onLoadStart property

@SupportedPlatforms.new(platforms: [AndroidPlatform(apiName: 'WebViewClient.onPageStarted', apiUrl: 'https://developer.android.com/reference/android/webkit/WebViewClient#onPageStarted(android.webkit.WebView,%20java.lang.String,%20android.graphics.Bitmap)'), IOSPlatform(apiName: 'WKNavigationDelegate.webView', apiUrl: 'https://developer.apple.com/documentation/webkit/wknavigationdelegate/1455621-webview'), MacOSPlatform(apiName: 'WKNavigationDelegate.webView', apiUrl: 'https://developer.apple.com/documentation/webkit/wknavigationdelegate/1455621-webview'), WebPlatform(note: "It will be dispatched at the same time of [onLoadStop] event because there isn't any way to capture the real load start event from an iframe. If `window.location.href` isn't accessible inside the iframe, the [url] parameter will have the current value of the `iframe.src` attribute."), WindowsPlatform(apiName: 'ICoreWebView2.add_NavigationStarting', apiUrl: 'https://learn.microsoft.com/en-us/microsoft-edge/webview2/reference/win32/iwebview2webview?view=webview2-0.8.355#add_navigationstarting'), LinuxPlatform(apiName: 'WebKitWebView::load-changed', apiUrl: 'https://wpewebkit.org/reference/stable/wpe-webkit-2.0/signal.WebView.load-changed.html', note: 'Fired when WebKitLoadEvent is WEBKIT_LOAD_STARTED.')]) void Function(T controller, WebUri? url)? onLoadStart

Event fired when the WebView starts to load an url.

Officially Supported Platforms/Implementations:

• Android WebView (Official API - WebViewClient.onPageStarted)
• iOS WKWebView (Official API - WKNavigationDelegate.webView)
• macOS WKWebView (Official API - WKNavigationDelegate.webView)
• Web <iframe> but requires same origin:
  • It will be dispatched at the same time of onLoadStop event because there isn't any way to capture the real load start event from an iframe. If window.location.href isn't accessible inside the iframe, the url parameter will have the current value of the iframe.src attribute.
• Windows WebView2 (Official API - ICoreWebView2.add_NavigationStarting)
• Linux WPE WebKit (Official API - WebKitWebView::load-changed):
  • Fired when WebKitLoadEvent is WEBKIT_LOAD_STARTED.

Parameters - Officially Supported Platforms/Implementations:

• url: all platforms

Use the PlatformWebViewCreationParams.isPropertySupported method to check if this property is supported at runtime.

Implementation

@SupportedPlatforms(
  platforms: [
    AndroidPlatform(
      apiName: 'WebViewClient.onPageStarted',
      apiUrl:
          'https://developer.android.com/reference/android/webkit/WebViewClient#onPageStarted(android.webkit.WebView,%20java.lang.String,%20android.graphics.Bitmap)',
    ),
    IOSPlatform(
      apiName: 'WKNavigationDelegate.webView',
      apiUrl:
          'https://developer.apple.com/documentation/webkit/wknavigationdelegate/1455621-webview',
    ),
    MacOSPlatform(
      apiName: 'WKNavigationDelegate.webView',
      apiUrl:
          'https://developer.apple.com/documentation/webkit/wknavigationdelegate/1455621-webview',
    ),
    WebPlatform(
      note:
          "It will be dispatched at the same time of [onLoadStop] event because there isn't any way to capture the real load start event from an iframe. If `window.location.href` isn't accessible inside the iframe, the [url] parameter will have the current value of the `iframe.src` attribute.",
    ),
    WindowsPlatform(
      apiName: 'ICoreWebView2.add_NavigationStarting',
      apiUrl:
          'https://learn.microsoft.com/en-us/microsoft-edge/webview2/reference/win32/iwebview2webview?view=webview2-0.8.355#add_navigationstarting',
    ),
    LinuxPlatform(
      apiName: 'WebKitWebView::load-changed',
      apiUrl:
          'https://wpewebkit.org/reference/stable/wpe-webkit-2.0/signal.WebView.load-changed.html',
      note: 'Fired when WebKitLoadEvent is WEBKIT_LOAD_STARTED.',
    ),
  ],
)
final void Function(T controller, WebUri? url)? onLoadStart;