[英]How can I change style of the original tabbed page bar (android with xamarin.forms)?
[英]Hide bottom tab bar in tabbed page in Android with Xamarin.Forms
我创建了一个标签页并将导航栏设置在底部。 现在我需要隐藏特定页面上的导航栏。 对于 iOS,我使用了此渲染器: here ,但我找不到 Android 的类似解决方案。 我用这个试过:
public TabbedPageRendererDroid(Context context) : base(context)
{
}
protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
{
base.OnElementPropertyChanged(sender, e);
if (e.PropertyName == "IsHidden")
{
TabLayout TabsLayout = null;
for (int i = 0; i < ChildCount; ++i)
{
Android.Views.View view = (Android.Views.View)GetChildAt(i);
if (view is TabLayout)
TabsLayout = (TabLayout)view;
}
if ((Element as CustomTabbedPage).IsHidden)
{
TabsLayout.Visibility = ViewStates.Invisible;
}
else
{
TabsLayout.Visibility = ViewStates.Visible;
}
}
}
这仅适用于顶部的普通导航栏,但不适用于底部导航栏,并且应用程序崩溃并出现此错误: System.NullReferenceException
。
Android 是否有任何解决方案,在此先感谢。
如果要在自定义渲染器中隐藏它,可以使用以下代码隐藏bottom navigation bar
,
public class ExtendedTabbedPageRenderer: TabbedPageRenderer
{
public ExtendedTabbedPageRenderer(Context context) : base(context) { }
protected override void OnElementChanged(ElementChangedEventArgs<TabbedPage> e)
{
base.OnElementChanged(e);
if (e.OldElement == null && e.NewElement != null)
{
for (int i = 0; i <= this.ViewGroup.ChildCount - 1; i++)
{
var childView = this.ViewGroup.GetChildAt(i);
if (childView is ViewGroup viewGroup)
{
for (int j = 0; j <= viewGroup.ChildCount - 1; j++)
{
var childRelativeLayoutView = viewGroup.GetChildAt(j);
if (childRelativeLayoutView is BottomNavigationView)
{
((BottomNavigationView)childRelativeLayoutView).Visibility = ViewStates.Gone;
}
}
}
}
}
}
顺便说一句,如果您显示一些需要使用 Navigation 隐藏BottomNavigationView
的页面。 您不需要使用上面的代码。 只需使用await Navigation.PushAsync(new ItemDetailPage(new ItemDetailViewModel(item)));
,这个BottomNavigationView
会像这个GIF一样被隐藏。
@Leon Lu 的贡献 - MSFT 帮助我找到了解决方案。 这是与此一起使用的 Android 渲染器。
using System;
using System.ComponentModel;
using Android.Content;
using Android.Support.Design.Widget;
using Android.Views;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android.AppCompat;
[assembly: ExportRenderer(typeof(CustomTabbedPage), typeof(TabbedPageRendererDroid))]
namespace myApp.Droid.Platform
{
[Obsolete]
public class TabbedPageRendererDroid : TabbedPageRenderer
{
private int TabBarHeight;
public TabbedPageRendererDroid(Context context) : base(context) { }
protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
{
base.OnElementPropertyChanged(sender, e);
ShowOrHideBottomNavBar((Element as CustomTabbedPage).IsHidden);
}
private void ShowOrHideBottomNavBar(bool hide)
{
for (int i = 0; i <= this.ViewGroup.ChildCount - 1; i++)
{
var childView = this.ViewGroup.GetChildAt(i);
if (childView is ViewGroup viewGroup)
{
for (int j = 0; j <= viewGroup.ChildCount - 1; j++)
{
var childRelativeLayoutView = viewGroup.GetChildAt(j);
if (childRelativeLayoutView is BottomNavigationView)
{
if (((BottomNavigationView)childRelativeLayoutView).LayoutParameters.Height != 0) TabBarHeight = ((BottomNavigationView)childRelativeLayoutView).LayoutParameters.Height;
var parameters = ((BottomNavigationView)childRelativeLayoutView).LayoutParameters;
parameters.Height = hide ? 0 : TabBarHeight;
((BottomNavigationView)childRelativeLayoutView).LayoutParameters = parameters;
}
}
}
}
}
}
}
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