Jiggle

Jiggle is a Gnome Shell extension that highlights the cursor position when the mouse is moved rapidly.

Installation Via GUI

Please see the following URL to install it for Gnome: https://extensions.gnome.org/extension/3438/jiggle/

Preferences

Setting	Description
Shake Threshold	How vigorous the cursor must shake for jiggling to be detected.
Log Level	How much Jiggle should log to journalctl.
Effect	Choose which effect is used when jiggling is detected.

Cursor Scaling

Show a larger cursor.

Setting	Description
Use System Cursor	When enabled, use the system cursor. Otherwise, Jiggle uses icons/jiggle-cursor.png.
Hide Original Cursor	When enabled, Jiggle attempts to hide and show the real cursor during its animation.
Growth Speed	How fast the cursor grows once jiggling is detected.
Shrink Speed	How fast the cursor shrinks once jiggling is no longer detected.

Fireworks

Set off fireworks.

Setting	Description
Burst Speed	How fast the firework particles fly.
Spark Count	How many particles the fireworks have.
Spark Trail	How far the particle trails are visible.

Spotlight

Shine a spotlight on the cursor.

Setting	Description
Size	Size of the spotlight.
Show Speed	How fast the spotlight fades in once jiggling is detected.
Hide Speed	How fast the spotlight fades once jiggling is no longer detected.

Cursor Trail

Leave a trail of cursors.

Setting	Description
Speed	Speed of the trail generation.

Known Issues

• Detecting mouse clicks/active windows isn't as straightforward as one would believe.
• Getting a higher quality system cursor image isn't either.

Patches welcome.

Development

Feel like building Jiggle from sources? Keep reading...

Anatomy Of An Effect

Jiggle effects use duck typing, and effects are expected to have the following methods:

Method	Description
render()	Executed in a timed loop, for repainting the screen.
run(x, y)	Executed when the cursor moves, with the x and y screen coordinates.
start()	Executed when jiggling is first detected.
stop()	Executed when jiggling is no longer detected.
update(settings)	Executed if any of the preferences are changed. settings is a Gio.Settings instance.

In addition, each effect package should also implement a new_effect function that returns a new instance of the effect.

Building

Tools required:

• GNU make
• docker
• bash
• glib-compile-schemas
• glade

make

Recompiling the Settings Schema and Preferences UI

Any changes to the settings or UI xml will require recompilation.

DO NOT edit ui/gtk4.ui directly, as it is generated from ui/gtk3.ui!!!

make compile

Testing

Tests use GjsUnit, which is included here.

make test

Docker Testing

Multiple systems can be tested via Docker:

make docker

Or, test a single system:

make docker_centos
make docker_debian
make docker_fedora

Please note that this can be very slow, as the images are built locally.

© 2020 Jeff Channell