[Android] Add support for text processing actions

ci/licenses_golden/licenses_flutter

@@ -3091,6 +3091,7 @@ ORIGIN: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/syst
 ORIGIN: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/systemchannels/NavigationChannel.java + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/systemchannels/PlatformChannel.java + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/systemchannels/PlatformViewsChannel.java + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/systemchannels/ProcessTextChannel.java + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/systemchannels/RestorationChannel.java + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/systemchannels/SpellCheckChannel.java + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/systemchannels/SystemChannel.java + ../../../flutter/LICENSE
@@ -3133,6 +3134,7 @@ ORIGIN: ../../../flutter/shell/platform/android/io/flutter/plugin/platform/Platf
 ORIGIN: ../../../flutter/shell/platform/android/io/flutter/plugin/platform/PlatformViewsController.java + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/android/io/flutter/plugin/platform/SingleViewPresentation.java + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/android/io/flutter/plugin/platform/VirtualDisplayController.java + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/shell/platform/android/io/flutter/plugin/text/ProcessTextPlugin.java + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/android/io/flutter/util/HandlerCompat.java + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/android/io/flutter/util/PathUtils.java + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/android/io/flutter/util/Preconditions.java + ../../../flutter/LICENSE
@@ -5861,6 +5863,7 @@ FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/system
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/systemchannels/NavigationChannel.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/systemchannels/PlatformChannel.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/systemchannels/PlatformViewsChannel.java
+FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/systemchannels/ProcessTextChannel.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/systemchannels/RestorationChannel.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/systemchannels/SettingsChannel.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/systemchannels/SpellCheckChannel.java
@@ -5908,6 +5911,7 @@ FILE: ../../../flutter/shell/platform/android/io/flutter/plugin/platform/Platfor
 FILE: ../../../flutter/shell/platform/android/io/flutter/plugin/platform/SingleViewPresentation.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/plugin/platform/SurfaceTexturePlatformViewRenderTarget.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/plugin/platform/VirtualDisplayController.java
+FILE: ../../../flutter/shell/platform/android/io/flutter/plugin/text/ProcessTextPlugin.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/util/HandlerCompat.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/util/PathUtils.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/util/Preconditions.java

shell/platform/android/AndroidManifest.xml

@@ -24,4 +24,12 @@
             </intent-filter>
         </activity>
     </application>
+
+    <!-- Required for io.flutter.plugin.text.ProcessTextPlugin to query activities that can process text. -->
+    <queries>
+        <intent>
+            <action android:name="android.intent.action.PROCESS_TEXT" />
+            <data android:mimeType="text/plain" />
+        </intent>
+    </queries>
  </manifest>

shell/platform/android/BUILD.gn

@@ -265,6 +265,7 @@ android_java_sources = [
   "io/flutter/embedding/engine/systemchannels/NavigationChannel.java",
   "io/flutter/embedding/engine/systemchannels/PlatformChannel.java",
   "io/flutter/embedding/engine/systemchannels/PlatformViewsChannel.java",
+  "io/flutter/embedding/engine/systemchannels/ProcessTextChannel.java",
   "io/flutter/embedding/engine/systemchannels/RestorationChannel.java",
   "io/flutter/embedding/engine/systemchannels/SettingsChannel.java",
   "io/flutter/embedding/engine/systemchannels/SpellCheckChannel.java",
@@ -312,6 +313,7 @@ android_java_sources = [
   "io/flutter/plugin/platform/SingleViewPresentation.java",
   "io/flutter/plugin/platform/SurfaceTexturePlatformViewRenderTarget.java",
   "io/flutter/plugin/platform/VirtualDisplayController.java",
+  "io/flutter/plugin/text/ProcessTextPlugin.java",
   "io/flutter/util/HandlerCompat.java",
   "io/flutter/util/PathUtils.java",
   "io/flutter/util/Preconditions.java",

shell/platform/android/io/flutter/embedding/engine/FlutterEngine.java

@@ -31,13 +31,15 @@
 import io.flutter.embedding.engine.systemchannels.MouseCursorChannel;
 import io.flutter.embedding.engine.systemchannels.NavigationChannel;
 import io.flutter.embedding.engine.systemchannels.PlatformChannel;
+import io.flutter.embedding.engine.systemchannels.ProcessTextChannel;
 import io.flutter.embedding.engine.systemchannels.RestorationChannel;
 import io.flutter.embedding.engine.systemchannels.SettingsChannel;
 import io.flutter.embedding.engine.systemchannels.SpellCheckChannel;
 import io.flutter.embedding.engine.systemchannels.SystemChannel;
 import io.flutter.embedding.engine.systemchannels.TextInputChannel;
 import io.flutter.plugin.localization.LocalizationPlugin;
 import io.flutter.plugin.platform.PlatformViewsController;
+import io.flutter.plugin.text.ProcessTextPlugin;
 import io.flutter.util.ViewUtils;
 import java.util.HashSet;
 import java.util.List;
@@ -95,6 +97,7 @@ public class FlutterEngine implements ViewUtils.DisplayUpdater {
   @NonNull private final NavigationChannel navigationChannel;
   @NonNull private final RestorationChannel restorationChannel;
   @NonNull private final PlatformChannel platformChannel;
+  @NonNull private final ProcessTextChannel processTextChannel;
   @NonNull private final SettingsChannel settingsChannel;
   @NonNull private final SpellCheckChannel spellCheckChannel;
   @NonNull private final SystemChannel systemChannel;
@@ -329,6 +332,7 @@ public FlutterEngine(
     mouseCursorChannel = new MouseCursorChannel(dartExecutor);
     navigationChannel = new NavigationChannel(dartExecutor);
     platformChannel = new PlatformChannel(dartExecutor);
+    processTextChannel = new ProcessTextChannel(dartExecutor, context.getPackageManager());
     restorationChannel = new RestorationChannel(dartExecutor, waitForRestorationData);
     settingsChannel = new SettingsChannel(dartExecutor);
     spellCheckChannel = new SpellCheckChannel(dartExecutor);
@@ -384,6 +388,9 @@ public FlutterEngine(
     }
 
     ViewUtils.calculateMaximumDisplayMetrics(context, this);
+
+    ProcessTextPlugin processTextPlugin = new ProcessTextPlugin(this.getProcessTextChannel());
+    this.pluginRegistry.add(processTextPlugin);
   }
 
   private void attachToJni() {
@@ -545,6 +552,12 @@ public PlatformChannel getPlatformChannel() {
     return platformChannel;
   }
 
+  /** System channel that sends text processing requests from Flutter to Android. */
+  @NonNull
+  public ProcessTextChannel getProcessTextChannel() {
+    return processTextChannel;
+  }
+
   /**
    * System channel to exchange restoration data between framework and engine.
    *

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

@@ -0,0 +1,122 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package io.flutter.embedding.engine.systemchannels;
+
+import android.content.pm.PackageManager;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import io.flutter.embedding.engine.dart.DartExecutor;
+import io.flutter.plugin.common.MethodCall;
+import io.flutter.plugin.common.MethodChannel;
+import io.flutter.plugin.common.StandardMethodCodec;
+import java.util.ArrayList;
+import java.util.Map;
+
+/**
+ * {@link ProcessTextChannel} is a platform channel that is used by the framework to initiate text
+ * processing feature in the embedding and for the embedding to send back the results.
+ *
+ * <p>When the framework needs to query the list of text processing actions (for instance to expose
+ * them in the selected text context menu), it will send to the embedding the message {@code
+ * ProcessText.queryTextActions}. In response, the {@link io.flutter.plugin.text.ProcessTextPlugin}
+ * will return a map of all activities that can process text. The map keys are generated IDs and the
+ * values are the activities labels. On the first request, the {@link
+ * io.flutter.plugin.text.ProcessTextPlugin} will make a call to Android's package manager to query
+ * all activities that can be performed for the {@code Intent.ACTION_PROCESS_TEXT} intent.
+ *
+ * <p>When a text processing action has to be executed, the framework will send to the embedding the
+ * message {@code ProcessText.processTextAction} with the {@code int id} of the choosen text action
+ * and the {@code String} of text to process as arguments. In response, the {@link
+ * io.flutter.plugin.text.ProcessTextPlugin} will make a call to the Android application activity to
+ * start the activity exposing the text action. The {@link io.flutter.plugin.text.ProcessTextPlugin}
+ * will return the processed text if there is one, or null if the activity did not return a
+ * transformed text.
+ *
+ * <p>{@link io.flutter.plugin.text.ProcessTextPlugin} implements {@link ProcessTextMethodHandler}
+ * that parses incoming messages from Flutter.
+ */
+public class ProcessTextChannel {
+  private static final String TAG = "ProcessTextChannel";
+  private static final String CHANNEL_NAME = "flutter/processtext";
+  private static final String METHOD_QUERY_TEXT_ACTIONS = "ProcessText.queryTextActions";
+  private static final String METHOD_PROCESS_TEXT_ACTION = "ProcessText.processTextAction";
+
+  public final MethodChannel channel;
+  public final PackageManager packageManager;
+  private ProcessTextMethodHandler processTextMethodHandler;
+
+  @NonNull
+  public final MethodChannel.MethodCallHandler parsingMethodHandler =
+      new MethodChannel.MethodCallHandler() {
+        @Override
+        public void onMethodCall(@NonNull MethodCall call, @NonNull MethodChannel.Result result) {
+          if (processTextMethodHandler == null) {
+            return;
+          }
+          String method = call.method;
+          Object args = call.arguments;
+          switch (method) {
+            case METHOD_QUERY_TEXT_ACTIONS:
+              try {
+                Map<String, String> actions = processTextMethodHandler.queryTextActions();
+                result.success(actions);
+              } catch (IllegalStateException exception) {
+                result.error("error", exception.getMessage(), null);
+              }
+              break;
+            case METHOD_PROCESS_TEXT_ACTION:
+              try {
+                final ArrayList<Object> argumentList = (ArrayList<Object>) args;
+                String id = (String) (argumentList.get(0));
+                String text = (String) (argumentList.get(1));
+                boolean readOnly = (boolean) (argumentList.get(2));
+                processTextMethodHandler.processTextAction(id, text, readOnly, result);
+              } catch (IllegalStateException exception) {
+                result.error("error", exception.getMessage(), null);
+              }
+              break;
+            default:
+              result.notImplemented();
+              break;
+          }
+        }
+      };
+
+  public ProcessTextChannel(
+      @NonNull DartExecutor dartExecutor, @NonNull PackageManager packageManager) {
+    this.packageManager = packageManager;
+    channel = new MethodChannel(dartExecutor, CHANNEL_NAME, StandardMethodCodec.INSTANCE);
+    channel.setMethodCallHandler(parsingMethodHandler);
+  }
+
+  /**
+   * Sets the {@link ProcessTextMethodHandler} which receives all requests to the text processing
+   * feature sent through this channel.
+   */
+  public void setMethodHandler(@Nullable ProcessTextMethodHandler processTextMethodHandler) {
+    this.processTextMethodHandler = processTextMethodHandler;
+  }
+
+  public interface ProcessTextMethodHandler {
+    /** Requests the map of text actions. Each text action has a unique id and a localized label. */
+    Map<String, String> queryTextActions();
+
+    /**
+     * Requests to run a text action on a given input text.
+     *
+     * @param id The ID of the text action returned by {@code ProcessText.queryTextActions}.
+     * @param input The text to be processed.
+     * @param readOnly Indicates to the activity if the processed text will be used as read-only.
+     *     see
+     *     https://developer.android.com/reference/android/content/Intent#EXTRA_PROCESS_TEXT_READONLY
+     * @param result The method channel result instance used to reply.
+     */
+    void processTextAction(
+        @NonNull String id,
+        @NonNull String input,
+        @NonNull boolean readOnly,
+        @NonNull MethodChannel.Result result);
+  }
+}