py_scrolly is a python script that provides a graphical and musical desktop toy. It takes lines from a text file and animates them on the system’s screen.
py_scrolly uses the following external modules:
- pygame – v2.0.1
- numpy – v1.20.3
These modules can be installed using pip, if needed:
pip install pygame
pip install numpy
..but you knew that already, right?
Using py_scrolly is pretty easy to do. Provided the module dependencies are installed then launching py_scrolly is as easy as typing:
python py_scrolly.py
….but you knew that already, right?
On starting up, py_scrolly will open a window [1] on your system’s desktop showing a line of text scrolling, right to left, across the screen. When the line of text scrolls off the left-hand end of the screen the next line of text will start scrolling, right to left, across the screen.
[1] While the py_scrolly.py can provide a fullscreen display it is designed to start up with windowed output. Pressing the ‘f’ key kicks the output into, and out of fullscreen mode.
Each line of text will be displayed using a different animation ‘effect’. Currently, the effects that are available to py_scrolly are:
- sinus – the text will form a rolling sinewave across the screen
- slider – the text will scroll across the screen in the style of a news screen textual tickertape
- magnify – similar to the slider effect but the middle of the line will appear magnified
These effects are applied to the different lines of text in a round-robin fashion. The current setup uses these effects in the order show above. The effects list ‘rolls over’ so after the magnify effect is used the script will start again with the sinus effect.
As this is intended as a “toy” there is little real input to the script. However the user does have some options that they can apply to affect the operation of the script. These are shown in the on-screen menu.
The options are, as follow:
| Key | Action |
|---|---|
| q | quit the script |
| f | flip the program between windowed and fullscreen view |
| m | mute, or unmute the music file that is playing |
| backspace | Hide or reveal the on-screen menu |
| spacebar | pause or resume the scrolling of the text across the screen. This does not affect the background animations or the playing of music |
There are some options available to the user to change the operation of the py_scrolly script.
The main changes are that the user can set the message lines that scroll across the screen. These are held in the message.txt file which is a plaintext file. The lines read from this file are displayed to screen in a rolling FIFO fashion. The script displays each line of text, one at a time. When it reaches the end of the message lines it starts again with the first line.
The change of graphical text effect is triggered when the py_scrolly script reaches the end of the line it is currently displaying. Whole paragraphs or a single letter can be made to scroll across the screen, being displayed with the current selected effect.
No message will be displayed onscreen if the script encounters an empty line in the message.txt file. It will just cause an apparent ‘pause’ before the next line of text is displayed. This is a design feature as it allows each displayed line time to reach the end of the screen before the next line is displayed.
If the message.txt file is not present in the same directory as the py_scrolly script is launched from then an error/’nag’ message will appear onscreen to inform the user that the script could not find this text file.
The music file that is included with the py_scrolly.py script is called “Mellow strain”. It is an MP3 transcoding of a MOD-format file that was produced by the artist and long time collaborator and friend, U4iaF8. It has been included in the release of the py_scrolly.py script with his permission.
The py_scrolly script is written so that it will play the first MP3 file that it finds in its current working directory. The user can play any MP3 file that they choose by putting the file into the directory with the py_scrolly.py script.
Please note: the py_scrolly script will play the FIRST MP3 file that it discovers in this directory. So an MP3 file with a filename that appears lower down a directory listing will be ignored. The user can either remove the mellow_strain.mp3 file or give their own MP3 file a name that starts with a letter in the range A-l.
The TrueType font file included with the py_scrolly script is called Rubik. It is available on an Open Fonts Licence which allows the font to be used freely in products. It can be downloaded from [Google Fonts] (https://fonts.google.com/specimen/Rubik)
The py_scrolly script works by looking to see if the Rubik font is already installed on your system and if it is, it will use that version. If the font is not already installed then the script checks if there is a Rubik.ttf file present. If there is, it loads that font file and uses that to render thescrolling text.
If the script cannot find the Rubik font either already installed or as a font file then it will default to using a system font.
At no time will this script install the font file to your system and so won't affect your system's state. The font file is supplied. The user can choose to install the font file if you want.
The PyGame module is the engine that drives the graphical output generated by py_scrolly.py. It can installed easily by typing the following into a terminal/command shell:
pip install pygame
py_scrolly uses the latest version of PyGame, which is currently V2.0.1 .
This is a learning project for me. I just couldn't face having to write yet another 'Hello world!' script to get started on a new language. I've previously mangled a few python scripts (usually downloaded) that were a couple of lines long to do some fairly mundane operations. This is my first full 'proper' python script. As such, I'm willing to admit that there may be some 'oversights'! :D
The initial targets for this script were just to get a python script up and running and, to see if I could get it to open a window on the screen. Once those targets were met, the design targets expanded. Below are some of the features I was aiming to incorporate in the code:
- Multiple lines of differing text scrolling across a screen
- Initial text effects are to "slide" the text across the screen and, to make the text follow a "sinus"
- Make it so the script can autoload new 'effects' when it is starts up
- Provide a shifting backdrop filled with stars
- Add stars streaming from the visual centre of the scene
- Make it easy to change the text that is being scrolled on the screen
- Make it easy to change the music playing in the background
- Have the mouse pointer autohide after ten seconds
There are also "failsafe" routines in the code. These do things like trap if there is no file containing the text messages or, there is no music file (an MP3) to play. It also is designed to use a certain font to display the messages. That font is supplied with the script and is open source. The script will check to see if the font is already installed on the system. If it is not then the script will access the font direct from the file, without installing it to your system.
[PyGame] (https://pygame.org) The PyGame module provides the engine to this script. It was chosen as I was looking for a module that would provide "easy to use" graphics functions that wouldn't requite installing too many addtional dependencies. PyGame provides just about everything in one install. It also supplies easy to use MP3 player functions, as well.
[U4iaF8 Mods] (https://modarchive.org/index.php?request=view_profile&query=69242) Just having the eye candy of jiggling, wiggly text scrolling across a screen is good but setting those moving lines to music is better. A big 'Thank You' goes to U4iaF8 for allowing me to use his 'Mellow strain' MOD with this script.
[Google Fonts] (https://fonts.google.com/specimen/Rubik) The scrolling text is rendered in the Rubik font. This font is available from Google:Fonts on an Open Fonts licence.
[GitHub:Magoninho] (https://github.com/Magoninho/3D-projection-tutorial/blob/main/projection.py) Magoninho gives an easy to understand script for doing 3D projections. The cube_rotate.py module is based largely on his code. There is some reworking to make it work as a module and also so that it renders to the proper surface in the py_scrolly setup. A big 'Thank you' to them for making this code available.