fei4xu / win32

Build Win32 apps with Dart!

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.

In addition to exposing the APIs themselves, this package offers a variety of instructive examples for more complex FFI usage scenarios.

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 Win32 developer. Other plugins may build on these primitives to provide a friendly API for Dart and Flutter developers. A good example of that is filepicker_windows, which offers a common item dialog suitable for incorporation into an existing Flutter app.

Usage

This package lets you write apps that use the Windows API directly from Dart, by wrapping common Win32, COM and Windows Runtime 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:

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 WindowProc 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

Samples

Dart samples

The package includes a number of examples in the example subdirectory. These examples use the Win32 API for all UI display and do not require Flutter.

Example	Description
hello.dart	Basic Petzoldian "hello world" Win32 app
bluetooth.dart	Demonstrate enumerating Bluetooth devices
calendar.dart	Gets information about the calendar from a WinRT API
console.dart	Shows usage of console APIs
credentials.dart	Adds a credential to the store and retrieves it
customwin.dart	Displays a non-rectangular window
devices.dart	Uses volume management APIs to list all disk devices
dialog.dart	Create a custom dialog box in code
dialogshow.dart	Creates a common item dialog (file picker) using COM
dump.dart	Use debugger libraries to print DLL exported functions
dynamic_load.dart	Demonstrate loading a DLL and calling it at runtime
filever.dart	Getting file version information from the file resource
guid.dart	Creates a globally unique identifier (GUID)
idispatch.dart	Demonstrates calling a method using IDispatch
knownfolder.dart	Retrieves known folders from the current user profile
manifest\	Demonstrates the use of app manifests for compiled apps
midi.dart	Demonstrates MIDI playback using MCI commands
modules.dart	Enumerates all loaded modules on the current system
monitor.dart	Uses DDC and monitor-config API to get monitor caps
msgbox.dart	Demonstrates a MessageBox from the console
notepad\	Lightweight replica of the Windows notepad applet
paint.dart	Demonstrates simple GDI drawing and min/max window sizing
play_sound.dart	Plays a WAV file through the Windows PlaySound API
screenshot.dart	Takes a screenshot of the current desktop
scroll.dart	Example of horizontal and vertical scrolling text window
sendinput.dart	Sends keyboard and mouse input to another window
snake.dart	Snake game using various GDI features
sysinfo.dart	Examples of getting device information from native C APIs
taskdialog.dart	Demonstrates using modern task dialog boxes
tetris\main.dart	Port of an open-source Tetris game to Dart
wallpaper.dart	Shows what wallpaper and background color are set
window.dart	Enumerates open windows and basic window manipulation
winmd.dart	Interrogate Windows Runtime types
wmi.dart	Using WMI from COM to retrieve device/OS information

Flutter samples

The explorer\ subdirectory contains an example of a simple Flutter app that uses the volume management Win32 APIs to find the disk drives connected to your computer and their volume IDs and attached paths.

Requirements

This package assumes the Dart 64-bit compiler, running on Windows. Many commands are tested on 32-bit Windows, but due to the lack of a compiler for 32-bit executables and the increasing lack of machines running 32-bit OSes, this is inevitably a low priority. The package is also tested on Windows-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 add based on user demand. I'm particularly interested in unblocking plugins for Windows. Please file feature requests and bugs at the issue tracker.

Disclaimer: This is a hobby project, and should not be viewed as having the same level of quality assurance as an official package from the Dart team. I'm a product manager having fun on my weekends!

Backwards compatibility

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

• Several times, my fixing a bug in the fidelity of the Win32 API has tightened the constraints over a parameter (for example, Pointer becomes Pointer<INPUT>). These changes should be signalled in the log.
• Adding new features 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.

One solution is to pin to a specific version of Win32, or declare a more tightly-bounded version dependency (e.g. '>=1.7.0 <1.8.0' rather than merely ^1.7.0). But the best approach is simply to test regularly with the latest version of this package, and continue to move your minimum forward. As the package matures, these issues should gradually fade away.

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