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terminal-escapes.md

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+#!/bin/env slides
+
+# Demystifying Terminal Escapes
+
+*by Bruce Hill*
+
+--------------------------------
+
+Have you ever wondered how Vim and other
+command-line programs manage to do cool
+stuff with your terminal?
+
+Like drawing all over the place without
+cluttering your command line history?
+
+--------------------------------
+
+Well, it's not magic, and you can do it too!
+
+-------------------------------
+
+There are three main topics I'll cover:
+
+1. Printing terminal escape sequences
+2. Getting and setting terminal information
+
+-------------------------------
+
+Most terminal emulators that you use
+(iTerm, alacritty, GNOME terminal, etc)
+are emulating old-school physical terminals
+like the VT100:
+
+```demo
+firefox --new-window https://en.wikipedia.org/wiki/VT100
+```
+
+-------------------------------
+
+The way that terminals used to work is that
+you would send bytes from a computer over
+a wire to a terminal (the termination point
+of the signal).
+
+## Commonly Sent
+
+- Text to print
+- Escape sequences
+
+-------------------------------
+
+# Escape Sequences
+
+In order to do stuff like move the cursor
+around, clear the screen, etc. you could
+send an escape sequence to the terminal.
+
+One common escape sequence you might know
+is the newline `\n` and carriage return `\r`
+escapes. These moved the carriage on a
+teletype to the next line or back to the
+start of a line.
+
+```demo
+term
+```
+
+-------------------------------
+
+# Operating System Commands
+
+More advanced escape sequences like
+**Operating System Commands** let you
+do more fancy stuff like moving the
+cursor position to an arbitrary X/Y
+position or setting the text color.
+
+The magic **Operating System Command** is two bytes:
+
+```
+\033[
+```
+
+Also known as `\x1B[` or `\e[`.
+
+```
+\033[
+```
+
+It tells the terminal that the next
+thing that follows isn't text to print
+but is a command that needs to run.
+
+-------------------------------
+
+Here are some fun operating system commands:
+
+```demo
+ansi | less -R
+```
+
+*You can run these yourself with just a print statement!*
+
+-------------------------------
+
+Here's what's actually getting sent to the terminal:
+
+```demo
+ansi | less
+```
+
+-------------------------------
+
+# Alternate Screens
+
+One of the most important operating system commands
+is toggling the alternate screen on and off:
+
+```
+Alternate screen on:
+\033[?1049h
+
+Alternate screen off:
+\033[?1049l
+```
+
+This is what lets you run a terminal program
+that doesn't spam the scrollback log!
+
+-------------------------------
+
+# Getting and Setting Info
+
+In C, there are some functions that let you
+get information about the terminal
+
+-------------------------------
+
+## tcgetattr/tcsetattr
+
+Useful for reading one keypress at a time!
+
+```c
+int tcgetattr(int fd, struct termios *termios_p);
+int tcsetattr(int fd, int optional_actions,
+              const struct termios *termios_p);
+void cfmakeraw(struct termios *termios_p);
+```
+
+```demo
+man tcsetattr
+```
+
+-------------------------------
+
+## ioctl
+
+Useful for getting terminal width/height!
+
+```c
+int ioctl(int fd, int op, ...);
+```
+
+```demo
+man ioctl
+```
+
+-------------------------------
+
+# BTUI
+
+I wrote a library called **BTUI**
+to do the bare minimum of this stuff:
+
+```demo
+firefox --new-window https://github.com/bruce-hill/btui
+```
+
+(I really don't like ncurses, it's very bloated and unwieldy)
+
+
+-------------------------------
+
+# slides
+
+This presentation is made using the BTUI library
+and its Python bindings.
+
+Thanks to Michael Rees for the idea
+to make a terminal slide presenter!
+
+```demo
+firefox --new-window https://github.com/bruce-hill/slides
+```
+
+-------------------------------
+
+# Goodbye!
+
+Thanks for your time!
+I'm **Bruce Hill** if you want to find me on zulip.
+
+-------------------------------
+
+# Bonus Demo 1: Conway's Game of Life
+
+```demo
+conway
+```
+
+-------------------------------
+
+# Bonus Demo 2: Double Pendulum
+
+```demo
+2pend
+```
+
+-------------------------------
+
+# Bonus Demo 3: Space Invaders
+
+```demo
+cd ~/software/btui/Python/invaders
+./invaders.py
+```
+
+-------------------------------
+
+# Bonus Demo 4: Alternate Character Set
+
+```demo
+alternate-character-set | less -r
+```