A package that wraps some of the most common Win32 API calls using FFI to make them accessible to Dart code without requiring a C compiler or the Windows SDK.

Part of the Dart | Windows suite of Windows packages.

Documentation

• Overview and concepts
• API reference

Usage

This package lets you write apps that use the Windows API directly from Dart, by wrapping common Win32 and COM APIs using Dart FFI.

You could use it to call a Win32 API like EnumFontFamiliesEx to enumerate all locally-installed fonts:

or access system information that is not exposed directly by the Dart framework libraries:

You could use it to build a Windows app with Flutter that relies on Win32 APIs:

You could even use it to build a traditional Win32 app, written purely in Dart, that could have come straight out of a classic Charles Petzold book on programming Windows apps:

or even, perhaps, a fully-fledged game using GDI:

You might even build a package that depends upon it, like dart_console, which enables advanced console manipulation:

or filepicker_windows, which provides a modern Windows file picker for Flutter:

By design, this package provides minimal modifications to the Win32 API to support Dart idioms. The goal is to provide high familiarity to an existing Windows developer. Other Dart packages may build on these primitives to provide a friendly API for Dart and Flutter developers. A good example of that is win32_registry, which offers a set of APIs for accessing the Windows Registry that don't require knowledge of FFI.

Getting started

Many more samples can be found in the example\ subdirectory, along with a test suite in the test\ subdirectory that shows other API calls.

A good starting point is hello.dart. This example demonstrates creating a Win32 window and responding to common messages such as WM_PAINT through a WNDPROC callback function.

To run it, type:

dart example\hello.dart

This should display a window with a text message.

This can be compiled into a standalone Win32 executable by running:

dart compile exe example\hello.dart -o example\bin\hello.exe

For more information on working with the Win32 library from Dart, consult the documentation.

Examples

There are many examples included with this package that demonstrate calling various Win32 and COM APIs. These can be found in the example\ folder; a short description of each example can be found here.

Packages built on win32

There are a growing number of packages that build on the relatively low-level APIs exposed by the Dart win32 package to provide more idiomatic class wrappers. These packages typically don't require any knowledge of Windows programming models or FFI, and are ideal for incorporation into Flutter apps for Windows.

A full list of these packages can be found on pub, and other packages from the Dart | Windows authors can be found here: https://github.com/dart-windows

• filepicker_windows: makes the Windows file open / save common dialog boxes available to Flutter and Dart apps.
• path_provider_windows: provides a way for Dart apps to find common Windows file locations (such as the documents directory).
• win32_clipboard: provides a friendly Dart API for accessing the Windows Clipboard.
• win32_gamepad: provides a friendly Dart API for accessing gamepads connected to a Windows machine.
• win32_gui: allows you to create Win32 GUI applications in an object-oriented style with some helpers.
• win32_registry: provides Dart classes for accessing and manipulating the Windows Registry.
• win32_runner: provides an experimental shell (or runner) for hosting Flutter apps without needing a C++ compiler to create the EXE.

Requirements

This package is designed to run on 64-bit editions of Windows. The primary target is Intel processors, but the package is also tested on ARM architecture, running in x64 emulation mode.

Features and bugs

The current package only projects a subset of the Win32 API, but new APIs will be added based on user demand, particularly if it unblocks the creation of new Dart packages for Windows. Please file feature requests and bugs at the issue tracker.

Backwards compatibility

The library version models semver, but you cannot assume a strict guarantee of no breaking changes between minor versions. That guarantee is not possible to make, for several reasons:

• The package is based on metadata published by Microsoft, which is generated by scraping Win32 SDK header files. As the quality of the scraper improves, there may be minor changes to some fields (for example, an unsigned integer may become a signed integer).
• Adding new APIs may itself cause a breaking change. For example, if you declare a missing Windows constant in your own code that is then added, Dart will complain about the duplicate definition.

If this causes you concern, our recommendation is to pin to a specific version of Win32. But the best approach is simply to test regularly with the latest version of this package, and continue to move your minimum forward.

Acknowledgements

The Tetris example listed above is a fuller worked example of a reasonably complete program that uses the Dart Win32 package. It is a port of a C version of the game by Chang-Hung Liang. More information...

The C implementation of Snake is by David Jones, and is ported with his permission.

The original C version of the Notepad example was authored by Charles Petzold, and is kindly licensed by him without restriction.

The original C version of the custom title bar example is by Dmitriy Kubyshkin and is licensed by him under the MIT License.

The summary Win32 API documentation comments are licensed by Microsoft under the Creative Commons Attribution 4.0 International Public License.