DrawThatThing

A cross-platform desktop application that converts images into automated mouse drag actions, allowing you to "replay" an image as a drawing.

Features

• Image Parsing: Load images and analyze pixel data using multiple parsing algorithms
• Mouse Automation: Convert parsed image data to mouse drag sequences and replay them
• Color Management: Define custom color palettes, pick colors from screen, mark background colors
• Plugin Architecture: Extensible bitmap readers and brush changers
• Global Hotkeys: System-wide keyboard shortcuts for quick actions
• Live Preview: See how the image will be drawn before executing

Project Structure

DrawThatThing/
├── DrawThatThing.Avalonia/         # Main Avalonia UI application
├── DrawThatThing.Core/             # Platform-agnostic core library (image parsers, preview)
├── DrawThatThing.Platform/         # Platform abstraction interfaces
├── DrawThatThing.Platform.Windows/ # Windows-specific implementations
├── DrawThatThing.Platform.macOS/   # macOS-specific implementations
├── DrawThatThing.Platform.Linux/   # Linux-specific implementations
├── DrawThatThing.sln               # Solution file
├── build.sh                        # Build script for Linux/macOS
├── build-macos-app.sh              # Builds DrawThatThing.app for macOS
└── build.cmd                       # Build script for Windows

---

Requirements

Platform	.NET SDK	Additional Requirements
All	.NET 9.0 SDK or later	-
Windows	-	None (Win32 APIs included)
macOS	-	Accessibility permissions (System Preferences → Security & Privacy → Privacy → Accessibility)
Linux	-	X11, libXtst (XTest extension)

Installing .NET 9 SDK

Windows

# Using winget
winget install Microsoft.DotNet.SDK.9

# Or download from https://dotnet.microsoft.com/download/dotnet/9.0

macOS

# Using Homebrew
brew install --cask dotnet-sdk

# Or download from https://dotnet.microsoft.com/download/dotnet/9.0

Linux (Ubuntu/Debian)

# Add Microsoft package repository
wget https://packages.microsoft.com/config/ubuntu/22.04/packages-microsoft-prod.deb -O packages-microsoft-prod.deb
sudo dpkg -i packages-microsoft-prod.deb
rm packages-microsoft-prod.deb

# Install .NET SDK
sudo apt-get update
sudo apt-get install -y dotnet-sdk-9.0

# Install X11 dependencies for mouse automation
sudo apt-get install -y libx11-dev libxtst-dev

Linux (Fedora)

sudo dnf install dotnet-sdk-9.0
sudo dnf install libX11-devel libXtst-devel

Linux (Arch)

sudo pacman -S dotnet-sdk
sudo pacman -S libx11 libxtst

---

Building from Source

# Restore dependencies
dotnet restore DrawThatThing.sln

# Build in Debug mode
dotnet build DrawThatThing.sln

# Build in Release mode
dotnet build DrawThatThing.sln -c Release

Or use the provided build scripts:

# Linux/macOS
./build.sh

# Windows
build.cmd

Running the Application

dotnet run --project DrawThatThing.Avalonia/DrawThatThing.Avalonia.csproj

Publishing Self-Contained Executables

Create standalone executables that don't require .NET to be installed:

Windows (x64)

dotnet publish DrawThatThing.Avalonia -c Release -r win-x64 --self-contained -o publish/win-x64

Windows (ARM64)

dotnet publish DrawThatThing.Avalonia -c Release -r win-arm64 --self-contained -o publish/win-arm64

macOS (Intel)

dotnet publish DrawThatThing.Avalonia -c Release -r osx-x64 --self-contained -o publish/osx-x64

macOS (Apple Silicon)

dotnet publish DrawThatThing.Avalonia -c Release -r osx-arm64 --self-contained -o publish/osx-arm64

Linux (x64)

dotnet publish DrawThatThing.Avalonia -c Release -r linux-x64 --self-contained -o publish/linux-x64

Linux (ARM64)

dotnet publish DrawThatThing.Avalonia -c Release -r linux-arm64 --self-contained -o publish/linux-arm64

---

Platform-Specific Notes

Windows

No additional configuration required. The application uses Win32 APIs for:

• Mouse control (user32.dll - SetCursorPos, mouse_event)
• Global hotkeys (user32.dll - RegisterHotKey)
• Screen capture (gdi32.dll - BitBlt)

macOS

The easiest way to run DrawThatThing on a Mac is as an application bundle:

./build-macos-app.sh            # creates publish/DrawThatThing.app
open publish/DrawThatThing.app

Running it as a bundle (rather than through dotnet run in a terminal) makes macOS ask for permissions for DrawThatThing itself instead of for your terminal app.

DrawThatThing needs two permissions, both under System Settings → Privacy & Security:

• Accessibility: to move and click the mouse. Without it macOS silently ignores the drawing. The app asks for it on start-up.
• Screen Recording (called Screen & System Audio Recording on macOS 15 and later): to pick colors from the screen with the "Pick color" hotkey. Without it the colors cannot be read and the app tells you so instead of adding a color. The app asks for it the first time you pick a color. You may have to restart the app after granting it.

The hotkeys are system-wide (you can use them while another app, e.g. your browser, is in front) and don't need any permission. macOS 15 (Sequoia) and later no longer allow system-wide hotkeys that only use Shift + Option, so on those versions the hotkeys are Control + Option + key instead. The window always shows the combination that is active.

The application uses:

• CoreGraphics for mouse control (CGEventCreateMouseEvent, CGEventPost)
• Carbon for global hotkeys (RegisterEventHotKey)
• CoreGraphics for screen capture (CGWindowListCreateImage, falling back to the screencapture tool)

Linux

Requires X11 and the XTest extension. Wayland is not currently supported for mouse automation or global hotkeys (under XWayland the hotkeys only fire while an X11 window has the focus).

Check if XTest is available:

xdpyinfo | grep -i xtest

Install dependencies:

# Ubuntu/Debian
sudo apt-get install libx11-6 libxtst6

# Fedora
sudo dnf install libX11 libXtst

# Arch
sudo pacman -S libx11 libxtst

For Wayland users: You may need to run the application under XWayland or switch to an X11 session for full functionality.

The application uses:

• X11 for mouse control (XTestFakeMotionEvent, XTestFakeButtonEvent)
• X11 for global hotkeys (XGrabKey)
• X11 for screen capture (XGetImage)

---

Global Hotkeys

Hotkey	macOS 15+	Action
Shift+Alt+C	Control+Option+C	Stop playback
Shift+Alt+S	Control+Option+S	Set the mouse start position to the cursor
Shift+Alt+A	Control+Option+A	Add the color under the cursor (and its position) to the palette
Shift+Alt+D	Control+Option+D	Toggle the debug panel
Shift+Alt+Q	Control+Option+Q	Add the cursor position as a debug point

On macOS before 15 the hotkeys are Shift+Option+….

---

Usage

1. Open the drawing application you want to draw in.
2. Build the Color Palette: hover over each color of the drawing application's palette and press the pick color hotkey. This stores where the color is on the screen, so DrawThatThing can click it when it needs that color. You can also type rows in by hand, mark a color as the background color (BG Color), delete rows with the Delete key (Cmd+Backspace on a Mac) or the right-click menu, and Export/Import palettes as CSV files.
3. Choose a Parser and adjust its Parser Settings:
   • AbstractReader: fills areas of the same color with strokes; needs a background color. MinimumStrokeSize skips tiny areas.
   • DetailedReader: chains neighboring pixels of the same color into strokes; skips white.
   • LinearReader: draws every dark pixel (MaxLight is the maximum R+G+B) using the black palette color.
   • PointReader: clicks every pixel on its own; MixPoints randomizes the order.
4. Click Parse Image (or drop an image onto the window) and check the preview. After changing the palette or the settings, Refresh parses the same image again, and Clear Unused Colors removes palette colors that the image doesn't use.
5. Hover over the spot where the top-left corner of the drawing should go and press the set start position hotkey, then click PLAY >>. Press the stop hotkey to stop.

Additional parsers can be added by putting a DLL with an IBitmapReader implementation (with a constructor taking the image path) into a Plugins folder next to the application's executable. For the macOS bundle that is DrawThatThing.app/Contents/MacOS/Plugins; adding files there invalidates the bundle's signature, so sign it again afterwards with codesign --force --deep --sign - DrawThatThing.app.

---

Troubleshooting

Mouse automation not working

Windows: Run the application as Administrator if mouse events are being blocked.

macOS: Ensure Accessibility permissions are granted (see macOS notes above). If you rebuilt the app, remove it from the Accessibility list and add it again; macOS ties the permission to the exact build.

Linux:

• Verify XTest extension is installed: xdpyinfo | grep -i xtest
• Ensure you're running under X11, not pure Wayland

Application won't start

All platforms: Verify .NET 9 SDK is installed: dotnet --version

Linux: Install missing dependencies:

sudo apt-get install libicu-dev libssl-dev

Hotkeys not responding

Check the combinations shown at the bottom of the window (Control + Option on macOS 15+). A hotkey shown in red could not be registered, usually because another application already uses that combination; quit the other application and restart DrawThatThing to get it back.

Linux: Ensure no other application is grabbing those key combinations.

Picking a color fails (macOS)

Grant the Screen Recording (Screen & System Audio Recording) permission and restart the application; macOS only applies it after a restart.

---

Links

• Project Page: http://egeozcan.github.com/DrawThatThing
• Issues: https://github.com/egeozcan/DrawThatThing/issues

---

License

This project is licensed under the GPL-3.0 License - see the LICENSE.txt file for details.