hints kitten: Workaround for some broken light color themes that make the hints text color too low contrast to read

Fixes #7330

kittens/hints/main.go

@@ -111,7 +111,28 @@ func decode_hint(x string, alphabet string) (ans int) {
 	return
 }
 
+func as_rgb(c uint32) [3]float32 {
+	return [3]float32{float32((c>>16)&255) / 255.0, float32((c>>8)&255) / 255.0, float32(c&255) / 255.0}
+}
+
+func hints_text_color(confval string) (ans string) {
+	ans = confval
+	if ans == "auto" {
+		ans = "bright-gray"
+		if bc, err := tui.ReadBasicColors(); err == nil {
+			bg := as_rgb(bc.Background)
+			c15 := as_rgb(bc.Color15)
+			c8 := as_rgb(bc.Color8)
+			if utils.RGBContrast(bg[0], bg[1], bg[2], c8[0], c8[1], c8[2]) > utils.RGBContrast(bg[0], bg[1], bg[2], c15[0], c15[1], c15[2]) {
+				ans = "bright-black"
+			}
+		}
+	}
+	return
+}
+
 func main(_ *cli.Command, o *Options, args []string) (rc int, err error) {
+	o.HintsTextColor = hints_text_color(o.HintsTextColor)
 	output := tui.KittenOutputSerializer()
 	if tty.IsTerminal(os.Stdin.Fd()) {
 		return 1, fmt.Errorf("You must pass the text to be hinted on STDIN")

kittens/hints/main.py

@@ -229,11 +229,11 @@ color.
 
 
 --hints-text-color
-default=bright-gray
+default=auto
 type=str
 The foreground color for text pointed to by the hints. You can use color names or hex values. For the eight basic
 named terminal colors you can also use the :code:`bright-` prefix to get the bright variant of the
-color.
+color. The default is to pick a suitable color automatically.
 
 
 --customize-processing