How to add custom view in Center of ToolbarItem from Renderer

问题

I am adding custom view in Center of ToolbarItem from NavigationPageRenderer for android. But it doesn't seems to be working. See my code below

public class CustomNavigationPageRenderer : NavigationPageRenderer
{
   public override void OnViewAdded(Android.Views.View child)
    {
        base.OnViewAdded(child);
        var lastPageElement?.Navigation?.NavigationStack?.Last().ToString();

        if (lastPage == "ParentDashboardPage")
        {
            LayoutInflater li = LayoutInflater.From(Context);
            Android.Views.View customView = li.Inflate(Resource.Layout.customActionbar, null);
            var _toolbar = FindViewById<Android.Support.V7.Widget.Toolbar>(Resource.Id.toolbar);
            _toolbar.RemoveAllViews();
            //_toolbar.AddView(text,new Toolbar.LayoutParams(GravityFlags.Center)); Even this not working
            _toolbar.AddView(customView);
        }
    }
}

customActionbar.axml file below:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content">
    <TextView
        android:layout_width="wrap_content"
        android:text=" Dashboard"
        android:textColor="@color/white"
        android:layout_gravity="center"
        android:id="@+id/tvActionBarTitle"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:layout_centerVertical="true"
        android:layout_centerInParent="true"
        android:textSize="17dp" />
    <ImageView
        android:layout_gravity="right"
        android:layout_width="30dp"
        android:layout_height="wrap_content"
        android:id="@+id/item2"
        android:src="@drawable/bell"
        android:layout_alignParentRight="true" />
</RelativeLayout>

Output screensshot below:

回答1:

If you are using a Xamarin.Forms app based on Shell then you can easily achieve this using Shell.TitleView without the need of a custom renderer, define your title content, bind it or even style it as you like.

Inside your ContentPage:

<Shell.TitleView>
    <StackLayout Orientation="Horizontal" Spacing="0">
        <Label Text="Dashboard"
               Opacity="1"
               FontAttributes="Bold"
               FontSize="20"
               TextColor="White"
               HorizontalOptions="CenterAndExpand"
               HorizontalTextAlignment="Center"
               VerticalTextAlignment="Center"/>

        <ImageButton Source="Bell.png"
                     VerticalOptions="CenterAndExpand"
                     HorizontalOptions="End"
                     BackgroundColor="transparent"/>
    </StackLayout>
</Shell.TitleView>

Also if you need to apply some special adjustments platform-dependent you can use OnPlatform.

Why I choosed those attributes of the style?

To be as close as possible to native default text title. Related question:

Defining Shell.TitleView while preserving the title text of tabs in shell, but seems showing in a different font

来源：https://stackoverflow.com/questions/49913799/how-to-add-custom-view-in-center-of-toolbaritem-from-renderer

标签