taskbar-calculator
A simple, small calculator placed discreetly near the Windows Taskbar or anywhere on the screen taskbar-calculator.marcomaroni.it
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.gitattributes
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AboutDialog.cpp
App.cpp
BuildCounter.txt
Calculator.cpp
Calculator.h
CalculatorWindow.cpp
CalculatorWindow.h
CLAUDE.md
DateFormatSettingsRes.h
icon1.ico
LICENSE
README.md
resource.h
Settings.cpp
Settings.h
StartupManager.cpp
StartupManager.h
stdafx.cpp
stdafx.h
targetver.h
TaskbarCalculator.manifest
TaskbarCalculator.rc
TaskbarCalculator.rc2
TaskbarCalculator.sln
TaskbarCalculator.vcproj
TaskbarCalculator.vcxproj
TaskbarCalculator.vcxproj.filters
TrayIcon.cpp
TrayIcon.h
Utils.cpp
Utils.h
version.h
VisualStyle.cpp
VisualStyle.h
README.md

TaskbarCalculator #

TaskbarCalculator is a C++/Win32 application for Windows 11 that sits in the notification area (system tray) and shows an always-on-top calculator window driven by keyboard input.

The project started as a migration of a previous DeskBand (an in-process COM extension hosted by the taskbar), which Windows 11 no longer loads for third-party shell extensions. The current version is a standalone executable that adds a tray icon: left-click shows/hides the window, right-click opens a menu with Show/Hide, Start at login, About, and Exit. A global hotkey, Win+Alt+C, toggles the window from any application (if the combination is already taken by another app it is silently ignored, and the tray click still works).

Supported platforms: Windows 10 and later (start-at-login relies on the WinRT StartupTask API, which requires Windows 10+).

Code layout #

  • App.cpp — entry point (wWinMain), single-instance handling, tray icon, and hidden owner window.
  • CalculatorWindow.cpp/.h — calculator window, keyboard input handling, number formatting based on regional settings, positioning and persistence.
  • Calculator.cpp/.h — calculation engine, independent from the UI, based on a state machine (init, first_oper, operation, second_oper, result, error). Supports the four basic operations, square root, percentage, sign change, and reciprocal (1/x).
  • Settings.cpp/.h, StartupManager.cpp/.h, VisualStyle.cpp/.h, TrayIcon.cpp/.h, Utils.cpp/.h — support modules (registry-based window position/visibility, start at login, classic/themed visuals, tray icon, misc utilities).

More detailed architecture and conventions are documented in CLAUDE.md.

Build #

Requires Visual Studio 2022 (v143 toolset), Windows SDK 10.0.26100.0, and the C++/WinRT components for the start-at-login feature.

msbuild TaskbarCalculator.vcxproj /p:Configuration=Debug   /p:Platform=x64
msbuild TaskbarCalculator.vcxproj /p:Configuration=Release /p:Platform=x64

Build the .vcxproj directly, not the .sln (which references a setup project not included in this repository). The executable is produced at x64\<Config>\TaskbarCalculator.exe.

Test #

The calculation engine (Calculator.cpp/.h) is decoupled from the precompiled header and is compiled and run separately with a small header-only harness:

tests\build-and-run.cmd

from an "x64 Native Tools Command Prompt".

Packaging #

Two distribution paths are supported:

  • Classic installer: Packaging\TaskbarCalculatorSetup.iss, compiled with Inno Setup (ISCC.exe), or via the Packaging\build-setup.cmd script, which runs a Release x64 build and compiles the installer in one step.
  • MSIX: PowerShell scripts in Packaging\ (MakeAssets.ps1, MakeCert.ps1, BuildMsix.ps1), kept for a possible future Microsoft Store submission.

In both cases, start-at-login uses the MSIX StartupTask API when the app is packaged, falling back to the HKCU\...\Run registry value when installed via the classic path.

License #

Copyright (C) 2026 Marco Maroni

TaskbarCalculator is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License version 3 as published by the Free Software Foundation. See the LICENSE file for the full text.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. The GPLv3 is a strong copyleft license: any derivative work must also be released as open source under a GPL-compatible license, and incorporating this program into proprietary software is not permitted.