Fill the screen with tilde lines

Cargo.lock

@@ -36,6 +36,7 @@ dependencies = [
 name = "rs-kilo"
 version = "0.1.0"
 dependencies = [
+ "libc 0.2.62 (registry+https://github.com/rust-lang/crates.io-index)",
  "nix 0.15.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 

Cargo.toml

@@ -7,5 +7,6 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+libc = "0.2"
 # Rust wrappers for C/POSIX headers
 nix = "0.15.0"

src/editor.rs

@@ -1,23 +1,28 @@
 //! Editor functionality
 use crate::helpers::*;
 
-use nix::sys::termios::Termios;
-use nix::unistd::read;
-
 use std::io;
 use std::io::prelude::*;
-use std::io::{BufReader, Error, Stdin};
+use std::io::BufReader;
-use std::str::Chars;
 
 /// Main structure for the editor
 ///
 /// impl blocks are split similarly to the original C implementation
-pub struct Editor {}
+#[derive(Debug, Default)]
+pub struct Editor {
+    screen_cols: u16,
+    screen_rows: u16,
+}
 
 // init
 impl Editor {
     pub fn new() -> Self {
-        Editor {}
+        let mut instance = Self::default();
+        let size = instance.get_window_size();
+        instance.screen_cols = size.cols;
+        instance.screen_rows = size.rows;
+
+        instance
     }
 }
 
@@ -42,10 +47,41 @@ impl Editor {
 
         return Some(output);
     }
+
+    fn get_cursor_position(&mut self) -> TermSize {
+        let stdout = io::stdout();
+        let mut handle = stdout.lock();
+        let buffer = String::from("\x1b[6n").into_bytes();
+        handle.write(&buffer).unwrap();
+
+        let stdin = io::stdin();
+        let stdin = stdin.lock();
+        let mut in_buf = String::new().into_bytes();
+        let mut input = BufReader::with_capacity(32, stdin);
+        input.read_until('R' as u8, &mut in_buf).unwrap();
+
+        // @TODO Find a solution to retrieve the cursor coordinates
+        unimplemented!();
+    }
+
+    fn get_window_size(&mut self) -> TermSize {
+        match get_term_size() {
+            Some(size) => size,
+            None => {
+                let stdout = io::stdout();
+                let mut handle = stdout.lock();
+                let buffer = String::from("\x1b[999C\x1b[999B").into_bytes();
+                handle.write(&buffer).unwrap();
+
+                self.get_cursor_position()
+            }
+        }
+    }
 }
 
 // Input
 impl Editor {
+    /// Route user input to the appropriate handler method
     pub fn process_keypress(&mut self) -> Option<()> {
         match self.read_key() {
             // Just continue the input loop on an "empty" keypress
@@ -54,6 +90,8 @@ impl Editor {
                 let first = chars[0];
 
                 if first == ctrl_key('q') {
+                    clear_and_reset();
+
                     // Break out of the input loop
                     return None;
                 }
@@ -69,11 +107,29 @@ impl Editor {
 
 // Output
 impl Editor {
-    pub fn refresh_screen() {
+    fn draw_rows(&mut self) {
+        let stdout = io::stdout();
+        let mut handle = stdout.lock();
+        let buffer = String::from("~\r\n").into_bytes();
+
+        for _ in 0..self.screen_rows as usize {
+            handle.write(&buffer).unwrap();
+        }
+    }
+
+    pub fn refresh_screen(&mut self) {
         let stdout = io::stdout();
         let mut handle = stdout.lock();
 
+        // Clear screen
         let mut buffer = String::from("\x1b[2J").into_bytes();
+        handle.write_all(&mut buffer).unwrap();
+
+        // Reposition cursor
+        let mut buffer = String::from("\x1b[H").into_bytes();
+        handle.write_all(&mut buffer).unwrap();
+
+        self.draw_rows();
 
         handle.write_all(&mut buffer).unwrap();
     }

src/helpers.rs

@@ -1,15 +1,37 @@
+use libc::ioctl;
 /// Helper functions, especially to reproduce C std/posix functions
+use libc::{c_ushort, STDOUT_FILENO, TIOCGWINSZ};
+
 use nix::errno::*;
 use nix::sys::termios;
 use nix::sys::termios::{
     ControlFlags, InputFlags, LocalFlags, OutputFlags, SpecialCharacterIndices, Termios,
 };
-use nix::Error as NixError;
 
-use std::io::Error;
+use std::io;
+use std::io::prelude::*;
 use std::os::unix::io::RawFd;
 use std::process::exit;
 
+#[derive(Debug)]
+pub struct TermSize {
+    /// number of rows
+    pub rows: u16,
+    /// number of columns
+    pub cols: u16,
+}
+
+#[repr(C)]
+#[derive(Debug)]
+struct UnixTermSize {
+    /// number of rows
+    pub rows: c_ushort,
+    /// number of columns
+    pub cols: c_ushort,
+    x: c_ushort,
+    y: c_ushort,
+}
+
 // Redefine the posix constants for rust land
 
 /// The value of the raw file descriptor for STDIN
@@ -33,6 +55,8 @@ pub fn ctrl_key(c: char) -> char {
 }
 
 pub fn die(code: &Errno, msg: &str) -> ! {
+    clear_and_reset();
+
     eprintln!("{:?} ({})", code, msg);
 
     exit(1)
@@ -86,3 +110,36 @@ pub fn enable_raw_mode() {
 pub fn disable_raw_mode(original: &Termios) {
     termios::tcsetattr(STDIN_FILENO, termios::SetArg::TCSAFLUSH, original).unwrap();
 }
+
+pub fn clear_and_reset() {
+    let stdout = io::stdout();
+    let mut handle = stdout.lock();
+
+    // Clear screen
+    let mut buffer = String::from("\x1b[2J").into_bytes();
+    handle.write_all(&mut buffer).unwrap();
+
+    // Reposition cursor
+    let mut buffer = String::from("\x1b[H").into_bytes();
+    handle.write_all(&mut buffer).unwrap();
+}
+
+pub fn get_term_size() -> Option<TermSize> {
+    let raw = UnixTermSize {
+        rows: 0,
+        cols: 0,
+        x: 0,
+        y: 0,
+    };
+
+    let r = unsafe { ioctl(STDOUT_FILENO, TIOCGWINSZ.into(), &raw) };
+
+    if r == 0 {
+        Some(TermSize {
+            rows: raw.rows,
+            cols: raw.cols,
+        })
+    } else {
+        None
+    }
+}

src/main.rs

@@ -17,8 +17,12 @@ fn main() {
     // Main input loop. Editor::process_keypress uses an Option Enum as a sentinel.
     // `None` is returned on a quit action, in other cases, `Some(())` is returned,
     // continuing the loop
-    while editor.process_keypress().is_some() {
+    loop {
-        // loop
+        editor.refresh_screen();
+
+        if editor.process_keypress().is_none() {
+            break;
+        }
     }
 
     // Restore previous terminal flags before exit