Question

因此，我的Xamarin应用程序中有一个工具栏，我想更改Android应用程序的后退按钮的颜色（我认为iOS应用程序的蓝色可以很好地适应我的背景）。

我知道已经问过这个问题，但是这些解决方案都不适合我。（我用https://xamgirl.com/transparent-navigation-bar-in-xamarin-forms/将工具栏更改为透明，也许很重要。）

有人可以帮我吗？

CustomNavigationPage.cs

using Xamarin.Forms;

namespace TransparentNavBarXForms
{
    public partial class CustomNavigationPage : NavigationPage
    {
        public CustomNavigationPage() : base()
        {
            InitializeComponent();
        }

        public CustomNavigationPage(Page root) : base(root)
        {
            InitializeComponent();
        }

        public bool IgnoreLayoutChange { get; set; } = false;

        protected override void OnSizeAllocated(double width, double height)
        {
            if (!IgnoreLayoutChange)
                base.OnSizeAllocated(width, height);
        }
    }
}

CustomNavigationPage.xaml

<?xml version="1.0" encoding="utf-8" ?>
<NavigationPage
    xmlns="http://xamarin.com/schemas/2014/forms"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
    x:Class="TransparentNavBarXForms.CustomNavigationPage"
    xmlns:iOS="clr-namespace:Xamarin.Forms.PlatformConfiguration.iOSSpecific;assembly=Xamarin.Forms.Core"
    iOS:NavigationPage.IsNavigationBarTranslucent="True"
    BarTextColor="White">
    <NavigationPage.BarBackgroundColor>
        <OnPlatform x:TypeArguments="Color">
            <On Platform="Android, iOS" Value="Transparent" />
        </OnPlatform>
    </NavigationPage.BarBackgroundColor>
</NavigationPage>

iOSCustomNavigationRenderer

using System.ComponentModel;
using Xamarin.Forms;
using Xamarin.Forms.Platform.iOS;
using UIKit;
using System;
using TransparentNavBarXForms;
using TransparentNavBarXForms.iOS.Renderers;

[assembly: ExportRenderer(typeof(CustomNavigationPage), typeof(CustomNavigationRenderer))]
namespace TransparentNavBarXForms.iOS.Renderers
{
    public class CustomNavigationRenderer : NavigationRenderer
    {
        public override void ViewDidLoad()
        {
            base.ViewDidLoad();

            UINavigationBar.Appearance.SetBackgroundImage(new UIImage(), UIBarMetrics.Default);
            UINavigationBar.Appearance.ShadowImage = new UIImage();
            UINavigationBar.Appearance.BackgroundColor = UIColor.Clear;
            UINavigationBar.Appearance.TintColor = UIColor.White;
            UINavigationBar.Appearance.BarTintColor = UIColor.Clear;
            UINavigationBar.Appearance.Translucent = true;
        }

        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
            }

            base.Dispose(disposing);
        }
    }
}

CustomNavigationPageRenderer

using Android.Support.V7.Widget;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;
using Xamarin.Forms.Platform.Android.AppCompat;
using AView = Android.Views.View;
using Android.App;
using Android.Content;
using Android.Widget;
using TransparentNavBarXForms;
using TransparentNavBarXForms.Droid.Renderers;

[assembly: ExportRenderer(typeof(CustomNavigationPage), typeof(CustomNavigationPageRenderer))]
namespace TransparentNavBarXForms.Droid.Renderers
{
    public class CustomNavigationPageRenderer : NavigationPageRenderer
    {
        public CustomNavigationPageRenderer(Context context) : base(context)
        {

        }

        IPageController PageController => Element as IPageController;
        CustomNavigationPage CustomNavigationPage => Element as CustomNavigationPage;

        protected override void OnLayout(bool changed, int l, int t, int r, int b)
        {
            CustomNavigationPage.IgnoreLayoutChange = true;
            base.OnLayout(changed, l, t, r, b);
            CustomNavigationPage.IgnoreLayoutChange = false;

            int containerHeight = b - t;

            PageController.ContainerArea = new Rectangle(0, 0, Context.FromPixels(r - l), Context.FromPixels(containerHeight));

            for (var i = 0; i < ChildCount; i++)
            {
                AView child = GetChildAt(i);

                if (child is Android.Support.V7.Widget.Toolbar)
                {
                    continue;
                }

                child.Layout(0, 0, r, b);
            }
        }
    }
}

App.xaml.cs

public partial class App : Application
    {
        public App()
        {
            InitializeComponent();

            MainPage = new CustomNavigationPage(new MainPage());
        }
    }

Answer 1

不使用自定义渲染器就可以尝试的一件事是创建自己的导航工具栏。例如，您创建一个StackLayout myCustonNavbar;，在其中插入所需的所有元素（如特定颜色的后退按钮），然后可以使用NavigationPage.SetTitleView(this, myCustonNavbar)

Answer 2

您可以使用下面的style.xml更改后退按钮的颜色。

 <style name="MainTheme.Base2" parent="Theme.AppCompat.Light.NoActionBar">
<item name="drawerArrowStyle">@style/DrawerArrowStyle</item>
</style>
<style name="DrawerArrowStyle" parent="@style/Widget.AppCompat.DrawerArrowToggle">
<item name="spinBars">true</item>
<item name="color">#2196F3</item>

在MainActivity中更改主题：

   [Activity(Label = "XamarinDemo", Icon = "@mipmap/icon", Theme = "@style/MainTheme.Base2", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation)]

原始后退按钮的颜色为白色：

我将后退按钮的颜色设置为蓝色：

在Xamarin.Android中更改后退按钮颜色

2 个答案: