Rotary IME

A demo rotary IME.

Bug: 131421840
Bug: 152439508
Test: manual
Change-Id: I81e943ca0bdee9b8b83b67c8be884d8392e9aa10

10 files changed, 627 insertions, 0 deletions

diff --git a/RotaryIME/Android.bp b/RotaryIME/Android.bp
new file mode 100644
index 0000000..bef2697
--- /dev/null
+++ b/RotaryIME/Android.bp
@@ -0,0 +1,35 @@
+//
+// Copyright (C) 2020 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+android_app {
+    name: "RotaryIME",
+
+    srcs: ["src/**/*.java"],
+    resource_dirs: ["res"],
+
+    sdk_version: "system_current",
+
+    static_libs: [
+        "car-ui-lib",
+    ],
+
+    owner: "google",
+    certificate: "shared",
+
+    optimize: {
+        enabled: false,
+    }
+}
diff --git a/RotaryIME/AndroidManifest.xml b/RotaryIME/AndroidManifest.xml
new file mode 100644
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+++ b/RotaryIME/AndroidManifest.xml
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+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2020 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="com.android.car.rotaryime">
+
+  <application android:label="@string/ime_name">
+    <service
+        android:name=".RotaryIme"
+        android:label="@string/ime_name"
+        android:permission="android.permission.BIND_INPUT_METHOD">
+      <intent-filter>
+        <action android:name="android.view.InputMethod" />
+      </intent-filter>
+      <meta-data android:name="android.view.im" android:resource="@xml/ime" />
+    </service>
+  </application>
+</manifest>
diff --git a/RotaryIME/readme.md b/RotaryIME/readme.md
new file mode 100644
index 0000000..50fcd16
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+++ b/RotaryIME/readme.md
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+# Rotary IME: Sample input method for rotary controller
+
+This is a sample IME for use with a rotary controller. It is intentionally very basic so that it's
+easy to understand the code. It doesn't support multiple locales / layouts. It doesn't support
+password fields, numeric fields, etc.
+
+## Building
+```
+make RotaryIME
+```
+
+## Installing
+```
+adb install out/target/product/[hardware]/system/app/RotaryIME/RotaryIME.apk
+```
+
+## Using
+
+Once installed, configure the `rotary_input_method` string resource in the
+`CarRotaryController` package to refer to this IME:
+```
+    <string name="rotary_input_method" translatable="false">com.android.car.rotaryime/.RotaryIme</string>
+```
+Then build and install `CarRotaryController`. There is no need to enable this
+IME or select it; the `RotaryService` will select it automatically in rotary mode.
diff --git a/RotaryIME/res/color/key_background.xml b/RotaryIME/res/color/key_background.xml
new file mode 100644
index 0000000..1a4a2c4
--- /dev/null
+++ b/RotaryIME/res/color/key_background.xml
@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2020 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+  <item android:state_pressed="true" android:color="@color/key_background_pressed" />
+  <item android:state_focused="true" android:color="@color/key_background_focused" />
+  <item android:color="@color/key_background_normal" />
+</selector>
diff --git a/RotaryIME/res/layout/horizontal_keyboard.xml b/RotaryIME/res/layout/horizontal_keyboard.xml
new file mode 100644
index 0000000..f76b6b4
--- /dev/null
+++ b/RotaryIME/res/layout/horizontal_keyboard.xml
@@ -0,0 +1,196 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2020 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<LinearLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:orientation="vertical"
+    android:background="#2c2c2c">
+  <com.android.car.ui.FocusParkingView
+      android:layout_width="wrap_content"
+      android:layout_height="wrap_content" />
+  <com.android.car.ui.FocusArea
+      android:id="@+id/letters"
+      android:layout_width="match_parent"
+      android:layout_height="wrap_content"
+      android:orientation="horizontal">
+    <TextView
+        android:id="@+id/a"
+        android:text="@string/key_label_a"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_b"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_c"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_d"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_e"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_f"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_g"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_h"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_i"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_j"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_k"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_l"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_m"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_n"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_o"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_p"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_q"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_r"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_s"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_t"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_u"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_v"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_w"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_x"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_y"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_z"
+        style="@style/Key" />
+    <TextView
+        android:id="@+id/delete"
+        android:text="@string/key_label_delete"
+        style="@style/Key" />
+  </com.android.car.ui.FocusArea>
+  <com.android.car.ui.FocusArea
+      android:id="@+id/other_keys"
+      android:layout_width="match_parent"
+      android:layout_height="wrap_content"
+      android:orientation="horizontal">
+    <TextView
+        android:id="@+id/close"
+        android:text="@string/key_close_label"
+        style="@style/Key" />
+    <TextView
+        android:id="@+id/dash"
+        android:text="@string/key_dash_label"
+        style="@style/Key" />
+    <TextView
+        android:id="@+id/quote"
+        android:text="@string/key_quote_label"
+        style="@style/Key" />
+    <TextView
+        android:id="@+id/apostrophe"
+        android:text="@string/key_apostropohe_label"
+        style="@style/Key" />
+    <TextView
+        android:id="@+id/exclamation_mark"
+        android:text="@string/key_exclamation_mark_label"
+        style="@style/Key" />
+    <TextView
+        android:id="@+id/question_mark"
+        android:text="@string/key_question_mark_label"
+        style="@style/Key" />
+    <TextView
+        android:id="@+id/semicolon"
+        android:text="@string/key_semicolon_label"
+        style="@style/Key" />
+    <TextView
+        android:id="@+id/colon"
+        android:text="@string/key_colon_label"
+        style="@style/Key" />
+    <TextView
+        android:id="@+id/comma"
+        android:text="@string/key_comma_label"
+        style="@style/Key" />
+    <TextView
+        android:id="@+id/period"
+        android:text="@string/key_period_label"
+        style="@style/Key" />
+    <TextView
+        android:layout_width="120dp"
+        android:id="@+id/space"
+        style="@style/Key" />
+    <TextView
+        android:id="@+id/zero"
+        android:text="@string/key_label_0"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_1"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_2"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_3"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_4"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_5"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_6"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_7"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_8"
+        style="@style/Key" />
+    <TextView
+        android:text="@string/key_label_9"
+        style="@style/Key" />
+  </com.android.car.ui.FocusArea>
+</LinearLayout>
diff --git a/RotaryIME/res/values/colors.xml b/RotaryIME/res/values/colors.xml
new file mode 100644
index 0000000..e2bc73d
--- /dev/null
+++ b/RotaryIME/res/values/colors.xml
@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2020 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<resources>
+  <color name="key_background_normal">#404040</color>
+  <color name="key_background_focused">#6080c0</color>
+  <color name="key_background_pressed">#a0c0ff</color>
+</resources>
diff --git a/RotaryIME/res/values/strings.xml b/RotaryIME/res/values/strings.xml
new file mode 100644
index 0000000..8ff29a7
--- /dev/null
+++ b/RotaryIME/res/values/strings.xml
@@ -0,0 +1,67 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2020 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<resources>
+  <string name="ime_name">Rotary</string>
+  <string name="label_subtype_generic">%s</string>
+  <string name="key_label_a">A</string>
+  <string name="key_label_b">B</string>
+  <string name="key_label_c">C</string>
+  <string name="key_label_d">D</string>
+  <string name="key_label_e">E</string>
+  <string name="key_label_f">F</string>
+  <string name="key_label_g">G</string>
+  <string name="key_label_h">H</string>
+  <string name="key_label_i">I</string>
+  <string name="key_label_j">J</string>
+  <string name="key_label_k">K</string>
+  <string name="key_label_l">L</string>
+  <string name="key_label_m">M</string>
+  <string name="key_label_n">N</string>
+  <string name="key_label_o">O</string>
+  <string name="key_label_p">P</string>
+  <string name="key_label_q">Q</string>
+  <string name="key_label_r">R</string>
+  <string name="key_label_s">S</string>
+  <string name="key_label_t">T</string>
+  <string name="key_label_u">U</string>
+  <string name="key_label_v">V</string>
+  <string name="key_label_w">W</string>
+  <string name="key_label_x">X</string>
+  <string name="key_label_y">Y</string>
+  <string name="key_label_z">Z</string>
+  <string name="key_label_delete">⌫</string>
+  <string name="key_close_label">▼</string>
+  <string name="key_dash_label">-</string>
+  <string name="key_quote_label">\"</string>
+  <string name="key_apostropohe_label">\'</string>
+  <string name="key_exclamation_mark_label">!</string>
+  <string name="key_question_mark_label">\?</string>
+  <string name="key_semicolon_label">;</string>
+  <string name="key_colon_label">:</string>
+  <string name="key_comma_label">,</string>
+  <string name="key_period_label">.</string>
+  <string name="key_label_0">0</string>
+  <string name="key_label_1">1</string>
+  <string name="key_label_2">2</string>
+  <string name="key_label_3">3</string>
+  <string name="key_label_4">4</string>
+  <string name="key_label_5">5</string>
+  <string name="key_label_6">6</string>
+  <string name="key_label_7">7</string>
+  <string name="key_label_8">8</string>
+  <string name="key_label_9">9</string>
+</resources>
diff --git a/RotaryIME/res/values/styles.xml b/RotaryIME/res/values/styles.xml
new file mode 100644
index 0000000..6604d6f
--- /dev/null
+++ b/RotaryIME/res/values/styles.xml
@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2020 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<resources>
+  <style name="Key">
+    <item name="android:layout_height">wrap_content</item>
+    <item name="android:layout_width">0dp</item>
+    <item name="android:layout_weight">1</item>
+    <item name="android:layout_margin">2dp</item>
+    <item name="android:gravity">center</item>
+    <item name="android:background">@color/key_background</item>
+    <item name="android:textColor">#ffffff</item>
+    <item name="android:textSize">30dp</item>
+  </style>
+</resources>
diff --git a/RotaryIME/res/xml/ime.xml b/RotaryIME/res/xml/ime.xml
new file mode 100644
index 0000000..41e3eec
--- /dev/null
+++ b/RotaryIME/res/xml/ime.xml
@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+  ~ Copyright (C) 2020 The Android Open Source Project
+  ~
+  ~ Licensed under the Apache License, Version 2.0 (the "License");
+  ~ you may not use this file except in compliance with the License.
+  ~ You may obtain a copy of the License at
+  ~
+  ~      http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+<input-method xmlns:android="http://schemas.android.com/apk/res/android">
+  <subtype
+      android:label="@string/label_subtype_generic"
+      android:imeSubtypeLocale="en_US"
+      android:imeSubtypeMode="keyboard"/>
+</input-method>
diff --git a/RotaryIME/src/com/android/car/rotaryime/RotaryIme.java b/RotaryIME/src/com/android/car/rotaryime/RotaryIme.java
new file mode 100644
index 0000000..4d7f3e4
--- /dev/null
+++ b/RotaryIME/src/com/android/car/rotaryime/RotaryIme.java
@@ -0,0 +1,181 @@
+package com.android.car.rotaryime;
+
+import static android.view.KeyEvent.KEYCODE_1;
+import static android.view.KeyEvent.KEYCODE_A;
+import static android.view.KeyEvent.KEYCODE_APOSTROPHE;
+import static android.view.KeyEvent.KEYCODE_COMMA;
+import static android.view.KeyEvent.KEYCODE_DEL;
+import static android.view.KeyEvent.KEYCODE_PERIOD;
+import static android.view.KeyEvent.KEYCODE_SEMICOLON;
+import static android.view.KeyEvent.KEYCODE_SLASH;
+import static android.view.KeyEvent.KEYCODE_SPACE;
+import static android.view.KeyEvent.META_SHIFT_ON;
+
+import android.inputmethodservice.InputMethodService;
+import android.os.Handler;
+import android.os.Looper;
+import android.os.Message;
+import android.os.SystemClock;
+import android.view.InputDevice;
+import android.view.KeyCharacterMap;
+import android.view.KeyEvent;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.TextView;
+import androidx.annotation.NonNull;
+
+/**
+ * Sample IME for rotary controllers.  This is intentionally very basic so that it's easy to
+ * understand the code. It doesn't support multiple locales / layouts. It doesn't support password
+ * fields, numeric fields, etc.
+ */
+public class RotaryIme extends InputMethodService {
+
+  /** Message requesting that the view in the {@code obj} field have its pressed state cleared. */
+  private static final int MSG_CLEAR_PRESSED = 1;
+
+  /** How many milliseconds a key should remain pressed after the user clicks it. */
+  private static final long PRESSED_MS = 200;
+
+  /** A handler for clearing the pressed state shortly after a key is pressed. */
+  private final Handler mHandler = new ImeHandler(Looper.getMainLooper());
+
+  @Override
+  public boolean onEvaluateFullscreenMode() {
+    // Don't go full-screen, even in landscape. This IME is very short so it fits easily.
+    return false;
+  }
+
+  @Override
+  public View onCreateInputView() {
+    ViewGroup rootView = (ViewGroup) getLayoutInflater().inflate(R.layout.horizontal_keyboard,
+        /* root= */ null);
+
+    // Since the IME isn't in the application window, when the user presses the center button on the
+    // rotary controller to press the focused key on this keyboard, ACTION_CLICK will be performed
+    // on the key which will invoke its click handler. Long press will similarly result in the key's
+    // long click handler being invoked.
+
+    // The first row contains letters and the delete key.
+    ViewGroup letters = rootView.findViewById(R.id.letters);
+    int aIndex = findChild(letters, rootView.findViewById(R.id.a));
+    for (int i = 0; i < 26; i++) {
+      TextView keyTextView = (TextView) letters.getChildAt(aIndex + i);
+      int keyCode = KEYCODE_A + i;
+      keyTextView.setOnClickListener(view -> handleKeyClick(view, keyCode));
+      keyTextView.setOnLongClickListener(view -> handleKeyLongClick(view, keyCode));
+    }
+
+    rootView.findViewById(R.id.delete).setOnClickListener(
+            view -> handleKeyClick(view, KEYCODE_DEL));
+
+    // The second row contains the close key, symbols, space, and digits.
+    rootView.findViewById(R.id.close).setOnClickListener(
+            view -> requestHideSelf(/* flags= */ 0));
+    rootView.findViewById(R.id.dash).setOnClickListener(
+            view -> handleKeyClick(view, KeyEvent.KEYCODE_MINUS));
+    rootView.findViewById(R.id.quote).setOnClickListener(
+            view -> handleKeyClick(view, KEYCODE_APOSTROPHE, META_SHIFT_ON));
+    rootView.findViewById(R.id.apostrophe).setOnClickListener(
+            view -> handleKeyClick(view, KEYCODE_APOSTROPHE));
+    rootView.findViewById(R.id.exclamation_mark).setOnClickListener(
+            view -> handleKeyClick(view, KEYCODE_1, META_SHIFT_ON));
+    rootView.findViewById(R.id.question_mark).setOnClickListener(
+            view -> handleKeyClick(view, KEYCODE_SLASH, META_SHIFT_ON));
+    rootView.findViewById(R.id.semicolon).setOnClickListener(
+            view -> handleKeyClick(view, KEYCODE_SEMICOLON));
+    rootView.findViewById(R.id.colon).setOnClickListener(
+            view -> handleKeyClick(view, KEYCODE_SEMICOLON, META_SHIFT_ON));
+    rootView.findViewById(R.id.comma).setOnClickListener(
+            view -> handleKeyClick(view, KEYCODE_COMMA));
+    rootView.findViewById(R.id.period).setOnClickListener(
+            view -> handleKeyClick(view, KEYCODE_PERIOD));
+    rootView.findViewById(R.id.space).setOnClickListener(
+            view -> handleKeyClick(view, KEYCODE_SPACE));
+    ViewGroup otherKeys = rootView.findViewById(R.id.other_keys);
+    int zeroIndex = findChild(otherKeys, rootView.findViewById(R.id.zero));
+    for (int i = 0; i < 10; i++) {
+      int keyCode = KeyEvent.KEYCODE_0 + i;
+      otherKeys.getChildAt(zeroIndex + i).setOnClickListener(
+              view -> handleKeyClick(view, keyCode));
+    }
+
+    return rootView;
+  }
+
+  /** Returns {@code child}'s index within {@code parent} or -1 if not found. */
+  private static int findChild(ViewGroup parent, View child) {
+    for (int i = 0; i < parent.getChildCount(); i++) {
+      if (parent.getChildAt(i) == child) {
+        return i;
+      }
+    }
+    return -1;
+  }
+
+  /**
+   * Handles a click on the key {@code view} by sending events with the given {@code keyCode}. Use
+   * this convenience method for unshifted keys.
+   */
+  private void handleKeyClick(View view, int keyCode) {
+    handleKeyClick(view, keyCode, /* metaState= */ 0);
+  }
+
+  /**
+   * Handles a click on the key {@code view} by sending events with the given {@code keyCode}
+   * and {@code metaState}. Use {@link KeyEvent#META_SHIFT_ON} to access shifted keys such as
+   * question mark (shift slash). Use zero for unshifted keys.
+   */
+  private void handleKeyClick(View view, int keyCode, int metaState) {
+    animatePressed(view);
+    sendDownUpKeyEvents(keyCode, metaState);
+  }
+
+  /**
+   * Handles a long click on the key {@code view} by sending events with the given {@code keyCode}
+   * and {@link KeyEvent#META_SHIFT_ON} to produce shifted keys such as capital letters.
+   */
+  private boolean handleKeyLongClick(View view, int keyCode) {
+    animatePressed(view);
+    sendDownUpKeyEvents(keyCode, META_SHIFT_ON);
+    return true;
+  }
+
+  /**
+   * Sends an {@link KeyEvent#ACTION_DOWN} event followed by an {@link KeyEvent#ACTION_UP} event
+   * with the given {@code keyCode} and {@code metaState}.
+   */
+  private void sendDownUpKeyEvents(int keyCode, int metaState) {
+    long uptimeMillis = SystemClock.uptimeMillis();
+    KeyEvent downEvent = new KeyEvent(uptimeMillis, uptimeMillis, KeyEvent.ACTION_DOWN,
+        keyCode, /* repeat= */ 0, metaState, KeyCharacterMap.VIRTUAL_KEYBOARD, /* scancode= */ 0,
+        KeyEvent.FLAG_SOFT_KEYBOARD, InputDevice.SOURCE_KEYBOARD);
+    KeyEvent upEvent = new KeyEvent(uptimeMillis, uptimeMillis, KeyEvent.ACTION_UP,
+        keyCode, /* repeat= */ 0, metaState, KeyCharacterMap.VIRTUAL_KEYBOARD, /* scancode= */ 0,
+        KeyEvent.FLAG_SOFT_KEYBOARD, InputDevice.SOURCE_KEYBOARD);
+    getCurrentInputConnection().sendKeyEvent(downEvent);
+    getCurrentInputConnection().sendKeyEvent(upEvent);
+  }
+
+  /** Sets {@code view}'s pressed state and clears it {@link #PRESSED_MS} later. */
+  private void animatePressed(View view) {
+    view.setPressed(true);
+    Message message = mHandler.obtainMessage(MSG_CLEAR_PRESSED, view);
+    mHandler.removeMessages(MSG_CLEAR_PRESSED);
+    mHandler.sendMessageDelayed(message, PRESSED_MS);
+  }
+
+  /** A handler for clearing the pressed state shortly after a key is pressed. */
+  private static class ImeHandler extends Handler {
+    ImeHandler(@NonNull Looper looper) {
+      super(looper);
+    }
+
+    @Override
+    public void handleMessage(@NonNull Message msg) {
+      if (msg.what == MSG_CLEAR_PRESSED) {
+        ((View) msg.obj).setPressed(false);
+      }
+    }
+  }
+}