#qpainter (WIP)

a QPainter FFI binding.

https://github.com/user-attachments/assets/7bf54e83-af97-4696-811e-e9e032dcc787

#Support C++ class (partialy method)

#QtCore

QtCore
- QString
- QColor
- QStringList
- QPointF
- QSizeF
- QRectF
QtGUI
- QApplication
- QPainter
- QPen
- QBrush
- QFont
- QFontMetricsF

#Entry

Window::show
event handler
- paint
- key_press
- key_release
- mouse_double_click
- mouse_press
- mouse_release
- mouse_move

#Native build and validation

Requires Python 3, CMake, Make, pkg-config, Qt 6 Core/Gui/Widgets development files, and a C++23 compiler supporting explicit object parameters (Clang 18+). On Ubuntu 24.04:

sudo apt-get install clang-18 cmake make qt6-base-dev pkg-config
export MOON_CC=clang-18 CXX=clang++-18
moon build --target native src/main
QT_QPA_PLATFORM=offscreen moon test --target native
bash scripts/check-native.sh

On macOS, install Qt 6 and LLVM with Homebrew, expose Qt's pkg-config files, and set MOON_CC/CXX to that LLVM installation. The build script discovers Qt through CMake and pkg-config; QT6_INCLUDE is no longer required.

The regression tests cover UTF-16 conversion (including embedded NUL and surrogate pairs), geometry getters, and an offscreen window receiving paint callbacks. They do not verify interactive input or rendering on a real display. QPAINTER_SANITIZE=1 instruments the bridge and MoonBit executable with ASan and UBSan; CI treats sanitizer diagnostics as failures.

Event callbacks use MoonBit-generated FuncRef adapters and an opaque managed context. The C++ side retains callbacks while a window exists and transfers an owned reference to each adapter; it never invokes a closure's internal code pointer. Tests exercise paint, resize, key, and mouse callbacks under sanitizers.

Qt retains the argc and argv passed to QApplication::new; their MoonBit owners must remain alive until the application has finished using them.

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