Add an API sample to show subtype enabler.

At least on AOSP InputMethodManager#showInputMethodAndSubtypeEnabler()
has been broken for long time.  Also, there has been a valid alternative
way to do the same thing.

This CL adds an API sample to officially encourage people to use
Settings.ACTION_INPUT_METHOD_SUBTYPE_SETTINGS intent rather than trying
to rely on InputMethodManager#showInputMethodAndSubtypeEnabler(), which
is highly likely to be broken.

Bug: 26189558
Change-Id: I915a2d81948598ed08b4ef9111bdd128fd93f3df

samples/ApiDemos/AndroidManifest.xml

@@ -2137,6 +2137,14 @@
             </intent-filter>
         </activity>
 
+        <activity android:name=".inputmethod.ShowInputMethodAndSubtypeEnabler"
+                  android:label="Views/Input Method/ShowInputMethodAndSubtypeEnabler">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.SAMPLE_CODE" />
+            </intent-filter>
+        </activity>
+
         <activity android:name=".view.EditTextDemo"
                   android:label="Views/Text/EditText">
             <intent-filter>

samples/ApiDemos/src/com/example/android/apis/inputmethod/ShowInputMethodAndSubtypeEnabler.java

@@ -0,0 +1,104 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+package com.example.android.apis.inputmethod;
+
+import android.app.Activity;
+import android.content.Context;
+import android.content.Intent;
+import android.os.Bundle;
+import android.provider.Settings;
+import android.text.TextUtils;
+import android.view.View;
+import android.view.inputmethod.InputMethodInfo;
+import android.view.inputmethod.InputMethodManager;
+import android.widget.Button;
+import android.widget.LinearLayout;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static android.widget.LinearLayout.VERTICAL;
+
+/**
+ * Demonstrates how to show the input method subtype enabler without relying on
+ * {@link InputMethodManager#showInputMethodAndSubtypeEnabler(String)}, which is highly likely to be
+ * broken.
+ */
+public class ShowInputMethodAndSubtypeEnabler extends Activity {
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+
+        final LinearLayout layout = new LinearLayout(this);
+        layout.setOrientation(VERTICAL);
+
+        {
+            final Button button = new Button(this);
+            button.setText("Show (All IMEs)");
+            button.setOnClickListener(new View.OnClickListener() {
+                @Override
+                public void onClick(View v) {
+                    showInputMethodAndSubtypeEnabler(ShowInputMethodAndSubtypeEnabler.this, null);
+                }
+            });
+            layout.addView(button);
+        }
+
+        for (InputMethodInfo imi : getEnabledInputMethodsThatHaveMultipleSubtypes()) {
+            final Button button = new Button(this);
+            final String id = imi.getId();
+            button.setText("Show (" + id + ")");
+            button.setOnClickListener(new View.OnClickListener() {
+                @Override
+                public void onClick(View v) {
+                    showInputMethodAndSubtypeEnabler(ShowInputMethodAndSubtypeEnabler.this, id);
+                }
+            });
+            layout.addView(button);
+        }
+        setContentView(layout);
+    }
+
+//BEGIN_INCLUDE(showInputMethodAndSubtypeEnabler)
+    static void showInputMethodAndSubtypeEnabler(Context context, String inputMethodId) {
+        final Intent intent = new Intent(Settings.ACTION_INPUT_METHOD_SUBTYPE_SETTINGS);
+        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK
+                | Intent.FLAG_ACTIVITY_RESET_TASK_IF_NEEDED
+                | Intent.FLAG_ACTIVITY_CLEAR_TOP);
+        if (!TextUtils.isEmpty(inputMethodId)) {
+            intent.putExtra(Settings.EXTRA_INPUT_METHOD_ID, inputMethodId);
+        }
+        context.startActivity(intent, null);
+    }
+//END_INCLUDE(showInputMethodAndSubtypeEnabler)
+
+    private List<InputMethodInfo> getEnabledInputMethodsThatHaveMultipleSubtypes() {
+        final InputMethodManager imm =
+                (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
+        final List<InputMethodInfo> result = new ArrayList<>();
+        if (imm == null) {
+            return result;
+        }
+        for (InputMethodInfo imi : imm.getEnabledInputMethodList()) {
+            if (imi.getSubtypeCount() > 1) {
+                result.add(imi);
+            }
+        }
+        return result;
+    }
+}