feat(webview props) onLoadProgresss property (#53)

* Added the onLoadProgress property to the iOS wkwebview and Android webview

README.md

       <WebView
         source={{ uri: 'https://infinite.red/react-native' }}
         style={{ marginTop: 20 }}
+        onLoadProgress={e=>console.log(e.nativeEvent.progress)}
       />
     );
   }

android/src/main/java/com/reactnativecommunity/webview/RNCWebViewManager.java

 import com.reactnativecommunity.webview.events.TopLoadingFinishEvent;
 import com.reactnativecommunity.webview.events.TopLoadingStartEvent;
 import com.reactnativecommunity.webview.events.TopMessageEvent;
+import com.reactnativecommunity.webview.events.TopLoadingProgressEvent;
 import java.io.UnsupportedEncodingException;
 import java.util.ArrayList;
 import java.util.HashMap;
  * {@link WebView} instances could emit following direct events:
  *  - topLoadingFinish
  *  - topLoadingStart
- *  - topLoadingError
+ *  - topLoadingStart
+ *  - topLoadingProgress
  *
  * Each event will carry the following properties:
  *  - target - view's react tag
         return true;
       }
 
+
+    @Override
+    public void onProgressChanged(WebView webView, int newProgress) {
+        super.onProgressChanged(webView, newProgress);
+        WritableMap event = Arguments.createMap();
+        event.putDouble("target", webView.getId());
+        event.putString("title", webView.getTitle());
+        event.putBoolean("canGoBack", webView.canGoBack());
+        event.putBoolean("canGoForward", webView.canGoForward());
+        event.putDouble("progress", (float)newProgress/100);
+        dispatchEvent(
+                  webView,
+                  new TopLoadingProgressEvent(
+                      webView.getId(),
+                      event));
+    }
+
       @Override
       public void onGeolocationPermissionsShowPrompt(String origin, GeolocationPermissions.Callback callback) {
         callback.invoke(origin, true, false);
     view.setWebViewClient(new RNCWebViewClient());
   }
 
+  @Override
+  public Map getExportedCustomDirectEventTypeConstants() {
+    MapBuilder.Builder builder = MapBuilder.builder();
+    builder.put("topLoadingProgress", MapBuilder.of("registrationName", "onLoadingProgress"));
+    return builder.build();
+  }
+
   @Override
   public @Nullable Map<String, Integer> getCommandsMap() {
     return MapBuilder.of(

android/src/main/java/com/reactnativecommunity/webview/events/TopLoadingProgressEvent.java

+package com.reactnativecommunity.webview.events;
+
+import com.facebook.react.bridge.WritableMap;
+import com.facebook.react.uimanager.events.Event;
+import com.facebook.react.uimanager.events.RCTEventEmitter;
+
+public class TopLoadingProgressEvent extends Event<TopLoadingProgressEvent> {
+    public static final String EVENT_NAME = "topLoadingProgress";
+    private WritableMap mEventData;
+
+    public TopLoadingProgressEvent(int viewId, WritableMap eventData) {
+        super(viewId);
+        mEventData = eventData;
+    }
+
+    @Override
+    public String getEventName() {
+        return EVENT_NAME;
+    }
+
+    @Override
+    public boolean canCoalesce() {
+        return false;
+    }
+
+    @Override
+    public short getCoalescingKey() {
+        // All events for a given view can be coalesced.
+        return 0;
+    }
+
+    @Override
+    public void dispatch(RCTEventEmitter rctEventEmitter) {
+        rctEventEmitter.receiveEvent(getViewTag(), getEventName(), mEventData);
+    }
+}

docs/Reference.md

 - [`onLoad`](Reference.md#onload)
 - [`onLoadEnd`](Reference.md#onloadend)
 - [`onLoadStart`](Reference.md#onloadstart)
+- [`onLoadProgress`](Reference.md#onloadprogress)
 - [`onMessage`](Reference.md#onmessage)
 - [`onNavigationStateChange`](Reference.md#onnavigationstatechange)
 - [`originWhitelist`](Reference.md#originwhitelist)
 
 ## Methods Index
 
-* [`extraNativeComponentConfig`](Reference.md#extranativecomponentconfig)
-* [`goForward`](Reference.md#goforward)
-* [`goBack`](Reference.md#goback)
-* [`reload`](Reference.md#reload)
-* [`stopLoading`](Reference.md#stoploading)
+- [`extraNativeComponentConfig`](Reference.md#extranativecomponentconfig)
+- [`goForward`](Reference.md#goforward)
+- [`goBack`](Reference.md#goback)
+- [`reload`](Reference.md#reload)
+- [`stopLoading`](Reference.md#stoploading)
 
 ---
 
 
 **Load uri**
 
-* `uri` (string) - The URI to load in the `WebView`. Can be a local or remote file.
-* `method` (string) - The HTTP Method to use. Defaults to GET if not specified. On Android, the only supported methods are GET and POST.
-* `headers` (object) - Additional HTTP headers to send with the request. On Android, this can only be used with GET requests.
-* `body` (string) - The HTTP body to send with the request. This must be a valid UTF-8 string, and will be sent exactly as specified, with no additional encoding (e.g. URL-escaping or base64) applied. On Android, this can only be used with POST requests.
+- `uri` (string) - The URI to load in the `WebView`. Can be a local or remote file.
+- `method` (string) - The HTTP Method to use. Defaults to GET if not specified. On Android, the only supported methods are GET and POST.
+- `headers` (object) - Additional HTTP headers to send with the request. On Android, this can only be used with GET requests.
+- `body` (string) - The HTTP body to send with the request. This must be a valid UTF-8 string, and will be sent exactly as specified, with no additional encoding (e.g. URL-escaping or base64) applied. On Android, this can only be used with POST requests.
 
 **Static HTML**
 
 _Note that using static HTML requires the WebView property [originWhiteList](Reference.md#originWhiteList) to `['*']`._
 
-* `html` (string) - A static HTML page to display in the WebView.
-* `baseUrl` (string) - The base URL to be used for any relative links in the HTML.
+- `html` (string) - A static HTML page to display in the WebView.
+- `baseUrl` (string) - The base URL to be used for any relative links in the HTML.
 
 | Type   | Required |
 | ------ | -------- |
 
 The `nativeConfig` prop expects an object with the following keys:
 
-* `component` (any)
-* `props` (object)
-* `viewManager` (object)
+- `component` (any)
+- `props` (object)
+- `viewManager` (object)
 
 | Type   | Required |
 | ------ | -------- |
 
 ---
 
+### `onLoadProgress`
+
+Function that is invoked when the `WebView` is loading.
+
+> **_Note_**
+>
+> On iOS, when useWebKit=false, this prop will not work.
+> On android, You can't get the url property, meaning that `event.nativeEvent.url` will be null.
+
+| Type     | Required |
+| -------- | -------- |
+| function | No       |
+
+---
+
 ### `onMessage`
 
 A function that is invoked when the webview calls `window.postMessage`. Setting this property will inject a `postMessage` global into your webview, but will still call pre-existing values of `postMessage`.
 
 A floating-point number that determines how quickly the scroll view decelerates after the user lifts their finger. You may also use the string shortcuts `"normal"` and `"fast"` which match the underlying iOS settings for `UIScrollViewDecelerationRateNormal` and `UIScrollViewDecelerationRateFast` respectively:
 
-* normal: 0.998
-* fast: 0.99 (the default for iOS web view)
+- normal: 0.998
+- fast: 0.99 (the default for iOS web view)
 
 | Type   | Required | Platform |
 | ------ | -------- | -------- |
 
 Possible values for `mixedContentMode` are:
 
-* `never` (default) - WebView will not allow a secure origin to load content from an insecure origin.
-* `always` - WebView will allow a secure origin to load content from any other origin, even if that origin is insecure.
-* `compatibility` - WebView will attempt to be compatible with the approach of a modern web browser with regard to mixed content.
+- `never` (default) - WebView will not allow a secure origin to load content from an insecure origin.
+- `always` - WebView will allow a secure origin to load content from any other origin, even if that origin is insecure.
+- `compatibility` - WebView will attempt to be compatible with the approach of a modern web browser with regard to mixed content.
 
 | Type   | Required | Platform |
 | ------ | -------- | -------- |
 
 Possible values for `dataDetectorTypes` are:
 
-* `phoneNumber`
-* `link`
-* `address`
-* `calendarEvent`
-* `none`
-* `all`
+- `phoneNumber`
+- `link`
+- `address`
+- `calendarEvent`
+- `none`
+- `all`
 
 With the [new WebKit](Reference.md#usewebkit) implementation, we have three new values:
 
-* `trackingNumber`
-* `flightNumber`
-* `lookupSuggestion`
+- `trackingNumber`
+- `flightNumber`
+- `lookupSuggestion`
 
 | Type             | Required | Platform |
 | ---------------- | -------- | -------- |

ios/RNCWKWebView.m

 @property (nonatomic, copy) RCTDirectEventBlock onLoadingStart;
 @property (nonatomic, copy) RCTDirectEventBlock onLoadingFinish;
 @property (nonatomic, copy) RCTDirectEventBlock onLoadingError;
+@property (nonatomic, copy) RCTDirectEventBlock onLoadingProgress;
 @property (nonatomic, copy) RCTDirectEventBlock onShouldStartLoadWithRequest;
 @property (nonatomic, copy) RCTDirectEventBlock onMessage;
 @property (nonatomic, copy) WKWebView *webView;
 
 - (void)dealloc
 {
-
+    if(_webView){
+        [_webView removeObserver:self forKeyPath:@"estimatedProgress"];
+    }
 }
 
 /**
     _webView.navigationDelegate = self;
     _webView.scrollView.scrollEnabled = _scrollEnabled;
     _webView.scrollView.bounces = _bounces;
+    [_webView addObserver:self forKeyPath:@"estimatedProgress" options:NSKeyValueObservingOptionOld | NSKeyValueObservingOptionNew context:nil];
 
 #if defined(__IPHONE_OS_VERSION_MAX_ALLOWED) && __IPHONE_OS_VERSION_MAX_ALLOWED >= 110000 /* __IPHONE_11_0 */
     if ([_webView.scrollView respondsToSelector:@selector(setContentInsetAdjustmentBehavior:)]) {
   }
 }
 
+- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context{
+    if ([keyPath isEqual:@"estimatedProgress"] && object == self.webView) {
+        if(_onLoadingProgress){
+             NSMutableDictionary<NSString *, id> *event = [self baseEvent];
+            [event addEntriesFromDictionary:@{@"progress":[NSNumber numberWithDouble:self.webView.estimatedProgress]}];
+            _onLoadingProgress(event);
+        }
+    }else{
+        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
+    }
+}
+
 - (void)setBackgroundColor:(UIColor *)backgroundColor
 {
   _savedBackgroundColor = backgroundColor;

ios/RNCWKWebViewManager.m

 RCT_EXPORT_VIEW_PROPERTY(onLoadingStart, RCTDirectEventBlock)
 RCT_EXPORT_VIEW_PROPERTY(onLoadingFinish, RCTDirectEventBlock)
 RCT_EXPORT_VIEW_PROPERTY(onLoadingError, RCTDirectEventBlock)
+RCT_EXPORT_VIEW_PROPERTY(onLoadingProgress, RCTDirectEventBlock)
 RCT_EXPORT_VIEW_PROPERTY(onShouldStartLoadWithRequest, RCTDirectEventBlock)
 RCT_EXPORT_VIEW_PROPERTY(injectedJavaScript, NSString)
 RCT_EXPORT_VIEW_PROPERTY(allowsInlineMediaPlayback, BOOL)

js/WebView.android.js

   WebViewNavigationEvent,
   WebViewSharedProps,
   WebViewSource,
+  WebViewProgressEvent,
 } from './WebViewTypes';
 
 const resolveAssetSource = Image.resolveAssetSource;
         onLoadingStart={this.onLoadingStart}
         onLoadingFinish={this.onLoadingFinish}
         onLoadingError={this.onLoadingError}
+        onLoadingProgress={this.onLoadingProgress}
         testID={this.props.testID}
         geolocationEnabled={this.props.geolocationEnabled}
         mediaPlaybackRequiresUserAction={
     const { onMessage } = this.props;
     onMessage && onMessage(event);
   };
+  
+  onLoadingProgress = (event: WebViewProgressEvent) => {
+    const { onLoadProgress} = this.props;
+    onLoadProgress && onLoadProgress(event);
+  }
 }
 
 const RNCWebView = requireNativeComponent('RNCWebView');

js/WebView.ios.js

   WebViewNavigationEvent,
   WebViewSharedProps,
   WebViewSource,
+  WebViewProgressEvent,
 } from './WebViewTypes';
 
 const resolveAssetSource = Image.resolveAssetSource;
         onLoadingStart={this._onLoadingStart}
         onLoadingFinish={this._onLoadingFinish}
         onLoadingError={this._onLoadingError}
+        onLoadingProgress={this._onLoadingProgress}
         messagingEnabled={messagingEnabled}
         onMessage={this._onMessage}
         onShouldStartLoadWithRequest={onShouldStartLoadWithRequest}
     onMessage && onMessage(event);
   };
 
+  _onLoadingProgress = (event: WebViewProgressEvent) => {
+    const {onLoadProgress} = this.props;
+    onLoadProgress && onLoadProgress(event);
+  }
+
   componentDidUpdate(prevProps: WebViewSharedProps) {
     if (!(prevProps.useWebKit && this.props.useWebKit)) {
       return;

js/WebViewTypes.js

   canGoForward: boolean,
 |}>;
 
+export type WebViewProgressEvent = $ReadOnly<{|
+    ...WebViewNativeEvent,
+    progress: number,
+|}>
+
 export type WebViewNavigation = $ReadOnly<{|
   ...WebViewNativeEvent,
   navigationType:
    */
   onMessage?: (event: WebViewMessageEvent) => mixed,
 
+  /**
+   * Function that is invoked when the `WebView` is loading.
+   */
+  onLoadProgress?: (event: WebViewProgressEvent) => mixed,
+
   /**
    * Boolean value that forces the `WebView` to show the loading view
    * on the first load.