Synthesize Android MotionEvents with the long form obtain method.

The simple form MotionEvent.obtain method I used before does not allow
to synthesize multi pointer events.

shell/platform/android/io/flutter/plugin/platform/PlatformViewsController.java

@@ -15,10 +15,14 @@ import io.flutter.plugin.common.StandardMethodCodec;
 import io.flutter.view.FlutterView;
 import io.flutter.view.TextureRegistry;
 
+import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
+import static android.view.MotionEvent.PointerCoords;
+import static android.view.MotionEvent.PointerProperties;
+
 /**
  * Manages platform views.
  * <p>
@@ -191,19 +195,26 @@ public class PlatformViewsController implements MethodChannel.MethodCallHandler
     private void onTouch(MethodCall call, MethodChannel.Result result) {
         List<Object> args = call.arguments();
 
+        float density = mFlutterView.getContext().getResources().getDisplayMetrics().density;
+
         int id = (int) args.get(0);
         int downTime = (int) args.get(1);
         int eventTime = (int) args.get(2);
         int action = (int) args.get(3);
-        double x = (double) args.get(4);
-        double y = (double) args.get(5);
-        double pressure = (double) args.get(6);
-        double size = (double) args.get(7);
-        int metaState = (int) args.get(8);
-        double xPrecision = (double) args.get(9);
-        double yPrecision = (double) args.get(10);
+        int pointerCount = (int) args.get(4);
+        PointerProperties[] pointerProperties =
+                parsePointerPropertiesList(args.get(5)).toArray(new PointerProperties[pointerCount]);
+        PointerCoords[] pointerCoords =
+                parsePointerCoordsList(args.get(6), density).toArray(new PointerCoords[pointerCount]);
+
+        int metaState = (int) args.get(7);
+        int buttonState = (int) args.get(8);
+        float xPrecision = (float) (double) args.get(9);
+        float yPrecision = (float) (double) args.get(10);
         int deviceId = (int) args.get(11);
         int edgeFlags = (int) args.get(12);
+        int source = (int) args.get(13);
+        int flags = (int) args.get(14);
 
         View view = vdControllers.get(id).getView();
         if (view == null) {
@@ -215,27 +226,72 @@ public class PlatformViewsController implements MethodChannel.MethodCallHandler
             return;
         }
 
-        float density = mFlutterView.getContext().getResources().getDisplayMetrics().density;
-
         MotionEvent event = MotionEvent.obtain(
                 downTime,
                 eventTime,
                 action,
-                (float) x * density,
-                (float) y * density,
-                (float) pressure,
-                (float) size,
+                pointerCount,
+                pointerProperties,
+                pointerCoords,
                 metaState,
-                (float) xPrecision,
-                (float) yPrecision,
+                buttonState,
+                xPrecision,
+                yPrecision,
                 deviceId,
-                edgeFlags
+                edgeFlags,
+                source,
+                flags
         );
 
         view.onTouchEvent(event);
         result.success(null);
     }
 
+    @SuppressWarnings("unchecked")
+    private static List<PointerProperties> parsePointerPropertiesList(Object rawPropertiesList) {
+        List<Object> rawProperties = (List<Object>) rawPropertiesList;
+        List<PointerProperties> pointerProperties = new ArrayList<>();
+        for (Object o : rawProperties) {
+            pointerProperties.add(parsePointerProperties(o));
+        }
+        return pointerProperties;
+    }
+
+    @SuppressWarnings("unchecked")
+    private static PointerProperties parsePointerProperties(Object rawProperties) {
+        List<Object> propertiesList = (List<Object>) rawProperties;
+        PointerProperties properties = new MotionEvent.PointerProperties();
+        properties.id = (int) propertiesList.get(0);
+        properties.toolType = (int) propertiesList.get(1);
+        return properties;
+    }
+
+    @SuppressWarnings("unchecked")
+    private static List<PointerCoords> parsePointerCoordsList(Object rawCoordsList, float density) {
+        List<Object> rawCoords = (List<Object>) rawCoordsList;
+        List<PointerCoords> pointerCoords = new ArrayList<>();
+        for (Object o : rawCoords) {
+            pointerCoords.add(parsePointerCoords(o, density));
+        }
+        return pointerCoords;
+    }
+
+    @SuppressWarnings("unchecked")
+    private static PointerCoords parsePointerCoords(Object rawCoords, float density) {
+        List<Object> coordsList = (List<Object>) rawCoords;
+        PointerCoords coords = new MotionEvent.PointerCoords();
+        coords.orientation = (float) (double) coordsList.get(0);
+        coords.pressure = (float) (double) coordsList.get(1);
+        coords.size = (float) (double) coordsList.get(2);
+        coords.toolMajor = (float) (double) coordsList.get(3) * density;
+        coords.toolMinor = (float) (double) coordsList.get(4) * density;
+        coords.touchMajor = (float) (double) coordsList.get(5) * density;
+        coords.touchMinor = (float) (double) coordsList.get(6) * density;
+        coords.x = (float) (double) coordsList.get(7) * density;
+        coords.y = (float) (double) coordsList.get(8) * density;
+        return coords;
+    }
+
     private int toPhysicalPixels(double logicalPixels) {
         float density = mFlutterView.getContext().getResources().getDisplayMetrics().density;
         return (int) Math.round(logicalPixels * density);