doc: document makeDesktopItem

```

::::

### `makeDesktopItem` {#trivial-builder-makeDesktopItem}

Write an [XDG desktop file](https://specifications.freedesktop.org/desktop-entry-spec/1.4/) to the Nix store.

This function is usually used to add desktop items to a package through the `copyDesktopItems` hook.

`makeDesktopItem` adheres to version 1.4 of the specification.

#### Inputs {#trivial-builder-makeDesktopItem-inputs}

`makeDesktopItem` takes an attribute set that accepts most values from the [XDG specification](https://specifications.freedesktop.org/desktop-entry-spec/1.4/ar01s06.html).

All recognised keys from the specification are supported with the exception of the "Hidden" field. The keys are converted into camelCase format, but correspond 1:1 to their equivalent in the specification: `genericName`, `noDisplay`, `comment`, `icon`, `onlyShowIn`, `notShowIn`, `dbusActivatable`, `tryExec`, `exec`, `path`, `terminal`, `mimeTypes`, `categories`, `implements`, `keywords`, `startupNotify`, `startupWMClass`, `url`, `prefersNonDefaultGPU`.

The "Version" field is hardcoded to the version `makeDesktopItem` currently adheres to.

The following fields are either required, are of a different type than in the specification, carry specific default values, or are additional fields supported by `makeDesktopItem`:

`name` (String)

: The name of the desktop file in the Nix store.

`type` (String; _optional_)

: Default value: `"Application"`

`desktopName` (String)

: Corresponds to the "Name" field of the specification.

`actions` (List of Attribute set; _optional_)

: A list of attribute sets {name, exec?, icon?}

`extraConfig` (Attribute set; _optional_)

: Additional key/value pairs to be added verbatim to the desktop file. Attributes need to be prefixed with 'X-'.

#### Examples {#trivial-builder-makeDesktopItem-examples}

::: {.example #ex-makeDesktopItem}

# Usage 1 of `makeDesktopItem`

Write a desktop file `/nix/store/<store path>/my-program.desktop` to the Nix store.

```nix

{makeDesktopItem}:

makeDesktopItem {

  name = "my-program";

  desktopName = "My Program";

  genericName = "Video Player";

  noDisplay = false;

  comment = "Cool video player";

  icon = "/path/to/icon";

  onlyShowIn = [ "KDE" ];

  dbusActivatable = true;

  tryExec = "my-program";

  exec = "my-program --someflag";

  path = "/some/working/path";

  terminal = false;

  actions.example = {

    name = "New Window";

    exec = "my-program --new-window";

    icon = "/some/icon";

  };

  mimeTypes = [ "video/mp4" ];

  categories = [ "Utility" ];

  implements = [ "org.my-program" ];

  keywords = [ "Video" "Player" ];

  startupNotify = false;

  startupWMClass = "MyProgram";

  prefersNonDefaultGPU = false;

  extraConfig.X-SomeExtension = "somevalue";

}

```

:::

::: {.example #ex2-makeDesktopItem}

# Usage 2 of `makeDesktopItem`

Override the `hello` package to add a desktop item.

```nix

{ copyDesktopItems

, hello

, makeDesktopItem }:

hello.overrideAttrs {

  nativeBuildInputs = [ copyDesktopItems ];

  desktopItems = [(makeDesktopItem {

    name = "hello";

    desktopName = "Hello";

    exec = "hello";

  })];

}

```

:::

### `writeTextFile` {#trivial-builder-writeTextFile}

Write a text file to the Nix store.