X-Git-Url: https://gerrit.automotivelinux.org/gerrit/gitweb?a=blobdiff_plain;f=docs%2F3_Developer_Guides%2F3_Creating_a_New_Application.md;h=c98cf1c3618681f2ae7973b5a1c8ea63ca01a452;hb=c72bd577eb1fec884f27f01f3e76875202716e0f;hp=6c382fd35de4b949d636066d15bc45c9c63a8326;hpb=8160b5cdc8547277f3f31ee1e41524754d5d987d;p=AGL%2Fdocumentation.git diff --git a/docs/3_Developer_Guides/3_Creating_a_New_Application.md b/docs/3_Developer_Guides/3_Creating_a_New_Application.md index 6c382fd..c98cf1c 100644 --- a/docs/3_Developer_Guides/3_Creating_a_New_Application.md +++ b/docs/3_Developer_Guides/3_Creating_a_New_Application.md @@ -2,4 +2,132 @@ title: Creating a New Application --- -TBD \ No newline at end of file +Applications are either software designed to perform a specific task during a limited amount of +time, or graphical applications presenting the user with an interface they can interact with. + +Such applications are executed by `applaunchd`, the AGL +[application launcher service](1_Application_Framework/2_Application_Startup/). + +# Basic requirements + +In order to be enumerated by `applaunchd`, applications must provide the a `.desktop` file, as +defined by the [Desktop Entry specification](https://specifications.freedesktop.org/desktop-entry-spec/desktop-entry-spec-latest.html). + +The desktop entry file should be installed to `/usr/share/applications` (or the `applications` +sub-directory of any entry present in the `XDG_DATA_DIRS` environment variable) and have a +meaningful name. It is considered good practice to use reverse-DNS notation for the desktop +entry file name, following the recommendations of the [D-Bus specification](https://dbus.freedesktop.org/doc/dbus-specification.html#message-protocol-names): +- this avoids potential name collisions with other desktop entry files +- it makes it easier to enable [D-Bus activation](#d-bus-activation) during the application + development cycle if needed +- for [graphical applications](#graphical-applications), it ensures the chosen Wayland `app-id` + will be unique + +Such a file must contain at least the following keys: +- `Type`: desktop entry type, must be set to `Application` +- `Name`: application name, as it should be displayed in menus and application launchers +- `Exec`: full path to the main executable + +Below is an example of a minimal desktop entry file: + +``` +[Desktop Entry] +Type=Application +Name=Example Application +Exec=/usr/bin/example-app +``` + +Graphical applications must also provide an `Icon` entry pointing to the application icon. +The value for this entry must either be the full path to the icon's file or, for icons part +of an existing [icon theme](https://specifications.freedesktop.org/icon-theme-spec/icon-theme-spec-latest.html), +the name of an element of this theme. + +In addition, a number of optional fields can be used to change how `applaunchd` will consider the +application: +- `Version`: version of the Desktop Entry Specification the file conforms to, must be `1.5` +- `Hidden`: boolean value, if `true` the application is always ignored by `applaunchd` and + won't be listed nor executed +- `Terminal`: boolean value, if `true` the application is excluded when requesting the list of + graphical applications from `applaunchd` +- `DBusActivatable`: boolean value, must be `true` for [D-Bus activated applications](#d-bus-activation) +- `Implements`: list of D-Bus interfaces the application implements, only used for D-Bus activated + applications. + +Finally, graphical applications may also define the `StartupWMClass` key in some cases. Please +refer to the [graphical applications](#graphical-applications) section for more information. + +# D-Bus activation + +Similarly to [services](2_Creating_a_New_Service.md/#d-bus-activation), applications can +also be activated through D-Bus. + +Such applications must name their `.desktop` file after the D-Bus name they register. In addition, +this file must contain the following entries: + +``` +DBusActivatable=true +Implements=IFACE1;IFACE2;... +``` + +Where `IFACEn` are the names of the D-Bus interfaces the application implements. + +In addition, they must provide a D-Bus service file named `NAME.service` and installed +to `/usr/share/dbus-1/services`. + +The contents of the D-Bus service file must be the following: + +``` +[D-BUS Service] +Name=NAME +Exec=/path/to/executable +``` + +For example, an application registering the `org.automotivelinux.Example` D-Bus name +and implementing the `org.automotivelinux.Example.Search1` and `org.automotivelinux.Example.Execute1` +interfaces would provide the following files: + +* Desktop entry (`/usr/share/applications/org.automotivelinux.Example.desktop`): + +``` +[Desktop Entry] +Type=Application +Version=1.5 +Name=Example Application +Exec=/usr/bin/example-app +Icon=example-icon +Terminal=false +DBusActivatable=true +Implements=org.automotivelinux.Example.Search1;org.automotivelinux.Example.Execute1 +``` + +* D-Bus service file (`/usr/share/dbus-1/services/org.automotivelinux.Example.service`): + +``` +[D-BUS Service] +Name=org.automotivelinux.Example +Exec=/usr/bin/example-app +``` + +*Note: in addition to their own D-Bus interface, D-Bus activated applications must also +implement the `org.freedesktop.Application` interface as defined in the +[Desktop Entry specification](https://specifications.freedesktop.org/desktop-entry-spec/1.1/ar01s07.html).* + +# Graphical applications + +In addition, graphical applications need to comply with a few more requirements: + +1. Each application must set a Wayland application ID appropriately as soon as its main window +is created. + +2. The `app-id` must be specified in the desktop entry file by adding the following line: + +``` +StartupWMClass=APP_ID +``` + +3. The desktop entry file must be named `APP_ID.desktop`. + +Doing so will ensure other software can associate the actual `app-id` to the proper application. + +*Note: application ID's are set using the [XDG toplevel](https://wayland-book.com/xdg-shell-basics/xdg-toplevel.html) +Wayland interface.*