feat: add adaptive text color for publication date over images

- Install fast-average-color library for image color detection
- Create useAdaptiveTextColor hook to analyze top-right image corner
- Update ReaderHeader to dynamically adjust date text/shadow colors
- Ensures publication date is readable on both light and dark backgrounds

package-lock.json

@@ -22,6 +22,7 @@
         "applesauce-react": "^4.0.0",
         "applesauce-relay": "^4.0.0",
         "date-fns": "^4.1.0",
+        "fast-average-color": "^9.5.0",
         "nostr-tools": "^2.4.0",
         "prismjs": "^1.30.0",
         "react": "^18.2.0",
@@ -6086,6 +6087,15 @@
       "integrity": "sha512-fjquC59cD7CyW6urNXK0FBufkZcoiGG80wTuPujX590cB5Ttln20E2UB4S/WARVqhXffZl2LNgS+gQdPIIim/g==",
       "license": "MIT"
     },
+    "node_modules/fast-average-color": {
+      "version": "9.5.0",
+      "resolved": "https://registry.npmjs.org/fast-average-color/-/fast-average-color-9.5.0.tgz",
+      "integrity": "sha512-nC6x2YIlJ9xxgkMFMd1BNoM1ctMjNoRKfRliPmiEWW3S6rLTHiQcy9g3pt/xiKv/D0NAAkhb9VyV+WJFvTqMGg==",
+      "license": "MIT",
+      "engines": {
+        "node": ">= 12"
+      }
+    },
     "node_modules/fast-deep-equal": {
       "version": "3.1.3",
       "resolved": "https://registry.npmjs.org/fast-deep-equal/-/fast-deep-equal-3.1.3.tgz",

package.json

@@ -25,6 +25,7 @@
     "applesauce-react": "^4.0.0",
     "applesauce-relay": "^4.0.0",
     "date-fns": "^4.1.0",
+    "fast-average-color": "^9.5.0",
     "nostr-tools": "^2.4.0",
     "prismjs": "^1.30.0",
     "react": "^18.2.0",

src/components/ReaderHeader.tsx

@@ -3,6 +3,7 @@ import { FontAwesomeIcon } from '@fortawesome/react-fontawesome'
 import { faHighlighter, faClock, faNewspaper } from '@fortawesome/free-solid-svg-icons'
 import { format } from 'date-fns'
 import { useImageCache } from '../hooks/useImageCache'
+import { useAdaptiveTextColor } from '../hooks/useAdaptiveTextColor'
 import { UserSettings } from '../services/settingsService'
 import { Highlight, HighlightLevel } from '../types/highlights'
 import { HighlightVisibility } from './HighlightsPanel'
@@ -34,6 +35,7 @@ const ReaderHeader: React.FC<ReaderHeaderProps> = ({
   highlightVisibility = { nostrverse: true, friends: true, mine: true }
 }) => {
   const cachedImage = useImageCache(image)
+  const { textColor, shadowColor } = useAdaptiveTextColor(cachedImage)
   const formattedDate = published ? format(new Date(published * 1000), 'MMM d, yyyy') : null
   const isLongSummary = summary && summary.length > 150
   
@@ -83,7 +85,13 @@ const ReaderHeader: React.FC<ReaderHeaderProps> = ({
             </div>
           )}
           {formattedDate && (
-            <div className="publish-date-topright">
+            <div 
+              className="publish-date-topright"
+              style={{ 
+                color: textColor,
+                textShadow: `0 2px 4px ${shadowColor}`
+              }}
+            >
               {formattedDate}
             </div>
           )}
@@ -125,7 +133,13 @@ const ReaderHeader: React.FC<ReaderHeaderProps> = ({
       {title && (
         <div className="reader-header">
           {formattedDate && (
-            <div className="publish-date-topright">
+            <div 
+              className="publish-date-topright"
+              style={{ 
+                color: textColor,
+                textShadow: `0 2px 4px ${shadowColor}`
+              }}
+            >
               {formattedDate}
             </div>
           )}

src/hooks/useAdaptiveTextColor.ts

@@ -0,0 +1,88 @@
+import { useEffect, useState } from 'react'
+import FastAverageColor from 'fast-average-color'
+
+interface AdaptiveTextColor {
+  textColor: string
+  shadowColor: string
+}
+
+/**
+ * Hook to determine optimal text and shadow colors based on image background
+ * Samples the top-right corner of the image to ensure publication date is readable
+ * 
+ * @param imageUrl - The URL of the image to analyze
+ * @returns Object containing textColor and shadowColor for optimal contrast
+ */
+export function useAdaptiveTextColor(imageUrl: string | undefined): AdaptiveTextColor {
+  const [colors, setColors] = useState<AdaptiveTextColor>({
+    textColor: '#ffffff',
+    shadowColor: 'rgba(0, 0, 0, 0.5)'
+  })
+
+  useEffect(() => {
+    if (!imageUrl) {
+      // No image, use default white text
+      setColors({
+        textColor: '#ffffff',
+        shadowColor: 'rgba(0, 0, 0, 0.5)'
+      })
+      return
+    }
+
+    const fac = new FastAverageColor()
+    const img = new Image()
+    img.crossOrigin = 'anonymous'
+    
+    img.onload = async () => {
+      try {
+        const width = img.naturalWidth
+        const height = img.naturalHeight
+        
+        // Sample top-right corner (last 25% width, first 25% height)
+        const color = await fac.getColor(img, {
+          left: Math.floor(width * 0.75),
+          top: 0,
+          width: Math.floor(width * 0.25),
+          height: Math.floor(height * 0.25)
+        })
+        
+        // Use library's built-in isLight check for optimal contrast
+        if (color.isLight) {
+          setColors({
+            textColor: '#000000',
+            shadowColor: 'rgba(255, 255, 255, 0.5)'
+          })
+        } else {
+          setColors({
+            textColor: '#ffffff',
+            shadowColor: 'rgba(0, 0, 0, 0.5)'
+          })
+        }
+      } catch (error) {
+        // Fallback to default on error
+        console.error('Error analyzing image color:', error)
+        setColors({
+          textColor: '#ffffff',
+          shadowColor: 'rgba(0, 0, 0, 0.5)'
+        })
+      }
+    }
+    
+    img.onerror = () => {
+      // Fallback to default if image fails to load
+      setColors({
+        textColor: '#ffffff',
+        shadowColor: 'rgba(0, 0, 0, 0.5)'
+      })
+    }
+    
+    img.src = imageUrl
+
+    return () => {
+      fac.destroy()
+    }
+  }, [imageUrl])
+
+  return colors
+}
+