Hierarchy Viewer Internals

Hierarchy Viewer Internals

Kyungmin Lee
Software Platform Lab., LG Electronics
snailee@gmail.com

What-How-Why-Why not?
http://sangminpark.wordpress.com/2011/09/02/what-how-why-why-not/

What?
Why?

Why not?

When?
Who?

How?

Past

Present

The 9th Kandroid Conference

Future

Goal
Android와 같은 S/W 플랫폼이 성장하고 널리 확산되는데 있어 SDK(Software
Development Kit)의 역할은 매우 큽니다. 아무리 좋은 기능과 성능을 제공하는
플랫폼이라 할지라도 그 위에서 동작하는 앱을 만드는 게 어렵다면 그 플랫폼은
개발자들로부터 외면 받게 됩니다. 이는 해당 플랫폼에서 이용 가능한 앱의 개수가 줄고
품질이 저하되는 결과를 만들게 되어 그 플랫폼은 사용자들에게도 외면 받게 됩니다. 이로
인해 개발자들이 다시금 그 플랫폼을 외면하게 만드는 악순환이 형성됩니다. 이러한
악순환을 끊기 위한 첫 걸음은 바로 개발 생산성을 높여주는 SDK를 잘 만들어 제공하는
것입니다. 따라서 Android 기술 분야에서 경쟁력을 확보하고 주도권을 갖기 위해서는
Android 플랫폼을 제대로 이해하는 것 뿐만 아니라 Android SDK를 제대로 분석하고
개선할 수 있어야 합니다.
이번 세션에서는 "Android SDK 기술의 이해"라는 큰 주제의 첫 꼭지로써 Android
UI(User Interface)를 디버깅하고 프로파일링하는데 사용하는 Hierarchy Viewer를
분석하고자 합니다. 먼저, Hierarchy Viewer를 분석하는데 필요한 몇몇 배경 지식을
설명한 후 Hierarchy Viewer의 내부 구조와 동작 방식을 살펴보겠습니다.
From the Conference Program Overview


SDK (Software Development Kit)
A software development kit (SDK or "devkit") is typically a set of software
development tools that allows for the creation of applications for a certain
software package, software framework, hardware platform, computer system,
video game console, operating system, or similar platform.
It may be something as simple as an application programming interface (API)
in the form of some files to interface to a particular programming language or
include sophisticated hardware to communicate with a certain embedded
system. Common tools include debugging aids and other utilities often presented
in an integrated development environment (IDE). SDKs also frequently include
sample code and supporting technical notes or other supporting documentation
to help clarify points from the primary reference material.
From Wikipedia

Small No. of
Low Quality
Apps

Bad
SDK

Ignored by
Developers

VS.

Large No. of
Hig Quality
Apps

Ignored by
Users

Good
SDK

Attract
Developers

Attract
Users

Android SDK & Hierarchy Viewer
SDK Tools contains tools for debugging and testing
your application and other utility tools.
SDK Platform-tools contains platform-dependent tools for
developing and debugging your application.
Documentation contains a local copy of the latest multi-version
documentation for the Android framework API.

Each SDK platform component includes a fully compliant
• Android library,
• system image (API Level <= 13),
• sample code (API Level <= 6), and
• emulator skins.

Hierarchy Viewer
• Related to graphics
• Complex enough to get insights on
how to develop a tool for Android

Samples contains the sample code and apps available
for each Android development platform.
http://developer.android.com/guide/developing/tools/index.html


Hierarchy Viewer

List of Windows

Properties of a View

Hierarchy of Views in an Window

Layout of Views


Hierarchy Viewer Architecture
4939

Another Target or Emulator

…

Hierarchy
Viewer

4940
4939

4939

Window
Window
Window
…

system server

View
View

View
…

user app.
View

Port Forwarding
View

adb forward tcp:4939 tcp:4939

View
…

user app.
View

ADB
Server

ADB
Daemon

View

View
…

user app.
USB|TCP
Host

Target|Emulator

Roadmap
Questions

Answers

How to get information?
List of Windows

Window & View System 5
Hierarchy of Views in Window
Java Reflection

1

Properties of View
Java Annotations

2

Binder IPC

4

How to deliver information?
Between processes in target
Between host and target

Android Debug Bridge 3

Hierarchy
Viewer
Internals

6

Reflection & Annotation in General
In computer science, reflection is
the process by which a computer
program can observe and
modify its own structure and
behavior at runtime.

Type, interface, class, methods, attributes,
variables, functions, control structures, etc.

Metadata

From Wikipedia
Meta Object

Meta Level

Set/Get
Metadata
(Value)

1

Add New
Metadata
(Type)

2
Application

Base Level

Base Object

Annotation

Reflection
1

Introspection

2

Intercession

In programming, annotations are used mainly for
the purpose of expanding code documentation
and comments. … as a special form of syntactic
metadata in the source code.

From Wikipedia

Using Java Reflection

•
•
•
•

B
C
D
F






byte
char
double
float

•
•
•
•

I
J
S
Z






int
long
short
boolean

• Lclass-name  class-name


Using Java Annotations


Using Java Annotations

Built-in Annotations

Android Debug Bridge
adbd
Target
(USB mode)
cmd-line adb (in platform-tools)

adbd

ADB Server
DDMS (in tools)

Act as proxy between
clients & daemons
(multiplexing loop)

Target
(TCP mode)

adbd

Emulator
Hierarchy Viewer (in tools)

USB Connection
TCP Connection

ADB Clients


ADB Daemons

ADB Architecture
ADB client

Service
Service
Service

5037

ADB client

USB|TCP

Service
Service
Service

ADB Server

adbd

…

fork

Service

adb port
console port

5555

Service

5554

…

5555

adbd
Guest (10.0.2.15)
Emulator
Host

Target


Connection to Emulator
ADB Server

Emulator

Network Address in Emulator
Network Address

Description

10.0.2.1

Router/gateway address

10.0.2.2

Special alias to your host loopback interface
(i.e., 127.0.0.1 on your development machine)

10.0.2.3

First DNS server

10.0.2.4 / 10.0.2.5 / 10.0.2.6

Optional second, third and fourth DNS server (if any)

10.0.2.15

The emulated device's own network/ethernet interface

127.0.0.1

The emulated device's own loopback interface


ADB Services
Host Services

host:version

host:connect

host:transport:<serial>

host:emulator:<port>

host:kill

host:disconnect

host:transport-usb

wait-for-usb|local|any

host:devices

host:get-serialno

host:transport-local

host:track-devices

host:get-state

host:transport-any

root:

tcpip:

sync:

tcp:<port>

dev:<path>

host-serial:<serial>

backup:

usb:

tcp:<port>:<server-name>

local:<path>

host-usb

restore:

recover:<size>

host-local

remount:

jdwp:<pid>

dns:<server-name>

localabstract:<path>

host

reboot:

track-jdwp

framebuffer

localfilesystem:<path>

Local Services

<host-prefix>

dns

forward:<local>;<remote>

shell:command arg1 arg2 …

killforward:<local>;<remote>

shell:

localreserved:<path>

log:<name>

Providing “Simple” Host Service
<Request> := <Length><Payload>
• <Length> := Payload length, as 4-byte
hexadecimal string in ASCII
• <Payload> := Request data

ADB client
connect 3

10 “OKAY0004001d”
7 “000Chost:version”

fdevent
loop

5037

listen 2

8 read

4

alistener
[smart]

5

create

6
create

install_listener 1

main()

A listener is an entity which
• binds and listens to a local port,
• creates an asocket upon receiving a
connection on that port, and
• connect the new local connection to a
specific service.

asocket
[local]

accept

<Response> :=
• “OKAY”, for success
• “FAIL”<Length><Reason>, for failure
• “OKAY”<Length><Version>, for version query
• …

9

enqueue

asocket
[smart]

struct alistener {
alistener *next;
alistener *prev;

ADB Server
Host

fdevent fde;
int fd;

Phase 1: ADB Server Startup

const char *local_name;
const char *connect_to;
atransport *transport;
adisconnect disconnect;

Phase 2: Connection Establishment

Phase 3: Service Request/Response


};

Providing “Not-so-simple” Host Service
An asocket represents one half of a connection
between local and remote entity.
• A local asocket is bound to a file descriptor.
• A remote asocket is bound to an atransport.

ADB client

1

<request>

15 <response>
11

struct asocket {
asocket *next;
asocket *prev;

<response>

unsigned id;
int closing;
asocket *peer;

14 write

7

2 read

“OKAY”

asocket
[local]

8

3

12
13

read

enqueue

enqueue

asocket
[smart]

9 close

asocket
[local]

6 create

write

create

5

fdevent fde;
int fd;

10
service
thread

apacket *pkt_first;
apacket *pkt_last;

4 create

int (*enqueue)(asocket *s, apacket *pkt);
void (*ready)(asocket *s);
void (*close)(asocket *s);

ADB Server
Host

void *extra;
atransport *transport;
};

Phase 3: Service Request
Phase 4: Service Response
* Phase 1 & 2 Omitted


Providing “Complex” Local Service
struct apacket {
apacket *next;
unsigned len;
unsigned char *ptr;
amessage msg;
unsigned char data[MAX_PAYLOAD];
};

ADB client
<request>

1

12 “OKAY”

22 <response>

21 write

struct amessage {
unsigned command;
unsigned arg0;
unsigned arg1;
unsigned data_length;
unsigned data_check;
unsigned magic;
};

enqueue

asocket
[remote]

asocket
[local]

6

3

enqueue

7 close

4 send

Host

18
<A_WRTE>

atransport

ADB Server

create

13

20

enqueue

asocket
[smart]

read

17

2 read

<A_OKAY>

5

asocket
[remote]
send

19

12

atransport

<A_OPEN>

Phase 3: Service Request
Phase 4: Service Response
• Phase 1 & 2 Omitted


16
asocket
[local]

11 create

10 create

8

<response>

create

create

service
thread

adbd

9

14 write

Target
#define
#define
#define
#define
#define
#define

A_SYNC
A_CNXN
A_OPEN
A_OKAY
A_CLSE
A_WRTE

0x434e5953
0x4e584e43
0x4e45504f
0x59414b4f
0x45534c43
0x45545257

15

ADB Source Files
$ANDROID_TOP/system/core/adb
console.c

commandline.c

adb_client.c

adb.c

backup_service.c

file_sync_client.c

fdevent.c

file_sync_service.c

get_my_path_linux.c

transort.c

remount_service.c

get_my_path_darwin.c

transport_local.c

jdwp_service.c

get_my_path_windows.c

tansport_usb.c

framebuffer_service.c

get_my_path_freebsd.c

services.c

usb_linux_clients.c

usb_vendors.c

sockets.c

log_service.c

utils.c

usb_libusb.c

usb_macos.c

usb_linux.c

usb_windows.c

Sources for adb (client & server)

Sources for adbd

Changing Transport Mode: USB  TCP
1
6

2

…

3

$setprop service.adb.tcp.port 5555
$stop adbd
$start adbd

4

2

5


Changing Transport Mode: TCP  USB
1

* Protocol fault error if USB not connected
2

$setprop service.adb.tcp.port -1
$stop adbd
$start adbd

* USB need to be re-connected

3


Using Service Manager
Service
Manager

User Application Process

Binder Service

ActivityThread
Looper
main()

Message
Queue

Permission
Unique Name

HelloAndroid
Receiver

H
Handle Message()

Service

Provider

ViewRoot
Impl

Activity
Manager
Service

Activity

Handle Message()

1

activity:0x1

View

7

RUNTIME

Dalvik Virtual
Machine

5

LIBRARIES

9
0x0:1:activity

4
RUNTIME
Core Libraries

Binder
Context
Manager

6

L IBRARIES

8
Binder
Service

Core Libraries

Shared Memory
Driver

0x0000a000

activity:0x1

Custom
Impl.

10

LINUX KERNEL

System
Server

0x0:1:activity

Dalvik Virtual
Machine

3

LIBRARIES

0x0:3:activity:0x1

2

0x0:3:activity:0x0000a000

Binder (IPC) Driver


From the 8th Kandroid Conference

Invoking Service

Binder Service

ActivityThread
Looper
main()

Message
Queue

Permission
Unique Name

HelloAndroid
Receiver

H
Handle Message()

Service
Provider

ViewRoot
Impl
Handle Message()

ActivityManager
Service
IActivityManager
3 : startActivity
…
[parcel]

Activity

activity:0x1

View

1

Core Libraries

L IBRARIES

Binder
Thread
Pool

Binder
Service
Binder
Context
Manager

Dalvik Virtual
Machine

Shared Memory
Driver

0x0000a000

activity:0x1

Custom
Impl.

RUNTIME

LINUX KERNEL

System
Server

Service
Manager


BT #1

3

2

Core Libraries
Dalvik Virtual
Machine

…

LIBRARIES

LIBRARIES

0x1:3:[parcel]

RUNTIME
4

0x0000a000:3:[parcel]
Binder (IPC) Driver



Launching Activity
IApplicationThread

Activity
Manager
Service

8
Activity
Thread

Application
Thread

7

LAUNCH_ACTIVITY

IActivityManager.
startActivity()

H

handleMessage()
sendMessage()

IApplicationThread.
scheduleLaunchActivity()

1

10

Looper

6
IApplicationThread.
bindApplication()

Message
Queue
5

handle

9

&addr

IActivityManager.
attachApplication()

4
IActivityManager

System Server


2 fork request

Zygote

3

fork



Creating Window
create
2
Activity
Thread

1

H

4

LAUNCH_ACTIVITY

Looper

8

onStart()

7

onResume()

create

Message
Queue

ViewRootImpl
handleMessage()

create

9

10

3

onCreate()

6

handleMessage()

Activity

Adding Window

ViewRootImpl
$W

5

create

PhoneWindow

create
PhoneWindow
$DecorView
(FrameLayout)
LinearLayout

FrameLayout

FrameLayout
(id/content)

TextView
(id/title)

LinearLayout

TextView


Adding Window
IWindowManager

Window
Manager
Service

Activity
Thread

Looper
8
Message
Queue

IWindowManager.
openSession( )

ViewRootImpl

1
IWindowSession.
add( )

handleMessage()

7

&addr

sendMessage()

3

create

2

handle

Session
(Per User Application)

4 create

6

ViewRootImpl
$W

5

WindowState

(Per Window)

IWindow


System Server

User Application Process Internal

IApplicationThread

ActivityThread
$Application
Thread

BroadcastReceiver
• onReceive()

Service
Activity
Manager
Service

H
handleMessage()

ViewRootImpl
$W

Activity
Thread

sendMessage()

IWindow

Window
Manager
Service

Looper
Binder IPC
Thread Pool
BT #1

ViewRootImpl
handleMessage()

sendMessage()

Message
Queue

•
•
•
•
•

onCreate()
onStartCommand()
onBind()
onUnbind()
onDesstory()

ContentProvider
• onCreate()

Activity
•
•
•
•
•
•
•

onCreate()
onStart()
onResume()
onPause()
onStop()
onDestory()
onRestart()

View

• onMeasure()
• onLayout()
• onDraw()

BT #N

System
Server


Layering Windows (Surfaces)
System Windows
HIDDEN_NAV_CONSUMER_LAYER (24)
POINTER_LAYER (23)

STATUS_BAR_PANEL_LAYER (15)

BOOT_PROGRESS_LAYER (22)

STATUS_BAR_LAYER (14)

SECURE_SYSTEM_OVERLAY_LAYER (21)

STATUS_BAR_SUB_PANEL_LAYER (13)

DRAG_LAYER (20)

KEYGUARD_DIALOG_LAYER (12)

SYSTEM_ERROR_LAYER (19)

KEYGUARD_LAYER (11)

NAVIGATION_BAR_LAYER (18)

INPUT_METHOD_DIALOG_LAYER (10)

SYSTEM_OVERLAY_LAYER (17)

INPUT_METHOD_LAYER (9)

VOLUME_OVERLAY_LAYER (16)

SYSTEM_ALERT_LAYER (8)
PRIORITY_PHONE_LAYER (7)

Application Windows Including
• TYPE_BASE_APPLICATION
• TYPE_APPLICATION
• TYPE_APLICATION_STARTING

TOAST_LAYER (6)

SYSTEM_DIALOG_LAYER (5)
SEARCH_BAR_LAYER (4)
PHONE_LAYER (3)
WALLPAPER_LAYER (2)

APPLICATION_SUB_PANEL_SUBLAYER (+2)
APPLICATION_PANEL_SUBLAYER (+1)
APPLICATION_LAYER (2)
APPLICATION_MEDIA_OVERLAY_SUBLAYER (-1)
APPLICATION_MEDIA_SUBLAYER (-2)

Sub Windows
• TYPE_APPLICATION_PANEL
• TYPE_APPLICATION_ATTACHED_DIALOG


Hierarchy Viewer Commands
ViewServer Control

Version Information

boolean startViewServer(int port)

COMMAND_PROTOCOL_VERSION = “PROTOCOL”

boolean stopViewServer()

COMMAND_SERVER_VERSION = “SERVER”
(In com.android.server.wm.ViewServer)

boolean isViewServerRunning ()
(In android.view.IWindowManager)

Window Information
COMMAND_WINDOW_MANAGER_LIST = “LIST”
COMMAND_WINDOW_MANAGER_AUTOLIST = “AUTOLIST”

View Information/Control

COMMAND_WINDOW_MANAGER_GET_FOCUS = “GET_FOCUS”

REMOTE_COMMAND_CAPTURE = “CAPTURE”
REMOTE_COMMAND_DUMP = “DUMP”
REMOTE_COMMAND_INVALIDATE = “INVALIDATE”
REMOTE_COMMAND_REQUEST_LAYOUT = “REQUEST_LAYOUT”
REMOTE_PROFILE = “PROFILE”
REMOTE_COMMAND_CAPTURE_LAYERS = “CAPTURE_LAYERS”
REMOTE_COMMAND_OUTPUT_DISPLAYLIST = “OUTPUT_DISPLAYLIST”
(In android.view.ViewDebug)


(In com.android.server.wm.ViewServer)

Controlling View Server
Remote View Server [port=4939]
4939

4939

Hierarchy
Viewer
1
2

10
create

8

listen

Thread

9

create

…

Thread Pool
ViewServer

“host:transport:<serialno>”

WindowManagerService
“shell:service call window 1 i32 4939”

7

create & start

system server
6

ADB
Server

IWindowManager.startViewServer(4939)

shell:service call window 1 i32 <port>
/system/bin/

shell:service call window 2
shell:service call window 3

service

/system/bin/

sh

3

T

T

“shell:service call window 1 i32 4939”

adbd

4

5

[fork] service call window 1 i32 4939

[fork] /system/bin/sh –c service call window 1 i32 4939

USB|TCP

Target

Host

ViewServer Multi-Threading


Querying Version Information

Hierarchy
Viewer

4939

1 connect

2

accept

Thread

5

6 read

run()

4 submit
T

Host
① “SERVER”
② “PROTOCOL”

7

3

T

create

run()

…

Thread Pool

ViewServer

① “4”
② “4”

system server
Target

Phase 1: Connection Establishment
Phase 2: Command/Result
• ADB (Server & Daemon) Omitted

$View
Server
Worker


Querying Windows
<command>

1

Hierarchy
Viewer

2

read

3

invoke

T

T

…

Thread Pool

run()

$View
Server
Worker

4

Host

<result>

ViewServer

① viewServerListWindows()
② viewServerGetFocusedWindow()
③ addWindowChangeListener()


system server
Target

<command>

<result>

① “LIST”
② “GET_FOCUS”
③ “AUTOLIST”

① “413931a8 StatusBar” and
“411945c1 com.android.browser/com.android.browser.BrowserActivity“ and
…
“DONE.”
② “411945c1 com.android.browser/com.android.browser.BrowserActivity”
③ “LIST UPDATE” and/or
“FOCUS UPDATE”

• Phase 1 Omitted


Querying/Controlling Views
1

<command>

2

Hierarchy
Viewer

read

3

T

T

viewServerWindowCommand()

…

Thread Pool

run()

$View
Server
Worker

ViewServer

Host


4
8 <result>

system server

findWindow()

5 IWindow.executeCommand()
dispatchCommand()

ViewDebug
<command>
①
②
③
④
⑤
⑥
⑦

6

7 invoke

“DUMP 411945c1”
“CAPTURE_LAYERS 411945c1”
“CAPTURE 411945c1 android.widget.Button@405185a8”
“OUTPUT_DISPLAYLIST android.widget.Button@405185a8”
“INVALIDATE android.widget.Button@405185a8”
“REQUEST_LAYOUT android.widget.Button@405185a8”
“PROFILE android.widget.Button@405185a8”

ViewRootImpl

View
View

View
…

• Phase 1 Omitted

$W

user application
Target


Dumping View Hierarchy


Dumping View Properties


Selecting View Properties

Cache


Annotating View Properties


Summary
Questions

Answers

How to get information?
List of Windows

Window & View System 5
Hierarchy of Views in Window
Java Reflection

1

Properties of View
Java Annotations

2

Binder IPC

4

How to deliver information?
Between processes in target
Between host and target

Android Debug Bridge 3

Hierarchy
Viewer
Internals

6

References
•

General
–
–
–
–

•

Java Reflection
–
–

•

http://www.kandroid.org/board/board.php?board=conference&command=body&no=76

Window and View System
–

•

http://www.slideshare.net/tetsu.koba/adbandroid-debug-bridge-how-it-works
http://developer.android.com/guide/developing/tools/adb.html
http://developer.android.com/guide/developing/tools/emulator.html

Binder IPC
–

•

http://docs.oracle.com/javase/tutorial/java/javaOO/annotations.html
http://www.ibm.com/developerworks/kr/library/j-annotate1/index.html
http://www.ibm.com/developerworks/kr/library/j-annotate2.html
http://www.slideshare.net/jennapederson/decorating-code-7252638

Android Debug Bridge
–
–
–

•

http://docs.oracle.com/javase/tutorial/reflect/index.html
http://www.slideshare.net/CiaranMcHale/java-reflection-explained-simply

Java Annotations
–
–
–
–

•

Wikipedia (http://en.wikipedia.org/wiki/)
Java Documentation (http://docs.oracle.com/javase/6/docs/)
Android Documentation (http://developer.android.com/index.html)
Android Source Code (http://source.android.com/)

http://www.kandroid.org/board/board.php?board=conference&command=body&no=19

Hierarchy Viewer
–

http://developer.android.com/guide/developing/debugging/debugging-ui.html

Hierarchy Viewer Internals

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