Android icon image scaling works.

android/src/main/java/com/mapbox/mapboxgl/MapboxMapController.java

@@ -54,11 +54,7 @@
 
 import java.io.IOException;
 import java.io.InputStream;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
 import java.util.concurrent.atomic.AtomicInteger;
 
 import static com.mapbox.mapboxgl.MapboxMapsPlugin.CREATED;
@@ -412,14 +408,16 @@ public void onMethodCall(MethodCall call, MethodChannel.Result result) {
         Convert.interpretSymbolOptions(call.argument("options"), symbolBuilder);
         final Symbol symbol = symbolBuilder.build();
         final String symbolId = String.valueOf(symbol.getId());
-        try { // Will throw if image does not exist (assumes it's a default icon)
+
+        // Will throw if image does not exist (assumes it's a default icon)
+        try {
           DisplayMetrics displayMetrics = context.getResources().getDisplayMetrics();
-          float density = displayMetrics.density;
-          Bitmap bitmap = getImage(symbol, density);
+          Bitmap bitmap = getImage(symbol, displayMetrics.density);
           mapboxMap.getStyle().addImage(symbol.getIconImage(), bitmap);
         } catch (IOException e) {
           e.printStackTrace();
         }
+
         symbols.put(symbolId, new SymbolController(symbol, true, this));
         result.success(symbolId);
         break;
@@ -490,16 +488,6 @@ public void onMethodCall(MethodCall call, MethodChannel.Result result) {
     }
   }
 
-  public Bitmap getImage(Symbol symbol, float density) throws IOException {
-    AssetManager assetManager = registrar.context().getAssets();
-    String assetPath = registrar.lookupKeyForAsset(symbol.getIconImage());
-    AssetFileDescriptor assetFileDescriptor = assetManager.openFd(assetPath);
-    InputStream a = assetFileDescriptor.createInputStream();
-    Bitmap bitmap = BitmapFactory.decodeStream(a);
-    assetFileDescriptor.close();
-    return bitmap;
-  }
-
   @Override
   public void onCameraMoveStarted(int reason) {
     final Map<String, Object> arguments = new HashMap<>(2);
@@ -763,4 +751,70 @@ private int checkSelfPermission(String permission) {
       permission, android.os.Process.myPid(), android.os.Process.myUid());
   }
 
+  // Tries to find highest scale image for display type
+  private Bitmap getImage(Symbol symbol, float density) throws IOException {
+    AssetManager assetManager = registrar.context().getAssets();
+    String assetPath;
+    AssetFileDescriptor assetFileDescriptor = null;
+
+    // Split possible path into
+    List<String> imagePathList = new ArrayList<>(Arrays.asList(symbol.getIconImage().split("/")));
+
+    if (imagePathList.size() > 1) { // Should stop most default icons
+      for (int i = (int) density; i >= 1; i--) { // Goes down by 1 each time (e.g. 3.0 -> 2.0 -> 1.0)
+
+        // If on last size, set default value
+        if (i == 1) {
+          assetPath = registrar.lookupKeyForAsset(symbol.getIconImage());
+          assetFileDescriptor = assetManager.openFd(assetPath);
+          break;
+        }
+
+        // Add possible size to list
+        String strDensity = Float.toString((float) i) + "x";
+        int size = imagePathList.size();
+        imagePathList.add(size - 1, strDensity);
+
+        // Turn array into a string
+        String imagePath;
+        StringBuilder stringBuilder = new StringBuilder();
+        for (int j = 0; j < imagePathList.size(); j++) {
+          stringBuilder.append(imagePathList.get(j));
+          if (j != imagePathList.size() - 1) {
+            stringBuilder.append("/");
+          }
+        }
+        imagePath = stringBuilder.toString();
+
+        // Reset for next time
+        imagePathList = Arrays.asList(symbol.getIconImage().split("/"));
+
+        // Get possible path
+        assetPath = registrar.lookupKeyForAsset(imagePath);
+
+
+        try {
+          // Read path (throws if doesn't exist)
+          assetFileDescriptor = assetManager.openFd(assetPath);
+          break; // If exists, break
+        } catch (IOException e) {
+          if (assetFileDescriptor != null) {
+            assetFileDescriptor.close(); // Path doesn't exist but still close for memory
+          }
+        }
+      }
+    }
+
+    if (assetFileDescriptor == null) { // Verify it's not a default icon
+      assetPath = registrar.lookupKeyForAsset(symbol.getIconImage());
+      assetFileDescriptor = assetManager.openFd(assetPath); // Sets back to default
+    }
+
+    InputStream assetStream = assetFileDescriptor.createInputStream();
+    Bitmap bitmap = BitmapFactory.decodeStream(assetStream);
+    assetFileDescriptor.close(); // Close for memory
+
+    return bitmap;
+  }
+
 }