#9 Fix tmux pane window size detection

CHANGELOG.md

@@ -1,3 +1,7 @@
+# Unreleased
+  - Fix #9: Query console window size through platform terminal APIs so tmux
+    panes report their pane dimensions instead of the outer terminal size.
+
 # 5.0.0
   - *BREAKING*: Raise the minimum Dart SDK constraint to `>=3.10.0`.
   - *BREAKING*: Update `win32` dependency support to `>=6.0.1 <7.0.0`.

lib/src/console.dart

@@ -127,7 +127,7 @@ class Console {
   /// Returns the width of the current console window in characters.
   int get windowWidth {
     if (hasTerminal) {
-      return stdout.terminalColumns;
+      return _termlib.windowWidth ?? stdout.terminalColumns;
     } else {
       // Treat a window that has no terminal as if it is 80x25. This should be
       // more compatible with CI/CD environments.
@@ -138,7 +138,7 @@ class Console {
   /// Returns the height of the current console window in characters.
   int get windowHeight {
     if (hasTerminal) {
-      return stdout.terminalLines;
+      return _termlib.windowHeight ?? stdout.terminalLines;
     } else {
       // Treat a window that has no terminal as if it is 80x25. This should be
       // more compatible with CI/CD environments.

lib/src/ffi/termlib.dart

@@ -13,6 +13,9 @@ import 'unix/termlib_unix.dart';
 import 'win/termlib_win.dart';
 
 abstract class TermLib {
+  int? get windowHeight;
+  int? get windowWidth;
+
   int setWindowHeight(int height);
   int setWindowWidth(int width);
 

lib/src/ffi/unix/termios.dart

@@ -64,6 +64,9 @@ const int TCSAFLUSH = 2; // drain output, flush input
 const int VMIN = 16; // minimum number of characters to receive
 const int VTIME = 17; // time in 1/10s before returning
 
+const int TIOCGWINSZ_LINUX = 0x5413;
+const int TIOCGWINSZ_MACOS = 0x40087468;
+
 // typedef unsigned long   tcflag_t;
 typedef tcflag_t = UnsignedLong;
 
@@ -104,16 +107,44 @@ base class TermIOS extends Struct {
   external int c_ospeed;
 }
 
+// struct winsize {
+//   unsigned short ws_row;
+//   unsigned short ws_col;
+//   unsigned short ws_xpixel;
+//   unsigned short ws_ypixel;
+// };
+base class WinSize extends Struct {
+  @UnsignedShort()
+  external int ws_row;
+  @UnsignedShort()
+  external int ws_col;
+  @UnsignedShort()
+  external int ws_xpixel;
+  @UnsignedShort()
+  external int ws_ypixel;
+}
+
 // int tcgetattr(int, struct termios *);
-typedef TCGetAttrNative = Int32 Function(
-    Int32 fildes, Pointer<TermIOS> termios);
+typedef TCGetAttrNative =
+    Int32 Function(Int32 fildes, Pointer<TermIOS> termios);
 typedef TCGetAttrDart = int Function(int fildes, Pointer<TermIOS> termios);
 
 // int tcsetattr(int, int, const struct termios *);
-typedef TCSetAttrNative = Int32 Function(
-  Int32 fildes,
-  Int32 optional_actions,
-  Pointer<TermIOS> termios,
-);
-typedef TCSetAttrDart = int Function(
-    int fildes, int optional_actions, Pointer<TermIOS> termios);
+typedef TCSetAttrNative =
+    Int32 Function(
+      Int32 fildes,
+      Int32 optional_actions,
+      Pointer<TermIOS> termios,
+    );
+typedef TCSetAttrDart =
+    int Function(int fildes, int optional_actions, Pointer<TermIOS> termios);
+
+// int ioctl(int, unsigned long, ...);
+typedef IOCtlNative =
+    Int32 Function(
+      Int32 fildes,
+      UnsignedLong request,
+      Pointer<WinSize> winsize,
+    );
+typedef IOCtlDart =
+    int Function(int fildes, int request, Pointer<WinSize> winsize);

lib/src/ffi/unix/termlib_unix.dart

@@ -23,6 +23,32 @@ class TermLibUnix implements TermLib {
 
   late final TCGetAttrDart tcgetattr;
   late final TCSetAttrDart tcsetattr;
+  late final IOCtlDart ioctl;
+
+  int get _windowSizeRequest =>
+      Platform.isMacOS ? TIOCGWINSZ_MACOS : TIOCGWINSZ_LINUX;
+
+  int? _readWindowSize(int Function(WinSize size) value) {
+    final winsize = calloc<WinSize>();
+    try {
+      for (final fd in [STDOUT_FILENO, STDIN_FILENO, STDERR_FILENO]) {
+        if (ioctl(fd, _windowSizeRequest, winsize) == 0 &&
+            winsize.ref.ws_col > 0 &&
+            winsize.ref.ws_row > 0) {
+          return value(winsize.ref);
+        }
+      }
+      return null;
+    } finally {
+      calloc.free(winsize);
+    }
+  }
+
+  @override
+  int? get windowHeight => _readWindowSize((size) => size.ws_row);
+
+  @override
+  int? get windowWidth => _readWindowSize((size) => size.ws_col);
 
   @override
   int setWindowHeight(int height) {
@@ -47,8 +73,10 @@ class TermLibUnix implements TermLib {
       ..ref.c_cflag = (origTermIOS.c_cflag & ~CSIZE) | CS8
       ..ref.c_lflag = origTermIOS.c_lflag & ~(ECHO | ICANON | IEXTEN | ISIG)
       ..ref.c_cc = origTermIOS.c_cc
-      ..ref.c_cc[VMIN] = 0 // VMIN -- return each byte, or 0 for timeout
-      ..ref.c_cc[VTIME] = 1 // VTIME -- 100ms timeout (unit is 1/10s)
+      ..ref.c_cc[VMIN] =
+          0 // VMIN -- return each byte, or 0 for timeout
+      ..ref.c_cc[VTIME] =
+          1 // VTIME -- 100ms timeout (unit is 1/10s)
       ..ref.c_ispeed = origTermIOS.c_ispeed
       ..ref.c_oflag = origTermIOS.c_ospeed;
 
@@ -74,6 +102,7 @@ class TermLibUnix implements TermLib {
     tcsetattr = _stdlib.lookupFunction<TCSetAttrNative, TCSetAttrDart>(
       'tcsetattr',
     );
+    ioctl = _stdlib.lookupFunction<IOCtlNative, IOCtlDart>('ioctl');
 
     // store console mode settings so we can return them again as necessary
     _origTermIOSPointer = calloc<TermIOS>();

lib/src/ffi/win/termlib_win.dart

@@ -18,6 +18,26 @@ class TermLibWindows implements TermLib {
   late final HANDLE inputHandle;
   late final HANDLE outputHandle;
 
+  int? _readWindowSize(int Function(CONSOLE_SCREEN_BUFFER_INFO info) value) {
+    final pBufferInfo = calloc<CONSOLE_SCREEN_BUFFER_INFO>();
+    try {
+      if (!GetConsoleScreenBufferInfo(outputHandle, pBufferInfo).value) {
+        return null;
+      }
+      return value(pBufferInfo.ref);
+    } finally {
+      calloc.free(pBufferInfo);
+    }
+  }
+
+  @override
+  int? get windowHeight =>
+      _readWindowSize((info) => info.srWindow.Bottom - info.srWindow.Top + 1);
+
+  @override
+  int? get windowWidth =>
+      _readWindowSize((info) => info.srWindow.Right - info.srWindow.Left + 1);
+
   @override
   int setWindowHeight(int height) {
     throw UnsupportedError(