bluelich / uebersicht

ˈyːbɐˌzɪçt

Übersicht

Keep an eye on what's happening on your machine and in the world.

For general info check out the Übersicht website.

Writing Widgets

In essence, widgets are plain JavaScript objects that define a few key properties and methods. They need to be defined in a single file with a .js or .coffee extension for Übersicht to pick them up. Übersicht will listen to file changes inside your widget directory, so you can edit widgets and see the result live.

They can also be written in CoffeeScript which has a cleaner multi-line string syntax that comes in handy in several places. This documentation will use the CoffeScript syntax, but here is a small example widget in pure JavaScript. As an alternative, you could use CoffeScript's back-tick ` operator to only write the relevant parts in JavaScript.

The following properties and methods are currently supported:

command

A string containing the shell command to be executed, for example:

command: "echo Hello World"

Note, that in some cases they need to properly escaped, like:

command: "ps axo \"rss,pid,ucomm\" | sort -nr | head -n3"

refreshFrequency

An integer specifying how often the above command is executed. It defines the delay in milliseconds between consecutive commands executions. Example:

refreshFrequency: 10000

You can also specify refreshFrequency as a string, like '2 days', '1d', '10h', '2.5 hrs', '2h', '1m', or '5s'.

refreshFrequency: '10s'  # equates to 10000

The default is 1000 (1s). If set to false the widget won't refresh automatically.

style

A string defining the css style of this widget, which is also used to control the position. In order to allow for easy scoping of CSS rules, styles are written using the Stylus preprocessor. Example:

style: """
  top:  0
  left: 0
  color: #fff

  .some-class
    box-shadow: 0 0 2px rgba(#000, 0.1)
"""

For convenience, the nib library for Stylus is included, so mixins for CSS3 are available.

Note that widgets are positioned absolute in relation to the screen (minus the menu bar), so a widget with top: 0 and left: 0 will be positioned in the top left corner of the screen, just below the menu bar.

render : output

A function returning a HTML string to render this widget. It gets the output of command passed in as a string. For example, a widget with:

command: "echo Hello World!"

render: (output) -> """
  <h1>#{output}</h1>
"""

would render as Hello World!. Usually, your output will be something more complicated, for example a JSON string, so you will have to parse it first.

The default implementation of render just returns output.

afterRender : domEl

A function that gets called, as the name suggests, after render with a reference to our newly rendered DOM element. It can be used to do one time setups that you wouldn't want to do on every update.

update : output, domEl

A function implementing update behavior of this widget. If specified, render will be called once when the widget is first initialized. Afterwards, update will be called for every refresh cycle. If no update method is provided, render will be called instead.

Since render will simply replace the inner HTML of a widget every time, you can use render to do a partial update of your widgets, kick off animations etc. For example, if the output of your command returns a percentage, you could do something like:

# we don't care about output here
render: (_) -> """
  <div class='bar'></div>
"""

update: (output, domEl) ->
  $(domEl).find('.bar').css height: output+'%'

This will set the height of .bar every time this widget refreshes. As you can see, jQuery is available.

Widget Internals

For writing more advanced widgets you might not want to rely on the standard 'run command, then redraw' cycle and instead manage some of the widget internals yourself. There are a few methods you can use from within render, afterRender and update

@stop()

Stop the widget from updating if a refreshFrequency is set. The widget won't update until @start is called.

@start()

Start updating a previously stopped widget again. Does nothing if refreshFrequency is set to false.

@refresh()

Runs the command and redraws the widget as it normally would as part of a refresh cycle. If no command is set, the widget will only redraw.

@run(command, callback)

Runs a shell command and calls callback with the result. Command is a string containing the shell command, just like the command property of a widget. Callback is called with err (if any) and stdout, in standard node fashion.

Geolocation API

While the WebView used by Übersicht seems to provide the standard HTML5 geolocation API, it is not functional and there seems to be no way to enable it. Übersicht now provides a custom implementation, which tries to follow the standard implementation as closely as possible. However, so far it provides only the basics and might still be somewehat unstable. The api can be found under window.geolocation (instead of window.navigator.geolocation). And supports the following methods

geolocation.getCurrentPosition(callback)

geolocation.watchPosition(callback)

geolocation.clearWatch(watchId)

Check the documentation for details on how to use these methods. The main difference to the standard API is that none of them accept options (the accuracy for position data is always set to the highest) and error reporting has not be implemented yet.

However, in a adition to the standard Position object provided by the standard API, Übersicht provides an extra address property with the following fields:

• Street
• City
• ZIP
• Country
• State
• CountryCode

Hosted Functionality

A global object called uebersicht exists which exposes extra functionality that is typically not available in a browser. At the moment it is very limited:

uebersicht.makeBgSlice(canvas)

Has been deprecated as of version 0.8 in favor of -webkit-backdrop-filter. It should be available on all systems that have Safari 9+ installed. https://developer.mozilla.org/en-US/docs/Web/CSS/backdrop-filter

Building Übersicht

To build Übersicht you will need to have NodeJS and a few dependencies installed:

setup

Install node and npm using homebrew

brew install node

then run

npm install -g coffee-script
npm install -g grunt-cli

finally, inside the server dir run

npm install

git and unicode characters

Git might not like the umlaut (ü) in some of the path names and will constantly show them as untracked files. To get rid of this issue, I had to use

git config core.precomposeunicode false

However, the common advice is to set this to true. It might depend on the OS and git version which one to use.

building

The code base consists of two parts, a cocoa app and a NodeJS app inside server/. To build the node app seperately, use grunt release. This happens automatically every time you build using XCode.

The node app can be run standalone using

coffee server/server.coffee -d <path/to/widget/dir> -p <port>

Then point your browser to localhost:<port>. While developing you can use

cd server
grunt

to continuously watch, compile and run specs.

Building in Xcode

The first time opening the project in Xcode you might see this message when trying to build: "The run destination My Mac is not valid for Running the scheme 'Übersicht'."

Click on Uebersicht in the project navigator and then select the menu Editor > Validate Settings... and click Perform Changes.

You can then attempt to build, you may then be presented with code sign issues, click Fix Issue to continue.

Now you need to remove the code signing shell script, select the Übersicht target and under Build Phases remove the code in the Code Sign Frameworks section.

You should now be able to build successfully.

There is one last step on the Node.js side to complete. For the sake of brevity, this link will solve your problem:

http://stackoverflow.com/questions/31254725/transport-security-has-blocked-a-cleartext-http

Legal

The source for Übersicht is released under the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

© 2014 Felix Hageloh