Embedding web content into a Flutter web app

In some cases, Flutter web applications need to embed web content not rendered by Flutter. For example, embedding a google_maps_flutter view (which uses the Google Maps JavaScript SDK) or a video_player (which uses a standard video element).

Flutter web can render arbitrary web content within the boundaries of a Widget, and the primitives used to implement the example packages mentioned previously, are available to all Flutter web applications.

The HtmlElementView Flutter widget reserves a space in the layout to be filled with any HTML Element. It has two constructors:

• HtmlElementView.fromTagName.
• HtmlElementView and registerViewFactory.

The HtmlElementView.fromTagName constructor creates an HTML Element from its tagName, and provides an onElementCreated method to configure that element before it's injected into the DOM:

// Create a `video` tag, and set its `src` and some `style` properties...
HtmlElementView.fromTag('video', onElementCreated: (Object video) {
  video as web.HTMLVideoElement;
  video.src = 'https://interactive-examples.mdn.mozilla.net/media/cc0-videos/flower.mp4';
  video.style.width = '100%';
  video.style.height = '100%';
  // other customizations to the element...
});

To learn more about the way to interact with DOM APIs, check out the HTMLVideoElement class in package:web.

To learn more about the video Object that is cast to web.HTMLVideoElement, check out Dart's JS Interoperability documentation.

If you need more control over generating the HTML code you inject, you can use the primitives that Flutter uses to implement the fromTagName constructor. In this scenario, register your own HTML Element factory for each type of HTML content that needs to be added to your app.

The resulting code is more verbose, and has two steps per platform view type:

1. Register the HTML Element Factory using platformViewRegistry.registerViewFactory provided by dart:ui_web.
2. Place the widget with the desired viewType with HtmlElementView('viewType') in your app's widget tree.

For more details about this approach, check out HtmlElementView widget docs.

Embedding a full HTML page inside a Flutter app is such a common feature, that the Flutter team offers a plugin to do so:

• package:webview_flutter