CircleSearch — Circle to Search for Windows

Draw a circle around anything on your screen to search, OCR, translate, or reverse-image-search it — inspired by Android's Circle to Search feature.

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Solution Structure

CircleSearch.sln
├── CircleSearch/              ← Settings UI (WPF-UI + Fluent Design, .NET 10)
├── CircleSearch.Core/         ← Background service: hotkey listener + process orchestrator
├── CircleSearch.Tray/         ← System tray app (WPF-UI, persistent in taskbar)
├── CircleSearch.Overlay/      ← Fullscreen drawing overlay + action popup (pure WPF)
├── CircleSearch.CFS/          ← Shared IPC library (ConfluxService — named-pipe messaging)
└── CircleSearch.Installer/    ← WPF installer (self-contained single-file .exe)

How the processes connect

CircleSearch (Settings UI)
    │  ConfluxService (MainToCore / CoreToMain)
    ▼
CircleSearch.Core  ◄───────────────────────────────┐
    │  ConfluxService (CoreToTray / TrayToCore)    │
    ▼                                              │
CircleSearch.Tray  ────────────────────────────────┘
    (system tray, always running)

CircleSearch.Core
    │  spawns on hotkey press
    ▼
CircleSearch.Overlay  (short-lived, exits after one capture)

CircleSearch.Core is the hub. It owns the global hotkey registration, launches/monitors the other processes, and routes messages between them via ConfluxService.

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Architecture Overview

ConfluxService (CFS)

A lightweight named-pipe IPC library shared by all projects. Each channel is a pair of directional pipes carrying name|value messages. Processes call Register() then StartServiceAsync() to begin listening, and Send(name, value) to dispatch.

CircleSearch.Core

• Runs as a background console process (no window).
• Registers the global hotkey via GlobalHotkeyService — a pure Win32 P/Invoke loop on a dedicated thread (no Windows.Forms dependency).
• On hotkey press, spawns CircleSearch.Overlay.exe with the current overlay config as CLI args.
• Bridges messages between CircleSearch (settings UI) and CircleSearch.Tray so neither needs to talk to each other directly.
• Handles hotkey-change and overlaycfg-change messages to update hotkey registration or forward new config to the next overlay launch.

CircleSearch (Settings UI)

• WPF-UI / Fluent Design settings window, built on .NET Generic Host with DI.
• Single-instance enforced via a named Mutex + named pipe: a second launch sends "SHOW" to the running instance and exits.
• Communicates settings changes to Core over CFS (hotkey-change, overlaycfg-change).
• Supports a View At Boot mode: if disabled, the process exits immediately after sending config to Core, leaving Core and Tray running silently.

CircleSearch.Tray

• Persistent system-tray icon built with WPF-UI's TrayIcon.
• Connects to Core over CFS; relays tray menu actions (Open, Home, Settings, Exit) as tray-event messages.
• Reacts to main-event notifications from Core to update language, theme, material, and corner radius at runtime without restarting.

CircleSearch.Overlay

• Launched fresh for each capture session; exits automatically when the action popup closes.
• Receives its entire config (search engine, OCR language, opacity, accent color) as CLI arguments parsed by OverlayConfig.ParseArgs().
• OverlayWindow covers all monitors (VirtualScreen* bounds), captures a full screenshot on load via BitBlt WinAPI, and renders a smooth freehand stroke using Bézier geometry (CircleHelper.CreateSmoothPath).
• On mouse-up, crops the bounding region of the drawn stroke (DPI-aware) and opens ActionPopup.
• ActionPopup runs Tesseract OCR asynchronously via the Tesseract NuGet package (TesseractEngine → PixConverter.ToPix → page.GetText()).

CircleSearch.Installer

• Single-file WPF installer: all app binaries and CircleSearch.Installer.exe itself are embedded as a ZIP resource inside the installer executable.
• On install: extracts the payload to the chosen directory, creates shortcuts, registers with Windows (Add/Remove Programs), and optionally sets up autostart.
• On uninstall: kills running processes, removes files, shortcuts, startup entry, and registry keys; schedules self-deletion via a cmd.exe deferred command.
• Debugging the installer project in Visual Studio works without a payload.zip present. The ZIP is only required (and enforced) when publishing in Release via build.bat.

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Prerequisites

1. .NET 10 SDK

Download from: https://dotnet.microsoft.com/download/dotnet/10.0

2. Tesseract traineddata files (required for text recognition)

The Overlay project uses the Tesseract NuGet package (v5.2.0) — no manual DLL installation needed. However, you still need to provide the language data files. Place them in a tessdata/ folder next to CircleSearch.Overlay.exe:

<install dir>/
├── CircleSearch.Overlay.exe
└── tessdata/
    ├── eng.traineddata          ← English (required)
    └── vie.traineddata          ← Vietnamese (optional)

Download .traineddata files for any languages you need from the official repository: https://github.com/tesseract-ocr/tessdata

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Build

Release — single-file installer (recommended)

Run build.bat from the repository root:

build.bat

The script performs the following steps automatically:

1. Publishes CircleSearch, CircleSearch.Overlay, CircleSearch.Tray, and CircleSearch.Core into a temporary installer-output\publish\ folder.
2. Creates an empty payload.zip placeholder so the installer project compiles on pass 1.
3. Publishes CircleSearch.Installer (pass 1) to obtain the installer executable.
4. Copies CircleSearch.Installer.exe into publish\ so it is included in the payload.
5. Zips the entire publish\ folder into CircleSearch.Installer\Resources\payload.zip.
6. Republishes CircleSearch.Installer (pass 2) with the real payload embedded.
7. Removes all intermediate files (publish\ folder and payload.zip).

Result: a single installer-output\CircleSearch.Installer.exe that contains every binary needed to install the application.

Note: payload.zip is a build-time artifact and is not committed to the repository. It is created and deleted automatically by build.bat.

Debug — Visual Studio

Open CircleSearch.sln in Visual Studio 2022 or later and set CircleSearch.Installer as the startup project (or any other project you want to debug). Building and running in Debug configuration works normally without payload.zip present — the payload check is skipped and the embedded resource is omitted in non-Release builds.

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Running

Via installer

Run CircleSearch.Installer.exe, choose an install directory, and click Install. The installer will:

1. Extract all application files to the chosen directory.
2. Optionally create a Desktop and/or Start Menu shortcut.
3. Optionally register CircleSearch.exe to run at Windows startup.
4. Register the application in Add or Remove Programs for clean uninstallation.

After installation, launch CircleSearch from the shortcut or Start Menu. CircleSearch.exe is the single entry point — it automatically spawns Core, Tray, and all background services.

Manually (without installer)

1. Publish all four app projects to the same output folder (or run build.bat and copy publish\ contents).
2. Place Tesseract tessdata/ folder next to CircleSearch.Overlay.exe.
3. Launch CircleSearch.exe — this is the single entry point. It automatically starts Core and Tray in the background.
4. Press the hotkey (default Ctrl + Win + Z) to activate the overlay.

Note: CircleSearch.exe can be set to run at Windows startup via the Settings UI. When the View At Boot option is disabled, the settings window will not appear on startup — Core and Tray continue running silently in the background.

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Usage

1. Activate — Press the hotkey (default Ctrl + Win + Z).
2. Draw — Hold left mouse button and draw a circle or region around the content you want.
3. Choose an action from the popup:
   • 🔍 Search — OCR the region and search with your chosen engine (Google, Bing, etc.)
   • 🖼️ Search by image — Copy the region to clipboard and open Google Lens
   • 📋 Copy text — OCR offline and copy result to clipboard
   • 🌐 Translate — OCR and open Google Translate
4. Dismiss — Press Esc or click outside the popup.

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Settings

Open CircleSearch.exe to configure:

Setting	Description
Hotkey	Modifier keys (Ctrl / Win / Alt / Shift) + any key
Search engine	Google, Bing, DuckDuckGo, Yandex, Baidu
OCR language	Any language supported by your tessdata/ folder
Start with Windows	Register/remove from Windows startup
Overlay opacity	Dimming level of the fullscreen overlay
Accent color	Color of the drawn stroke and selection rectangle

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Troubleshooting

Problem	Cause	Fix
eng.traineddata missing	Tessdata missing	Download from github.com/tesseract-ocr/tessdata and place in tessdata/ next to the exe
Hotkey not working	Conflicting shortcut	Change the key combination in Settings
Overlay does not appear	Core not running	Make sure CircleSearch.exe was launched — it spawns Core automatically
Poor OCR results	Region too small or blurry	Draw a larger area; ensure the text is legible on screen
Settings window won't open twice	Single-instance guard	The first instance will be focused automatically
Installer shows wrong size (~5 MB)	payload.zip was not embedded	Delete any leftover payload.zip and re-run build.bat from scratch

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Why four processes?

Process	Reason for isolation
Core	Needs to stay alive in the background without a UI window; owns the hotkey Win32 message loop on a dedicated thread
Settings UI	Heavy WPF-UI / Fluent Design stack; only needed when the user wants to change settings
Tray	Must remain persistent in the system tray even when the settings window is closed
Overlay	Spawned fresh per capture so any crash or resource leak is self-contained; terminates immediately after use

Inter-process communication is handled entirely by ConfluxService (named pipes), keeping each process decoupled and independently deployable.