alternate screen (fixes #63)

examples/alternate.rs

@@ -0,0 +1,21 @@
+use std::io;
+
+use console::Term;
+
+fn main() -> io::Result<()> {
+    let term = Term::stdout();
+    let (height, width) = term.size();
+    term.hide_cursor()?;
+    term.enter_alternate_screen()?;
+
+    let s = "press any key to quit";
+    let x = (width as usize / 2) - (s.len() / 2);
+    let y = height as usize / 2;
+    term.move_cursor_to(x, y)?;
+    term.write_str(&s)?;
+    term.read_key()?;
+
+    term.exit_alternate_screen()?;
+    term.show_cursor()?;
+    Ok(())
+}

src/common_term.rs

@@ -70,3 +70,13 @@ pub fn show_cursor(out: &Term) -> io::Result<()> {
 pub fn hide_cursor(out: &Term) -> io::Result<()> {
     out.write_str("\x1b[?25l")
 }
+
+#[inline]
+pub fn enter_alternate_screen(out: &Term) -> io::Result<()> {
+    out.write_str("\x1b[?1049h")
+}
+
+#[inline]
+pub fn exit_alternate_screen(out: &Term) -> io::Result<()> {
+    out.write_str("\x1b[?1049l")
+}

src/term.rs

@@ -440,6 +440,18 @@ impl Term {
         hide_cursor(self)
     }
 
+    /// Enter alternate screen
+    #[inline]
+    pub fn enter_alternate_screen(&self) -> io::Result<()> {
+        enter_alternate_screen(self)
+    }
+
+    /// Exit alternate screen
+    #[inline]
+    pub fn exit_alternate_screen(&self) -> io::Result<()> {
+        exit_alternate_screen(self)
+    }
+
     // helpers
 
     #[cfg(all(windows, feature = "windows-console-colors"))]

src/windows_term.rs

@@ -300,6 +300,20 @@ pub fn hide_cursor(out: &Term) -> io::Result<()> {
     Ok(())
 }
 
+pub fn enter_alternate_screen(out: &Term) -> io::Result<()> {
+    if out.is_msys_tty {
+        return common_term::enter_alternate_screen(out);
+    }
+    Ok(())
+}
+
+pub fn exit_alternate_screen(out: &Term) -> io::Result<()> {
+    if out.is_msys_tty {
+        return common_term::exit_alternate_screen(out);
+    }
+    Ok(())
+}
+
 fn get_console_screen_buffer_info(hand: HANDLE) -> Option<(HANDLE, CONSOLE_SCREEN_BUFFER_INFO)> {
     let mut csbi: CONSOLE_SCREEN_BUFFER_INFO = unsafe { mem::zeroed() };
     match unsafe { GetConsoleScreenBufferInfo(hand, &mut csbi) } {