Add icon for aquirable tiles in city screen.

Credits.md

@@ -377,4 +377,4 @@ All the following are from [the Noun Project](https://thenounproject.com) licenc
 * [Sleep](https://thenounproject.com/search/?q=sleep&i=1760085) By Saeful Muslim 
 * [Banner](https://thenounproject.com/term/banner/866282/) By Emir Palavan for embarked units
 * [Arrow](https://thenounproject.com/term/arrow/18123/) By uzeir syarief for moving between idle units
-
+* [Replace](https://thenounproject.com/search/?q=replace&i=17858) By Mike Rowe, AU

core/src/com/unciv/logic/city/CityInfo.kt

@@ -209,5 +209,16 @@ class CityInfo {
             cityConstructions.removeBuilding(building.name)
         isBeingRazed=false
     }
+
+    fun canAcquireTile(newTileInfo: TileInfo): Boolean {
+        val owningCity = newTileInfo.getCity()
+        if (owningCity!=null && owningCity!=this
+                && newTileInfo.getOwner()!!.isPlayerCivilization()
+                && newTileInfo.arialDistanceTo(getCenterTile()) <= 3
+                && newTileInfo.neighbors.any{it.getCity()==this}) {
+            return true
+        }
+        return false
+    }
     //endregion
 }

core/src/com/unciv/ui/cityscreen/CityScreen.kt

@@ -158,8 +158,13 @@ class CityScreen(internal val city: CityInfo) : CameraStageBaseScreen() {
 
             // this needs to happen on update, because we can buy tiles, which changes the definition of the bought tiles...
             if (tileInfo.getCity()!=city) { // outside of city
-                tileGroup.setColor(0f, 0f, 0f, 0.3f)
-                tileGroup.yieldGroup.isVisible = false
+                if(city.canAcquireTile(tileInfo)){
+                    tileGroup.addAcquirableIcon()
+                    tileGroup.yieldGroup.isVisible = false
+                } else {
+                    tileGroup.setColor(0f, 0f, 0f, 0.3f)
+                    tileGroup.yieldGroup.isVisible = false
+                }
             } else if(tileInfo !in tilesInRange){ // within city but not close enough to be workable
                 tileGroup.yieldGroup.isVisible = false
             }
@@ -240,10 +245,7 @@ class CityScreen(internal val city: CityInfo) : CameraStageBaseScreen() {
             if(goldCostOfTile>city.civInfo.gold) buyTileButton.disable()
             tileTable.add(buyTileButton)
         }
-        if(tile.getOwner()!=null && tile.getCity()!=city
-                && tile.getOwner()!!.isPlayerCivilization()
-                && tile.arialDistanceTo(city.getCenterTile()) <= 3
-                && tile.neighbors.any{it.getCity()==city}){
+        if(city.canAcquireTile(tile)){
             val acquireTileButton = TextButton("Acquire".tr(),skin)
             acquireTileButton.onClick { city.expansion.takeOwnership(tile); game.screen = CityScreen(city); dispose() }
             tileTable.add(acquireTileButton)

core/src/com/unciv/ui/cityscreen/CityTileGroup.kt

@@ -46,7 +46,7 @@ class CityTileGroup(private val city: CityInfo, tileInfo: TileInfo) : TileGroup(
             populationImage!!.setPosition(width / 2 - populationImage!!.width / 2,
                     height * 0.85f - populationImage!!.height / 2)
 
-            if (tileInfo.isWorked()) {
+            if (tileInfo.isWorked() || city.canAcquireTile(tileInfo)) {
                 populationImage!!.color = Color.WHITE
             }
             else if(!tileInfo.isCityCenter()){

core/src/com/unciv/ui/tilegroups/TileGroup.kt

@@ -23,7 +23,7 @@ open class TileGroup(var tileInfo: TileInfo) : Group() {
 
     var resourceImage: Actor? = null
     var improvementImage: Actor? = null
-    var populationImage: Image? = null
+    var populationImage: Image? = null //reuse for acquire icon
     private val roadImages = HashMap<TileInfo, RoadImage>()
     private val borderImages = HashMap<TileInfo, List<Image>>() // map of neighboring tile to border images
     protected var civilianUnitImage: Group? = null
@@ -100,6 +100,18 @@ open class TileGroup(var tileInfo: TileInfo) : Group() {
         addActor(hexagon)
     }
 
+    fun addAcquirableIcon(){
+        this.
+        populationImage = ImageGetter.getStatIcon("Acquire")
+        populationImage!!.run {
+            color = Color.GREEN.cpy().lerp(Color.BLACK, 0.5f)
+            setSize(20f, 20f)
+            center(this@TileGroup)
+            x += 20 // right
+        }
+        addActor(populationImage)
+    }
+
     fun addPopulationIcon() {
         this.
         populationImage = ImageGetter.getStatIcon("Population")