tty: modify WindowSize method to return windowsize object

Modify the WindowSize method of the Tty interface to return a WindowSize
object. This object includes the window size in pixels, for use in
direct drawing of sixels. Terminals that do not support this feature
will have pixel sizes of 0,0.

stdin_unix.go

@@ -27,6 +27,7 @@ import (
 	"syscall"
 	"time"
 
+	"golang.org/x/sys/unix"
 	"golang.org/x/term"
 )
 
@@ -133,11 +134,14 @@ func (tty *stdIoTty) Stop() error {
 	return nil
 }
 
-func (tty *stdIoTty) WindowSize() (int, int, error) {
-	w, h, err := term.GetSize(tty.fd)
+func (tty *stdIoTty) WindowSize() (WindowSize, error) {
+	size := WindowSize{}
+	ws, err := unix.IoctlGetWinsize(tty.fd, unix.TIOCGWINSZ)
 	if err != nil {
-		return 0, 0, err
+		return size, err
 	}
+	w := int(ws.Col)
+	h := int(ws.Row)
 	if w == 0 {
 		w, _ = strconv.Atoi(os.Getenv("COLUMNS"))
 	}
@@ -150,7 +154,11 @@ func (tty *stdIoTty) WindowSize() (int, int, error) {
 	if h == 0 {
 		h = 25 // default
 	}
-	return w, h, nil
+	size.Width = w
+	size.Height = h
+	size.PixelWidth = int(ws.Xpixel)
+	size.PixelHeight = int(ws.Ypixel)
+	return size, nil
 }
 
 func (tty *stdIoTty) NotifyResize(cb func()) {

tscreen.go

@@ -1091,19 +1091,22 @@ func (t *tScreen) Size() (int, int) {
 }
 
 func (t *tScreen) resize() {
-	if w, h, e := t.tty.WindowSize(); e == nil {
-		if w != t.w || h != t.h {
-			t.cx = -1
-			t.cy = -1
-
-			t.cells.Resize(w, h)
-			t.cells.Invalidate()
-			t.h = h
-			t.w = w
-			ev := NewEventResize(w, h)
-			_ = t.PostEvent(ev)
-		}
+	ws, err := t.tty.WindowSize()
+	if err != nil {
+		return
 	}
+	if ws.Width == t.w && ws.Height == t.h {
+		return
+	}
+	t.cx = -1
+	t.cy = -1
+
+	t.cells.Resize(ws.Width, ws.Height)
+	t.cells.Invalidate()
+	t.h = ws.Height
+	t.w = ws.Width
+	ev := &EventResize{t: time.Now(), ws: ws}
+	_ = t.PostEvent(ev)
 }
 
 func (t *tScreen) Colors() int {
@@ -1894,8 +1897,8 @@ func (t *tScreen) engage() error {
 		return err
 	}
 	t.running = true
-	if w, h, err := t.tty.WindowSize(); err == nil && w != 0 && h != 0 {
-		t.cells.Resize(w, h)
+	if ws, err := t.tty.WindowSize(); err == nil && ws.Width != 0 && ws.Height != 0 {
+		t.cells.Resize(ws.Width, ws.Height)
 	}
 	stopQ := make(chan struct{})
 	t.stopQ = stopQ

tty.go

@@ -50,7 +50,7 @@ type Tty interface {
 
 	// WindowSize is called to determine the terminal dimensions.  This might be determined
 	// by an ioctl or other means.
-	WindowSize() (width int, height int, err error)
+	WindowSize() (WindowSize, error)
 
 	io.ReadWriteCloser
 }

tty_unix.go

@@ -27,6 +27,7 @@ import (
 	"syscall"
 	"time"
 
+	"golang.org/x/sys/unix"
 	"golang.org/x/term"
 )
 
@@ -136,11 +137,14 @@ func (tty *devTty) Stop() error {
 	return nil
 }
 
-func (tty *devTty) WindowSize() (int, int, error) {
-	w, h, err := term.GetSize(tty.fd)
+func (tty *devTty) WindowSize() (WindowSize, error) {
+	size := WindowSize{}
+	ws, err := unix.IoctlGetWinsize(tty.fd, unix.TIOCGWINSZ)
 	if err != nil {
-		return 0, 0, err
+		return size, err
 	}
+	w := int(ws.Col)
+	h := int(ws.Row)
 	if w == 0 {
 		w, _ = strconv.Atoi(os.Getenv("COLUMNS"))
 	}
@@ -153,7 +157,11 @@ func (tty *devTty) WindowSize() (int, int, error) {
 	if h == 0 {
 		h = 25 // default
 	}
-	return w, h, nil
+	size.Width = w
+	size.Height = h
+	size.PixelWidth = int(ws.Xpixel)
+	size.PixelHeight = int(ws.Ypixel)
+	return size, nil
 }
 
 func (tty *devTty) NotifyResize(cb func()) {