feat: add node colors (#618)

app/src/main/java/com/geeksville/mesh/NodeInfo.kt

@@ -1,5 +1,6 @@
 package com.geeksville.mesh
 
+import android.graphics.Color
 import android.os.Parcelable
 import com.geeksville.mesh.util.bearing
 import com.geeksville.mesh.util.latLongToMeter
@@ -153,6 +154,15 @@ data class NodeInfo(
     var environmentMetrics: EnvironmentMetrics? = null,
 ) : Parcelable {
 
+    val colors: Pair<Int, Int>
+        get() { // returns foreground and background @ColorInt for each 'num'
+            val r = (num and 0xFF0000) shr 16
+            val g = (num and 0x00FF00) shr 8
+            val b = num and 0x0000FF
+            val brightness = ((r * 0.299) + (g * 0.587) + (b * 0.114)) / 255
+            return Pair(if (brightness > 0.5) Color.BLACK else Color.WHITE, Color.rgb(r, g, b))
+        }
+
     val batteryLevel get() = deviceMetrics?.batteryLevel
     val voltage get() = deviceMetrics?.voltage
     val batteryStr get() = if (batteryLevel in 1..100) String.format("%d%%", batteryLevel) else ""

app/src/main/java/com/geeksville/mesh/ui/UsersFragment.kt

@@ -1,5 +1,6 @@
 package com.geeksville.mesh.ui
 
+import android.content.res.ColorStateList
 import android.os.Bundle
 import android.text.method.LinkMovementMethod
 import android.view.LayoutInflater
@@ -205,8 +206,13 @@ class UsersFragment : ScreenFragment("Users"), Logging {
         override fun onBindViewHolder(holder: ViewHolder, position: Int) {
             val n = nodes[position]
             val user = n.user
-            holder.chipNode.text = user?.shortName ?: "UNK"
-            val name = user?.longName ?: "Unknown node"
+            val (textColor, nodeColor) = n.colors
+            with(holder.chipNode) {
+                text = user?.shortName ?: "UNK"
+                chipBackgroundColor = ColorStateList.valueOf(nodeColor)
+                setTextColor(textColor)
+            }
+            val name = user?.longName ?: getString(R.string.unknown_username)
             holder.nodeNameView.text = name
 
             val pos = n.validPosition