From 8931062a7036ecc6c9c882c5f39ffa6e2ab6c476 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Fri, 17 Jan 2025 20:22:10 +0530
Subject: [PATCH] hints kitten: Workaround for some broken light color themes
 that make the hints text color too low contrast to read

Fixes #7330
---
 docs/changelog.rst     |  2 ++
 kittens/hints/main.go  | 21 +++++++++++++++++++++
 kittens/hints/main.py  |  4 ++--
 tools/tui/ui_kitten.go | 31 +++++++++++++++++++++++++++++++
 tools/utils/colors.go  | 21 +++++++++++++++++++++
 5 files changed, 77 insertions(+), 2 deletions(-)
 create mode 100644 tools/utils/colors.go

diff --git a/docs/changelog.rst b/docs/changelog.rst
index c4759b015..ed6942eb7 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -89,6 +89,8 @@ Detailed list of changes
 
 - Splits layout: Allow setting the bias of the current split using ``layout_action bias`` (:iss:`8222`)
 
+- hints kitten: Workaround for some broken light color themes that make the hints text color too low contrast to read (:iss:`7330`)
+
 
 0.39.0 [2025-01-16]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/kittens/hints/main.go b/kittens/hints/main.go
index c8c408c49..b3512fa59 100644
--- a/kittens/hints/main.go
+++ b/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")
diff --git a/kittens/hints/main.py b/kittens/hints/main.py
index 62b77231d..53aee8479 100644
--- a/kittens/hints/main.py
+++ b/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
diff --git a/tools/tui/ui_kitten.go b/tools/tui/ui_kitten.go
index eead85bb4..b09aa028a 100644
--- a/tools/tui/ui_kitten.go
+++ b/tools/tui/ui_kitten.go
@@ -20,6 +20,37 @@ var RunningAsUI = sync.OnceValue(func() bool {
 	return os.Getenv("KITTEN_RUNNING_AS_UI") != ""
 })
 
+type BasicColors struct {
+	Foreground uint32 `json:"foreground"`
+	Background uint32 `json:"background"`
+	Color0     uint32 `json:"color0"`
+	Color1     uint32 `json:"color1"`
+	Color2     uint32 `json:"color2"`
+	Color3     uint32 `json:"color3"`
+	Color4     uint32 `json:"color4"`
+	Color5     uint32 `json:"color5"`
+	Color6     uint32 `json:"color6"`
+	Color7     uint32 `json:"color7"`
+	Color8     uint32 `json:"color8"`
+	Color9     uint32 `json:"color9"`
+	Color10    uint32 `json:"color10"`
+	Color11    uint32 `json:"color11"`
+	Color12    uint32 `json:"color12"`
+	Color13    uint32 `json:"color13"`
+	Color14    uint32 `json:"color14"`
+	Color15    uint32 `json:"color15"`
+}
+
+func ReadBasicColors() (ans BasicColors, err error) {
+	q := os.Getenv("KITTY_BASIC_COLORS")
+	if q == "" {
+		err = fmt.Errorf("No KITTY_BASIC_COLORS env var")
+	} else {
+		err = json.Unmarshal(utils.UnsafeStringToBytes(q), &ans)
+	}
+	return
+}
+
 func PrepareRootCmd(root *cli.Command) {
 	if RunningAsUI() {
 		root.CallbackOnError = func(cmd *cli.Command, err error, during_parsing bool, exit_code int) int {
diff --git a/tools/utils/colors.go b/tools/utils/colors.go
new file mode 100644
index 000000000..35da17552
--- /dev/null
+++ b/tools/utils/colors.go
@@ -0,0 +1,21 @@
+package utils
+
+import (
+	"fmt"
+)
+
+var _ = fmt.Print
+
+func RGBLuminance(r, g, b float32) float32 {
+	// From ITU BT 601 https://www.itu.int/rec/R-REC-BT.601
+	return 0.299*r + 0.587*g + 0.114*b
+}
+
+func RGBContrast(r1, g1, b1, r2, g2, b2 float32) float32 {
+	al := RGBLuminance(r1, g1, b1)
+	bl := RGBLuminance(r2, g2, b2)
+	if al < bl {
+		al, bl = bl, al
+	}
+	return (al + 0.05) / (bl + 0.05)
+}