Win-Canvas 🖼️

An infinite canvas for managing open application windows, built with Rust and the Windows DWM Thumbnail API.

Features

• 🎯 Global Hotkey — Press Ctrl+Alt+Space to toggle the canvas overlay
• 📐 Live Window Thumbnails — See all your open windows rendered live by the Windows compositor
• 🔍 Infinite Zoom — Scroll wheel to zoom in/out without any quality loss (DWM renders at native resolution)
• ✋ Pan Canvas — Right-click drag to pan around the canvas
• 🖱️ Move Windows — Left-click drag to rearrange window thumbnails on the canvas
• ⚡ Quick Switch — Click any window thumbnail to instantly switch to it

How It Works

Win-Canvas leverages the DWM (Desktop Window Manager) Thumbnail API to display live, resolution-independent previews of all open windows. Unlike screenshot-based approaches:

• Thumbnails are composited directly by Windows — zero quality loss at any zoom level
• Content updates in real-time — you see live window content, not snapshots
• Zero-copy — no pixel data is transferred; DWM handles all rendering

Controls

Action	Input
Toggle canvas	Ctrl + Alt + Space
Zoom in/out	Scroll wheel
Pan canvas	Right-click + drag
Move window	Left-click + drag
Switch to window	Left-click (no drag)
Close canvas	Escape

Building

cargo build --release

The binary will be at target/release/win-canvas.exe.

Running

cargo run --release

The app runs in the background with no visible window. Press Ctrl+Alt+Space to open the canvas.

Requirements

• Windows 10/11 (requires DWM, which is enabled by default)
• Desktop composition must be enabled (default on modern Windows)

Architecture

src/
├── main.rs          # Entry point, message loop, WM_PAINT rendering
├── canvas.rs        # Canvas state: pan, zoom, window layout, coordinate transforms
├── dwm.rs           # DWM thumbnail registration and management
├── enumerate.rs     # Enumerate visible top-level windows
├── hotkey.rs        # Global hotkey (Ctrl+Alt+Space)
├── input.rs         # Mouse input helpers
└── window.rs        # Win32 overlay window creation

Tech Stack

• Rust — Memory safety, no GC
• windows crate v0.58 — Native Win32 API bindings
• DWM Thumbnail API — Live, compositor-rendered window previews
• GDI — Title labels, borders, UI text (lightweight, no heavy rendering framework needed)