How to make HybridWebView go back when device back button is pressed - android-webview

Question

I have a Xamarin.Forms app with a HybridWebView and a HybridWebViewRenderer in the Droid project.
I am trying to make the web view navigate back when the device's back button is pressed.
It looks pretty simple if I was just using a Xamarin.Forms WebView within my page. I would just do it like this...
protected override bool OnBackButtonPressed()
{
_webView.GoBack();
return true;
}
But the HybridWebView does not have a GoBack() method.
In my Droid project, the only place where I have access to the WebView is in the HybridWebViewRenderer but I cannot listen for the OnBackButtonPressed event here.
Anyone know how I can make a HybridWebView navigate back when the device's back button is pressed?

Answer 1

Calling window.history.back(); from Javascript might be a dirty solution.
Also, calling the renderer's method from a PCL class should not be a problem.
The PCL class:
public class MyHybridWebView : HybridWebView
{
public event EventHandler<EventArgs> DoSomeNative;
public void CallNative()
{
DoSomeNative(this, EventArgs.Empty);
}
}
The renderer:
public class MyHybridWebViewRenderer : HybridWebViewRenderer
{
protected override void OnElementChanged(ElementChangedEventArgs<View> e)
{
base.OnElementChanged(e);
if (e.OldElement != null || Element == null)
{
return;
}
(e.NewElement as MyHybridWebView).DoSomeNative += (sender, args) =>
{
//Do something
//Don't forget to unsubscribe in Dispose
};
}
}

Answer 2

My solution that is working are as follows:
HybridWebView that extends the View:
I created 2 event listeners and 1 bool property.
public event EventHandler<EventArgs> GoBackOnNativeEventListener;
public event EventHandler<EventArgs> CanGoBackOnNativeEventListener;
public bool _CanGoBack { get; set; }
Methods:
public bool GoBack()
{
GoBackOnNative();
return true;
}
private void GoBackOnNative()
{
GoBackOnNativeEventListener(this, EventArgs.Empty);
}
public bool CanGoBack()
{
CanGoBackOnNative();
return _CanGoBack;
}
private void CanGoBackOnNative()
{
CanGoBackOnNativeEventListener(this, EventArgs.Empty);
}
In iOS render
public class WebViewRender : HybridWebViewRenderer
{
protected override void OnElementChanged(ElementChangedEventArgs e)
{
base.OnElementChanged(e);
if (Control != null && e.NewElement != null)
{
InitializeCommands((ClickableWebView)e.NewElement);
}
}
private void InitializeCommands(ClickableWebView element)
{
element.RefreshCommand = () =>
{
Control?.Reload();
};
element.GoBackCommand = () =>
{
var ctrl = Control;
if (ctrl == null)
return;
if (ctrl.CanGoBack)
ctrl.GoBack();
};
element.CanGoBackFunction = () =>
{
var ctrl = Control;
if (ctrl == null)
return false;
return ctrl.CanGoBack;
};
element.CanGoForwardFunction = () =>
{
var ctrl = Control;
if (ctrl == null)
return false;
return ctrl.CanGoForward;
};
element.GoFrowardCommand = () =>
{
var ctrl = Control;
if (ctrl == null)
return;
if (ctrl.CanGoForward)
ctrl.GoForward();
};
}
}
On renderer I bind the listener:
e.NewElement.GoBackOnNativeEventListener += (sender, args) =>
{
Control.GoBack();
};
e.NewElement.CanGoBackOnNativeEventListener += (sender, args) =>
{
_cangoback = Control.CanGoBack();
var hybridWebView = Element as HybridWebView;
hybridWebView._CanGoBack = _cangoback;
};
Finally on xaml.cs, on method OnBackButtonPressed(), I do like:
if (hybridWebView.CanGoBack())
{
hybridWebView.GoBack();
return true;
}
else
return base.OnBackButtonPressed();