v0.2.1 tui enhancement and better narrow layouts

tui/choice.go

@@ -2,20 +2,51 @@ package tui
 
 import "github.com/lixenwraith/terminal"
 
-// Choice draws options in a row at (x, y), the chosen one bracketed in the
-// accent style and the rest muted ("raw [txt] json"), and returns the
-// columns it drew
-func (r Region) Choice(x, y int, options []string, chosen int, th Theme) int {
-	start := x
-	for i, o := range options {
-		open, close, style := " ", " ", th.Muted
-		if i == chosen {
-			open, close, style = "[", "]", th.Accent
+// Radio draws options as radio buttons in a row at (x, y): the chosen one
+// with the On glyph in the accent style, the rest with Off, muted ("○ raw
+// ● txt  ○ json"); chosen -1 marks none. Where the row does not fit, it shows
+// the options around the chosen one, a muted '…' where others are hidden.
+// It returns the columns it drew.
+func (r Region) Radio(x, y int, options []string, chosen int, th Theme) int {
+	width := func(lo, hi int) int { // the window [lo, hi), its '…' marks included
+		w := -2
+		for _, o := range options[lo:hi] {
+			w += RuneLen(o) + 4
 		}
-		r.TextStyled(x, y, open+o+close, style)
-		x += RuneLen(o) + 2
+		return w + 2*min(lo, 1) + 3*min(len(options)-hi, 1)
 	}
-	return x - start
+	lo, hi := 0, len(options)
+	if width(lo, hi) > r.W-x && hi > 0 {
+		lo = max(0, min(chosen, hi-1))
+		hi = lo + 1
+		for grown := true; grown; {
+			grown = false
+			if hi < len(options) && width(lo, hi+1) <= r.W-x {
+				hi, grown = hi+1, true
+			}
+			if lo > 0 && width(lo-1, hi) <= r.W-x {
+				lo, grown = lo-1, true
+			}
+		}
+	}
+	start := x
+	if lo > 0 {
+		r.TextStyled(x, y, "…", th.Muted)
+		x += 2
+	}
+	for i := lo; i < hi; i++ {
+		mark, style := th.Glyphs.Off, th.Muted
+		if i == chosen {
+			mark, style = th.Glyphs.On, th.Accent
+		}
+		r.TextStyled(x, y, Truncate(string(mark)+" "+options[i], max(0, r.W-x)), style)
+		x += RuneLen(options[i]) + 4
+	}
+	if hi < len(options) {
+		r.TextStyled(x, y, "…", th.Muted)
+		x += 3
+	}
+	return max(0, min(x-2, r.W)-start)
 }
 
 // StepChoice moves a choice among n options on Left or Right (h, l),