Three desktop calculators for Windows in the Apple Liquid Glass style: one in C# and WPF, two in Electron. Each has its own expression engine with no eval, and 701 tests, most of them properties over random input.
Download for Windows · Русская версия этого файла
Every release has a portable .exe (no installation) and an installer for each of the three.
Expressions with operator precedence, computed in decimal, so 0.1 + 0.2 is exactly 0.3. Brackets with implicit multiplication, scientific functions, memory, history, and undo/redo for every key press. The engine (CalcPro.Core) knows nothing about WPF: tokenizer, Pratt parser, evaluator, and a command per key press. More
Four modes: Standard, Scientific with DEG/RAD/GRAD and 2nd, Fraction, where fractions are typed "in a column" with a cursor, and Programmer, 64-bit integers in HEX, DEC, OCT and BIN with bitwise operations (Calc Pro has it too). The parser is shunting-yard. More
A copy of the iPhone calculator: step-by-step evaluation without precedence (2 + 3 × 4 = gives 20, as on the phone), round buttons that stay round at any window size, a scientific panel, and history. The interface is in Russian, numbers are written the Russian way: 1 234,5. More
All three have the same five themes as Paint Pro, with the same colours: Стеклянная (glass, the default), Строгая (formal), Светлая (light), Ночная (night) and Тёплая (warm). The calculators and Paint were meant to look like one family, and now they do. The theme is picked from the palette button (Calc Pro, Calc Pro Glass) or the ••• menu (Calculator iOS 26), changes the window at once and is remembered between runs.
All three shrink as far as the calculator built into Windows, whose minimum is 320×500, or further: Calc Pro to 320×500, Calc Pro Glass and Calculator iOS 26 to 280×500. In a low window the display and the gaps give up height first, so the keys of the scientific mode still fit. In a narrow Calc Pro the history opens in place of the keypad, as in the Windows calculator, with a back button in its header; it goes back to its column when the window is wide again. A long result on the display gets smaller instead of losing digits under …, and a long example in the history wraps.
All three open where and how large they were closed, maximized too. Whatever the saved file holds, the window opens where it can be seen and taken by its title bar: on a monitor that has been unplugged it opens centred on the main one, larger than the screen it is cut to it, below the minimum it is raised to it, and a damaged file gives the default size. The rule is a plain function with property tests over random screen layouts (window-state.js in the Electron apps, WindowPlacement in Calc Pro); they found that on a screen lower than the minimum window the title bar was pushed above the screen. The file is written through a temporary one, so a killed process leaves the old file rather than half of a new one.
Calc Pro now draws its own title bar in the colours of the theme, with the app name, round minimize and close buttons like those of Calc Pro Glass and corners rounded a little more than Windows 11 does (14 px). Snapping, resizing by the edge and maximizing work as before; a maximized window keeps off the taskbar.
dotnet test calcpro-wpf\CalcPro.sln # 409 (xUnit + FsCheck)
cd calcpro-glass; npm test; npm run test:e2e # 213 + e2e in Electron
cd ios-calculator; npm test; npm run test:e2e # 79 + e2e in ElectronMost tests state a law instead of an example: a random expression tree printed with minimal brackets parses back into the same tree; sin² + cos² = 1; undoing every key press returns the initial state. The key-press state machines get thousands of random sequences, and after every single press the display, the expression and the memory are checked. docs/TESTING.md lists them all (in Russian).
These properties keep finding real bugs. Getting this repository ready for publication, the random-keys property of Calc Pro Glass found that EE right after = glued an E onto a stale display (0E) which the next digit then wiped. The README screenshots found two more in Calc Pro: the expression line showed * and / while the buttons say × and ÷, and the memory badge stretched into a tall bar.
The theme tests read the theme files themselves: all five must define the same keys, text must keep at least 4.5:1 on its keys in every theme, and the markup may reach theme colours only through the theme. They found that the AC, ± and % keys were below that contrast in two themes, 3.37:1 in glass and 2.60:1 in formal, and that was fixed before the release.
Checks for the small window: WindowLayoutTests pin the rule itself (the minimum, the thresholds, the history closing when the window narrows and coming back when it widens, as an FsCheck property over random sequences of widths), and the screenshot program opens the real window at 320×500 and fails if any visible button leaves the window, is under 20 px, does not fit its grid cell, or if a line of the history or the display is cut off. That check found two bugs before the release: AC, C, ⌫, the operators and the scientific keys have their own style with a minimum height of 42 and were cut in half by the lower rows, and the display showed 14662398875… for 146623988754610578. The end-to-end runs of both Electron apps resize the window to 280×500 and check every key in every mode, and a long example in the history.
CI runs the C# and JavaScript engine tests on every push. The end-to-end runs need a real Electron window and are run locally before a release.
.NET SDK 8+, Node.js 20+ and Inno Setup 6 (for the Calc Pro installer):
.\build.ps1 # tests, portable and setup for all three into .\dist
.\build.ps1 -Only glass # one app: wpf | glass | ios
.\build.ps1 -SkipTests # packaging onlyFrom sources:
dotnet run --project calcpro-wpf\src\CalcPro.Wpf
cd calcpro-glass; npm ci; npm start
cd ios-calculator; npm ci; npm startNo screenshot here was taken from the screen. calcpro-wpf/tools/CalcPro.Screenshots opens the real MainWindow far off screen, presses keys through the view model's commands and renders the window itself with RenderTargetBitmap. The two Electron apps have tools/make-screenshots.js: the real page in a hidden window with an in-memory session, real clicks, and capturePage(). No other window can get into the frame.
build.ps1 everything into dist/
docs/TESTING.md what the tests check
calcpro-wpf/ Calc Pro: CalcPro.Core (engine), CalcPro.Wpf (window), tests, installer
calcpro-glass/ Calc Pro Glass: src/calc-core.js (engine without DOM), src/app.js, test, e2e
ios-calculator/ Calculator iOS 26: src/calc-engine.js (engine without DOM), src/app.js, test, e2e
MIT, see LICENSE.