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John Lindgren 3fc66d4525 util: fix non-linear behavior of wlr_box_closest_point()
Per comments in util/box.h, the width and height of a wlr_box are
exclusive; that is, for a 100x100 box at (0,0), the point (99,99) is
inside it while the point (100,100) is outside it.

Thus mathematically, there exists no single closest point to the
bottom-right corner of the box while remaining inside it. You can
construct an infinite series approaching the limit, such as {(99,99),
(99.9,99.9), (99.99,99.99)...}, but since the intervals are half-open,
there is no "last" point.

wlr_box_closest_point() must therefore define an arbitrary "closest"
point. For points below and to the right of the box, the current
implementation returns (box.x + width - 1, box.y + height - 1). Let's
continue to do this.

However, the current implementation is non-linear: with the example
100x100 box, it will return an input point of (99.9,99.9) unchanged, but
for an input point (100.1,100.1) the returned point will jump back to
(99.0,99.0).

In practice, this non-linearity results in strange behaviors when
driving the mouse cursor to a screen corner. On a 1920x1080 display for
example, driving the cursor quickly to the bottom-left corner results in
a position of exactly (0,1079). Continuing to slowly nudge the cursor
downward results in the position jumping between (0,1079) and other,
fractional coordinates such as (0,1079.88).

The fractional coordinates expose some client/toolkit-side bugs (which,
to be clear, should be fixed on the client side), but IMHO the wlroots
behavior is also inconsistent and wrong -- when I drive the mouse cursor
into the corner of the screen, it should come to a stop at a fixed
position, not jitter around.
2024-03-28 12:51:53 +00:00
.builds ci: drop stale dependencies 2023-12-10 14:29:23 +01:00
.gitlab/issue_templates Add GitLab issue template 2023-10-08 11:29:13 +00:00
backend drm/backend: add support for cursor hotspots 2024-03-22 13:54:18 -05:00
docs docs: add architecture document 2023-10-10 09:50:57 +00:00
examples examples: send xdg_toplevel configure events 2024-03-15 13:20:35 +01:00
include touch: make cancel functions take a wlr_seat_client 2024-03-28 09:33:54 +00:00
protocol ext-foreign-toplevel-list-v1: new protocol implementation 2024-02-12 01:05:19 +01:00
render gles2: Avoid crash when glGetInteger64vEXT is missing 2024-03-12 19:06:21 +01:00
tinywl tinywl: destroy wlr_renderer, wlr_allocator and wlr_cursor 2024-03-14 10:07:56 +00:00
types touch: make cancel functions take a wlr_seat_client 2024-03-28 09:33:54 +00:00
util util: fix non-linear behavior of wlr_box_closest_point() 2024-03-28 12:51:53 +00:00
xcursor Define _POSIX_C_SOURCE globally 2024-02-15 15:41:12 +01:00
xwayland xwayland: add wlr_xwayland_get_xwm_connection 2024-03-09 11:21:17 +00:00
.editorconfig Relax 80 column limit 2022-11-22 18:19:46 +00:00
.gitignore gitignore: remove build dir entries 2022-06-14 10:08:54 +02:00
.gitlab-ci.yml ci: add .gitlab-ci.yml 2021-11-01 16:51:18 +01:00
.mailmap mailmap: map Isaac's old email to the new one 2024-03-04 14:01:00 +01:00
CONTRIBUTING.md contributing: add safety section 2023-10-04 11:08:58 +02:00
LICENSE license: add copyright line for all contributors 2023-07-05 10:27:50 +02:00
README.md backend/drm: use libdisplay-info to parse EDID 2023-02-28 14:44:02 +00:00
meson.build Define _POSIX_C_SOURCE globally 2024-02-15 15:41:12 +01:00
meson_options.txt backend/session: make optional 2022-11-25 16:15:29 +00:00
wlroots.syms build: simplify version script 2021-06-17 11:03:21 +02:00

README.md

wlroots

Pluggable, composable, unopinionated modules for building a Wayland compositor; or about 60,000 lines of code you were going to write anyway.

  • wlroots provides backends that abstract the underlying display and input hardware, including KMS/DRM, libinput, Wayland, X11, and headless backends, plus any custom backends you choose to write, which can all be created or destroyed at runtime and used in concert with each other.
  • wlroots provides unopinionated, mostly standalone implementations of many Wayland interfaces, both from wayland.xml and various protocol extensions. We also promote the standardization of portable extensions across many compositors.
  • wlroots provides several powerful, standalone, and optional tools that implement components common to many compositors, such as the arrangement of outputs in physical space.
  • wlroots provides an Xwayland abstraction that allows you to have excellent Xwayland support without worrying about writing your own X11 window manager on top of writing your compositor.
  • wlroots provides a renderer abstraction that simple compositors can use to avoid writing GL code directly, but which steps out of the way when your needs demand custom rendering code.

wlroots implements a huge variety of Wayland compositor features and implements them right, so you can focus on the features that make your compositor unique. By using wlroots, you get high performance, excellent hardware compatibility, broad support for many wayland interfaces, and comfortable development tools - or any subset of these features you like, because all of them work independently of one another and freely compose with anything you want to implement yourself.

Check out our wiki to get started with wlroots. Join our IRC channel: #wlroots on Libera Chat.

A variety of wrapper libraries are available for using it with your favorite programming language.

Building

Install dependencies:

  • meson
  • wayland
  • wayland-protocols
  • EGL and GLESv2 (optional, for the GLES2 renderer)
  • Vulkan loader, headers and glslang (optional, for the Vulkan renderer)
  • libdrm
  • GBM (optional, for the GBM allocator)
  • libinput (optional, for the libinput backend)
  • xkbcommon
  • udev (optional, for the session)
  • pixman
  • libseat (optional, for the session)
  • hwdata (optional, for the DRM backend)
  • libdisplay-info (optional, for the DRM backend)
  • libliftoff (optional, for the DRM backend)

If you choose to enable X11 support:

  • xwayland (build-time only, optional at runtime)
  • libxcb
  • libxcb-render-util
  • libxcb-wm
  • libxcb-errors (optional, for improved error reporting)

Run these commands:

meson setup build/
ninja -C build/

Install like so:

sudo ninja -C build/ install

Contributing

See CONTRIBUTING.md.