add an example for simple textarea with variable height

Cargo.toml

@@ -32,3 +32,7 @@ required-features = ["crossterm"]
 [[example]]
 name = "single_line"
 required-features = ["crossterm"]
+
+[[example]]
+name = "variable"
+required-features = ["crossterm"]

README.md

@@ -51,6 +51,7 @@ cargo run --example minimal
 - [termion](./examples/termion.rs): Minimal usage with [termion][] support
 - [multi](./examples/multi.rs): Two split textareas in a screen and switch them
 - [single_line](./examples/single_line.rs): Single line input form with float number validation
+- [variable](./examples/variable.rs): Simple textarea with variable height following the number of lines
 - [editor](./examples/editor.rs): Simple text editor to edit multiple files
 
 ## Minimal Usage

examples/variable.rs

@@ -0,0 +1,54 @@
+use crossterm::event::{DisableMouseCapture, EnableMouseCapture};
+use crossterm::terminal::{
+    disable_raw_mode, enable_raw_mode, EnterAlternateScreen, LeaveAlternateScreen,
+};
+use std::io;
+use tui::backend::CrosstermBackend;
+use tui::layout::{Constraint, Layout};
+use tui::widgets::{Block, Borders};
+use tui::Terminal;
+use tui_textarea::{Input, Key, TextArea};
+
+fn main() -> io::Result<()> {
+    let stdout = io::stdout();
+    let mut stdout = stdout.lock();
+
+    enable_raw_mode()?;
+    crossterm::execute!(stdout, EnterAlternateScreen, EnableMouseCapture)?;
+    let backend = CrosstermBackend::new(stdout);
+    let mut term = Terminal::new(backend)?;
+
+    let mut textarea = TextArea::default();
+    textarea.set_block(
+        Block::default()
+            .borders(Borders::ALL)
+            .title("Textarea with Variable Height"),
+    );
+
+    loop {
+        term.draw(|f| {
+            let len = textarea.lines().len() as u16 + 2; // + 2 for borders
+            let chunks = Layout::default()
+                .constraints([Constraint::Length(len), Constraint::Min(1)].as_slice())
+                .split(f.size());
+            f.render_widget(textarea.widget(), chunks[0]);
+        })?;
+        match Input::from(crossterm::event::read()?) {
+            Input { key: Key::Esc, .. } => break,
+            input => {
+                textarea.input(input);
+            }
+        }
+    }
+
+    disable_raw_mode()?;
+    crossterm::execute!(
+        term.backend_mut(),
+        LeaveAlternateScreen,
+        DisableMouseCapture
+    )?;
+    term.show_cursor()?;
+
+    println!("Lines: {:?}", textarea.lines());
+    Ok(())
+}