Use hex values & add theme_color in manifest.json

It looks like support for hsl color values within the manifest
is limited so we have to convert the colors to hex

internal/glance/config-fields.go

@@ -32,6 +32,10 @@ func (c *hslColorField) String() string {
 	return fmt.Sprintf("hsl(%.1f, %.1f%%, %.1f%%)", c.Hue, c.Saturation, c.Lightness)
 }
 
+func (c *hslColorField) ToHex() string {
+	return hslToHex(c.Hue, c.Saturation, c.Lightness)
+}
+
 func (c *hslColorField) UnmarshalYAML(node *yaml.Node) error {
 	var value string
 

internal/glance/config.go

@@ -39,6 +39,7 @@ type config struct {
 
 	Theme struct {
 		BackgroundColor          *hslColorField `yaml:"background-color"`
+		BackgroundColorAsHex     string         `yaml:"-"`
 		PrimaryColor             *hslColorField `yaml:"primary-color"`
 		PositiveColor            *hslColorField `yaml:"positive-color"`
 		NegativeColor            *hslColorField `yaml:"negative-color"`

internal/glance/glance.go

@@ -96,6 +96,12 @@ func newApplication(config *config) (*application, error) {
 	config.Theme.CustomCSSFile = app.resolveUserDefinedAssetPath(config.Theme.CustomCSSFile)
 	config.Branding.LogoURL = app.resolveUserDefinedAssetPath(config.Branding.LogoURL)
 
+	if config.Theme.BackgroundColor != nil {
+		config.Theme.BackgroundColorAsHex = config.Theme.BackgroundColor.ToHex()
+	} else {
+		config.Theme.BackgroundColorAsHex = "#151519"
+	}
+
 	if config.Branding.FaviconURL == "" {
 		config.Branding.FaviconURL = app.StaticAssetPath("favicon.png")
 	} else {
@@ -111,11 +117,7 @@ func newApplication(config *config) (*application, error) {
 	}
 
 	if config.Branding.AppBackgroundColor == "" {
-		config.Branding.AppBackgroundColor = ternary(
+		config.Branding.AppBackgroundColor = config.Theme.BackgroundColorAsHex
-			config.Theme.BackgroundColor != nil,
-			config.Theme.BackgroundColor.String(),
-			"hsl(240, 8%, 9%)",
-		)
 	}
 
 	var manifestWriter bytes.Buffer

internal/glance/templates/document.html

@@ -11,7 +11,7 @@
     <meta name="mobile-web-app-capable" content="yes">
     <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
     <meta name="apple-mobile-web-app-title" content="{{ .App.Config.Branding.AppName }}">
-    <meta name="theme-color" content="{{ if ne nil .App.Config.Theme.BackgroundColor }}{{ .App.Config.Theme.BackgroundColor }}{{ else }}hsl(240, 8%, 9%){{ end }}">
+    <meta name="theme-color" content="{{ .App.Config.Theme.BackgroundColorAsHex }}">
     <link rel="apple-touch-icon" sizes="512x512" href='{{ .App.Config.Branding.AppIconURL }}'>
     <link rel="manifest" href='{{ .App.VersionedAssetPath "manifest.json" }}'>
     <link rel="icon" type="image/png" href="{{ .App.Config.Branding.FaviconURL }}" />

internal/glance/templates/manifest.json

@@ -2,6 +2,7 @@
     "name": "{{ .App.Config.Branding.AppName }}",
     "display": "standalone",
     "background_color": "{{ .App.Config.Branding.AppBackgroundColor }}",
+    "theme_color": "{{ .App.Config.Branding.AppBackgroundColor }}",
     "scope": "/",
     "start_url": "/",
     "icons": [

internal/glance/utils.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"fmt"
 	"html/template"
+	"math"
 	"net/http"
 	"net/url"
 	"os"
@@ -182,3 +183,58 @@ func ternary[T any](condition bool, a, b T) T {
 // Having compile time errors about unused variables is cool and all, but I don't want to
 // have to constantly comment out my code while I'm working on it and testing things out
 func ItsUsedTrustMeBro(...any) {}
+
+func hslToHex(h, s, l float64) string {
+	s /= 100.0
+	l /= 100.0
+
+	var r, g, b float64
+
+	if s == 0 {
+		r, g, b = l, l, l
+	} else {
+		hueToRgb := func(p, q, t float64) float64 {
+			if t < 0 {
+				t += 1
+			}
+			if t > 1 {
+				t -= 1
+			}
+			if t < 1.0/6.0 {
+				return p + (q-p)*6.0*t
+			}
+			if t < 1.0/2.0 {
+				return q
+			}
+			if t < 2.0/3.0 {
+				return p + (q-p)*(2.0/3.0-t)*6.0
+			}
+			return p
+		}
+
+		q := 0.0
+		if l < 0.5 {
+			q = l * (1 + s)
+		} else {
+			q = l + s - l*s
+		}
+
+		p := 2*l - q
+
+		h /= 360.0
+
+		r = hueToRgb(p, q, h+1.0/3.0)
+		g = hueToRgb(p, q, h)
+		b = hueToRgb(p, q, h-1.0/3.0)
+	}
+
+	ir := int(math.Round(r * 255.0))
+	ig := int(math.Round(g * 255.0))
+	ib := int(math.Round(b * 255.0))
+
+	ir = int(math.Max(0, math.Min(255, float64(ir))))
+	ig = int(math.Max(0, math.Min(255, float64(ig))))
+	ib = int(math.Max(0, math.Min(255, float64(ib))))
+
+	return fmt.Sprintf("#%02x%02x%02x", ir, ig, ib)
+}