cd62b330be
Margins are a method to stick lines to the top and bottom of a buffer and ignore them during console-rotations. We keep 3 different buffers, two static buffers for the top and bottom margin and one buffer for the scroll region. The scroll region is always big enough to hold all three buffers even though it does not contain them. This allows us to merge the margins back to the scroll-buffer very fast without reallocations. The buffer layout is the top-margin at the top. The scroll region is below and the bottom margin is at the bottom. If we rotate the buffer, we do not touch the margins but simply rotate the scroll buffer. This may corrupt the scroll-back buffer but there is no sane way to implement this. The original VTs did not support this either. Even though we have multiple buffers we keep the buffer-fill logic. That is, the scroll buffer is not always fully filled. However, if we merge back the bottom buffer to the scroll buffer, we set the scroll buffer to be fully filled. Otherwise, we would have artifacts at the bottom. The top margin does not show this behavior as it is not affected by rotations below the fill-line. Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
= KMSCON =
Kmscon is a simple terminal emulator based on linux kernel mode setting (KMS).
It is an attempt to replace the in-kernel VT implementation with a userspace
console.
== Requirements ==
Kmscon requires the following software:
- libdrm: accessing the kernel graphics layer
- mesa: providing an OpenGL implementation (must be compiled with EGL, gbm
and GL libraries)
- udev: providing input device hotplug
- xproto (build time dependency): definition of key symbols
- libxkbcommon: keyboard handling (optional but strongly recommended)
Without libxkbcommon, basic US-ASCII input is provided.
- glib: only for Unicode handling
- One of:
- freetype2: drawing generic text
- pango: drawing text with pango (use --enable-pango)
Pango requires: glib, cairo, pangocairo, pango and freetype2
== Install ==
To compile the kmscon binary, run the standard autotools commands:
$ ./configure [--enable-debug] [--enable-pango]
$ make
$ make install
To compile the test applications, run:
$ make check
== License ==
This software is licensed under the terms of the MIT license. Please see
./COPYING for further information.
== FAQ ==
=== Why didn't you use libvte or similar terminal emulators? ===
All existing terminal emulators I found highly depend on X. Also, their code
base often is a horrible mess. I haven't had the time to convert them to use
other drawing functions than Xlib, yet.
If you feel like doing this work, please notify me. I would be glad to adjust
my code to work with other terminal emulators.
== Contact ==
This software is maintained by:
David Herrmann <dh.herrmann@googlemail.com>
If you have any questions, do not hesitate to contact one of the maintainers.
== Code Base ==
The kmscon code is split into several independent subsystems:
- output:
This code manages the KMS/DRI output and provides OpenGL framebuffers.
- console:
This draws the text on the screen and provides an API for any terminal
emulator to visualize its contents.
- eloop:
Main loop implementation.
- log:
Log file handling.
- unicode:
Provides basic Unicode handling.
- font:
Font loading, caching and drawing operations.
- input:
All linux input events are captured here and converted to Unicode
characters for input handling.
- vt:
The linux VT subsystem integration. This allows to run the application in
a classic linux VT like X does.
- vte:
The terminal emulator library.
- terminal:
Connects the console, output, input and vte handling into a real terminal.
- main:
This connects all subsystems into a usable console application.