cfnet用于嵌入式_arcan: Arcan是一个功能强大的开发框架，可用于专门的嵌入式应用程序的用户界面，也可用于完整的独立桌面环境...

Arcan

Arcan is a powerful development framework for creating virtually anything from

user interfaces for specialized embedded applications all the way to full-blown

standalone desktop environments.

At its heart lies a robust and portable multimedia engine, with a well-tested

and well-documented Lua scripting interface. The development emphasizes

security, debuggability and performance -- guided by a principle of least

surprise in terms of API design.

For more details about capabilities, design, goals, current development,

roadmap, changelogs, notes on contributing and so on, please refer to the

arcan-wiki.

There is also a website that collects other links,

announcements, releases, videos / presentations and so on.

For community contact, check out the IRC channel #arcan on irc.freenode.net.

For developer information, see the HACKING.md

Getting Started

Some distributions, e.g. voidlinux have most of arcan

as part of its packages, so you can save yourself some work going for one of

those.

Docker- container templates (mainly used for headless development and testing)

can be found here, quality varies wildly from bad to poor (just like Docker):

dockerfiles.

Compiling from Source

There are many ways to tune the build steps in order to reduce dependencies.

There are even more ways to configure and integrate the components depending

on what you are going for,

Most options are exposed via the build output from running cmake on the src

directory.

For the sake of simplicity over size, there is a build preset, 'everything'

which is the one we will use here.

Dependencies

Specific package names depend on your distribution, but common ones are:

sqlite3, openal-soft, sdl2, opengl, luajit, gbm, kms, freetype, harfbuzz

libxkbcommon

For encoding and decoding options you would also want:

libvlc-core (videolan), the ffmpeg suite, leptonica, tesseract

libvncserver libusb1

First we need some in-source dependencies that are cloned manually for now:

git clone https://github.com/letoram/arcan.git

cd external/git

../clone.sh

cd ../arcan

These are typically not needed, with the exception of our temporary openAL

patches pending refactoring of that subsystem in time for the ~0.7 series of

releases.

Compiling

Now we can configure and build the main engine:

mkdir build

cd build

cmake -DBUILD_PRESET="everything" ../src

Like with other CMake based projects, you can add:

-DCMAKE_BUILD_TYPE=Debug

To switch from a release build to a debug one.

When it has finished probing dependencies, you will get a report of which

dependencies that has been found and which features that were turned on/off,

or alert you if some of the required dependencies could not be found.

Make and install like normal (i.e. make, sudo make install). A number of

binaries are produced, with the 'main' one being called simply arcan. To

test 'in source' (without installing) you should be able to run:

./arcan -T ../data/scripts -p ../data/resources ../data/appl/welcome

The -T argument sets our built-in/shared set of scripts, the -p where shared

resources like fonts and so on can be found, and the last argument being

the actual 'script' to run.

With installation, this should reduce to:

arcan welcome

It will automatically try to figure out if it should be a native display

server or run nested within another or even itself based on the presence

of various environment variables (DISPLAY, WAYLAND_DISPLAY, ARCAN_CONNPATH).

'welcome' is a name of a simple builtin welcome screen, that will shut down

automatically after a few seconds of use.

For something of more directly useful, you can try the builtin appl 'console':

arcan console

Which should work just like your normal console command-line, but with the

added twist of being able to run (arcan compatible) graphical applications

as well. For other projects, see the 'Related Projects' further below.

If input devices are misbehaving, the quick and dirty 'eventtest' in:

/path/to/arcan/tests/interactive/eventtest

Might be useful in figuring out who to blame.

Hook-Scripts

Another way to extend engine behavior regardless of the appl being used are

so called hook-scripts. These reside inside the 'system script path' covered

by the -T command-line argument, or the default of shared/arcan/scripts.

The idea is that these should be able to provide 'toggle on' features that

would need cooperation from within the engine, in order to do quick custom

modifications or help bridge other tools.

A good example is 'external_input':

arcan -H hooks/external_input.lua -H hooks/external_input.lua myappl

This would open up two connection points, 'extio_1', 'extio_2' that will

allow one client to connect and provide input that will appear to the 'myappl'

appl as coming from the engine.

These are covered in more detail in the manpage.

Networking

Arcan-net is a binary that allows you to forward one or many arcan clients

over a network. It is built by default, and can be triggered both as a

separate network tool as well as being launched indirectly from shmif by

setting ARCAN_CONNPATH=a12://id@host:port, or when issuing a migration

request by the window manager.

See also: src/a12/net/README.md and src/a12/net/HACKING.md.

Wayland

The 'arcan-wayland' or 'waybridge', as it is refered to in some places is

binary adds support for wayland and X clients (via Xwayland). It can be run as

either a global system service, e.g.

arcan-wayland -xwl

Or on a case by case basis, like:

arcan-wayland -exec weston-terminal

For a compliant wayland client, and:

arcan-wayland -xwl -exec xterm

For an X client. The 'per case' basis is recommended as it is safer and more

secure than letting multiple clients share the same bridge process, at a

negilable cost. The downside is that some complex clients that rely on making

multiple distinct wayland connections may fail to do so.

There is a number of tuning and troubleshooting options due to the

complexity of using wayland, consult the manpage and --help toggle.

Database

All runtime configuration is consolidated into a database, either the default

'arcan.sqlite' one or an explicitly set one (arcan -d mydb.sqlite).

This is used for platform specific options, engine specific options and for

trusted clients that the running scripts are allowed to start. It is also used

as a configuration key-value store for any arcan applications that are running.

As a quick example, this is how to inspect and modify keys that 'Durden'

are currently using:

arcan_db show_appl durden

arcan_db add_appl_kv durden shadow_on true

Advanced configuration for some video platforms can be set via the reserved

arcan appl name. This would, for instance, set the primary graphics card

device name for the 'egl-dri' platform version:

arcan_db add_appl_kv arcan video_device=/dev/dri/card2

To add 'launch targets', you can use something like:

arcan_db add_target net BIN /usr/bin/arcan-net -l netfwd

arcan_db add_config arcan-net default 10.0.0.10 6666

arcan_db add_target xterm BIN /usr/bin/arcan-wayland -exec-x11

This allow applications to start a program as a trusted child (that inherits

its connection primitives rather than to try and find them using some OS

dependent namespace). The example above would have spawned arcan-net in the

local mode where clients connecting to the 'netfwd' connpath would be

redirected to the server listening at 10.0.0.10:6666.

There are many controls and options for this tool, so it is suggested that you

look at its manpage for further detail and instructions.

Headless Mode

The 'everything' build option should also produce a binary called

'arcan_headless', at least on BSDs and Linux. This binary can be used to run

arcan without interfering with your other graphics and display system. Given

access to a 'render node' (/dev/dri/renderD128 and so on) and it should also

work fine inside containers and other strict sandboxing solutions.

To make it useful, it can record/stream to a virtual screen. An example of

such a setup following the example above would be:

ARCAN_VIDEO_ENCODE=protocol=vnc arcan_headless console

Assuming the build-system found the libvncserver dependency, this should

leave you with an exposed (insecure, unprotected, ...) vnc server at

localhost+5900. See afsrv_encode for a list of arguments that can be added

to the encode environment in order to control what happens.

Related Projects

If you are not interested in developing something of your own, you will

likely find little use with the parts of this project alone. Here are some

projects that you might want to look into:

Durden is the main desktop

environment that uses this project as its display server.

Safespaces is an experimental

VR/3D desktop environment.

Prio is a simple window manager

that mimics Plan9- Rio.

Arcan-Devices accumulates

extra drivers.

To get support for more types of clients and so on, there is also:

Wayland support (see Wayland section below, and src/wayland/README.md).

QEmu a patched QEmu version that

adds a -ui arcan option.

Xarcan is a patched Xorg that

allows you to run an X session 'as a window'.

Tools

There is also a number of helper tools that can be used to add certain

features, such as support for VR devices and tray-icons. These are built

separately and can be found in the tools/ subdirectory. They have their

own separate build systems and corresponding README.md files.

They work on the assumption that arcan and its respective libraries have been

built and installed. They are lockstepped and versioned to the engine, so if

you upgrade it, make sure to rebuild the tools as well.

The main tools of interest are:

Acfgfs

Acfgfs is a tool that lets you mount certain arcan applications as a FUSE

file-system. The application has to explicitly support it. For the Durden

desktop environment, you can use global/settings/system/control=somename

and then:

arcan_cfgfs --control=/path/to/durden/ipc/somename /mnt/desktop

And desktop control / configuration should be exposed in the specified

mountpoint.

Aclip

Aclip is a clipboard manager similar to Xclip. It allows for bridging the

clipboard between a desktop environment like Durden, and that of an X server.

This requires that clipboard bridging has been allowed (disabled by default

for security reaons). In Durden this is activated via

global/settings/system/clipboard where you can control how much clipboard

access the tool gets.

Aloadimage

Aloadimage is a simple sandboxing image loader, similar to xloadimage. It

is useful both for testing client behavior when developing applications

using arcan, but also as an image viewer in its own right, with reasonably

fast image loading, basic playlist controls and so on.

Vrbridge

VR bridge is an optional input driver that provides the arcan_vr binary

which adds support for various head-mounted displays. More detailed

instructions on its setup and use can be found as part of the Safespaces

project mentioned in the 'Related Projects 'section.

Trayicon

Arcan-trayicon is a tool that chain-loads another arcan client, along with

two reference images (active and inactive). It tries to register itself in

the icon-tray of a running arcan application, though it must explicitly

enable the support. In Durden, this is done via the path:

global/settings/statusbar/buttons/right/add_external=tray

Then you can use:

ARCAN_CONNPATH=tray arcan-trayicon active.svg inactive.svg afsrv_terminal

Or some other arcan client that will then be loaded when the tray button is

clicked, confined into a popup and then killed off as the popup is destroyed.

This is a quick and convenient way to wrap various system services and external

command scripts.