I'm running Ubuntu Gnome, gnome shell version 3.24.2. I'm trying to create a gnome shell extension, and am using Javascript.
In my extension and in Javascript, how do I create a global key binding that is recognized from anywhere in Gnome? I want to bind a function to that key binding so that when the user presses the key combination then the said function is executed.
There's virtually no documentation on gnome-shell extension development. So asking here is my only option. Please don't refer me to the following stackoverflow question, since its answer is for Gnome 3.22 and I sincerely hope there's an easier way to create a key-binding: Gnome Shell Extension Key Binding
There a pretty complete answer here: How to handle keyboard events in gnome shell extensions?
You may find the easiest way is to use Gnome Shell's DBus interface, but dealing with shortcut conflicts and handling the signal callbacks is unavoidable:
Bus Name: org.gnome.Shell -> Path: /org/gnome/Shell -> Interface:
org.gnome.Shell
Relevant Methods:
GrabAccelerator(String accelerator, UInt32 flags) -> (UInt32 action)
UngrabAccelerator(UInt32 action) -> (Boolean success)
Signal:
AcceleratorActivate(UInt32, Dict of {String, Variant})
Related
What's the best way to open a file in the default application from Vala?
A bit like how xdg-open works.
I found some existing code in another application, but later on I also found this
GLib.AppInfo.launch_default_for_uri method.
A simple example:
var file = File.new_for_path (file_path);
if (file.query_exists ()) {
try {
AppInfo.launch_default_for_uri (file.get_uri (), null);
} catch (Error e) {
warning ("Unable to launch %s", file_path);
}
}
If you're using GTK, then you've also got Gtk.gtk_show_uri_on_window(), which uses the GLib stuff under the hood.
As far as I know there is only one implementation of the relevant freedesktop.org standards.
That is the reference implementation in xdg-utils:
https://www.freedesktop.org/wiki/Software/xdg-utils/
The tools are written in shell script, for example here is the source code for xdg-open:
https://cgit.freedesktop.org/xdg/xdg-utils/tree/scripts/xdg-open.in
So by far the easiest way is to just call the xdg-open script via Process.spawn_async and friends.
If you insist on using a library function you would have to implement a standard conforming library yourself.
Update:
There are quite a few libraries in various languages that implement some of the freedesktop.org standards, for example here is a list on GitHub:
https://github.com/topics/xdg
For example here is a similar tool to xdg-open written in D:
https://github.com/FreeSlave/mimeapps/blob/master/source/mimeapps.d
What I didn't find so far is a Vala / GLib or plain C library that could easily be used from a Vala application.
Update 2:
Actually it turns out there is something for that purpose in GLib (or more precisely in Gio):
https://valadoc.org/gio-2.0/GLib.AppInfo.launch_default_for_uri_async.html
https://developer.gnome.org/gio/stable/GAppInfo.html
So you should be able to use the GLib.AppInfo.launch_default_for_uri_async method.
Is it possible to get the operating system in maxima? I have some code that needs the unix / or windows \ for path names. How can I find out which operating system the code is running in?
To give some context, I have the following code:
windows: false$
divider: "/"$
if (windows) then divider: "\\"$
initfile: concat(maxima_userdir, divider, "maxima-init.mac");
load(operatingsystem)$
dir: getcurrentdirectory();
if (substring(dir, slength(dir)) # divider) then dir: concat(dir, divider)$
repo: concat(dir, "$$$.mac")$
live: concat(dir, "live_packages", divider, "$$$.mac")$
with_stdout(initfile, printf(true, ""))$
with_stdout(initfile, printf(true, concat("file_search_maxima: append (file_search_maxima, [
~s,
~s
]);"), repo, live))$
Take a look at the output of build_info, specifically the field host (i.e. foo#host where foo : build_info()). See ? build_info for more information.
On my (Linux) system I get: x86_64-unknown-linux-gnu I think on MS Windows you'll get a string containing windows or at least win or maybe win32.
There may be other ways to figure out the system type so let me know if that doesn't work for you. Also it is possible that there is a global variable floating around which tells the path separator; I would have to look for that.
If you're not adverse to writing a little bit of Lisp code, another approach is to use the file and directory functions in Common Lisp, which are more extensive than in Maxima. See the section on filenames in the Common Lisp Hyperspec. I think maybe MERGE-PATHNAMES and/or MAKE-PATHNAME might be relevant.
So i got a new keyboard wit hG-keys. (hotkeys) And i'm not familiar with lua...
So could anybody give me a very simple command that sets my pc to sleep? please?
if gkey == 7 and mkey == 1 then
if event == "G_PRESSED" then
end
end
gkeys
so gkey is the key that is pressed, and mkey is the set it uses. i can have up to 54 differint scripts/macro's.
I want to know what i have to put after the last 'then' so my pc goes to sleep.
thx ahead
edit 1:
got this:
if gkey == 1 and mkey == 3 then
if event == "G_PRESSED" then
execute("rundll32.exe powrprof.dll,SetSuspendState 0,1,0");
end
end
error is: [string "LuaVM"]:40: attempt to call global 'execute'(a nil value)
and with os.execute i get this error:
[string "LuaVM"]:40: attempt to index global 'os'(a nil value)
final answer: not possible with gseries keyboard. use a shortcut
Given the reference to G-keys and the G_PRESSED in your code snippet, I am assuming you have one of the Logitech G-Series keyboards. These keyboards can be programmed so that certain keys run Lua scripts using a custom Lua 5.1 interpreter. The documentation is included with Logitech's Gaming Software program.
According to the documentation, only some of the standard library functions are supported: the string, math and table are available. However, the io, os and debug libraries are not available.
So I doubt you'll be able to make your PC go to sleep.
EDIT in response to OP edit: the Lua library you have access to has the os library removed, so you're probably not going to be able to make your computer sleep directly.
There might be an indirect way to do this by writing something that listens for debugging messages, which you can generate with OutputDebugMessage. There's a Team Speak plugin that does this. But it's probably beyond your programming ability right now and far beyond the scope of a Stackoverflow post to explain.
You can use os.execute to run an executable from Lua.
If you google "Windows sleep command line" you'll get another Stackoverflow post which shows two ways of doing it. One requires that you turn hibernation off, the other requires that you download an additional utility (PsShutdown).
Assuming you've downloaded PsShutdown and put it somewhere in your PATH, then you can use the following to sleep the computer:
os.execute('psshutdown -d -t 0')
I use VLC media player 1.1.9 on Ubuntu 11.04. I'm trying to experiment with lua extensions for VLC; so I've added the file test.lua in ~/.local/share/vlc/lua/extensions/, which has only these two lines:
fps="25.000"
frame_duration=1/tonumber(fps)
When I run vlc with verbose output for debugging, I get (edited to split on multiple lines:):
$ vlc --verbose 2
...
[0xa213874] lua generic warning: Error loading script
~/.local/share/vlc/lua/extensions/test.lua:
.../.local/share/vlc/lua/extensions/test.lua:2:
attempt to call global 'tonumber' (a nil value)
...
Now, as far as I know, tonumber as function is part of Lua5.1 proper (Lua 5.1 Reference Manual: tonumber) - and on my system:
$ locate --regex 'lua.*so.*' | head -4
/usr/lib/libipelua.so.7.0.10
/usr/lib/liblua5.1.so
/usr/lib/liblua5.1.so.0
/usr/lib/liblua5.1.so.0.0.0
... apparently I do have Lua 5.1 installed.
So, why do I get an error on using tonumber here - and how can I use this (and other) standard functions in a VLC lua extension properly?
Documentation is sparse for VLC Lua extensions to say the least but I did find an example in the github vlc repository here: https://github.com/videolan/vlc/blob/master/share/lua/extensions/VLSub.lua
Judging from that example it appears you need to supply some basic event functions for your addon for VLC to call into when certain events happen. Some of the obvious callback handlers I've noticed:
descriptor, this should return a table that contains fields describing your addon.
activate, this seems to get called when you activate it from view menubar.
deactivate, called when you deactivate the addon from view menubar.
plus a couple of other functions like close and input_change which you can guess what they're for.
From my brief testing done on VLC 2.0.8 under Win7 it appears VLC loads the lua extension using an empty sandbox environment. This is likely the reason you're getting nil for tonumber and I'm betting none of the other standard lua functions are accessible either when you try to perform computation at this global scope.
However, if I move that code into one of the event handling functions then all those standard functions are accessible again. For example:
function descriptor()
return
{
title = "Test Ext";
version = "0.1";
author = "";
shortdesc = "Testing Lua Extension";
capabilities = {};
description = "VLC Hello Test Addon";
}
end
function activate()
print "test activating"
local fps = tonumber "25.000"
local frame_duration = 1 / fps
print(frame_duration)
return true
end
-- ...
That prints out what you would expect in the console debug log. Now the documentation (what little there is) doesn't mention any of this but what's probably happening here is VLC is injecting the standard lua functions and vlc api table into the sandboxed environment when any of these event handlers get called. But during the extension loading phase, it is done in an empty sandbox environment which explains why all those lua function calls end up being nil when you try to use it at the outter most scope.
I recommend cloning the VLC source tree from github and then performing a grep on the C source that's embedding lua to see what VLC is really doing behind the scenes. Most of the relevant code will likely be here: https://github.com/videolan/vlc/tree/master/modules/lua
Probably some extension script installed in your system overwrites the function and the Lua interpreter instance is shared between all extension scripts, so you end up not being able to call the function if that script is called before yours.
As a quick workaround, Lua being dynamically typed, you can still do things like:
1 / "25.000"
and the string will be coerced to a number.
Alternatively, you can define a tonumber equivalent like:
string_to_num = function(s) return s + 0 end
This again relies on dynamic typing.
How can I start a process in mono using the Process.Start API? My best guess would be the following (in F#):
let start (path : string) =
System.Diagnostics.Process.Start("/usr/bin/env", sprintf "mono \"%s\"" path)
This seems to work in linux, but it is obviously not correct in Mono/Windows. Is there any way I could obtain the location of the mono executable programmatically?
It turns out that you can basically just Process.Start with just the target executable path, no need to specify the mono executable.
You can find the location of Mono on windows using the following registry keys
$version = HKLM_LOCAL_MACHINE\Software\Novell\Mono\DefaultCLR
$monoprefix = HKLM_LOCAL_MACHINE\Software\Novell\Mono\$version\SdkInstallRoot
where you use the version you found to find the mono prefix.
Taken from this page
Rather than starting a new instance of the CLR, you can start assemblies from within your existing instance. Microsoft documents the relevant functionality here: http://msdn.microsoft.com/en-us/library/yk22e11a%28v=vs.110%29.aspx. Mono implements this as well.
What you have to do is create a new AppDomain to provide you with an execution environment isolated from your current one, load an assembly in there, and execute it.
Example:
var domain = AppDomain.CreateDomain("Foo");
domain.ExecuteAssembly("Bar.exe");