问题描述
我想动态更改活动标签指示器的颜色.多个来源(
并且应该在 Xaml 中删除此属性:
<OnPlatform x:TypeArguments="颜色"><On Platform="Android" Value="Green"/></OnPlatform></TabbedPage.BarTextColor>
I want to change the color of the active tab indictor dynamically. Multiple sources (Xamarin support, Xamarin docs) suggest there is a method that does just this, but it has to be done as a platform-specific for android
On<Android>().SetBarSelectedItemColor(color)
However, I'm testing this from the stock android template in Visual studio and it has no effect. It doesn't matter if I run it in the TabbedPage constructor, or as an event later.
Version info:
Xamarin Forms: 3.5.0.129452
Visual Studio: 15.9.7
Xamarin.Android SDK: 9.1.7.0
Do platform-specifics only work under certain conditions?
Code:
Other than a few color binding experiments, it is stock code.
MainPage.xaml.cs (Note: App.OnChange does get triggered and the code is executed as expected)
using System;
using Xamarin.Forms;
using Xamarin.Forms.PlatformConfiguration.AndroidSpecific;
using Xamarin.Forms.Xaml;
namespace App1.Views
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class MainPage : Xamarin.Forms.TabbedPage
{
public MainPage()
{
InitializeComponent();
App.OnChange((prop, value) =>
{
if (prop == App.ActiveColorKey)
{
On<Xamarin.Forms.PlatformConfiguration.Android>().SetBarSelectedItemColor(Color.FromHex(value));
On<Xamarin.Forms.PlatformConfiguration.Android>().SetBarItemColor(Color.FromHex(value));
}
});
}
}
}
MainPage.xaml
<?xml version="1.0" encoding="utf-8" ?>
<TabbedPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:views="clr-namespace:App1.Views"
x:Class="App1.Views.MainPage" BarBackgroundColor="{DynamicResource TabColor}">
<TabbedPage.BarTextColor>
<OnPlatform x:TypeArguments="Color">
<On Platform="Android" Value="Green" />
</OnPlatform>
</TabbedPage.BarTextColor>
<TabbedPage.Children>
<NavigationPage Title="Browse">
<NavigationPage.Icon>
<OnPlatform x:TypeArguments="FileImageSource">
<On Platform="iOS" Value="tab_feed.png"/>
</OnPlatform>
</NavigationPage.Icon>
<x:Arguments>
<views:ItemsPage />
</x:Arguments>
</NavigationPage>
<NavigationPage Title="About dog" BarBackgroundColor="Red" BackgroundColor="Yellow">
<NavigationPage.Icon>
<OnPlatform x:TypeArguments="FileImageSource">
<On Platform="iOS" Value="tab_about.png"/>
</OnPlatform>
</NavigationPage.Icon>
<x:Arguments>
<views:AboutPage />
</x:Arguments>
</NavigationPage>
</TabbedPage.Children>
</TabbedPage>
From official document , you can set static color for BarSelectedItem as follow:
<TabbedPage ...
xmlns:android="clr-namespace:Xamarin.Forms.PlatformConfiguration.AndroidSpecific;assembly=Xamarin.Forms.Core"
android:TabbedPage.ToolbarPlacement="Bottom"
android:TabbedPage.BarItemColor="Black"
android:TabbedPage.BarSelectedItemColor="Red">
...
</TabbedPage>
Solution:
By using DynamicResource,it can set BarSelectedItemColor dynamically:
android:TabbedPage.BarSelectedItemColor="Red"
To this:
android:TabbedPage.BarSelectedItemColor="{DynamicResource BarSelectedItemColor}"
Complete sample code:
<TabbedPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:TabbedPageDemo;assembly=TabbedPageDemo"
x:Class="TabbedPageDemo.TabbedPageDemoPage"
xmlns:android="clr-namespace:Xamarin.Forms.PlatformConfiguration.AndroidSpecific;assembly=Xamarin.Forms.Core"
android:TabbedPage.ToolbarPlacement="Bottom"
android:TabbedPage.BarItemColor="Black"
android:TabbedPage.BarSelectedItemColor="{DynamicResource BarSelectedItemColor}">
<TabbedPage.Resources>
<ResourceDictionary>
<Color x:Key="BlueColor">Blue</Color>
<Color x:Key="YellowColor">Yellow</Color>
</ResourceDictionary>
</TabbedPage.Resources>
...
</TabbedPage>
Where you want to change color can be set in ContentPage
as follow:
Resources["BarSelectedItemColor"] = Resources["BlueColor"];
...
Resources["BarSelectedItemColor"] = Resources["YellowColor"];
If you do not need use this renderer,you should comment its reference. My Forms answer code will work.
//[assembly: ExportRenderer(typeof(TabbedPage), typeof(TabRenderer))]
And should remove this property in Xaml:
<TabbedPage.BarTextColor>
<OnPlatform x:TypeArguments="Color">
<On Platform="Android" Value="Green" />
</OnPlatform>
</TabbedPage.BarTextColor>
这篇关于Xamarin Forms 平台特定的 SetBarSelectedItemColor 没有效果的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!