Show welcome message

src/editor.rs

@@ -10,8 +10,9 @@ use std::io::BufReader;
 /// impl blocks are split similarly to the original C implementation
 #[derive(Debug, Default)]
 pub struct Editor {
-    screen_cols: u16,
-    screen_rows: u16,
+    screen_cols: usize,
+    screen_rows: usize,
+    output_buffer: String,
 }
 
 // init
@@ -19,8 +20,8 @@ impl Editor {
     pub fn new() -> Self {
         let mut instance = Self::default();
         let size = instance.get_window_size();
-        instance.screen_cols = size.cols;
-        instance.screen_rows = size.rows;
+        instance.screen_cols = size.cols as usize;
+        instance.screen_rows = size.rows as usize;
 
         instance
     }
@@ -107,30 +108,60 @@ impl Editor {
 
 // Output
 impl Editor {
-    fn draw_rows(&mut self) {
-        let stdout = io::stdout();
-        let mut handle = stdout.lock();
-        let buffer = String::from("~\r\n").into_bytes();
+    /// Equivalent of the abAppend function
+    /// in the original tutorial, just appends
+    /// to the `output_buffer` String in the
+    /// editor struct.
+    fn append_out(&mut self, str: &str) {
+        self.output_buffer.push_str(str);
+    }
 
-        for _ in 0..self.screen_rows as usize {
-            handle.write(&buffer).unwrap();
+    fn draw_rows(&mut self) {
+        for y in 0..self.screen_rows {
+            if y == (self.screen_rows / 3) {
+                let mut welcome = format!("Kilo editor -- version {}", env!("CARGO_PKG_VERSION"));
+                if welcome.len() > self.screen_cols {
+                    welcome.truncate(self.screen_cols)
+                }
+
+                // Center welcome message
+                let mut padding = (self.screen_cols - welcome.len()) / 2;
+                if padding > 0 {
+                    self.append_out("~");
+                    padding -= 1;
+                }
+                while padding > 0 {
+                    self.append_out(" ");
+                    padding -=1;
+                }
+
+                self.append_out(&welcome);
+            } else {
+                self.append_out("~");
+            }
+
+
+            self.append_out("\x1b[K");
+            if y < (self.screen_rows as usize - 1) {
+                self.append_out("\r\n");
+            }
         }
     }
 
     pub fn refresh_screen(&mut self) {
-        let stdout = io::stdout();
-        let mut handle = stdout.lock();
+        self.output_buffer.clear();
 
-        // 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();
+        //  Hide cursor, reposition cursor
+        self.append_out("\x1b[?25l");
+        self.append_out("\x1b[H");
 
         self.draw_rows();
 
-        handle.write_all(&mut buffer).unwrap();
+        self.append_out("\x1b[H");
+        self.append_out("\x1b[?25h");
+
+        let stdout = io::stdout();
+        let mut handle = stdout.lock();
+        handle.write_all(&self.output_buffer.as_bytes()).unwrap();
     }
 }