目前正在开发一个我想使用AppCompat的项目,并且在大多数页面上都要求设置标题和副标题.
它根本不能使用AppCompat – 既不设置属性也不使用自定义视图.
不使用AppCompat时,两者都按预期工作.完整的源代码可用here所以如果你好奇的话就运行应用程序:)
using System.ComponentModel;
using Android.App;
using Android.Widget;
using App1.Droid.Renderers;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;
#if __APPCOMPAT__
using NavigationRenderer = Xamarin.Forms.Platform.Android.AppCompat.NavigationPageRenderer;
#else
using NavigationRenderer = Xamarin.Forms.Platform.Android.NavigationRenderer;
#endif
[assembly: ExportRenderer(typeof(NavigationPage),typeof(NavigationPageRenderer))]
namespace App1.Droid.Renderers
{
public class NavigationPageRenderer : NavigationRenderer
{
protected override void OnElementChanged(ElementChangedEventArgs<NavigationPage> e)
{
base.OnElementChanged(e);
SetCustomView(e.NewElement.CurrentPage.GetType().Name);
}
private void SetCustomView(string view)
{
var activity = (Activity)Context;
#if __APPCOMPAT__
var actionBar = ((FormsAppCompatActivity)Context).SupportActionBar;
#else
var actionBar = activity.ActionBar;
#endif
actionBar.Title = view;
actionBar.Subtitle = " -> " + view;
var abv = new LinearLayout(activity)
{
Orientation = Orientation.Vertical
};
var main = new TextView(activity)
{
Text = view,};
main.SetTextColor(Color.Aqua.ToAndroid());
main.SetPadding(4,4,2,6);
abv.AddView(main);
abv.AddView(new TextView(activity)
{
Text = " -> " + view
});
actionBar.SetDisplayShowCustomEnabled(true);
actionBar.CustomView = abv;
}
protected override void OnElementPropertyChanged(object sender,PropertyChangedEventArgs e)
{
base.OnElementPropertyChanged(sender,e);
if (e.PropertyName.Equals("CurrentPage"))
{
SetCustomView(((NavigationPage)sender).CurrentPage.GetType().Name);
}
}
}
}
解决方法
所以它看起来像NavigationPage
uses its own Toolbar instance.这就是为什么在SupportActionBar上设置属性没有做任何事情.
我能够通过覆盖OnViewAdded()来获得它的工作,以便在添加时获得对新工具栏的引用：
public override void OnViewAdded(Android.Views.View child)
{
base.OnViewAdded(child);
if (child.GetType() == typeof(Support.Toolbar))
toolbar = (Support.Toolbar)child;
}
然后使用SetCustomView()内部的引用来设置Subtitle,因为Title已经自动设置.
