From 653bd18d5192d79254ef6961a54dea01f7bb11f2 Mon Sep 17 00:00:00 2001 From: Jan Tojnar Date: Fri, 11 Jun 2021 14:04:06 +0200 Subject: doc/gnome: document GIO modules In particular, that glib-networking is required for TLS support. --- doc/languages-frameworks/gnome.section.md | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) (limited to 'doc') diff --git a/doc/languages-frameworks/gnome.section.md b/doc/languages-frameworks/gnome.section.md index a1121efe3f0..11b49f4f235 100644 --- a/doc/languages-frameworks/gnome.section.md +++ b/doc/languages-frameworks/gnome.section.md @@ -8,12 +8,30 @@ Programs in the GNOME universe are written in various languages but they all use [GSettings](https://developer.gnome.org/gio/stable/GSettings.html) API is often used for storing settings. GSettings schemas are required, to know the type and other metadata of the stored values. GLib looks for `glib-2.0/schemas/gschemas.compiled` files inside the directories of `XDG_DATA_DIRS`. -On Linux, GSettings API is implemented using [dconf](https://wiki.gnome.org/Projects/dconf) backend. You will need to add `dconf` GIO module to `GIO_EXTRA_MODULES` variable, otherwise the `memory` backend will be used and the saved settings will not be persistent. +On Linux, GSettings API is implemented using [dconf](https://wiki.gnome.org/Projects/dconf) backend. You will need to add `dconf` [GIO module](#ssec-gnome-gio-modules) to `GIO_EXTRA_MODULES` variable, otherwise the `memory` backend will be used and the saved settings will not be persistent. Last you will need the dconf database D-Bus service itself. You can enable it using `programs.dconf.enable`. Some applications will also require `gsettings-desktop-schemas` for things like reading proxy configuration or user interface customization. This dependency is often not mentioned by upstream, you should grep for `org.gnome.desktop` and `org.gnome.system` to see if the schemas are needed. +### GIO modules {#ssec-gnome-gio-modules} + +GLib’s [GIO](https://developer.gnome.org/gio/stable/ch01.html) library supports several [extension points](https://developer.gnome.org/gio/stable/extending-gio.html). Notably, they allow: + +* implementing settings backends (already [mentioned](#ssec-gnome-settings)) +* adding TLS support +* proxy settings +* virtual file systems + +The modules are typically installed to `lib/gio/modules/` directory of a package and you need to add them to `GIO_EXTRA_MODULES` if you need any of those features. + +In particular, we recommend: + +* adding `dconf.lib` for any software on Linux that reads [GSettings](#ssec-gnome-settings) (even transitivily through e.g. GTK’s file manager) +* adding `glib-networking` for any software that accesses network using GIO or libsoup – glib-networking contains a module that implements TLS support and loads system-wide proxy settings + +To allow software to use various virtual file systems, `gvfs` package can be also added. But that is usually an optional feature so we typically use `gvfs` from the system (e.g. installed globally using NixOS module). + ### GdkPixbuf loaders {#ssec-gnome-gdk-pixbuf-loaders} GTK applications typically use [GdkPixbuf](https://developer.gnome.org/gdk-pixbuf/stable/) to load images. But `gdk-pixbuf` package only supports basic bitmap formats like JPEG, PNG or TIFF, requiring to use third-party loader modules for other formats. This is especially painful since GTK itself includes SVG icons, which cannot be rendered without a loader provided by `librsvg`. -- cgit 1.4.1