Fix non-vd android platform view input event offsets (flutter/engine#52532)

Fixes https://github.com/flutter/flutter/issues/146570, which tracks a regression from https://github.com/flutter/engine/pull/49268 regarding platform view inputs in some specific cases.

This PR translates the input event location to be the same as the location we calculated before https://github.com/flutter/engine/pull/49268, returning to the previous behavior, while maintaining the input event's verified status (I checked this manually with the `InputManager`).

Tested manually with the reproduction in the linked issue.

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style

engine/src/flutter/shell/platform/android/io/flutter/embedding/engine/systemchannels/PlatformViewsChannel.java

@@ -501,7 +501,12 @@ public class PlatformViewsChannel {
     public final int action;
     /** The number of pointers (e.g, fingers) involved in the touch event. */
     public final int pointerCount;
-    /** Properties for each pointer, encoded in a raw format. */
+    /**
+     * Properties for each pointer, encoded in a raw format.
+     * Expected to be formatted as a List[List[Integer]], where each inner list has two items:
+     * - An id, at index 0, corresponding to {@link android.view.MotionEvent.PointerProperties#id}
+     * - A tool type, at index 1, corresponding to {@link android.view.MotionEvent.PointerProperties#toolType}.
+     * */
     @NonNull public final Object rawPointerPropertiesList;
     /** Coordinates for each pointer, encoded in a raw format. */
     @NonNull public final Object rawPointerCoords;

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

@@ -4,8 +4,6 @@
 
 package io.flutter.plugin.platform;
 
-import static android.view.MotionEvent.PointerCoords;
-import static android.view.MotionEvent.PointerProperties;
 import static io.flutter.Build.API_LEVELS;
 
 import android.annotation.TargetApi;
@@ -668,6 +666,25 @@ public class PlatformViewsController implements PlatformViewsAccessibilityDelega
     return textureId;
   }
 
+  /**
+   * Translates an original touch event to have the same locations as the ones that Flutter
+   * calculates (because original + flutter's - original = flutter's).
+   *
+   * @param originalEvent The saved original input event.
+   * @param pointerCoords The coordinates that Flutter thinks the touch is happening at.
+   */
+  private static void translateMotionEvent(
+      MotionEvent originalEvent, PointerCoords[] pointerCoords) {
+    if (pointerCoords.length < 1) {
+      return;
+    }
+
+    float xOffset = pointerCoords[0].x - originalEvent.getX();
+    float yOffset = pointerCoords[0].y - originalEvent.getY();
+
+    originalEvent.offsetLocation(xOffset, yOffset);
+  }
+
   @VisibleForTesting
   public MotionEvent toMotionEvent(
       float density, PlatformViewsChannel.PlatformViewTouch touch, boolean usingVirtualDiplay) {
@@ -675,25 +692,27 @@ public class PlatformViewsController implements PlatformViewsAccessibilityDelega
         MotionEventTracker.MotionEventId.from(touch.motionEventId);
     MotionEvent trackedEvent = motionEventTracker.pop(motionEventId);
 
+    // Pointer coordinates in the tracked events are global to FlutterView
+    // The framework converts them to be local to a widget, given that
+    // motion events operate on local coords, we need to replace these in the tracked
+    // event with their local counterparts.
+    // Compute this early so it can be used as input to translateNonVirtualDisplayMotionEvent.
+    PointerCoords[] pointerCoords =
+        parsePointerCoordsList(touch.rawPointerCoords, density)
+            .toArray(new PointerCoords[touch.pointerCount]);
+
     if (!usingVirtualDiplay && trackedEvent != null) {
-      // We have the original event, deliver it as it will pass the verifiable
+      // We have the original event, deliver it after offsetting as it will pass the verifiable
       // input check.
+      translateMotionEvent(trackedEvent, pointerCoords);
       return trackedEvent;
     }
     // We are in virtual display mode or don't have a reference to the original MotionEvent.
     // In this case we manually recreate a MotionEvent to be delivered. This MotionEvent
     // will fail the verifiable input check.
-
-    // Pointer coordinates in the tracked events are global to FlutterView
-    // framework converts them to be local to a widget, given that
-    // motion events operate on local coords, we need to replace these in the tracked
-    // event with their local counterparts.
     PointerProperties[] pointerProperties =
         parsePointerPropertiesList(touch.rawPointerPropertiesList)
             .toArray(new PointerProperties[touch.pointerCount]);
-    PointerCoords[] pointerCoords =
-        parsePointerCoordsList(touch.rawPointerCoords, density)
-            .toArray(new PointerCoords[touch.pointerCount]);
 
     // TODO (kaushikiska) : warn that we are potentially using an untracked
     // event in the platform views.

engine/src/flutter/shell/platform/android/test/io/flutter/plugin/platform/PlatformViewsControllerTest.java

@@ -361,34 +361,48 @@ public class PlatformViewsControllerTest {
     assertNotEquals(resolvedEvent.getAction(), frameWorkTouch.action);
   }
 
-  @Ignore
-  @Test
-  public void itUsesActionEventTypeFromMotionEventForHybridPlatformViews() {
-    MotionEventTracker motionEventTracker = MotionEventTracker.getInstance();
-    PlatformViewsController platformViewsController = new PlatformViewsController();
-
-    MotionEvent original =
-        MotionEvent.obtain(
-            100, // downTime
-            100, // eventTime
-            1, // action
-            0, // x
-            0, // y
-            0 // metaState
-            );
-
-    // track an event that will later get passed to us from framework
+  private MotionEvent makePlatformViewTouchAndInvokeToMotionEvent(
+      PlatformViewsController platformViewsController,
+      MotionEventTracker motionEventTracker,
+      MotionEvent original,
+      boolean usingVirtualDisplays) {
     MotionEventTracker.MotionEventId motionEventId = motionEventTracker.track(original);
 
-    PlatformViewTouch frameWorkTouch =
+    // Construct a PlatformViewTouch.rawPointerPropertiesList by doing the inverse of
+    // PlatformViewsController.parsePointerPropertiesList.
+    List<List<Integer>> pointerProperties =
+            Arrays.asList(
+                    Arrays.asList(
+                            original.getPointerId(0),
+                            original.getToolType(0)
+                    )
+            );
+    // Construct a PlatformViewTouch.rawPointerCoords by doing the inverse of
+    // PlatformViewsController.parsePointerCoordsList.
+    List<List<Double>> pointerCoordinates =
+            Arrays.asList(
+                    Arrays.asList(
+                            (double) original.getOrientation(),
+                            (double) original.getPressure(),
+                            (double) original.getSize(),
+                            (double) original.getToolMajor(),
+                            (double) original.getToolMinor(),
+                            (double) original.getTouchMajor(),
+                            (double) original.getTouchMinor(),
+                            (double) original.getX(),
+                            (double) original.getY()
+                    )
+            );
+    // Make a platform view touch from the motion event.
+    PlatformViewTouch frameWorkTouchNonVd =
         new PlatformViewTouch(
             0, // viewId
             original.getDownTime(),
             original.getEventTime(),
-            2, // action
+            original.getAction(),
             1, // pointerCount
-            Arrays.asList(Arrays.asList(0, 0)), // pointer properties
-            Arrays.asList(Arrays.asList(0., 1., 2., 3., 4., 5., 6., 7., 8.)), // pointer coords
+            pointerProperties, // pointer properties
+            pointerCoordinates, // pointer coords
             original.getMetaState(),
             original.getButtonState(),
             original.getXPrecision(),
@@ -399,11 +413,38 @@ public class PlatformViewsControllerTest {
             original.getFlags(),
             motionEventId.getId());
 
-    MotionEvent resolvedEvent =
-        platformViewsController.toMotionEvent(
-            /*density=*/ 1, frameWorkTouch, /*usingVirtualDisplay=*/ false);
+    return platformViewsController.toMotionEvent(
+        1, // density
+        frameWorkTouchNonVd,
+        usingVirtualDisplays);
+  }
 
-    assertEquals(resolvedEvent.getAction(), frameWorkTouch.action);
+  @Test
+  public void toMotionEvent_returnsSameCoordsForVdAndNonVd() {
+    MotionEventTracker motionEventTracker = MotionEventTracker.getInstance();
+    PlatformViewsController platformViewsController = new PlatformViewsController();
+
+    MotionEvent original =
+        MotionEvent.obtain(
+            10, // downTime
+            10, // eventTime
+            261, // action
+            1, // x
+            1, // y
+            0 // metaState
+            );
+
+    MotionEvent resolvedNonVdEvent =
+        makePlatformViewTouchAndInvokeToMotionEvent(
+            platformViewsController, motionEventTracker, original, false);
+
+    MotionEvent resolvedVdEvent =
+        makePlatformViewTouchAndInvokeToMotionEvent(
+            platformViewsController, motionEventTracker, original, true);
+
+    assertEquals(resolvedVdEvent.getEventTime(), resolvedNonVdEvent.getEventTime());
+    assertEquals(resolvedVdEvent.getX(), resolvedNonVdEvent.getX(), 0.001f);
+    assertEquals(resolvedVdEvent.getY(), resolvedNonVdEvent.getY(), 0.001f);
   }
 
   @Test