Merge pull request #125 from theblackcat102/master

Added webview scrolling listener

Author: lejard-h

README.md

@@ -42,6 +42,23 @@ flutterWebviewPlugin.onUrlChanged.listen((String url) {
 });
 ```
 
+#### Listen for scroll event in webview
+
+```dart
+final flutterWebviewPlugin = new FlutterWebviewPlugin();
+flutterWebviewPlugin.onScrollYChanged.listen((double offsetY) { // latest offset value in vertical scroll
+  // compare vertical scroll changes here with old value
+});
+
+flutterWebviewPlugin.onScrollXChanged.listen((double offsetX) { // latest offset value in horizontal scroll
+  // compare horizontal scroll changes here with old value
+});
+
+````
+
+Note: Do note there is a slight difference is scroll distance between ios and android. Android scroll value difference tends to be larger than ios devices.
+
+
 #### Hidden WebView
 
 ```dart

android/src/main/java/com/flutter_webview_plugin/ObservableWebView.java

@@ -0,0 +1,49 @@
+package com.flutter_webview_plugin;
+
+import android.content.Context;
+import android.util.AttributeSet;
+import android.webkit.WebView;
+
+public class ObservableWebView extends WebView {
+    private OnScrollChangedCallback mOnScrollChangedCallback;
+
+    public ObservableWebView(final Context context)
+    {
+        super(context);
+    }
+
+    public ObservableWebView(final Context context, final AttributeSet attrs)
+    {
+        super(context, attrs);
+    }
+
+    public ObservableWebView(final Context context, final AttributeSet attrs, final int defStyle)
+    {
+        super(context, attrs, defStyle);
+    }
+
+    @Override
+    protected void onScrollChanged(final int l, final int t, final int oldl, final int oldt)
+    {
+        super.onScrollChanged(l, t, oldl, oldt);
+        if(mOnScrollChangedCallback != null) mOnScrollChangedCallback.onScroll(l, t, oldl, oldt);
+    }
+
+    public OnScrollChangedCallback getOnScrollChangedCallback()
+    {
+        return mOnScrollChangedCallback;
+    }
+
+    public void setOnScrollChangedCallback(final OnScrollChangedCallback onScrollChangedCallback)
+    {
+        mOnScrollChangedCallback = onScrollChangedCallback;
+    }
+
+    /**
+     * Impliment in the activity/fragment/view that you want to listen to the webview
+     */
+    public static interface OnScrollChangedCallback
+    {
+        public void onScroll(int l, int t, int oldl, int oldt);
+    }
+}

android/src/main/java/com/flutter_webview_plugin/WebviewManager.java

@@ -97,6 +97,18 @@ public boolean onKey(View v, int keyCode, KeyEvent event) {
             }
         });
 
+        observableWebView = (ObservableWebView) webView;
+        observableWebView.setOnScrollChangedCallback(new ObservableWebView.OnScrollChangedCallback(){
+            public void onScroll(int x, int y, int oldx, int oldy){
+                Map<String, Object> yDirection = new HashMap<>();
+                yDirection.put("yDirection", (double)y);
+                FlutterWebviewPlugin.channel.invokeMethod("onScrollYChanged", yDirection);
+                Map<String, Object> xDirection = new HashMap<>();
+                xDirection.put("xDirection", (double)x);
+                FlutterWebviewPlugin.channel.invokeMethod("onScrollXChanged", xDirection);
+            }
+        });
+
         webView.setWebViewClient(webViewClient);
         webView.setWebChromeClient(new WebChromeClient()
         {

example/ios/Flutter/flutter_assets/LICENSE

@@ -242,7 +242,7 @@
 			);
 			inputPaths = (
 				"${SRCROOT}/Pods/Target Support Files/Pods-Runner/Pods-Runner-frameworks.sh",
-				"${PODS_ROOT}/../../../../../flutter/bin/cache/artifacts/engine/ios/Flutter.framework",
+				"${PODS_ROOT}/../../../../../development/flutter/bin/cache/artifacts/engine/ios/Flutter.framework",
 				"${BUILT_PRODUCTS_DIR}/flutter_webview_plugin/flutter_webview_plugin.framework",
 			);
 			name = "[CP] Embed Pods Frameworks";

example/ios/Runner.xcodeproj/project.pbxproj

@@ -97,6 +97,23 @@ class _MyHomePageState extends State<MyHomePage> {
       }
     });
 
+
+    _onScrollYChanged = flutterWebviewPlugin.onScrollYChanged.listen((double y) {
+      if (mounted) {
+        setState(() {
+          _history.add("Scroll in  Y Direction: $y");
+        });
+      }
+    });
+
+    _onScrollXChanged = flutterWebviewPlugin.onScrollXChanged.listen((double x) {
+      if (mounted) {
+        setState(() {
+          _history.add("Scroll in  X Direction: $x");
+        });
+      }
+    });
+
     _onStateChanged =
         flutterWebviewPlugin.onStateChanged.listen((WebViewStateChanged state) {
       if (mounted) {

example/lib/main.dart

@@ -97,6 +97,8 @@ - (void)initWebview:(FlutterMethodCall*)call {
     self.webview.scrollView.showsHorizontalScrollIndicator = [scrollBar boolValue];
     self.webview.scrollView.showsVerticalScrollIndicator = [scrollBar boolValue];
 
+
+
     _enableZoom = [withZoom boolValue];
 
     [self.viewController.view addSubview:self.webview];
@@ -111,6 +113,14 @@ - (CGRect)parseRect:(NSDictionary *)rect {
                       [[rect valueForKey:@"height"] doubleValue]);
 }
 
+- (void) scrollViewDidScroll:(UIScrollView *)scrollView {
+    id xDirection = @{@"xDirection": @(scrollView.contentOffset.x) };
+    [channel invokeMethod:@"onScrollXChanged" arguments:xDirection];
+
+    id yDirection = @{@"yDirection": @(scrollView.contentOffset.y) };
+    [channel invokeMethod:@"onScrollYChanged" arguments:yDirection];
+}
+
 - (void)navigate:(FlutterMethodCall*)call {
     if (self.webview != nil) {
             NSString *url = call.arguments[@"url"];
@@ -213,6 +223,7 @@ - (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigati
     }
 }
 
+
 - (void)webView:(WKWebView *)webView didStartProvisionalNavigation:(WKNavigation *)navigation {
     [channel invokeMethod:@"onState" arguments:@{@"type": @"startLoad", @"url": webView.URL.absoluteString}];
 }

ios/Classes/FlutterWebviewPlugin.m

@@ -19,6 +19,8 @@ class FlutterWebviewPlugin {
   final _onDestroy = new StreamController<Null>.broadcast();
   final _onUrlChanged = new StreamController<String>.broadcast();
   final _onStateChanged = new StreamController<WebViewStateChanged>.broadcast();
+  final _onScrollXChanged = new StreamController<double>.broadcast();
+  final _onScrollYChanged = new StreamController<double>.broadcast();
   final _onHttpError = new StreamController<WebViewHttpError>.broadcast();
 
   static FlutterWebviewPlugin _instance;
@@ -37,7 +39,13 @@ class FlutterWebviewPlugin {
       case 'onUrlChanged':
         _onUrlChanged.add(call.arguments['url']);
         break;
-      case 'onState':
+      case "onScrollXChanged":
+        _onScrollXChanged.add(call.arguments["xDirection"]);
+        break;
+      case "onScrollYChanged":
+        _onScrollYChanged.add(call.arguments["yDirection"]);
+        break;
+      case "onState":
         _onStateChanged.add(
           new WebViewStateChanged.fromMap(
               new Map<String, dynamic>.from(call.arguments)),
@@ -61,6 +69,13 @@ class FlutterWebviewPlugin {
   /// more detail than other events
   Stream<WebViewStateChanged> get onStateChanged => _onStateChanged.stream;
 
+
+  /// Listening web view y position scroll change
+  Stream<double> get onScrollYChanged => _onScrollYChanged.stream;
+
+  /// Listening web view x position scroll change
+  Stream<double> get onScrollXChanged => _onScrollXChanged.stream;
+
   Stream<WebViewHttpError> get onHttpError => _onHttpError.stream;
 
   /// Start the Webview with [url]
@@ -172,6 +187,8 @@ class FlutterWebviewPlugin {
     _onDestroy.close();
     _onUrlChanged.close();
     _onStateChanged.close();
+    _onScrollXChanged.close();
+    _onScrollYChanged.close();
     _onHttpError.close();
     _instance = null;
   }