN and CarrierConfig
      • Carrier identification
      • Implement data plans
      • Device identifiers
      • eSIM
        • Implement eSIM
        • Modem requirements for eSIM support
        • eUICC APIs
        • Multiple enabled profiles
        • Handle eUICC API errors
        • Downloadable test profiles
        • eSIM transfer carrier integration
      • Improve VPN user experience
      • Multi-operator network support
      • Customize device behavior for out-of-balance users
      • RIL refactoring
      • Small cell support
      • UICC carrier privileges
    • Time
      • Overview
      • Location time zone detection
      • Telephony time zone detection
      • Network time detection
      • GNSS time detection
      • External time detection
      • Time source priority
      • Time zone policy and recommendations
      • Time zone rules
    • Ultra-wideband
      • Overview
      • UWB HAL interface
    • Wi-Fi
      • Overview
      • Wi-Fi HAL
      • Wi-Fi infrastructure features
      • Test, debug, and tune Wi-Fi
      • Android Packet Filter
      • Carrier Wi-Fi
      • MAC randomization behavior
      • Implement MAC randomization
      • Passpoint (Hotspot 2.0)
      • Wi-Fi STA/AP concurrency
      • Wi-Fi STA/STA concurrency
      • Trust on First Use (TOFU)
      • Wi-Fi Aware
      • Wi-Fi/cellular coex channel avoidance
      • Wi-Fi Direct
      • Wi-Fi Easy Connect
      • Wi-Fi hotspot (Soft AP)
      • Wi-Fi AP/AP concurrency
      • Wi-Fi low-latency mode
      • Wi-Fi network selection
      • Wi-Fi preferred network offload scanning
      • Wi-Fi Round Trip Time (RTT)
      • WPA3 and Wi-Fi Enhanced Open
      • Wi-Fi 7
    • Companion device profiles
    • Connectivity Diagnostics API
    • Connectivity user interface
    • Network selection
    • Ranging: Out-of-band message sequence and payload specification
    • Signal strength reporting
  • Data
    • Overview
    • Data usage tags explained
    • Data Saver mode
    • eBPF traffic monitoring
    • Exclude network types from usage data
    • Network interface statistics overview
    • Tethering data
    • Tethering hardware offload
    • Usage cycle reset dates
    • Kernel overview
    • Kernel changes
  • Display
    • Overview
    • Apps
      • Implement adaptive icons
      • App shortcuts
      • Implement circular icons
      • Conversation notifications and widgets
      • Window blurs
      • Widgets and shortcuts
      • Implement synchronized app transitions
    • Color
      • Color management
      • Display cutouts
      • Do not disturb
      • HDR video playback
      • Implement night light
      • Tone mapping HDR luminance to an SDR-compatible range
      • Material You design
      • Dynamic color
    • Multi-Window
      • Overview
      • Desktop windowing features
      • Split-screen interactions
      • Picture-in-picture
      • Window magnification
    • Multi-Display
      • Overview
      • Recommended practices
      • Testing and development environment
      • Frequently asked questions
      • Multi-resume
      • Activity launch policy
      • Display support
      • System decorations support
      • Lock screen
      • Input method editor support
      • Input routing
      • Multi-zone audio
    • Notifications
      • Notification history
      • Permission for opt-In notifications
    • Task Manager
    • Retail demo mode
    • Rotate suggestions
    • Implement text classifier
    • Mixed SDR and HDR composition
    • Media controls in System UI
    • WindowManager extensions
  • Fonts
    • Implement custom font fallback
  • Graphics
    • Overview
    • Architecture
    • BufferQueue and Gralloc
    • Implement DMABUF and GPU memory accounting
    • Trace window transitions using Winscope
      • Overview
      • Run Winscope
      • Capture traces
        • Overview
        • ViewCapture in system apps
        • On device
        • Use Winscope
        • Use adb commands
      • Load traces
      • Analyze traces
        • Overview
        • Timeline navigation
        • Trace search
        • SurfaceFlinger
        • WindowManager
        • Protolog
        • Shell transitions
        • ViewCapture
    • Surface and SurfaceHolder
      • Overview
      • SurfaceView and GLSurfaceView
      • SurfaceTexture
      • TextureView
    • SurfaceFlinger and WindowManager
      • Overview
      • System properties in SurfaceFlinger
    • Hardware Composer HAL
      • Overview
      • Implement HWC HAL
      • Hotplug handling
      • AIDL for HWC HAL
      • Client framebuffer management
      • Reduce graphics memory consumption
    • Layers and displays
    • VSync
    • Frame pacing
    • Multiple refresh rate
    • Adaptive refresh rate
    • EGLSurfaces and OpenGL ES
      • Overview
      • Implement OpenGL ES and EGL
      • OpenGLRenderer configuration
    • Vulkan
      • Overview
      • Implement Vulkan
    • Synchronization framework
    • Testing
      • Implementation testing
      • Integrate with Android CTS
      • drawElements Quality Program testing
    • Unsignaled buffer latching with AutoSingleLayer
    • Add new pixel formats to Android
    • HDR in Android screenshots
  • Interaction
    • Overview
    • Input
    • Overview
    • Key layout files
    • Key character map files
    • Input device configuration files
    • Migration guide
    • Keyboard devices
    • Touch devices
    • getevent tool
    • validatekeymaps tool
    • Haptics
    • Overview
    • Implement haptics
      • Overview
      • Implement constants and primitives
      • Map constants between HAL and API
      • Implement piecewise linear envelope effects
      • Assess the hardware
    • UX foundation for haptic framework
    • Haptics UX design
    • Hardware assessment
      • Overview
      • Set up the testing equipment
      • Set up the test software
      • Measure and record target effects