Adding hooks for Android dialogs upon console.prompt() and similar.

Adapting code from Android's JsDialogHelper, a private class in the
Android source code.

demos/mobile/android/app/src/main/java/com/google/blockly/android/webview/BlocklyWebViewFragment.java

@@ -1,5 +1,6 @@
 package com.google.blockly.android.webview;
 
+import android.annotation.SuppressLint;
 import android.os.Bundle;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
@@ -16,11 +17,13 @@ import android.webkit.WebView;
 public class BlocklyWebViewFragment extends Fragment {
     protected @Nullable WebView mWebView = null;
 
+    @SuppressLint("SetJavaScriptEnabled")
     @Nullable
     @Override
     public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container,
             @Nullable Bundle savedInstanceState) {
         mWebView = new WebView(inflater.getContext());
+        mWebView.setWebChromeClient(new WebChromeClient());
         WebSettings webSettings = mWebView.getSettings();
         webSettings.setJavaScriptEnabled(true);
         mWebView.loadUrl("file:///android_asset/blockly/webview.html");

demos/mobile/android/app/src/main/java/com/google/blockly/android/webview/JsDialogHelper.java

@@ -0,0 +1,163 @@
+/*
+ * Copyright (C) 2013 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.google.blockly.android.webview;
+
+import android.app.Activity;
+import android.content.Context;
+import android.content.DialogInterface;
+import android.os.Message;
+import android.support.annotation.Nullable;
+import android.support.v7.app.AlertDialog;
+import android.util.Log;
+import android.view.KeyEvent;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.inputmethod.EditorInfo;
+import android.webkit.JsPromptResult;
+import android.webkit.JsResult;
+import android.webkit.WebView;
+import android.widget.EditText;
+import android.widget.TextView;
+
+import com.example.blocklywebview.R;
+
+/**
+ * Helper class to create JavaScript dialogs.
+ * Adapted from android-9.0.0_r10/core/java/android/webkit/JsDialogHelper.java.
+ * Removes dialog title (page domain) and uses a larger prompt message area than original.
+ */
+public class JsDialogHelper {
+    private static final String TAG = "JsDialogHelper";
+    // Dialog types
+    /** An alert dialog, for console.alert(..). */
+    public static final int ALERT   = 1;
+    /** An alert dialog, for console.confirm(..). */
+    public static final int CONFIRM = 2;
+    /** An alert dialog, for console.prompt(..). */
+    public static final int PROMPT  = 3;
+
+    private final @Nullable String mDefaultValue;
+    private final JsResult mResult;
+    private final String mMessage;
+    private final int mType;
+    private final String mUrl;
+
+    public JsDialogHelper(JsResult result, int type, @Nullable String defaultValue,
+            String message, String url) {
+        if (type == PROMPT && !(result instanceof JsPromptResult)) {
+            throw new IllegalArgumentException("JsDialogHelper PROMPT requires JsPromptResult");
+        }
+        mResult = result;
+        mDefaultValue = defaultValue;
+        mMessage = message;
+        mType = type;
+        mUrl = url;
+    }
+
+    public JsDialogHelper(JsResult result, Message msg) {
+        mResult = result;
+        mDefaultValue = msg.getData().getString("default");
+        mMessage = msg.getData().getString("message");
+        mType = msg.getData().getInt("type");
+        mUrl = msg.getData().getString("url");
+    }
+
+    public boolean invokeCallback(WebChromeClient client, WebView webView) {
+        switch (mType) {
+            case ALERT:
+                return client.onJsAlert(webView, mUrl, mMessage, mResult);
+            case CONFIRM:
+                return client.onJsConfirm(webView, mUrl, mMessage, mResult);
+            case PROMPT:
+                return client.onJsPrompt(webView, mUrl, mMessage, mDefaultValue, (JsPromptResult) mResult);
+            default:
+                throw new IllegalArgumentException("Unexpected type: " + mType);
+        }
+    }
+
+    public void showDialog(Context context) {
+        if (!canShowAlertDialog(context)) {
+            Log.w(TAG, "Cannot create a dialog, the WebView context is not an Activity");
+            mResult.cancel();
+            return;
+        }
+        final EditText edit;
+        AlertDialog.Builder builder = new AlertDialog.Builder(context);
+        builder.setOnCancelListener(new CancelListener());
+        if (mType != PROMPT) {
+            edit = null;
+            builder.setMessage(mMessage);
+            builder.setPositiveButton(android.R.string.ok, new PositiveListener(null));
+        } else {
+            final View view = LayoutInflater.from(context).inflate(R.layout.js_prompt, null);
+            edit = view.findViewById(R.id.js_prompt_value);
+            edit.setText(mDefaultValue);
+            builder.setPositiveButton(android.R.string.ok, new PositiveListener(edit));
+            ((TextView) view.findViewById(R.id.js_prompt_message)).setText(mMessage);
+            builder.setView(view);
+
+            // TODO: Open keyboard and place text cursor.
+        }
+        if (mType != ALERT) {
+            builder.setNegativeButton(android.R.string.cancel, new CancelListener());
+        }
+        final AlertDialog dialog = builder.show();
+
+        if (edit != null) {  // Is it a prompt dialog?
+            edit.setOnEditorActionListener(new TextView.OnEditorActionListener() {
+                @Override
+                public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
+                    if (actionId == EditorInfo.IME_ACTION_DONE) {
+                        // TODO: Accept input, close keyboard, close dialog
+                        return true;
+                    }
+                    return false;
+                }
+            });
+        }
+    }
+
+    private class CancelListener implements DialogInterface.OnCancelListener,
+            DialogInterface.OnClickListener {
+        @Override
+        public void onCancel(DialogInterface dialog) {
+            mResult.cancel();
+        }
+        @Override
+        public void onClick(DialogInterface dialog, int which) {
+            mResult.cancel();
+        }
+    }
+
+    private class PositiveListener implements DialogInterface.OnClickListener {
+        private final EditText mEdit;
+        public PositiveListener(EditText edit) {
+            mEdit = edit;
+        }
+        @Override
+        public void onClick(DialogInterface dialog, int which) {
+            if (mEdit == null) {
+                mResult.confirm();
+            } else {
+                ((JsPromptResult) mResult).confirm(mEdit.getText().toString());
+            }
+        }
+    }
+
+    private static boolean canShowAlertDialog(Context context) {
+        return context instanceof Activity;
+    }
+}

demos/mobile/android/app/src/main/java/com/google/blockly/android/webview/WebChromeClient.java

@@ -0,0 +1,32 @@
+package com.google.blockly.android.webview;
+
+import android.webkit.JsPromptResult;
+import android.webkit.JsResult;
+import android.webkit.WebView;
+
+/**
+ * Provides native hooks for JavaScript console dialog functions.
+ */
+public class WebChromeClient extends android.webkit.WebChromeClient {
+    @Override
+    public boolean onJsAlert(WebView view, String url, String message, JsResult result) {
+        new JsDialogHelper(result, JsDialogHelper.ALERT, null, message, url)
+                .showDialog(view.getContext());
+        return true;
+    }
+
+    @Override
+    public boolean onJsConfirm(WebView view, String url, String message, JsResult result) {
+        new JsDialogHelper(result, JsDialogHelper.CONFIRM, null, message, url)
+                .showDialog(view.getContext());
+        return true;
+    }
+
+    @Override
+    public boolean onJsPrompt(WebView view, String url, String message, String defaultValue,
+            JsPromptResult result) {
+        new JsDialogHelper(result, JsDialogHelper.PROMPT, defaultValue, message, url)
+                .showDialog(view.getContext());
+        return true;
+    }
+}

demos/mobile/android/app/src/main/res/layout/js_prompt.xml

@@ -0,0 +1,37 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2008 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:orientation="vertical"
+              android:layout_width="match_parent"
+              android:layout_height="wrap_content"
+              android:gravity="center_horizontal"
+>
+    <TextView android:id="@+id/js_prompt_message"
+              style="?android:attr/textAppearanceMedium"
+              android:layout_width="match_parent"
+              android:layout_height="wrap_content"
+              android:padding="5dip"
+    />
+    <EditText android:id="@+id/js_prompt_value"
+              android:layout_width="match_parent"
+              android:layout_height="wrap_content"
+              android:textStyle="bold"
+              android:inputType="text"
+              android:selectAllOnFocus="true"
+              android:scrollHorizontally="true"
+              android:layout_marginTop="6dip"
+    />
+
+</LinearLayout>

demos/mobile/android/app/src/main/res/values/js_dialog_helper.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources xmlns:xliff="urn:oasis:names:tc:xliff:document:1.2">
+    <!-- Title for a JavaScript dialog. "The page at <url of current page> says:" -->
+    <string name="js_dialog_title">The page at \"<xliff:g id="title">%s</xliff:g>\" says:</string>
+    <!-- Default title for a javascript dialog -->
+    <string name="js_dialog_title_default">JavaScript</string>
+</resources>

demos/mobile/html/index.html

@@ -2,7 +2,7 @@
 <!-- HTML file to host Blockly in a mobile WebView. -->
 <html>
 <head>
-  <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
+  <!--<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">-->
   <style type="text/css">
     html, body, #blocklyDiv {
       border: 0;