# Windows

## Requirements

**Windows**:

You must be running 64 bit Windows 10, version 1703 or newer.

The build system requires [Developer Mode](https://docs.microsoft.com/en-us/windows/apps/get-started/enable-your-device-for-development) to be enabled.

**Visual Studio**:

Install the [Visual Studio build tools](https://visualstudio.microsoft.com/downloads/#build-tools-for-visual-studio-2019).

Make sure the "C++ build tools" box is selected, and leave the default optional
components enabled on the right.

**Python 3.8**:

Download Python 3.8 from <https://python.org>. Run the installer, and
customize the installation. Select "install for all users", and choose
the install path as c:\python. Currently the build scripts require
Python to be installed in that location.

When the install is done, click on the "remove the path limit" button.

**MSYS**:

Install [msys2](https://www.msys2.org/) into the default folder location.

After installation completes, run msys2, and run the following command:

```
$ pacman -S git gettext
```

**Bazelisk**:

Use Start>Run to open PowerShell. Create a folder to store Bazelisk
and its working data. Anki's build scripts expect to find it in \bazel on the same drive as the source folder.

```
PS> mkdir \bazel
PS> cd \bazel
```

Then grab Bazelisk:

```
PS> \msys64\usr\bin\curl -L https://github.com/bazelbuild/bazelisk/releases/download/v1.7.4/bazelisk-windows-amd64.exe -o bazel.exe
```

NOTE: At the time of writing, Windows Defender is claiming this file has a virus. If it disappears
the first time you run Bazel, restoring it from the Defender settings should allow you to proceed.

**Source folder**:

Anki's source files do not need to be in a specific location, but it's best
to avoid long paths, as they can cause problems.

## Build failures

The Javascript bundling on Windows is currently a bit flaky, so the initial
build will likely fail with an error about a missing rollup module. If you
get an error when running the commands below, try repeating them once or twice.

## Running Anki during development

Open PowerShell and change to the top level of Anki's source folder,
then run

```
.\run
```

This will build Anki and run it in place.

The first build will take while, as it downloads and builds a bunch of
dependencies. When the build is complete, Anki will automatically start.

To play audio, mpv.exe or mplayer.exe must be on the path. At the time
of writing, recording is not yet supported, as currently pyaudio is
not being installed.

## More

For info on running tests, building wheels and so on, please see
[Development](./development.md).

Note that where the instructions on that page say "bazel", please use ".\bazel"
instead. This runs bazel.bat inside the Anki source folder, instead of
calling Bazel directly. This takes care of setting up the path and output folder
correctly, which avoids issues with long path names.

## Cleaning notes

Unlike the old Make system, a "clean build" should almost never be required
unless you are debugging issues with the build system. But if you need to run
"bazel clean --expunge", make sure you remove the ts/node_modules folder
afterwards, or it will cause a "no such file or directory node_modules/anki"
error on the subsequent build on Windows.