(WIP) Scribe gestures

shell/platform/android/io/flutter/embedding/engine/systemchannels/ScribeChannel.java

@@ -142,6 +142,59 @@ public interface ScribeMethodHandler {
     void startStylusHandwriting();
   }
 
-  // TODO(justinmc): Scribe stylus gestures should be supported here.
-  // https://github.com/flutter/flutter/issues/156018
+  public void previewHandwritingGesture(
+      PreviewableHandwritingGesture gesture, CancellationSignal cancellationSignal) {
+    System.out.println("justin sending previewHandwritingGesture for gesture: " + gesture);
+    final HashMap<Object, Object> gestureMap = new HashMap<>();
+    if (gesture instanceof DeleteGesture) {
+      gestureMap.put("type", "delete");
+    } else if (gesture instanceof DeleteRangeGesture) {
+      gestureMap.put("type", "deleteRange");
+    } else if (gesture instanceof SelectGesture) {
+      gestureMap.put("type", "select");
+    } else if (gesture instanceof SelectRangeGesture) {
+      gestureMap.put("type", "selectRange");
+    } else {
+      return;
+    }
+
+    // TODO(justinmc): You'll need to provide some kind of API that allows users
+    // to cancel a previewed gesture. Maybe keep ahold of cancellationSignal
+    // here, then provide platform channel methods for cancel, isCanceled,
+    // setOnCancelListener, and throwIfCanceled.
+    channel.invokeMethod("ScribeClient.previewHandwritingGesture", gestureMap);
+  }
+
+  public void performHandwritingGesture(HandwritingGesture gesture, MethodChannel.Result result) {
+    System.out.println("justin sending performHandwritingGesture for gesture: " + gesture);
+
+    final HashMap<Object, Object> gestureMap = new HashMap<>();
+    if (gesture instanceof SelectGesture) {
+      final SelectGesture selectGesture = (SelectGesture) gesture;
+      final HashMap<Object, Object> selectionAreaMap = new HashMap<>();
+      final RectF selectionArea = selectGesture.getSelectionArea();
+      selectionAreaMap.put("bottom", selectionArea.bottom);
+      selectionAreaMap.put("top", selectionArea.top);
+      selectionAreaMap.put("left", selectionArea.left);
+      selectionAreaMap.put("right", selectionArea.right);
+      gestureMap.put("type", "select");
+      gestureMap.put("granularity", selectGesture.getGranularity());
+      gestureMap.put("selectionArea", selectionAreaMap);
+    } else if (gesture instanceof DeleteGesture) {
+      final DeleteGesture deleteGesture = (DeleteGesture) gesture;
+      final HashMap<Object, Object> deletionAreaMap = new HashMap<>();
+      final RectF deletionArea = deleteGesture.getDeletionArea();
+      deletionAreaMap.put("bottom", deletionArea.bottom);
+      deletionAreaMap.put("top", deletionArea.top);
+      deletionAreaMap.put("left", deletionArea.left);
+      deletionAreaMap.put("right", deletionArea.right);
+      gestureMap.put("type", "delete");
+      gestureMap.put("granularity", deleteGesture.getGranularity());
+      gestureMap.put("deletionArea", deletionAreaMap);
+    }
+    // TODO(justinmc): All other gestures.
+    // https://developer.android.com/reference/android/view/inputmethod/HandwritingGesture#public-methods
+
+    channel.invokeMethod("ScribeClient.performHandwritingGesture", gestureMap, result);
+  }
 }

shell/platform/android/io/flutter/plugin/editing/InputConnectionAdaptor.java

@@ -13,6 +13,7 @@
 import android.net.Uri;
 import android.os.Build;
 import android.os.Bundle;
+import android.os.CancellationSignal;
 import android.text.DynamicLayout;
 import android.text.Editable;
 import android.text.InputType;
@@ -26,21 +27,26 @@
 import android.view.inputmethod.EditorInfo;
 import android.view.inputmethod.ExtractedText;
 import android.view.inputmethod.ExtractedTextRequest;
+import android.view.inputmethod.HandwritingGesture;
 import android.view.inputmethod.InputContentInfo;
 import android.view.inputmethod.InputMethodManager;
+import android.view.inputmethod.PreviewableHandwritingGesture;
 import androidx.annotation.NonNull;
 import androidx.annotation.RequiresApi;
 import androidx.core.view.inputmethod.InputConnectionCompat;
 import io.flutter.Log;
 import io.flutter.embedding.engine.FlutterJNI;
 import io.flutter.embedding.engine.systemchannels.ScribeChannel;
 import io.flutter.embedding.engine.systemchannels.TextInputChannel;
+import io.flutter.plugin.common.MethodChannel;
 import java.io.ByteArrayOutputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.Executor;
+import java.util.function.IntConsumer;
 
 public class InputConnectionAdaptor extends BaseInputConnection
     implements ListenableEditingState.EditingStateWatcher {
@@ -275,9 +281,44 @@ public boolean setSelection(int start, int end) {
     return result;
   }
 
-  // TODO(justinmc): Scribe stylus gestures should be supported here via
-  // performHandwritingGesture.
-  // https://github.com/flutter/flutter/issues/156018
+  @Override
+  public boolean previewHandwritingGesture(
+      PreviewableHandwritingGesture gesture, CancellationSignal cancellationSignal) {
+    System.out.println(
+        "justin previewHandwritingGesture gesture: " + gesture + ", " + cancellationSignal);
+
+    scribeChannel.previewHandwritingGesture(gesture, cancellationSignal);
+    return true;
+  }
+
+  @Override
+  public void performHandwritingGesture(
+      HandwritingGesture gesture, Executor executor, IntConsumer consumer) {
+    System.out.println("justin performHandwritingGesture gesture: " + gesture);
+
+    final MethodChannel.Result result =
+        new MethodChannel.Result() {
+          @Override
+          public void success(Object result) {
+            executor.execute(() -> consumer.accept(HANDWRITING_GESTURE_RESULT_SUCCESS));
+          }
+
+          @Override
+          public void error(String errorCode, String errorMessage, Object errorDetails) {
+            executor.execute(() -> consumer.accept(HANDWRITING_GESTURE_RESULT_FAILED));
+          }
+
+          @Override
+          public void notImplemented() {
+            executor.execute(() -> consumer.accept(HANDWRITING_GESTURE_RESULT_UNSUPPORTED));
+          }
+          // TODO(justinmc): There are a few other HANDWRITING_GESTURE_RESULTs
+          // that may be useful, see
+          // https://developer.android.com/reference/android/view/inputmethod/InputConnection
+        };
+
+    scribeChannel.performHandwritingGesture((HandwritingGesture) gesture, result);
+  }
 
   // Sanitizes the index to ensure the index is within the range of the
   // contents of editable.

shell/platform/android/io/flutter/plugin/editing/TextInputPlugin.java

@@ -20,9 +20,17 @@
 import android.view.autofill.AutofillId;
 import android.view.autofill.AutofillManager;
 import android.view.autofill.AutofillValue;
+import android.view.inputmethod.DeleteGesture;
+import android.view.inputmethod.DeleteRangeGesture;
 import android.view.inputmethod.EditorInfo;
 import android.view.inputmethod.InputConnection;
 import android.view.inputmethod.InputMethodManager;
+import android.view.inputmethod.InsertGesture;
+import android.view.inputmethod.InsertModeGesture;
+import android.view.inputmethod.JoinOrSplitGesture;
+import android.view.inputmethod.RemoveSpaceGesture;
+import android.view.inputmethod.SelectGesture;
+import android.view.inputmethod.SelectRangeGesture;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.annotation.VisibleForTesting;
@@ -34,7 +42,9 @@
 import io.flutter.embedding.engine.systemchannels.TextInputChannel.TextEditState;
 import io.flutter.plugin.platform.PlatformViewsController;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.HashMap;
+import java.util.Set;
 
 /** Android implementation of the text input plugin. */
 public class TextInputPlugin implements ListenableEditingState.EditingStateWatcher {
@@ -350,10 +360,25 @@ public InputConnection createInputConnection(
     if (Build.VERSION.SDK_INT >= API_LEVELS.API_34) {
       EditorInfoCompat.setStylusHandwritingEnabled(outAttrs, true);
     }
-    // TODO(justinmc): Scribe stylus gestures should be supported here via
-    // outAttrs.setSupportedHandwritingGestures and
-    // outAttrs.setSupportedHandwritingGesturePreviews.
-    // https://github.com/flutter/flutter/issues/156018
+
+    EditorInfoCompat.setStylusHandwritingEnabled(outAttrs, true);
+    outAttrs.setSupportedHandwritingGestures(
+        Arrays.asList(
+            SelectGesture.class,
+            SelectRangeGesture.class,
+            InsertGesture.class,
+            InsertModeGesture.class,
+            DeleteGesture.class,
+            DeleteRangeGesture.class,
+            SelectRangeGesture.class,
+            JoinOrSplitGesture.class,
+            RemoveSpaceGesture.class));
+    outAttrs.setSupportedHandwritingGesturePreviews(
+        Set.of(
+            SelectGesture.class,
+            SelectRangeGesture.class,
+            DeleteGesture.class,
+            DeleteRangeGesture.class));
 
     InputConnectionAdaptor connection =
         new InputConnectionAdaptor(