diff --git a/shell/platform/android/BUILD.gn b/shell/platform/android/BUILD.gn
index eed010506b3b9..3fe51be12a214 100644
--- a/shell/platform/android/BUILD.gn
+++ b/shell/platform/android/BUILD.gn
@@ -417,6 +417,7 @@ action("robolectric_tests") {
sources = [
"test/io/flutter/FlutterTestSuite.java",
"test/io/flutter/SmokeTest.java",
+ "test/io/flutter/embedding/android/AndroidKeyProcessorTest.java",
"test/io/flutter/embedding/android/FlutterActivityAndFragmentDelegateTest.java",
"test/io/flutter/embedding/android/FlutterActivityTest.java",
"test/io/flutter/embedding/android/FlutterAndroidComponentTest.java",
@@ -435,6 +436,7 @@ action("robolectric_tests") {
"test/io/flutter/embedding/engine/loader/ApplicationInfoLoaderTest.java",
"test/io/flutter/embedding/engine/plugins/shim/ShimPluginRegistryTest.java",
"test/io/flutter/embedding/engine/renderer/FlutterRendererTest.java",
+ "test/io/flutter/embedding/engine/systemchannels/KeyEventChannelTest.java",
"test/io/flutter/embedding/engine/systemchannels/PlatformChannelTest.java",
"test/io/flutter/embedding/engine/systemchannels/RestorationChannelTest.java",
"test/io/flutter/external/FlutterLaunchTests.java",
diff --git a/shell/platform/android/io/flutter/embedding/android/AndroidKeyProcessor.java b/shell/platform/android/io/flutter/embedding/android/AndroidKeyProcessor.java
index 5d823ef8ab674..094b8ef1c53e8 100644
--- a/shell/platform/android/io/flutter/embedding/android/AndroidKeyProcessor.java
+++ b/shell/platform/android/io/flutter/embedding/android/AndroidKeyProcessor.java
@@ -4,37 +4,122 @@
package io.flutter.embedding.android;
+import android.util.Log;
import android.view.KeyCharacterMap;
import android.view.KeyEvent;
+import android.view.View;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import io.flutter.embedding.engine.systemchannels.KeyEventChannel;
import io.flutter.plugin.editing.TextInputPlugin;
+import java.util.AbstractMap.SimpleImmutableEntry;
+import java.util.ArrayDeque;
+import java.util.Deque;
+import java.util.Map.Entry;
+/**
+ * A class to process key events from Android, passing them to the framework as messages using
+ * {@link KeyEventChannel}.
+ *
+ *
A class that sends Android key events to the framework, and re-dispatches those not handled by
+ * the framework.
+ *
+ *
Flutter uses asynchronous event handling to avoid blocking the UI thread, but Android requires
+ * that events are handled synchronously. So, when a key event is received by Flutter, it tells
+ * Android synchronously that the key has been handled so that it won't propagate to other
+ * components. Flutter then uses "delayed event synthesis", where it sends the event to the
+ * framework, and if the framework responds that it has not handled the event, then this class
+ * synthesizes a new event to send to Android, without handling it this time.
+ */
public class AndroidKeyProcessor {
+ private static final String TAG = "AndroidKeyProcessor";
+ private static long eventIdSerial = 0;
+
@NonNull private final KeyEventChannel keyEventChannel;
@NonNull private final TextInputPlugin textInputPlugin;
private int combiningCharacter;
+ @NonNull private EventResponder eventResponder;
+ /**
+ * Constructor for AndroidKeyProcessor.
+ *
+ *
The view is used as the destination to send the synthesized key to. This means that the the
+ * next thing in the focus chain will get the event when the framework returns false from
+ * onKeyDown/onKeyUp
+ *
+ *
It is possible that that in the middle of the async round trip, the focus chain could
+ * change, and instead of the native widget that was "next" when the event was fired getting the
+ * event, it may be the next widget when the event is synthesized that gets it. In practice, this
+ * shouldn't be a huge problem, as this is an unlikely occurance to happen without user input, and
+ * it may actually be desired behavior, but it is possible.
+ *
+ * @param view takes the activity to use for re-dispatching of events that were not handled by the
+ * framework.
+ * @param keyEventChannel the event channel to listen to for new key events.
+ * @param textInputPlugin a plugin, which, if set, is given key events before the framework is,
+ * and if it has a valid input connection and is accepting text, then it will handle the event
+ * and the framework will not receive it.
+ */
public AndroidKeyProcessor(
- @NonNull KeyEventChannel keyEventChannel, @NonNull TextInputPlugin textInputPlugin) {
+ @NonNull View view,
+ @NonNull KeyEventChannel keyEventChannel,
+ @NonNull TextInputPlugin textInputPlugin) {
this.keyEventChannel = keyEventChannel;
this.textInputPlugin = textInputPlugin;
+ this.eventResponder = new EventResponder(view);
+ this.keyEventChannel.setEventResponseHandler(eventResponder);
}
- public void onKeyUp(@NonNull KeyEvent keyEvent) {
+ /**
+ * Called when a key up event is received by the {@link FlutterView}.
+ *
+ * @param keyEvent the Android key event to respond to.
+ * @return true if the key event should not be propagated to other Android components. Delayed
+ * synthesis events will return false, so that other components may handle them.
+ */
+ public boolean onKeyUp(@NonNull KeyEvent keyEvent) {
+ if (eventResponder.dispatchingKeyEvent) {
+ // Don't handle it if it is from our own delayed event synthesis.
+ return false;
+ }
+
Character complexCharacter = applyCombiningCharacterToBaseCharacter(keyEvent.getUnicodeChar());
- keyEventChannel.keyUp(new KeyEventChannel.FlutterKeyEvent(keyEvent, complexCharacter));
+ KeyEventChannel.FlutterKeyEvent flutterEvent =
+ new KeyEventChannel.FlutterKeyEvent(keyEvent, complexCharacter, eventIdSerial++);
+ keyEventChannel.keyUp(flutterEvent);
+ eventResponder.addEvent(flutterEvent.eventId, keyEvent);
+ return true;
}
- public void onKeyDown(@NonNull KeyEvent keyEvent) {
+ /**
+ * Called when a key down event is received by the {@link FlutterView}.
+ *
+ * @param keyEvent the Android key event to respond to.
+ * @return true if the key event should not be propagated to other Android components. Delayed
+ * synthesis events will return false, so that other components may handle them.
+ */
+ public boolean onKeyDown(@NonNull KeyEvent keyEvent) {
+ if (eventResponder.dispatchingKeyEvent) {
+ // Don't handle it if it is from our own delayed event synthesis.
+ return false;
+ }
+
+ // If the textInputPlugin is still valid and accepting text, then we'll try
+ // and send the key event to it, assuming that if the event can be sent,
+ // that it has been handled.
if (textInputPlugin.getLastInputConnection() != null
&& textInputPlugin.getInputMethodManager().isAcceptingText()) {
- textInputPlugin.getLastInputConnection().sendKeyEvent(keyEvent);
+ if (textInputPlugin.getLastInputConnection().sendKeyEvent(keyEvent)) {
+ return true;
+ }
}
Character complexCharacter = applyCombiningCharacterToBaseCharacter(keyEvent.getUnicodeChar());
- keyEventChannel.keyDown(new KeyEventChannel.FlutterKeyEvent(keyEvent, complexCharacter));
+ KeyEventChannel.FlutterKeyEvent flutterEvent =
+ new KeyEventChannel.FlutterKeyEvent(keyEvent, complexCharacter, eventIdSerial++);
+ keyEventChannel.keyDown(flutterEvent);
+ eventResponder.addEvent(flutterEvent.eventId, keyEvent);
+ return true;
}
/**
@@ -70,7 +155,7 @@ private Character applyCombiningCharacterToBaseCharacter(int newCharacterCodePoi
return null;
}
- Character complexCharacter = (char) newCharacterCodePoint;
+ char complexCharacter = (char) newCharacterCodePoint;
boolean isNewCodePointACombiningCharacter =
(newCharacterCodePoint & KeyCharacterMap.COMBINING_ACCENT) != 0;
if (isNewCodePointACombiningCharacter) {
@@ -82,7 +167,8 @@ private Character applyCombiningCharacterToBaseCharacter(int newCharacterCodePoi
combiningCharacter = plainCodePoint;
}
} else {
- // The new character is a regular character. Apply combiningCharacter to it, if it exists.
+ // The new character is a regular character. Apply combiningCharacter to it, if
+ // it exists.
if (combiningCharacter != 0) {
int combinedChar = KeyCharacterMap.getDeadChar(combiningCharacter, newCharacterCodePoint);
if (combinedChar > 0) {
@@ -94,4 +180,92 @@ private Character applyCombiningCharacterToBaseCharacter(int newCharacterCodePoi
return complexCharacter;
}
+
+ private static class EventResponder implements KeyEventChannel.EventResponseHandler {
+ // The maximum number of pending events that are held before starting to
+ // complain.
+ private static final long MAX_PENDING_EVENTS = 1000;
+ final Deque> pendingEvents = new ArrayDeque>();
+ @NonNull private final View view;
+ boolean dispatchingKeyEvent = false;
+
+ public EventResponder(@NonNull View view) {
+ this.view = view;
+ }
+
+ /**
+ * Removes the pending event with the given id from the cache of pending events.
+ *
+ * @param id the id of the event to be removed.
+ */
+ private KeyEvent removePendingEvent(long id) {
+ if (pendingEvents.getFirst().getKey() != id) {
+ throw new AssertionError(
+ "Event response received out of order. Should have seen event "
+ + pendingEvents.getFirst().getKey()
+ + " first. Instead, received "
+ + id);
+ }
+ return pendingEvents.removeFirst().getValue();
+ }
+
+ /**
+ * Called whenever the framework responds that a given key event was handled by the framework.
+ *
+ * @param id the event id of the event to be marked as being handled by the framework. Must not
+ * be null.
+ */
+ @Override
+ public void onKeyEventHandled(long id) {
+ removePendingEvent(id);
+ }
+
+ /**
+ * Called whenever the framework responds that a given key event wasn't handled by the
+ * framework.
+ *
+ * @param id the event id of the event to be marked as not being handled by the framework. Must
+ * not be null.
+ */
+ @Override
+ public void onKeyEventNotHandled(long id) {
+ dispatchKeyEvent(removePendingEvent(id));
+ }
+
+ /** Adds an Android key event with an id to the event responder to wait for a response. */
+ public void addEvent(long id, @NonNull KeyEvent event) {
+ if (pendingEvents.size() > 0 && pendingEvents.getFirst().getKey() >= id) {
+ throw new AssertionError(
+ "New events must have ids greater than the most recent pending event. New id "
+ + id
+ + " is less than or equal to the last event id of "
+ + pendingEvents.getFirst().getKey());
+ }
+ pendingEvents.addLast(new SimpleImmutableEntry(id, event));
+ if (pendingEvents.size() > MAX_PENDING_EVENTS) {
+ Log.e(
+ TAG,
+ "There are "
+ + pendingEvents.size()
+ + " keyboard events that have not yet received a response. Are responses being "
+ + "sent?");
+ }
+ }
+
+ /**
+ * Dispatches the event to the activity associated with the context.
+ *
+ * @param event the event to be dispatched to the activity.
+ */
+ public void dispatchKeyEvent(KeyEvent event) {
+ // Since the framework didn't handle it, dispatch the key again.
+ if (view != null) {
+ // Turn on dispatchingKeyEvent so that we don't dispatch to ourselves and
+ // send it to the framework again.
+ dispatchingKeyEvent = true;
+ view.getRootView().dispatchKeyEvent(event);
+ dispatchingKeyEvent = false;
+ }
+ }
+ }
}
diff --git a/shell/platform/android/io/flutter/embedding/android/FlutterView.java b/shell/platform/android/io/flutter/embedding/android/FlutterView.java
index 860d9c4786025..5b7af5a1c8cbc 100644
--- a/shell/platform/android/io/flutter/embedding/android/FlutterView.java
+++ b/shell/platform/android/io/flutter/embedding/android/FlutterView.java
@@ -679,8 +679,7 @@ public boolean onKeyUp(int keyCode, @NonNull KeyEvent event) {
return super.onKeyUp(keyCode, event);
}
- androidKeyProcessor.onKeyUp(event);
- return super.onKeyUp(keyCode, event);
+ return androidKeyProcessor.onKeyUp(event) || super.onKeyUp(keyCode, event);
}
/**
@@ -700,8 +699,7 @@ public boolean onKeyDown(int keyCode, @NonNull KeyEvent event) {
return super.onKeyDown(keyCode, event);
}
- androidKeyProcessor.onKeyDown(event);
- return super.onKeyDown(keyCode, event);
+ return androidKeyProcessor.onKeyDown(event) || super.onKeyDown(keyCode, event);
}
/**
@@ -851,7 +849,7 @@ public void attachToFlutterEngine(@NonNull FlutterEngine flutterEngine) {
this.flutterEngine.getPlatformViewsController());
localizationPlugin = this.flutterEngine.getLocalizationPlugin();
androidKeyProcessor =
- new AndroidKeyProcessor(this.flutterEngine.getKeyEventChannel(), textInputPlugin);
+ new AndroidKeyProcessor(this, this.flutterEngine.getKeyEventChannel(), textInputPlugin);
androidTouchProcessor =
new AndroidTouchProcessor(this.flutterEngine.getRenderer(), /*trackMotionEvents=*/ false);
accessibilityBridge =
diff --git a/shell/platform/android/io/flutter/embedding/engine/systemchannels/AccessibilityChannel.java b/shell/platform/android/io/flutter/embedding/engine/systemchannels/AccessibilityChannel.java
index 90455bcecefc2..87db8cf09f245 100644
--- a/shell/platform/android/io/flutter/embedding/engine/systemchannels/AccessibilityChannel.java
+++ b/shell/platform/android/io/flutter/embedding/engine/systemchannels/AccessibilityChannel.java
@@ -73,6 +73,7 @@ public void onMessage(
break;
}
}
+ reply.reply(null);
}
};
diff --git a/shell/platform/android/io/flutter/embedding/engine/systemchannels/KeyEventChannel.java b/shell/platform/android/io/flutter/embedding/engine/systemchannels/KeyEventChannel.java
index 1b03c94184221..3638c2d364ae7 100644
--- a/shell/platform/android/io/flutter/embedding/engine/systemchannels/KeyEventChannel.java
+++ b/shell/platform/android/io/flutter/embedding/engine/systemchannels/KeyEventChannel.java
@@ -9,29 +9,104 @@
import android.view.KeyEvent;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
-import io.flutter.embedding.engine.dart.DartExecutor;
+import io.flutter.Log;
import io.flutter.plugin.common.BasicMessageChannel;
+import io.flutter.plugin.common.BinaryMessenger;
import io.flutter.plugin.common.JSONMessageCodec;
import java.util.HashMap;
import java.util.Map;
+import org.json.JSONException;
+import org.json.JSONObject;
-/** TODO(mattcarroll): fill in javadoc for KeyEventChannel. */
+/**
+ * Event message channel for key events to/from the Flutter framework.
+ *
+ *
Sends key up/down events to the framework, and receives asynchronous messages from the
+ * framework about whether or not the key was handled.
+ */
public class KeyEventChannel {
+ private static final String TAG = "KeyEventChannel";
- @NonNull public final BasicMessageChannel