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Weston Plugin BaLayer Manageme

Ossama Othman20 September 2012

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Context

GNU/Linux based IVI platform

Multiple screens

Multiple ECUs

Applications may be distributed

across multiple screens and

ECUs

IVI-specific UI paradigms

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Minimal resources for in-house

development of suitable IVIcompositor, etc.

Costs

Lack of expertise in interface

between user space, kernel and

graphics hardware

Existing desktop solutions may

not satisfy IVI UI requirements

Problems

Kernel

KMS

DRM Gra

Hardware

Graphics

User Space

Compositor Inpu

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Solution Wayland and Weston

Core compositing functionality

Handle kernel-space interaction

Efficient IPC

Open-sourceFTW!

Weston IVI plugin Addresses IVI related UI feature

gaps in Weston

Simple and focused

Wayland

Client

W

Weston

Backend Shell

IVI Shell

Plugin

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Weston IVI Plugin Interface for

GENIVI-style Layer Management

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Identifying Feature Gaps

GENIVI Layer Management

Client Interface FeatureWayland Protocol

Surface Lifecycle Management Yes

Surface PositioningYes, but through input device, not

supplied coordinate

Surface Visibility No

Surface Opacity No

Layer Lifecycle Management No

Layer Positioning No

Layer Visibility No

Render order of surfaces in layer No

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Writing the Weston IVI Plugin Interface

Group operations according to layer management object ty

Surface Layer

Display

Weston plugin interface format matches Wayland protocol

Map Wayland protocol interface to each object type One Wayland request per feature (operation)

Set position, opacity, visibility, etc

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Wayland Protocol Interface XML Format

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Subset of Wayland Protocol Elements

Protocol XML

ElementDescription

protocolTop-level element that affects how files and #includeguards generated by wa

are named

interface Element that encapsulates a set of operations that may be performed on a corre

request Server side operation called on object by client that is completed async

event Client side operation asynchronously called by server side (e.g. Weston) when

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Wayland Protocol Argument TypesWayland

Argument TypeNative Type Descript

int int32_t 32 bit signed

uint uint32_t 32 bit unsigned

fixed wl_fixed_tdouble-precision float

convert to native doubwl_fixed_{to,fro

string char const * nil-terminated

array struct wl_array *Structure containing po

its length

fd int open file des

new_idstruct wl_object * orstructwl_resource *

Object reference passe

requests

objectstruct wl_object * orstructwl_resource *

Object reference (e.wl_surface)

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Caveats

No concept of synchronous return valuese.g. get oper

Wayland protocol Clients should cache old value until eventarrives asynchrono

new value

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Weston IVI Plugin Implementation

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Weston Plugin Requirements

Plugin entry point

Initialization function called by Weston compositor upon succe

plugin

int module_init(struct weston_compositor *);

Previously shell_init()

Plugin must currently be built inside Weston source tree

Weston does not yet export plugin interface or library

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Weston Plugin Components

ivi-shell.xml

Wayland protocol based plugin

interface

ivi-shell.c

Plugin implementation

Generated files ivi-shell-server-protocol.h

ivi-shell-protocol.c

wayland-scanner

ivi-shell-server-protocol.h ivi-shell-prot

ivi-shell.c

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Weston Plugin Implementation

Request implementation prototypes found in generated ivi-shell-ser

protocol.hheader

static void lm_surface_set_opacity(struct wl_client * client,

struct wl_resource * resour

struct wl_resource * opacit

static const struct lm_surface_interface lm_surface_implementa

lm_surface_set_opacity

};

Register implementation

struct wl_resource * resource =

wl_client_add_object(client, &lm_surface_interface

&lm_surface_implementation, id

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Using the Weston IVI Plugin

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Configure Weston to Use IVI Plugin

weston.inisearch path $XDG_CONFIG_HOME/.config/

$HOME/.config/

Automake-style plugin install directory $(libdir)/weston/

Set name of plugin in weston.ini[shell]

type=ivi-shell.so

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Invocation of IVI Plugin Operations

Client side build Add ivi-shell-protocol.cto client source build

Client side code

#include ivi-shell-client-protocol.h

void foo(){

lm_surface_set_visibility();

}

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Weston IVI Plugin vs. GENIVI Layer

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Architectures

Client

GE

LM Communicator IPC (e.g. D-B

GENIVI LM Client Library

Communicator Plugin

Com

Client

WestonIVI

Plugin

Wayland IPC

GENIVI LM Client Library

IVI Plugin Client Stublibwayland

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Architectural Comparison

Weston IVI Plugin

Weston-specific Small codebase

Efficient IPC

Simple architecture

Network transparency supportin Wayland/Weston is still

pending

GENIVI Layer Manag

Highly extensible Rendering plugins

Wayland

X

Direct FB

Communicator plug

D-Bus

TCP/IP

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Summary

Existing desktop style window management is insufficient

some cases

Applications are not necessarily run in windows

Westons extensibility is key to creating IVI UI with minima

No need for IVI UI developers to create compositor from scratc

Allows IVI UI developers to focus on their own IVI-specific nee

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References

Wayland

http://wayland.freedesktop.org/

http://cgit.freedesktop.org/wayland

GENIVI

http://www.genivi.org/

Media & Graphics Expert Group

http://wayland.freedesktop.org/http://cgit.freedesktop.org/waylandhttp://www.genivi.org/http://www.genivi.org/http://www.genivi.org/http://cgit.freedesktop.org/waylandhttp://cgit.freedesktop.org/waylandhttp://wayland.freedesktop.org/http://wayland.freedesktop.org/

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Legal

INFORMATION IN THIS DOCUMENT IS PROVIDED IN CONNECTION WITH INTEL PRODUCTS.

PROVIDED IN INTEL'S TERMS AND CONDITIONS OF SALE FOR SUCH PRODUCTS, INTEL ASS

LIABILITY WHATSOEVER, AND INTEL DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY REL

AND/OR USE OF INTEL PRODUCTS, INCLUDING LIABILITY OR WARRANTIES RELATING TO FITPARTICULAR PURPOSE, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT, COPYRIG

INTELLECTUAL PROPERTY RIGHT.

Intel may make changes to specifications, product descriptions, and plans at any time, without notice.

All dates provided are subject to change without notice.

Intel is a trademark of Intel Corporation in the U.S. and other countries.

*Other names and brands may be claimed as the property of others.

Copyright 2012, Intel Corporation. All rights are protected.

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