font size unix & windows

examples/is_tty.rs

@@ -1,14 +1,16 @@
 use crossterm::{
     execute,
-    terminal::{size, SetSize},
+    terminal::{font_size, size, SetSize},
     tty::IsTty,
 };
 use std::io::{stdin, stdout};
 
 pub fn main() {
-    println!("{:?}", size().unwrap());
+    println!("size: {:?}", size().unwrap());
     execute!(stdout(), SetSize(10, 10)).unwrap();
-    println!("{:?}", size().unwrap());
+    println!("resized: {:?}", size().unwrap());
+
+    println!("font_size: {:?}", font_size().unwrap());
 
     if stdin().is_tty() {
         println!("Is TTY");

src/terminal.rs

@@ -137,6 +137,11 @@ pub fn size() -> io::Result<(u16, u16)> {
     sys::size()
 }
 
+/// Returns the terminal font size in pixels.
+pub fn font_size() -> io::Result<(u16, u16)> {
+    sys::font_size()
+}
+
 /// Disables line wrapping.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub struct DisableLineWrap;

src/terminal/sys.rs

@@ -4,14 +4,16 @@
 #[cfg(feature = "events")]
 pub use self::unix::supports_keyboard_enhancement;
 #[cfg(unix)]
-pub(crate) use self::unix::{disable_raw_mode, enable_raw_mode, is_raw_mode_enabled, size};
+pub(crate) use self::unix::{
+    disable_raw_mode, enable_raw_mode, font_size, is_raw_mode_enabled, size,
+};
 #[cfg(windows)]
 #[cfg(feature = "events")]
 pub use self::windows::supports_keyboard_enhancement;
 #[cfg(windows)]
 pub(crate) use self::windows::{
-    clear, disable_raw_mode, enable_raw_mode, is_raw_mode_enabled, scroll_down, scroll_up,
-    set_size, set_window_title, size,
+    clear, disable_raw_mode, enable_raw_mode, font_size, is_raw_mode_enabled, scroll_down,
+    scroll_up, set_size, set_window_title, size,
 };
 
 #[cfg(windows)]

src/terminal/sys/unix.rs

@@ -48,6 +48,31 @@ pub(crate) fn size() -> io::Result<(u16, u16)> {
     tput_size().ok_or_else(|| std::io::Error::last_os_error().into())
 }
 
+#[allow(clippy::useless_conversion)]
+pub(crate) fn font_size() -> io::Result<(u16, u16)> {
+    // http://rosettacode.org/wiki/Terminal_control/Dimensions#Library:_BSD_libc
+    let mut size = winsize {
+        ws_row: 0,
+        ws_col: 0,
+        ws_xpixel: 0,
+        ws_ypixel: 0,
+    };
+
+    let file = File::open("/dev/tty").map(|file| (FileDesc::new(file.into_raw_fd(), true)));
+    let fd = if let Ok(file) = &file {
+        file.raw_fd()
+    } else {
+        // Fallback to libc::STDOUT_FILENO if /dev/tty is missing
+        STDOUT_FILENO
+    };
+
+    if wrap_with_result(unsafe { ioctl(fd, TIOCGWINSZ.into(), &mut size) }).is_ok() {
+        return Ok((size.ws_xpixel / size.ws_col, size.ws_ypixel / size.ws_row));
+    }
+
+    Err(std::io::Error::last_os_error().into())
+}
+
 pub(crate) fn enable_raw_mode() -> io::Result<()> {
     let mut original_mode = TERMINAL_MODE_PRIOR_RAW_MODE.lock();
 

src/terminal/sys/windows.rs

@@ -58,6 +58,11 @@ pub(crate) fn size() -> io::Result<(u16, u16)> {
     ))
 }
 
+pub(crate) fn font_size() -> io::Result<(u16, u16)> {
+    let size = ScreenBuffer::current()?.font_info()?.size();
+    Ok((size.width as u16, size.height as u16))
+}
+
 /// Queries the terminal's support for progressive keyboard enhancement.
 ///
 /// This always returns `Ok(false)` on Windows.