(iOS & Android) Add postMessage API support (#362)

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### Platforms affected
Android
iOS (both UIWebView & WKWebView implementations)

### What does this PR do?
Adds support for [postMessage API](https://developer.mozilla.org/en-US/docs/Web/API/Window/postMessage) enabling pages loaded into the InappBrowser to post messages back to the parent Webview of the Cordova app.

For example, sending event messages associated with UI interactions such as button clicks from the wrapped page back to the parent app Webview.

### What testing has been done on this change?
Automated tests have been extended to cover the `message` event.

### Checklist
- [x ] Commit message follows the format: "GH-3232: (android) Fix bug with resolving file paths", where CB-xxxx is the JIRA ID & "android" is the platform affected.
- [ x] Added automated test coverage as appropriate for this change.

README.md

@@ -213,6 +213,7 @@ The object returned from a call to `cordova.InAppBrowser.open` when the target i
   - __loaderror__: event fires when the `InAppBrowser` encounters an error when loading a URL.
   - __exit__: event fires when the `InAppBrowser` window is closed.
   - __beforeload__: event fires when the `InAppBrowser` decides whether to load an URL or not (only with option `beforeload=yes`).
+  - __message__: event fires when the `InAppBrowser` receives a message posted from the page loaded inside the `InAppBrowser` Webview.
 
 - __callback__: the function that executes when the event fires. The function is passed an `InAppBrowserEvent` object as a parameter.
 
@@ -238,6 +239,7 @@ function showHelp(url) {
 
     inAppBrowserRef.addEventListener('beforeload', beforeloadCallBack);
 
+    inAppBrowserRef.addEventListener('message', messageCallBack);
 }
 
 function loadStartCallBack() {
@@ -252,6 +254,13 @@ function loadStopCallBack() {
 
         inAppBrowserRef.insertCSS({ code: "body{font-size: 25px;" });
 
+        inAppBrowserRef.executeScript({ code: "\
+            var message = 'this is the message';\
+            var messageObj = {my_message: message};\
+            var stringifiedMessageObj = JSON.stringify(messageObj);\
+            webkit.messageHandlers.cordova_iab.postMessage(stringifiedMessageObj);"
+        });
+
         $('#status-message').text("");
 
         inAppBrowserRef.show();
@@ -300,11 +309,15 @@ function beforeloadCallback(params, callback) {
 
 }
 
+function messageCallback(params){
+    $('#status-message').text("message received: "+params.data.my_message);
+}
+
 ```
 
 ### InAppBrowserEvent Properties
 
-- __type__: the eventname, either `loadstart`, `loadstop`, `loaderror`, or `exit`. _(String)_
+- __type__: the eventname, either `loadstart`, `loadstop`, `loaderror`, `message` or `exit`. _(String)_
 
 - __url__: the URL that was loaded. _(String)_
 
@@ -312,6 +325,8 @@ function beforeloadCallback(params, callback) {
 
 - __message__: the error message, only in the case of `loaderror`. _(String)_
 
+- __data__: the message contents , only in the case of `message`. A stringified JSON object. _(String)_
+
 
 ### Supported Platforms
 
@@ -323,7 +338,11 @@ function beforeloadCallback(params, callback) {
 
 ### Browser Quirks
 
-`loadstart` and `loaderror` events are not being fired.
+`loadstart`, `loaderror`, `message` events are not fired.
+
+### Windows Quirks
+
+`message` event is not fired.
 
 ### Quick Example
 
@@ -344,6 +363,7 @@ function beforeloadCallback(params, callback) {
   - __loadstop__: event fires when the `InAppBrowser` finishes loading a URL.
   - __loaderror__: event fires when the `InAppBrowser` encounters an error loading a URL.
   - __exit__: event fires when the `InAppBrowser` window is closed.
+  - __message__: event fires when the `InAppBrowser` receives a message posted from the page loaded inside the `InAppBrowser` Webview.
 
 - __callback__: the function to execute when the event fires.
 The function is passed an `InAppBrowserEvent` object.

src/android/InAppBrowser.java

@@ -48,6 +48,7 @@ import android.view.inputmethod.InputMethodManager;
 import android.webkit.CookieManager;
 import android.webkit.CookieSyncManager;
 import android.webkit.HttpAuthHandler;
+import android.webkit.JavascriptInterface;
 import android.webkit.ValueCallback;
 import android.webkit.WebChromeClient;
 import android.webkit.WebSettings;
@@ -95,6 +96,7 @@ public class InAppBrowser extends CordovaPlugin {
     private static final String LOAD_START_EVENT = "loadstart";
     private static final String LOAD_STOP_EVENT = "loadstop";
     private static final String LOAD_ERROR_EVENT = "loaderror";
+    private static final String MESSAGE_EVENT = "message";
     private static final String CLEAR_ALL_CACHE = "clearcache";
     private static final String CLEAR_SESSION_CACHE = "clearsessioncache";
     private static final String HARDWARE_BACK_BUTTON = "hardwareback";
@@ -952,8 +954,24 @@ public class InAppBrowser extends CordovaPlugin {
                 settings.setBuiltInZoomControls(showZoomControls);
                 settings.setPluginState(android.webkit.WebSettings.PluginState.ON);
 
+                // Add postMessage interface
+                class JsObject {
+                    @JavascriptInterface
+                    public void postMessage(String data) {
+                        try {
+                            JSONObject obj = new JSONObject();
+                            obj.put("type", MESSAGE_EVENT);
+                            obj.put("data", new JSONObject(data));
+                            sendUpdate(obj, true);
+                        } catch (JSONException ex) {
+                            LOG.e(LOG_TAG, "data object passed to postMessage has caused a JSON error.");
+                        }
+                    }
+                }
+
                 if(android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.JELLY_BEAN_MR1) {
                     settings.setMediaPlaybackRequiresUserGesture(mediaPlaybackRequiresUserGesture);
+                    inAppWebView.addJavascriptInterface(new JsObject(), "cordova_iab");
                 }
 
                 String overrideUserAgent = preferences.getString("OverrideUserAgent", null);
@@ -1270,6 +1288,11 @@ public class InAppBrowser extends CordovaPlugin {
         public void onPageFinished(WebView view, String url) {
             super.onPageFinished(view, url);
 
+            // Set the namespace for postMessage()
+            if (Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.JELLY_BEAN_MR1){
+                injectDeferredObject("window.webkit={messageHandlers:{cordova_iab:cordova_iab}}", null);
+            }
+
             // CB-10395 InAppBrowser's WebView not storing cookies reliable to local device storage
             if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.LOLLIPOP) {
                 CookieManager.getInstance().flush();

src/ios/CDVUIInAppBrowser.m

@@ -337,6 +337,16 @@ static CDVUIInAppBrowser* instance = nil;
     [self.inAppBrowserViewController navigateTo:url];
 }
 
+-(void)createIframeBridge
+{
+    // Create an iframe bridge in the new document to communicate with the CDVThemeableBrowserViewController
+    NSString* jsIframeBridge = @"var e = _cdvIframeBridge=d.getElementById('_cdvIframeBridge'); if(!_cdvIframeBridge) {e = _cdvIframeBridge = d.createElement('iframe'); e.id='_cdvIframeBridge'; e.style.display='none'; d.body.appendChild(e);}";
+    // Add the postMessage API
+    NSString* jspostMessageApi = @"window.webkit={messageHandlers:{cordova_iab:{postMessage:function(message){_cdvIframeBridge.src='gap-iab://message/'+encodeURIComponent(message);}}}}";
+    // Inject the JS to the webview
+    [self.inAppBrowserViewController.webView stringByEvaluatingJavaScriptFromString:[NSString stringWithFormat:@"(function(d){%@%@})(document)", jsIframeBridge, jspostMessageApi]];
+}
+
 // This is a helper method for the inject{Script|Style}{Code|File} API calls, which
 // provides a consistent method for injecting JavaScript code into the document.
 //
@@ -348,9 +358,6 @@ static CDVUIInAppBrowser* instance = nil;
 
 - (void)injectDeferredObject:(NSString*)source withWrapper:(NSString*)jsWrapper
 {
-    // Ensure an iframe bridge is created to communicate with the CDVUIInAppBrowserViewController
-    [self.inAppBrowserViewController.webView stringByEvaluatingJavaScriptFromString:@"(function(d){_cdvIframeBridge=d.getElementById('_cdvIframeBridge');if(!_cdvIframeBridge) {var e = _cdvIframeBridge = d.createElement('iframe');e.id='_cdvIframeBridge'; e.style.display='none';d.body.appendChild(e);}})(document)"];
-
     if (jsWrapper != nil) {
         NSData* jsonData = [NSJSONSerialization dataWithJSONObject:@[source] options:0 error:nil];
         NSString* sourceArrayString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
@@ -472,6 +479,22 @@ static CDVUIInAppBrowser* instance = nil;
             }
             [self.commandDelegate sendPluginResult:pluginResult callbackId:scriptCallbackId];
             return NO;
+        }else if ([scriptCallbackId isEqualToString:@"message"] && (self.callbackId != nil)) {
+            // Send a message event
+            NSString* scriptResult = [url path];
+            if ((scriptResult != nil) && ([scriptResult length] > 1)) {
+                scriptResult = [scriptResult substringFromIndex:1];
+                NSError* __autoreleasing error = nil;
+                NSData* decodedResult = [NSJSONSerialization JSONObjectWithData:[scriptResult dataUsingEncoding:NSUTF8StringEncoding] options:kNilOptions error:&error];
+                if (error == nil) {
+                    NSMutableDictionary* dResult = [NSMutableDictionary new];
+                    [dResult setValue:@"message" forKey:@"type"];
+                    [dResult setObject:decodedResult forKey:@"data"];
+                    CDVPluginResult* pluginResult = [CDVPluginResult resultWithStatus:CDVCommandStatus_OK messageAsDictionary:dResult];
+                    [pluginResult setKeepCallback:[NSNumber numberWithBool:YES]];
+                    [self.commandDelegate sendPluginResult:pluginResult callbackId:self.callbackId];
+                }
+            }
         }
     }
 
@@ -513,6 +536,7 @@ static CDVUIInAppBrowser* instance = nil;
 
 - (void)webViewDidFinishLoad:(UIWebView*)theWebView
 {
+    [self createIframeBridge];
     if (self.callbackId != nil) {
         // TODO: It would be more useful to return the URL the page is actually on (e.g. if it's been redirected).
         NSString* url = [self.inAppBrowserViewController.currentURL absoluteString];

src/ios/CDVWKInAppBrowser.m

@@ -555,23 +555,37 @@ static CDVWKInAppBrowser* instance = nil;
     
     CDVPluginResult* pluginResult = nil;
     
-    NSDictionary* messageContent = (NSDictionary*) message.body;
-    NSString* scriptCallbackId = messageContent[@"id"];
-    
-    if([messageContent objectForKey:@"d"]){
-        NSString* scriptResult = messageContent[@"d"];
-        NSError* __autoreleasing error = nil;
-        NSData* decodedResult = [NSJSONSerialization JSONObjectWithData:[scriptResult dataUsingEncoding:NSUTF8StringEncoding] options:kNilOptions error:&error];
-        if ((error == nil) && [decodedResult isKindOfClass:[NSArray class]]) {
-            pluginResult = [CDVPluginResult resultWithStatus:CDVCommandStatus_OK messageAsArray:(NSArray*)decodedResult];
+    if([message.body isKindOfClass:[NSDictionary class]]){
+        NSDictionary* messageContent = (NSDictionary*) message.body;
+        NSString* scriptCallbackId = messageContent[@"id"];
+        
+        if([messageContent objectForKey:@"d"]){
+            NSString* scriptResult = messageContent[@"d"];
+            NSError* __autoreleasing error = nil;
+            NSData* decodedResult = [NSJSONSerialization JSONObjectWithData:[scriptResult dataUsingEncoding:NSUTF8StringEncoding] options:kNilOptions error:&error];
+            if ((error == nil) && [decodedResult isKindOfClass:[NSArray class]]) {
+                pluginResult = [CDVPluginResult resultWithStatus:CDVCommandStatus_OK messageAsArray:(NSArray*)decodedResult];
+            } else {
+                pluginResult = [CDVPluginResult resultWithStatus:CDVCommandStatus_JSON_EXCEPTION];
+            }
         } else {
-            pluginResult = [CDVPluginResult resultWithStatus:CDVCommandStatus_JSON_EXCEPTION];
+            pluginResult = [CDVPluginResult resultWithStatus:CDVCommandStatus_OK messageAsArray:@[]];
+        }
+        [self.commandDelegate sendPluginResult:pluginResult callbackId:scriptCallbackId];
+    }else if(self.callbackId != nil){
+        // Send a message event
+        NSString* messageContent = (NSString*) message.body;
+        NSError* __autoreleasing error = nil;
+        NSData* decodedResult = [NSJSONSerialization JSONObjectWithData:[messageContent dataUsingEncoding:NSUTF8StringEncoding] options:kNilOptions error:&error];
+        if (error == nil) {
+            NSMutableDictionary* dResult = [NSMutableDictionary new];
+            [dResult setValue:@"message" forKey:@"type"];
+            [dResult setObject:decodedResult forKey:@"data"];
+            CDVPluginResult* pluginResult = [CDVPluginResult resultWithStatus:CDVCommandStatus_OK messageAsDictionary:dResult];
+            [pluginResult setKeepCallback:[NSNumber numberWithBool:YES]];
+            [self.commandDelegate sendPluginResult:pluginResult callbackId:self.callbackId];
         }
-    } else {
-        pluginResult = [CDVPluginResult resultWithStatus:CDVCommandStatus_OK messageAsArray:@[]];
     }
-    
-    [self.commandDelegate sendPluginResult:pluginResult callbackId:scriptCallbackId];
 }
 
 - (void)didStartProvisionalNavigation:(WKWebView*)theWebView

tests/tests.js

@@ -24,6 +24,7 @@
 var cordova = require('cordova');
 var isWindows = cordova.platformId === 'windows';
 var isIos = cordova.platformId === 'ios';
+var isAndroid = cordova.platformId === 'android';
 var isBrowser = cordova.platformId === 'browser';
 
 window.alert = window.alert || navigator.notification.alert;
@@ -151,6 +152,32 @@ exports.defineAutoTests = function () {
                     done();
                 });
             });
+
+            it('inappbrowser.spec.7 should support message event', function (done) {
+                if (!isAndroid && !isIos) {
+                    return pending(cordova.platformId + ' platform doesn\'t support message event');
+                }
+                var messageKey = 'my_message';
+                var messageValue = 'is_this';
+                iabInstance = cordova.InAppBrowser.open(url, '_blank', platformOpts);
+                iabInstance.addEventListener('message', function (evt) {
+                    // Verify message event
+                    expect(evt).toBeDefined();
+                    expect(evt.type).toEqual('message');
+                    expect(evt.data).toBeDefined();
+                    expect(evt.data[messageKey]).toBeDefined();
+                    expect(evt.data[messageKey]).toEqual(messageValue);
+                    done();
+                });
+                iabInstance.addEventListener('loadstop', function (evt) {
+                    var code = '(function(){\n' +
+                        '    var message = {' + messageKey + ': "' + messageValue + '"};\n' +
+                        '    webkit.messageHandlers.cordova_iab.postMessage(JSON.stringify(message));\n' +
+                        '})()';
+                    iabInstance.executeScript({ code: code });
+                });
+
+            });
         });
     };
     if (isIos) {

types/index.d.ts

@@ -6,7 +6,7 @@
 // Copyright (c) Microsoft Open Technologies Inc
 // Licensed under the MIT license.
 // TypeScript Version: 2.3
-type channel = "loadstart" | "loadstop" | "loaderror" | "exit";
+type channel = "loadstart" | "loadstop" | "loaderror" | "exit" | "message";
 
 interface Window {
     /**

www/inappbrowser.js

@@ -38,7 +38,8 @@
             'loadstop': channel.create('loadstop'),
             'loaderror': channel.create('loaderror'),
             'exit': channel.create('exit'),
-            'customscheme': channel.create('customscheme')
+            'customscheme': channel.create('customscheme'),
+            'message': channel.create('message')
         };
     }