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Introduction to Android Window System
This document outlines an introduction to the Android window system presented by Chia-I Wu. It covers the basic building blocks of SurfaceManager, WindowManager, and ActivityManager. It discusses concepts under the hood like process view, zygote, and binder. It also provides guidance on development tools and code areas relevant to understanding the window system.
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Introduction to Android Window System
- 1. Outline Building Blocks Under the Hood Get Dirty Q&A Introduction to Android Window System Chia-I Wu olv@0xlab.org May 15, 2009 Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 2. Outline Building Blocks Under the Hood Get Dirty Q&A Building Blocks Overview Interested Components Under the Hood Random Topics Get Dirty Development Code Q&A Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 3. Outline Building Blocks Overview Under the Hood Interested Components Get Dirty Q&A Outline Building Blocks Overview Interested Components Under the Hood Random Topics Get Dirty Development Code Q&A Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 4. Outline Building Blocks Overview Under the Hood Interested Components Get Dirty Q&A System Architecture Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 5. Outline Building Blocks Overview Under the Hood Interested Components Get Dirty Q&A System Architecture Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 6. Outline Building Blocks Overview Under the Hood Interested Components Get Dirty Q&A System Architecture Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 7. Outline Building Blocks Overview Under the Hood Interested Components Get Dirty Q&A Building Blocks There are more, but we focus on SurfaceManager WindowManager ActivityManager Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 8. Outline Building Blocks Overview Under the Hood Interested Components Get Dirty Q&A SurfaceManager frameworks/base/libs/surfaceflinger/ a.k.a SurfaceFlinger Allocate surfaces. Backed by ashmem/pmem/? Composite surfaces Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 9. Outline Building Blocks Overview Under the Hood Interested Components Get Dirty Q&A WindowManager frameworks/base/services/java/ com/android/server/WindowManagerService.java About 9000 SLOC in one file. Poorly documented, bad namings, ... (Ask SurfaceManager to) create/layout surfaces on behalf of the clients Dispatch input events to clients Transition animation WindowManagerPolicy Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 10. Outline Building Blocks Overview Under the Hood Interested Components Get Dirty Q&A ActivityManager frameworks/base/services/java/ com/android/server/am/ Manage lifecycles of activities Manage stacking of activities Dispatch intents Spawn processes Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 11. Outline Building Blocks Overview Under the Hood Interested Components Get Dirty Q&A Confusions An activity has one or more windows (e.g. dialogs) A window has one or more surfaces (e.g. surface views) However, in window manager, a window is called a session A surface is called a window And an activity becomes roughly a token Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 12. Outline Building Blocks Overview Under the Hood Interested Components Get Dirty Q&A Special Keys HOME key BACK key Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 13. Outline Building Blocks Under the Hood Random Topics Get Dirty Q&A Outline Building Blocks Overview Interested Components Under the Hood Random Topics Get Dirty Development Code Q&A Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 14. Outline Building Blocks Under the Hood Random Topics Get Dirty Q&A Process View SurfaceManager, WindowManager, and SurfaceManager are threads of a single process (system server) Every application is usually a process of itself Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 15. Outline Building Blocks Under the Hood Random Topics Get Dirty Q&A Zygote Is a process started on system initialization Preloads java classes and resources Forks system server Listens silently on /dev/socket/zygote Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 16. Outline Building Blocks Under the Hood Random Topics Get Dirty Q&A Binder Early in the lifetime of an application process, thread(s) are created and blocked on /dev/binder Binder is used mainly for RPC Fragile Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 17. Outline Building Blocks Development Under the Hood Code Get Dirty Q&A Outline Building Blocks Overview Interested Components Under the Hood Random Topics Get Dirty Development Code Q&A Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 18. Outline Building Blocks Development Under the Hood Code Get Dirty Q&A Build System build/core/core/build-system.html . build/envsetup.sh showcommands export ANDROID JAVA HOME if non-standard Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 19. Outline Building Blocks Development Under the Hood Code Get Dirty Q&A adb ADBHOST for transport over TCP/IP kill-server remount pull/push logcat shell Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 20. Outline Building Blocks Development Under the Hood Code Get Dirty Q&A hierarchyviewer Display view hierarchy Display view Invalidate/Relayout Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 21. Outline Building Blocks Development Under the Hood Code Get Dirty Q&A Graphics: Memory Management SurfaceFlinger has a SurfaceHeapManager Every client has a MemoryDealer, as returned by SurfaceHeapManager Every surface of a client also has dealer(s), from client or GPU Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 22. Outline Building Blocks Development Under the Hood Code Get Dirty Q&A Graphics: Memory Management cont. A dealer consists of a heap and an allocator A heap represents a sharable big chunk of memory An allocator is an algorithm Small chunks of memory from the heap are returned Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 23. Outline Building Blocks Development Under the Hood Code Get Dirty Q&A Graphics: Memory Management cont. Real flow A client asks for a new surface, createSurface Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 24. Outline Building Blocks Development Under the Hood Code Get Dirty Q&A Graphics: Memory Management cont. Real flow A client asks for a new surface, createSurface createSurface calls createNormalSurfaceLocked Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 25. Outline Building Blocks Development Under the Hood Code Get Dirty Q&A Graphics: Memory Management cont. Real flow A client asks for a new surface, createSurface createSurface calls createNormalSurfaceLocked A layer is created and setBuffers is called to allocate buffers Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 26. Outline Building Blocks Development Under the Hood Code Get Dirty Q&A Graphics: Memory Management cont. Real flow A client asks for a new surface, createSurface createSurface calls createNormalSurfaceLocked A layer is created and setBuffers is called to allocate buffers Two dealers are created from client, one for front buffer and one for back buffer Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 27. Outline Building Blocks Development Under the Hood Code Get Dirty Q&A Graphics: Memory Management cont. Real flow A client asks for a new surface, createSurface createSurface calls createNormalSurfaceLocked A layer is created and setBuffers is called to allocate buffers Two dealers are created from client, one for front buffer and one for back buffer Two LayerBitmaps are created, initialized with the two dealers Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 28. Outline Building Blocks Development Under the Hood Code Get Dirty Q&A Graphics: Memory Management cont. Real flow A client asks for a new surface, createSurface createSurface calls createNormalSurfaceLocked A layer is created and setBuffers is called to allocate buffers Two dealers are created from client, one for front buffer and one for back buffer Two LayerBitmaps are created, initialized with the two dealers Heaps of dealers along with info about the layer are returned Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 29. Outline Building Blocks Development Under the Hood Code Get Dirty Q&A Hello World http://people.debian.org.tw/˜olv/surfaceflinger/demo.tar.gz Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 30. Outline Building Blocks Development Under the Hood Code Get Dirty Q&A Many Buffers Surface is double buffered EGLDisplaySurface is double buffered Same technique; Different code pathes, different purposes Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 31. Outline Building Blocks Development Under the Hood Code Get Dirty Q&A Double Buffering Sofware v.s. Hardware Memory copy Page flipping Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 32. Outline Building Blocks Development Under the Hood Code Get Dirty Q&A Dirty Region Associate buffers with dirty regions Copy back Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 33. Outline Building Blocks Development Under the Hood Code Get Dirty Q&A Frame 0 Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 34. Outline Building Blocks Development Under the Hood Code Get Dirty Q&A Frame 1 Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 35. Outline Building Blocks Development Under the Hood Code Get Dirty Q&A Frame 2 Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 36. Outline Building Blocks Under the Hood Get Dirty Q&A Outline Building Blocks Overview Interested Components Under the Hood Random Topics Get Dirty Development Code Q&A Chia-I Wu olv@0xlab.org Introduction to Android Window System
- 37. Outline Building Blocks Under the Hood Get Dirty Q&A Q&A Questions? Chia-I Wu olv@0xlab.org Introduction to Android Window System