Update styling of the media rail selection states.

app/src/main/java/org/thoughtcrime/securesms/mediapreview/mediarail/MediaRailAdapter.kt

@@ -4,6 +4,7 @@ import android.graphics.drawable.Drawable
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
+import android.widget.ImageView
 import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.ListAdapter
 import androidx.recyclerview.widget.RecyclerView
@@ -57,11 +58,13 @@ class MediaRailAdapter(private val glideRequests: GlideRequests, listener: RailI
     private val image: ThumbnailView
     private val outline: View
     private val captionIndicator: View
+    private val overlay: ImageView
 
     init {
       image = itemView.findViewById(R.id.rail_item_image)
       outline = itemView.findViewById(R.id.rail_item_outline)
       captionIndicator = itemView.findViewById(R.id.rail_item_caption)
+      overlay = itemView.findViewById(R.id.rail_item_overlay)
     }
 
     fun bind(
@@ -84,6 +87,9 @@ class MediaRailAdapter(private val glideRequests: GlideRequests, listener: RailI
 
     fun setSelectedItem(isActive: Boolean) {
       outline.visible = isActive
+
+      val resId = if (isActive) R.drawable.mediapreview_rail_item_overlay_selected else R.drawable.mediapreview_rail_item_overlay_unselected
+      overlay.setImageResource(resId)
     }
   }
 

app/src/main/res/drawable/mediapreview_rail_item_overlay_selected.xml

@@ -5,8 +5,6 @@
 
     <corners android:radius="8dp" />
 
-    <stroke
+    <solid android:color="#1F000000" />
-        android:width="1px"
-        android:color="@color/transparent_white_20" />
 
 </shape>

app/src/main/res/drawable/mediapreview_rail_item_overlay_unselected.xml

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<shape
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shape="rectangle">
+
+    <corners android:radius="8dp" />
+
+    <solid android:color="#3D000000" />
+
+</shape>

app/src/main/res/drawable/mediarail_media_outline.xml

@@ -4,5 +4,5 @@
 
     <stroke
         android:width="3dp"
-        android:color="@color/core_ultramarine"/>
+        android:color="@color/signal_light_colorNeutral"/>
 </shape>

app/src/main/res/layout/mediarail_media_item.xml

@@ -26,10 +26,11 @@
         tools:visibility="visible"/>
 
     <ImageView
+        android:id="@+id/rail_item_overlay"
         android:layout_width="45dp"
         android:layout_height="45dp"
         android:layout_gravity="center"
-        android:src="@drawable/mediapicker_item_border_dark"/>
+        android:src="@drawable/mediapreview_rail_item_overlay_unselected"/>
 
     <ImageView
         android:id="@+id/rail_item_caption"