added a CallBack support for scrolling in Y direction

Author: Reekoooo

packages/webview_flutter/android/src/main/java/io/flutter/plugins/webviewflutter/FlutterWebView.java

@@ -8,6 +8,7 @@
 import android.content.Context;
 import android.os.Build;
 import android.os.Handler;
+import android.util.Log;
 import android.view.View;
 import android.webkit.WebStorage;
 import android.webkit.WebView;
@@ -34,6 +35,21 @@ public class FlutterWebView implements PlatformView, MethodCallHandler {
     platformThreadHandler = new Handler(context.getMainLooper());
     // Allow local storage.
     webView.getSettings().setDomStorageEnabled(true);
+    // this is a test added to get call back to Y scroll position API 23;
+    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+
+
+      webView.setOnScrollChangeListener(new View.OnScrollChangeListener(){
+        @Override
+        public void onScrollChange(View v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {
+          methodChannel.invokeMethod("callback",scrollY);
+          //Log.d("Hi android","---------------ScrollY =  -----------------------------"+scrollY);
+
+        }
+      });
+    }
+
+
 
     methodChannel = new MethodChannel(messenger, "plugins.flutter.io/webview_" + id);
     methodChannel.setMethodCallHandler(this);

packages/webview_flutter/example/lib/main.dart

@@ -43,6 +43,9 @@ class WebViewExample extends StatelessWidget {
       // to allow calling Scaffold.of(context) so we can show a snackbar.
       body: Builder(builder: (BuildContext context) {
         return WebView(
+          onScrollYCallback: (y){
+            print("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@----------Y = $y   ---------------------");
+          },
           initialUrl: 'https://flutter.dev',
           javascriptMode: JavascriptMode.unrestricted,
           onWebViewCreated: (WebViewController webViewController) {

packages/webview_flutter/lib/webview_flutter.dart

@@ -69,6 +69,9 @@ typedef NavigationDecision NavigationDelegate(NavigationRequest navigation);
 /// Signature for when a [WebView] has finished loading a page.
 typedef void PageFinishedCallback(String url);
 
+/// Signature for when a [webView] Scrolled in Y direction.
+typedef Future<dynamic> ScrollYCallback (MethodCall call);
+
 final RegExp _validChannelNames = RegExp('^[a-zA-Z_][a-zA-Z0-9]*\$');
 
 /// A named channel for receiving messaged from JavaScript code running inside a web view.
@@ -117,9 +120,13 @@ class WebView extends StatefulWidget {
     this.navigationDelegate,
     this.gestureRecognizers,
     this.onPageFinished,
+    this.onScrollYCallback
+
   })  : assert(javascriptMode != null),
         super(key: key);
 
+  /// Web view scrolling in Y direction callBack.
+  final ScrollYCallback onScrollYCallback;
   /// If not null invoked once the web view is created.
   final WebViewCreatedCallback onWebViewCreated;
 
@@ -270,6 +277,7 @@ class _WebViewState extends State<WebView> {
     _controller.complete(controller);
     if (widget.onWebViewCreated != null) {
       widget.onWebViewCreated(controller);
+
     }
   }
 
@@ -367,6 +375,7 @@ class WebViewController {
     _settings = _WebSettings.fromWidget(_widget);
     _updateJavascriptChannelsFromSet(_widget.javascriptChannels);
     _channel.setMethodCallHandler(_onMethodCall);
+    _channel.setMethodCallHandler(_widget.onScrollYCallback);
   }
 
   final MethodChannel _channel;