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Since MetaWindowDrag took a lot of this code to handle window drags internally with less interactions with the rest of the stack, this code in display/window/keybindings is unused. Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2683>
186 lines
7.6 KiB
Plaintext
186 lines
7.6 KiB
Plaintext
This is not meant to be comprehensive by any means. Rather it is
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meant as just a brief overview of some of the bigger structures and
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files, with guides for a variety of task categories providing places
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to start looking in the code and things to look for.
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Overview
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Jobs of various files
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Major data structures and their relationships
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Getting started -- where to look
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Jobs of various files
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src/window.c is where all the guts of the window manager live. This is
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basically the only remotely scary file.
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src/frames.c is the GtkWidget that handles drawing window frames.
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src/core.h defines the interface used by the GTK portion of the window
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manager to talk to the other portions. There's some cruft in here that's
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unused, since nearly all window operations have moved out of this file so
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frameless apps can have window operations.
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src/ui.h defines the interface the plain Xlib portion of the window
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manager uses to talk to the GTK portion.
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src/theme.c and src/theme-parser.c have the theme system; this is
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well-modularized from the rest of the code, since the theme viewer app
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links to these files in addition to the WM itself.
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Major data structures and their relationships
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Major structs have a "Meta" prefix, thus MetaDisplay, MetaScreen,
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MetaWindow, etc. This serves as a way of namespacing in C. It also has
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the side effect of avoiding conflicts with common names that X already
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uses such as Display, Screen, Window, etc. Note that when I refer to a
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display below, I'm meaning a MetaDisplay and not a Display.
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Don't confuse displays and screens. While Metacity can run with multiple
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displays, it is kind of useless since you might as well just run two
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copies of Metacity. However, having multiple screens per display is
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useful and increasingly common (known as "multiscreen" and "xinerama"
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setups, where users make use of more than one monitor). You should
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basically think of a display as a combination of one or more monitors
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with a single keyboard (...and usually only one mouse).
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There is also a significant difference between multiscreen and xinerama
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as well. Basically, each MetaScreen is a root window (root node in the
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tree of windows). With Xinerama, a single root window appears to span
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multiple monitors, whereas with multiscreen a root window is confined to
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a single monitor. To re-emphasize the distinction between a display and
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a screen, the pointer and keyboard are shared between all root windows
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for a given display.
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The display keeps track of a lot of various global quantities, but in
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particular has a compositor and a list (GList) of screens.
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A compositor is an opaque structure (only defined in compositor.c),
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meaning that you'll only reference the API for it. It handles (or will
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handle) cool stuff with the new X extensions, such as smooth resizing and
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alpha transparency.
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A screen keeps track of a number of quantities as well, in particular a
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stack and a list of workspaces.
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A stack is basically a list of windows, and the depth order they have
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relative to each other (which thus determines which windows are on top
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and which are obscured).
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A workspace mostly contains a list of windows for the workspace, but also
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has a few other quantities as well (a list of struts which are areas
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where windows should not be placed and an mru_list or "most recently used
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window list").
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A window has a huge list of quantities for keeping track of things about
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a window on the screen. (We want to avoid making this list larger
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because the memory for all these quantities is per window.) One item in
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particular that a window has, though, is a frame.
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A frame is the decorations that surround the window (i.e. the titlebar and
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the minimize and close buttons and the part that you can use to resize),
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and contains a handful of variables related to that, but no other major
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structures.
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Getting started -- where to look
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Getting started on developing free software projects can often be like
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being dropped off in a town that is unknown to you and being told to make
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a map, when various road and building signs are missing or fading. To
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try to alleviate that initial difficulty in orientation, below I list a
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variety of general task categories with file, function, variable, and x
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property names that may be useful to fixing bugs or writing features that
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fall within that category.
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First, though, it's useful to note that most event and message passing
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goes through display.c:event_callback(), so that's often a good place to
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start reading for general familiarity with the code (actually, I'd
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suggest skipping down to the first switch statement within that
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function). Of course, not all events go through that function, as there
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are a few other places that handle events too such as frames.c.
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Anyway, without further ado, here are the categories and (hopefully)
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useful things to look at for each:
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Focus issues (i.e. issues with which window is active):
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doc/how-to-get-focus-right.txt
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meta_workspace_focus_default_window
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_NET_ACTIVE_WINDOW
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_NET_WM_USER_TIME
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meta_window_focus
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meta_display_(set_input|focus_the_no)_focus_window
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XSetInputFocus (only for purposes of understanding how X focus/input works)
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CurrentTime (mostly, you should just think "Bad; don't use it")
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Compositor stuff (X extension for eye candy like transparency):
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compositor.c
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The luminocity module in CVS
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Window depth (i.e. stacking or lowering/raising) issues:
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stack.c
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_NET_CLIENT_LIST_STACKING
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transient_for
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WM_TRANSIENT_FOR
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meta_window_(raise|lower)
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_NET_WM_WINDOW_TYPE
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_NET_WM_MOUSE_ACTION/_NET_WM_TAKE_ACTIVITY? (aren't yet in EWMH)
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Window placement issues:
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place.c
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constraints.c
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_NET_WM_STRUT
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WM_SIZE_HINTS
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Moving and resizing issues:
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constraints.c
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update_move
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update_resize
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meta-window-drag.c
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_NET_MOVERESIZE_WINDOW
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_NET_WM_STRUT
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Drag and drop issues:
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the XDND protocol (see http://www.newplanetsoftware.com/xdnd/ and
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http://freedesktop.org/Standards/XDND)
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_NET_WM_MOUSE_ACTION/_NET_WM_TAKE_ACTIVITY (aren't yet in EWMH)
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A general pointer: what causes the difficulty here is that when the
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application receives a mouse click to start a drag, it does a grab
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so that the window manager doesn't get any further events; thus
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correcting things require standards so that applications and window
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managers can collaborate correctly
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Theme issues: ???
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doc/theme-format.txt
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theme.c
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theme-parser.c
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(ui.c, core.c, frames.c, frame.c? I dunno...)
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Session management issues: ???
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session.c
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http://www.x.org/X11R6.8.1/doc/SM/xsmp.pdf ?
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http://www.x.org/X11R6.8.1/doc/SM/SMlib.pdf ?
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meta_window_apply_session_info
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Tasklist and Workspace switcher issues:
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window-props.c
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various functions in screen.c (especially ones using XChangeProperty)
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xprops.c
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The libwnck module in cvs
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meta_window_client_message
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Lots of the EWMH
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Window and workspace selection/changing issues:
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tabpopup.c
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keybindings.c, functions: *_workspace*, *_tab_*
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meta_screen_ensure_*_popup
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display.c, functions: *_tab*
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Key and mouse binding actions:
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keybindings.c
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meta_frames_button_(press|release)_event
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display.c: event_callback, but only the (Key|Button)_(Press|Release) cases
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Xinerama and multiscreen: ???
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In general, just search for Xinerama, but in particular see
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screen.c
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window.c
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place.c
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constraints.c
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