loop: fully clean up tty when stopping event loop

Previously, stopping the read thread would not fully clean up the tty.
This could result in issues such as #9 where the terminal state was
borked upon return to shell or if temporarily exiting the TUI.

Fixes: #9

examples/text_input.zig

@@ -82,6 +82,12 @@ pub fn main() !void {
                     vx.queueRefresh();
                 } else if (key.matches('n', .{ .ctrl = true })) {
                     try vx.notify("vaxis", "hello from vaxis");
+                    loop.stop();
+                    var child = std.process.Child.init(&.{"nvim"}, alloc);
+                    _ = try child.spawnAndWait();
+                    try loop.run();
+                    try vx.enterAltScreen();
+                    vx.queueRefresh();
                 } else if (key.matches(vaxis.Key.enter, .{})) {
                     text_input.clearAndFree();
                 } else {

src/Loop.zig

@@ -30,11 +30,17 @@ pub fn Loop(comptime T: type) type {
 
         /// stops reading from the tty and returns it to it's initial state
         pub fn stop(self: *Self) void {
-            if (self.vaxis.tty) |*tty| tty.stop();
+            if (self.vaxis.tty) |*tty| {
+                // stop the read loop, then join the thread
+                tty.stop();
                 if (self.thread) |thread| {
                     thread.join();
                     self.thread = null;
                 }
+                // once thread is closed we can deinit the tty
+                tty.deinit();
+                self.vaxis.tty = null;
+            }
         }
 
         /// returns the next available event, blocking until one is available

src/Tty.zig

@@ -25,6 +25,15 @@ should_quit: bool = false,
 
 buffered_writer: BufferedWriter,
 
+state: struct {
+    /// if we are in the alt screen
+    alt_screen: bool = false,
+    /// if we have entered kitty keyboard
+    kitty_keyboard: bool = false,
+    bracketed_paste: bool = false,
+    mouse: bool = false,
+} = .{},
+
 /// initializes a Tty instance by opening /dev/tty and "making it raw"
 pub fn init() !Tty {
     // Open our tty
@@ -42,6 +51,21 @@ pub fn init() !Tty {
 
 /// release resources associated with the Tty return it to its original state
 pub fn deinit(self: *Tty) void {
+    if (self.state.kitty_keyboard) {
+        _ = self.write(ctlseqs.csi_u_pop) catch {};
+    }
+    if (self.state.mouse) {
+        _ = self.write(ctlseqs.mouse_reset) catch {};
+    }
+    if (self.state.bracketed_paste) {
+        _ = self.write(ctlseqs.bp_reset) catch {};
+    }
+    if (self.state.alt_screen) {
+        _ = self.write(ctlseqs.rmcup) catch {};
+    }
+    // always show the cursor on exit
+    _ = self.write(ctlseqs.show_cursor) catch {};
+    self.flush() catch {};
     posix.tcsetattr(self.fd, .FLUSH, self.termios) catch |err| {
         log.err("couldn't restore terminal: {}", .{err});
     };

src/Vaxis.zig

@@ -42,15 +42,6 @@ screen: Screen,
 /// the next render
 screen_last: InternalScreen = undefined,
 
-state: struct {
-    /// if we are in the alt screen
-    alt_screen: bool = false,
-    /// if we have entered kitty keyboard
-    kitty_keyboard: bool = false,
-    bracketed_paste: bool = false,
-    mouse: bool = false,
-} = .{},
-
 caps: Capabilities = .{},
 
 /// if we should redraw the entire screen on the next render
@@ -86,23 +77,7 @@ pub fn init(alloc: std.mem.Allocator, _: Options) !Vaxis {
 /// optional so applications can choose to not free resources when the
 /// application will be exiting anyways
 pub fn deinit(self: *Vaxis, alloc: ?std.mem.Allocator) void {
-    if (self.tty) |_| {
+    if (self.tty) |*tty| {
-        var tty = &self.tty.?;
-        if (self.state.kitty_keyboard) {
-            _ = tty.write(ctlseqs.csi_u_pop) catch {};
-        }
-        if (self.state.mouse) {
-            _ = tty.write(ctlseqs.mouse_reset) catch {};
-        }
-        if (self.state.bracketed_paste) {
-            _ = tty.write(ctlseqs.bp_reset) catch {};
-        }
-        if (self.state.alt_screen) {
-            _ = tty.write(ctlseqs.rmcup) catch {};
-        }
-        // always show the cursor on exit
-        _ = tty.write(ctlseqs.show_cursor) catch {};
-        tty.flush() catch {};
         tty.deinit();
     }
     if (alloc) |a| {
@@ -147,20 +122,22 @@ pub fn window(self: *Vaxis) Window {
 /// enter the alternate screen. The alternate screen will automatically
 /// be exited if calling deinit while in the alt screen
 pub fn enterAltScreen(self: *Vaxis) !void {
-    if (self.state.alt_screen) return;
+    if (self.tty) |*tty| {
-    var tty = self.tty orelse return;
+        if (tty.state.alt_screen) return;
         _ = try tty.write(ctlseqs.smcup);
         try tty.flush();
-    self.state.alt_screen = true;
+        tty.state.alt_screen = true;
+    }
 }
 
 /// exit the alternate screen
 pub fn exitAltScreen(self: *Vaxis) !void {
-    if (!self.state.alt_screen) return;
+    if (self.tty) |*tty| {
-    var tty = self.tty orelse return;
+        if (!tty.state.alt_screen) return;
         _ = try tty.write(ctlseqs.rmcup);
         try tty.flush();
-    self.state.alt_screen = false;
+        tty.state.alt_screen = false;
+    }
 }
 
 /// write queries to the terminal to determine capabilities. Individual
@@ -487,16 +464,18 @@ pub fn render(self: *Vaxis) !void {
 }
 
 fn enableKittyKeyboard(self: *Vaxis, flags: Key.KittyFlags) !void {
-    self.state.kitty_keyboard = true;
+    if (self.tty) |*tty| {
         const flag_int: u5 = @bitCast(flags);
         try std.fmt.format(
-        self.tty.?.buffered_writer.writer(),
+            tty.buffered_writer.writer(),
             ctlseqs.csi_u_push,
             .{
                 flag_int,
             },
         );
-    try self.tty.?.flush();
+        try tty.flush();
+        tty.state.kitty_keyboard = true;
+    }
 }
 
 /// send a system notification
@@ -533,14 +512,15 @@ pub fn setTitle(self: *Vaxis, title: []const u8) !void {
 // beginning and end of a detected paste. All keystrokes between these
 // events were pasted
 pub fn setBracketedPaste(self: *Vaxis, enable: bool) !void {
-    if (self.tty == null) return;
+    if (self.tty) |*tty| {
-    self.state.bracketed_paste = enable;
         const seq = if (enable)
             ctlseqs.bp_set
         else
             ctlseqs.bp_reset;
-    _ = try self.tty.?.write(seq);
+        _ = try tty.write(seq);
-    try self.tty.?.flush();
+        try tty.flush();
+        tty.state.bracketed_paste = enable;
+    }
 }
 
 /// set the mouse shape
@@ -550,8 +530,8 @@ pub fn setMouseShape(self: *Vaxis, shape: Shape) void {
 
 /// turn mouse reporting on or off
 pub fn setMouseMode(self: *Vaxis, enable: bool) !void {
-    var tty = self.tty orelse return;
+    if (self.tty) |*tty| {
-    self.state.mouse = enable;
+        tty.state.mouse = enable;
         if (enable) {
             _ = try tty.write(ctlseqs.mouse_set);
             try tty.flush();
@@ -560,6 +540,7 @@ pub fn setMouseMode(self: *Vaxis, enable: bool) !void {
             try tty.flush();
         }
     }
+}
 
 pub fn loadImage(
     self: *Vaxis,