blighty 3.0.0

Desktop Widget Manager. Think of conky, but with Python instead of Lua.

Desktop Widget Manager

Think of Conky, but with Python instead of Lua.

    

Synopsis • Requirements • Installation • Usage

Synopsis

The Blighty project is inspired by Conky. In essence, it is a collection of objects that allow you to quickly create a transparent window that you can draw on with cairo. But instead of coding your widgets in Lua, that perhaps end up calling Python as external tools, you can now code them natively in Python.

Performance won't be as great as Conky, with probably more resource being used for the same end result, but native Python support opens up for a lot more customisation possibilities in a snap of your fingers.

There won't be much you can do with minimal effort out of the box while the project is in its infancy. If you like the idea, you are more than welcome to contribute to this project!

Requirements

• X11
• Xinerama
• cairo
• python3
• python3-gi (only for GTK Windows)
• gir1.2-gtk-3.0 (only for GTK Windows)
• gir1.2-glib-2.0 (only for GTK Windows)

Installation

Currently, Blighty needs to be built from its source code. The following installation instructions have been tested on Ubuntu 18.04. If you are using a different distribution, make sure that you install all the listed dependencies from your package repository.

To install the required dependencies, use the following command

sudo apt install xorg libxinerama-dev libcairo2-dev python3-gi gir1.2-gtk-3.0 gir1.2-glib-2.0

To install Blighty from PyPI, use the command

sudo -H python3 -m pip install blighty --upgrade

Should you encounter any problems installing Blighty from PyPI, then install it directly from GitHub with the following command.

sudo -H python3 -m pip install git+https://github.com/P403n1x87/blighty.git --upgrade

Usage

The official documentation is hosted on ReadTheDocs.io. Refer to the code in the examples folder for some simple examples.

This package makes it easy to create transparent windows that you can draw on with cairo. It takes all the boilerplate code away from you so that you can just focus on the artwork, pretty much as with Conky.

X11 Canvases

This is the closest to Conky that you can get for the moment, and the recommended way of using Blighty. Use the following approach to create a window with the Xlib directly.

from blighty import CanvasGravity
from blighty.x11 import Canvas, start_event_loop

class MyCanvas(Canvas):
  def on_draw(self, context):
    # context is an instance of a cairo context.
    # Refer to the Pycairo documentation.

if __name__ == "__main__":
  x, y, width, height = 10, 10, 200, 200

  # Instantiate the canvas
  canvas = MyCanvas(10, 10, width = 200, height = 200, gravity = CanvasGravity.SOUTH_EAST)

  # Map it on screen
  canvas.show()

  # Start the event loop
  start_event_loop()

The module implements a basic event loop so that the user interactions with the canvas can be handled. You can capture key and button presses by implementing the on_key_pressed(self, keysym, state) and on_button_pressed(self, button, state, x, y) method in your subclass of Canvas.

GTK Canvases

To create GTK-based canvases you can use the blighty.gtk.Canvas class, which is just a subclass of Gtk.Window.

from time import sleep
import blighty.gtk as b


class MyCanvas(b.Canvas):
    def on_draw(self, widget, cr):
        # Similar to the X11 case. However, note how
        # you have access to the whole GTK window
        # via the `widget` parameter. In principle you
        # can exploit it to add extra child widgets.
        # Use wisely.

if __name__ == "__main__":
    canvas = MyCanvas(0, 0, width=320, height=240)
    canvas.show_all()
    b.start_event_loop()

Animations

Animations can be controlled via the Canvas.interval attribute. This is the time in milliseconds that elapses between consecutive redraws of the Canvas.

Brushes

Since version 1.1.0.

Consider the following simple example of a clock widget.

from blighty import CanvasGravity
from blighty.x11 import Canvas, start_event_loop

import datetime

from math import pi as PI


class Clock(Canvas):
    def on_button_pressed(self, button, state, x, y):
        self.dispose()

    def hand(self, ctx, angle, length, thickness):
        ctx.save()
        ctx.set_source_rgba(1, 1, 1, 1)
        ctx.set_line_width(thickness)
        ctx.rotate(angle)
        ctx.move_to(0, length * .2)
        ctx.line_to(0, -length)
        ctx.stroke()
        ctx.restore()

    def on_draw(self, ctx):
        now = datetime.datetime.now()

        ctx.translate(self.width >> 1, self.height >> 1)

        self.hand(ctx,
            angle = now.second / 30 * PI,
            length = (self.height >> 1) * .9,
            thickness = 1
        )

        mins = now.minute + now.second / 60
        self.hand(ctx,
            angle = mins / 30 * PI,
            length = (self.height >> 1) * .8,
            thickness = 3
        )

        hours = (now.hour % 12) + mins / 60
        self.hand(ctx,
            angle = hours / 6 * PI,
            length = (self.height >> 1) * .5,
            thickness = 6
        )

It is clear that the hand method would be more appropriate for the instance of the cairo Context ctx. The coding would be simpler if we could call it as ctx.hand. Brushes allow you to re-bind methods from the Canvas subclass to the cairo context. Import the brush decorator from blighty with

from blighty import brush

and the use it to decorate the hand method. The self argument is no longer necessary, since it will be replaced by the cairo context instance. So the above code becomes

from blighty import CanvasGravity, brush
from blighty.x11 import Canvas, start_event_loop

import datetime

from math import pi as PI


class Clock(Canvas):
    def on_button_pressed(self, button, state, x, y):
        self.dispose()

    @brush
    def hand(ctx, angle, length, thickness):
        ctx.save()
        ctx.set_source_rgba(1, 1, 1, 1)
        ctx.set_line_width(thickness)
        ctx.rotate(angle)
        ctx.move_to(0, length * .2)
        ctx.line_to(0, -length)
        ctx.stroke()
        ctx.restore()

    def on_draw(self, ctx):
        now = datetime.datetime.now()

        ctx.translate(self.width >> 1, self.height >> 1)

        ctx.hand(
            angle = now.second / 30 * PI,
            length = (self.height >> 1) * .9,
            thickness = 1
        )

        mins = now.minute + now.second / 60
        ctx.hand(
            angle = mins / 30 * PI,
            length = (self.height >> 1) * .8,
            thickness = 3
        )

        hours = (now.hour % 12) + mins / 60
        ctx.hand(
            angle = hours / 6 * PI,
            length = (self.height >> 1) * .5,
            thickness = 6
        )

By default, methods of subclasses of Canvas that begin with draw_ are re-bound to the cairo context in the on_draw method. So the same as the above code could be achieved without the use of the brush decorator with

from blighty import CanvasGravity
from blighty.x11 import Canvas, start_event_loop

import datetime

from math import pi as PI


class Clock(Canvas):
    def on_button_pressed(self, button, state, x, y):
        self.dispose()

    def draw_hand(ctx, angle, length, thickness):
        ctx.save()
        ctx.set_source_rgba(1, 1, 1, 1)
        ctx.set_line_width(thickness)
        ctx.rotate(angle)
        ctx.move_to(0, length * .2)
        ctx.line_to(0, -length)
        ctx.stroke()
        ctx.restore()

    def on_draw(self, ctx):
        now = datetime.datetime.now()

        ctx.translate(self.width >> 1, self.height >> 1)

        ctx.draw_hand(
            angle = now.second / 30 * PI,
            length = (self.height >> 1) * .9,
            thickness = 1
        )

        mins = now.minute + now.second / 60
        ctx.draw_hand(
            angle = mins / 30 * PI,
            length = (self.height >> 1) * .8,
            thickness = 3
        )

        hours = (now.hour % 12) + mins / 60
        ctx.draw_hand(
            angle = hours / 6 * PI,
            length = (self.height >> 1) * .5,
            thickness = 6
        )

Brushes are implemented via the class ExtendedContext, which is just a wrapper around cairo.Context. The argument passed to the on_draw callback is hence an instance of this class. For convenience, it exposes the containing canvas instance via the canvas attribute so that it doesn't need to be passed to the brush method when you need to access some of the canvas attributes (e.g. its size) or methods.

Conky-like Graphs

Since version 3.0.0

If you really can't do without the Conky look, Blighty offers you Conky-like graphs out of the box.

All you have to do is create an instance of blighty.legacy.Graph by specifying the position and the size of the graph. Optionally, you can also pass a scale argument, which by default is set to 100 and defines the y scale of the graph. If you want the graph to auto-scale, use scale=None. You push values to the graph with the push_value method and draw it on a canvas with the draw method, which requires a Cairo context as argument.

License

GPLv3.