# Picom — Lightweight X11 Compositor with Animation Support

> A lightweight standalone compositor for X11 that provides window transparency, shadows, blur, rounded corners, and animations for tiling window manager setups.

## Install

Save in your project root:

# Picom — Lightweight X11 Compositor with Animation Support

## Quick Use
```bash
# Install on Debian/Ubuntu
sudo apt install picom
# Install on Arch
sudo pacman -S picom
# Start with default settings
picom &
# Start with a config file
picom --config ~/.config/picom/picom.conf &
```

## Introduction
Picom is a standalone compositor for X11, forked from Compton. It adds visual effects like transparency, shadows, blur, and rounded corners to windows managed by any window manager. Picom is the go-to compositor for tiling WM users who want a polished desktop without switching to a full compositing WM.

## What Picom Does
- Composites X11 windows with true transparency and opacity control
- Renders drop shadows behind windows with configurable radius and offset
- Applies background blur (Gaussian or dual-Kawase) behind transparent windows
- Draws rounded corners on window frames
- Supports window animations for open, close, and workspace transitions

## Architecture Overview
Picom uses the X Composite extension to redirect window rendering into offscreen pixmaps, then composites them onto the root window. It supports multiple backends: xrender (CPU-based), GLX (OpenGL), and the newer EGL backend. The animation system interpolates window geometry and opacity between states using configurable curves.

## Self-Hosting & Configuration
- Config file at `~/.config/picom/picom.conf` using a simple key-value format
- Set `shadow = true`, `shadow-radius`, and `shadow-offset-x/y` for shadows
- Configure blur with `blur-method = "dual_kawase"` and `blur-strength`
- Use `corner-radius` for rounded window corners
- Define window rules with `opacity-rule` and `shadow-exclude` using WM class matching

## Key Features
- Multiple backends: xrender, GLX, and EGL for different hardware profiles
- Dual-Kawase blur: efficient real-time background blur algorithm
- Animation support: smooth transitions for window open/close/move
- Per-window rules: set opacity, shadow, and blur exceptions by window class
- VSync: tear-free rendering with configurable sync strategies

## Comparison with Similar Tools
- **Compiz** — older compositing WM with many effects; heavier and less maintained
- **xcompmgr** — minimal X11 compositor; no blur, rounded corners, or animations
- **KWin** — KDE compositor; full desktop integration, not standalone
- **Mutter** — GNOME compositor; tied to the GNOME desktop
- **Hyprland** — Wayland compositor with built-in effects; not X11

## FAQ
**Q: Does Picom work on Wayland?**
A: No. Picom is X11-only. On Wayland, compositing is handled by the compositor itself (Sway, Hyprland).

**Q: How do I fix screen tearing with Picom?**
A: Enable VSync with `vsync = true` and try the GLX or EGL backend for best results.

**Q: Can I disable effects for specific applications?**
A: Yes. Use `shadow-exclude`, `opacity-rule`, and `blur-background-exclude` with window class or name matching.

**Q: What is the difference between GLX and EGL backends?**
A: EGL is the newer, preferred backend with better Wayland compatibility foundations. GLX is the legacy OpenGL path, still useful on older drivers.

## Sources
- https://github.com/yshui/picom
- https://wiki.archlinux.org/title/Picom

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Source: https://tokrepo.com/en/workflows/asset-e116c273
Author: AI Open Source