Some more work on docs/hacking-howto

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Michael Stapelberg 2009-03-07 06:24:31 +01:00
parent 35c04b448a
commit d2f663e1a8
1 changed files with 68 additions and 27 deletions

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@ -26,8 +26,8 @@ In the case of i3, the tasks (and order of them) are the following:
. Iterate through all existing windows (if the window manager is not started as the first
client of X) and manage them (= reparent them, create window decorations)
. When new windows are created, manage them
. Handle the clients _WM_STATE property, but only the _WM_STATE_FULLSCREEN
. Handle the clients WM_NAME property
. Handle the clients `_WM_STATE` property, but only the `_WM_STATE_FULLSCREEN`
. Handle the clients `WM_NAME` property
. Handle the clients size hints to display them proportionally
. Handle enter notifications (focus follows mouse)
. Handle button (as in mouse buttons) presses for focus/raise on click
@ -78,32 +78,59 @@ src/xinerama.c::
== Data structures
See include/data.h for documented data structures.
See include/data.h for documented data structures. The most important ones are explained
right here.
TODO: We need a slick graphic here
=== Virtual screens
A virtual screen (type i3Screen) is generated from the connected screens obtained
A virtual screen (type `i3Screen`) is generated from the connected screens obtained
through Xinerama. The difference to the raw Xinerama monitors as seen when using xrandr(1)
is that it falls back to the lowest common resolution of the logical screens.
For example, if your notebook has 1280x800 and you connect a video projector with
1024x768, set up in clone mode (xrandr --output VGA --mode 1024x768 --same-as LVDS),
1024x768, set up in clone mode (xrandr \--output VGA \--mode 1024x768 \--same-as LVDS),
i3 will have one virtual screen.
However, if you configure it using xrandr --output VGA --mode 1024x768 --right-of LVDS,
However, if you configure it using xrandr \--output VGA \--mode 1024x768 \--right-of LVDS,
i3 will generate two virtual screens. For each virtual screen, a new workspace will be
assigned. New workspaces are created on the screen you are currently on.
=== Workspace
A workspace is identified by its number. Basically, you could think of workspaces
as different desks in your bureau, if you like the desktop methaphor. They just contain
different sets of windows and are completely separate of each other. Other window
managers also call this ``Virtual desktops''.
=== The layout table
Each workspace has a table, which is just a two-dimensional dynamic array containing
Containers (see below). This table grows and shrinks as you need it (by moving windows
to the right you can create a new column in the table, by moving them to the bottom
you create a new row).
=== Container
A container is the content of a tables cell. It holds an arbitrary amount of windows
and has a specific layout (default layout or stack layout). Containers can consume
multiple table cells by modifying their colspan/rowspan attribute.
=== Client
A client is x11-speak for a window.
== List/queue macros
i3 makes heavy use of the list macros defined in BSD operating systems. To ensure
that the operating system on which i3 is compiled has all the awaited features,
i3 comes with include/queue.h. On BSD systems, you can use man queue(3). On Linux,
i3 comes with `include/queue.h`. On BSD systems, you can use man `queue(3)`. On Linux,
you have to use google.
The lists used are SLISTs (single linked lists) and CIRCLEQ (circular queues).
Usually, only forward traversal is necessary, so an SLIST works fine. However,
for the windows inside a container, a CIRCLEQ is necessary to go from the currently
The lists used are `SLIST` (single linked lists) and `CIRCLEQ` (circular queues).
Usually, only forward traversal is necessary, so an `SLIST` works fine. However,
for the windows inside a container, a `CIRCLEQ` is necessary to go from the currently
selected window to the window above/below.
== Naming conventions
@ -111,12 +138,12 @@ selected window to the window above/below.
There is a row of standard variables used in many events. The following names should be
chosen for those:
* "conn" is the xcb_connection_t
* "event" is the event of the particular type
* "container" names a container
* "client" names a client, for example when using a CIRCLEQ_FOREACH
* ``conn'' is the xcb_connection_t
* ``event'' is the event of the particular type
* ``container'' names a container
* ``client'' names a client, for example when using a `CIRCLEQ_FOREACH`
== Startup (src/mainx.c)
== Startup (src/mainx.c, main())
* Establish the xcb connection
* Check for XKB extension on the separate X connection
@ -157,7 +184,7 @@ The bound command is parsed directly in command mode.
== Manage windows (src/mainx.c, manage_window() and reparent_window())
manage_window() does some checks to decide whether the window should be managed at all:
`manage_window()` does some checks to decide whether the window should be managed at all:
* Windows have to be mapped, that is, visible on screen
* The override_redirect must not be set. Windows with override_redirect shall not be
@ -170,23 +197,23 @@ Reparenting means that for each window which is reparented, a new window, slight
than the original one, is created. The original window is then reparented to the bigger one
(called "frame").
After reparenting, the window type (_NET_WM_WINDOW_TYPE) is checked to see whether this
window is a dock (_NET_WM_WINDOW_TYPE_DOCK), like dzen2 for example. Docks are handled
After reparenting, the window type (`_NET_WM_WINDOW_TYPE`) is checked to see whether this
window is a dock (`_NET_WM_WINDOW_TYPE_DOCK`), like dzen2 for example. Docks are handled
differently, they dont have decorations and are not assigned to a specific container.
Instead, they are positioned at the bottom of the screen. To get the height which needsd
to be reserved for the window, the _NET_WM_STRUT_PARTIAL property is used.
to be reserved for the window, the `_NET_WM_STRUT_PARTIAL` property is used.
== What happens when an application is started?
i3 does not care for applications. All it notices is when new windows are mapped (see
src/handlers.c, handle_map_notify_event()). The window is then reparented (see section
`src/handlers.c`, `handle_map_notify_event()`). The window is then reparented (see section
"Manage windows").
After reparenting the window, render_layout() is called which renders the internal
After reparenting the window, `render_layout()` is called which renders the internal
layout table. The window was placed in the currently focused container and
therefore the new window and the old windows (if any) need te be moved/resized
so that the currently active layout (default mode/stacking mode) is rendered
correctly. To move/resize windows, a window is "configured" in X11-speak.
correctly. To move/resize windows, a window is ``configured'' in X11-speak.
Some applications, such as MPlayer obivously assume the window manager is stupid
and therefore configure their windows by themselves. This generates an event called
@ -194,7 +221,7 @@ configurenotify. i3 handles these events and pushes the window back to its posit
== _NET_WM_STATE
Only the _NET_WM_STATE_FULLSCREEN atom is handled. It calls toggle_fullscreen() for the
Only the _NET_WM_STATE_FULLSCREEN atom is handled. It calls ``toggle_fullscreen()'' for the
specific client which just configures the client to use the whole screen on which it
currently is. Also, it is set as fullscreen_client for the i3Screen.
@ -205,7 +232,9 @@ is re-rendered.
== Size hints
== Rendering
TODO
== Rendering (src/layout.c, render_layout() and render_container())
There are two entry points to rendering: render_layout() and render_container(). The
former one renders all virtual screens, the currently active workspace of each virtual
@ -244,6 +273,12 @@ this window is the currently focused one or the last focused one in a not focuse
or not focused at all) forming the background. Afterwards, two lighter lines are drawn
and the last step is drawing the windows title (see WM_NAME) onto it.
=== Fullscreen windows
For fullscreen windows, the `rect` (x, y, width, height) is not changed to allow the client
to easily go back to its previous position. Instead, fullscreen windows are skipped
when rendering.
=== Resizing containers
By clicking and dragging the border of a container, you can resize it freely.
@ -256,11 +291,11 @@ Like in vim, you can control i3 using commands. They are intended to be a powerf
alternative to lots of shortcuts, because they can be combined. There are a few special
commands, which are the following:
exec::
Starts the given command by passing it to /bin/sh.
exec <command>::
Starts the given command by passing it to `/bin/sh`.
restart::
Restarts i3 by executing argv[0] (the path with which you started i3) without forking.
Restarts i3 by executing `argv[0]` (the path with which you started i3) without forking.
w::
"With". This is used to select a bunch of windows. Currently, only selecting the whole
@ -273,3 +308,9 @@ The other commands are to be combined with a direction. The directions are h, j,
like in vim (h = left, j = down, k = up, l = right). When you just specify the direction
keys, i3 will move the focus in that direction. You can provide "m" or "s" before the
direction to move a window respectively or snap.
== Gotchas
* Forgetting to call `xcb_flush(conn);` after sending a request. This usually leads to
code which looks like it works fine but which does not work under certain conditions.