那些遇到过的问题

如果我的手机处于浅色或深色模式，如何制作带有文本和背景颜色的 Android 启动画面？

Ala*_*an2 5 android xamarin.android xamarin android-studio

我已经为此工作了一段时间，不幸的是，如果不使用图像，我无法达到预期的效果。我已经研究了 Stack Overflow 和几乎所有地方，但仍然没有找到完全可以做到这一点的解决方案。

我仍在尝试做的是：

  • 手机处于浅色模式 > 启动画面为白色背景，中间是黑色的 ABC 字样

  • 手机处于暗模式 > 启动画面为黑色背景，中间为白色的 ABC 字样

这是我到目前为止所拥有的：

SplashActivity.cs

namespace Japanese.Droid
{
    [Activity(Label = "Anki+", Theme = "@style/LaunchTheme", MainLauncher = true, NoHistory = true)]
    public class SplashActivity : Activity
    {
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样式文件

<style name="LaunchTheme" parent="Theme.AppCompat">
    <item name="android:windowBackground">@drawable/splash_screen</item>
    <item name="android:navigationBarColor">#ffffff</item>
</style>
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飞溅屏幕.xaml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@android:color/white"/>
    <item>
        <bitmap android:src="@drawable/splash_logo"
                android:tileMode="disabled"
                android:gravity="center"
                android:layout_gravity="center"/>
    </item>
</layer-list>
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splash_screen_night.xaml

<?xml version="1.0" encoding="UTF-8" ?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="@android:color/black"/>
    <item>
        <bitmap android:src="@drawable/splash_logo"
                android:tileMode="disabled"
                android:gravity="center"
                android:layout_gravity="center"/>
    </item>
</layer-list>
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飞溅活动

using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Support.V7.App;
using Android.Views;

namespace Test.Droid
{
    [Activity(Label = "Test+", Theme = "@style/LaunchTheme", MainLauncher = true, NoHistory = true)]
    public class SplashActivity : Activity
    {

        public override void OnCreate(Bundle savedInstanceState, PersistableBundle persistentState)
        {
            base.OnCreate(savedInstanceState, persistentState);

            //==================================== Code to hide the bottom 3 buttons on Android.
            int uiOptions = (int)Window.DecorView.SystemUiVisibility;
            uiOptions |= (int)SystemUiFlags.LowProfile;
            uiOptions |= (int)SystemUiFlags.Fullscreen;
            uiOptions |= (int)SystemUiFlags.HideNavigation;
            uiOptions |= (int)SystemUiFlags.ImmersiveSticky;
            Window.DecorView.SystemUiVisibility = (StatusBarVisibility)uiOptions;
            //===================================

            base.SetTheme(Resource.Style.MainTheme);
            Xamarin.Essentials.Platform.Init(this, savedInstanceState);
        }

        // Launches the startup task
        protected override void OnResume()
        {
            base.OnResume();

            //==================================== Code to hide the bottom 3 buttons on Android.
            int uiOptions = (int)Window.DecorView.SystemUiVisibility;
            uiOptions |= (int)SystemUiFlags.LowProfile;
            uiOptions |= (int)SystemUiFlags.Fullscreen;
            uiOptions |= (int)SystemUiFlags.HideNavigation;
            uiOptions |= (int)SystemUiFlags.ImmersiveSticky;
            Window.DecorView.SystemUiVisibility = (StatusBarVisibility)uiOptions;
            //===================================

            System.Threading.Tasks.Task startupWork = new System.Threading.Tasks.Task(() => { SimulateStartup(); });
            startupWork.Start();
        }


        // Simulates background work that happens behind the splash screen
        async void SimulateStartup()
        {
            await System.Threading.Tasks.Task.Delay(1000); // Simulate a bit of startup work.
            StartActivity(new Intent(Application.Context, typeof(MainActivity)));
        }

        public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Android.Content.PM.Permission[] grantResults)
        {
            Xamarin.Essentials.Platform.OnRequestPermissionsResult(requestCode, permissions, grantResults);
            base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
        }

        public override void OnBackPressed() { }
    }
}
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这使用了图像，但我想用文本来做。

有谁知道一种方法来做到这一点。我已经尽可能多地研究了这一点，向两个 Android 开发人员寻求帮助，但仍然没有人能想出一个简单的解决方案来做到这一点而不使用图像。

是否可以仅使用文本而不是Xamarin Android 应用程序的图像来执行此操作？

Nik*_*hil 5

为了实现这一点，您需要在 Android 项目的 Layout 文件夹中创建一个 SplashScreen.xml。此外，您还需要在两个文件夹中创建样式：values 和values-night。

您还需要一个单独的 SplashActivity.cs。我附上代码。

  1. 启动画面.xml

      <?xml version="1.0" encoding="utf-8"?>
  <RelativeLayout 
   xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:gravity="center_vertical" 
   android:background="#fff"
   android:id="@+id/splashview">
   <TextView
        android:id="@+id/txtAppVersion"
        android:text="Anki+"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_marginLeft="30dp"
        android:layout_marginBottom="30dp"
        android:textColor="#000"
        android:textSize="24sp"
        android:gravity="center_vertical" 
        android:layout_centerHorizontal="true"/>
    </RelativeLayout>
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  2. 值文件夹中的 Styles.xml。

    <style name="MainTheme" parent="MainTheme.Base">
    <item name="android:textAllCaps">false</item>
</style>

<style name="MainTheme.Base" parent="Theme.AppCompat.Light.DarkActionBar">
    <item name="windowNoTitle">true</item>
    <item name="windowActionBar">false</item>
    <item name="windowActionModeOverlay">true</item>
    <item name="elevation">0dp</item>
</style>

<style name="LaunchTheme" parent="Theme.AppCompat">
    <item name="android:windowNoTitle">true</item>
    <item name="android:windowActionBar">false</item>
    <item name="android:windowFullscreen">true</item>
    <item name="android:windowContentOverlay">@null</item>
    <item name="android:windowDisablePreview">true</item>
</style>
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  3. Values-night 文件夹中的 Styles.xml。

    <style name="MainTheme" parent="MainTheme.Base">
    <item name="android:textAllCaps">false</item>
</style>

<style name="MainTheme.Base" parent="Theme.AppCompat.Light.DarkActionBar">
    <item name="windowNoTitle">true</item>
    <item name="windowActionBar">false</item>
    <item name="windowActionModeOverlay">true</item>
    <item name="elevation">0dp</item>
</style>

<style name="LaunchTheme" parent="Theme.AppCompat">
    <item name="android:windowNoTitle">true</item>
    <item name="android:windowActionBar">false</item>
    <item name="android:windowFullscreen">true</item>
    <item name="android:windowContentOverlay">@null</item>
    <item name="android:windowDisablePreview">true</item>
</style>
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  4. SplashActivity.cs

    using System;
using Android.App;
using Android.Content;
using Android.Content.Res;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Plugin.CurrentActivity;

namespace MyProject.Droid
{
    [Activity(Label = "MyProject+", Theme = "@style/LaunchTheme", 
MainLauncher = true, NoHistory = true)]
public class SplashActivity : Activity
{

    public override void OnCreate(Bundle savedInstanceState, PersistableBundle persistentState)
    {
        base.OnCreate(savedInstanceState, persistentState);

        //==================================== Code to hide the bottom 3 buttons on Android.
        int uiOptions = (int)Window.DecorView.SystemUiVisibility;
        uiOptions |= (int)SystemUiFlags.LowProfile;
        uiOptions |= (int)SystemUiFlags.Fullscreen;
        uiOptions |= (int)SystemUiFlags.HideNavigation;
        uiOptions |= (int)SystemUiFlags.ImmersiveSticky;
        Window.DecorView.SystemUiVisibility = (StatusBarVisibility)uiOptions;
        //===================================

        base.SetTheme(Resource.Style.MainTheme);
        Xamarin.Essentials.Platform.Init(this, savedInstanceState);
    }

    // Launches the startup task
    protected override void OnResume()
    {
        base.OnResume();
        SetContentView(Resource.Layout.SplashScreen);
        bool isDarkTheme;

        //var isDarkTheme = Preferences.Get("isDarkTheme", false);
        if (Build.VERSION.SdkInt >= BuildVersionCodes.Froyo)
        {
            var uiModeFlags = CrossCurrentActivity.Current.AppContext.Resources.Configuration.UiMode & UiMode.NightMask;
            if (uiModeFlags == UiMode.NightYes)
                isDarkTheme = true;
            else isDarkTheme = false;
        }
        else
            isDarkTheme = false;

        if (isDarkTheme)
        {
            FindViewById<RelativeLayout>(Resource.Id.splashview).SetBackgroundColor(Android.Graphics.Color.ParseColor("#000000"));
            FindViewById<TextView>(Resource.Id.txtAppVersion).SetTextColor(Android.Graphics.Color.ParseColor("#FFFFFF"));
        }
        else
        {
            FindViewById<RelativeLayout>(Resource.Id.splashview).SetBackgroundColor(Android.Graphics.Color.ParseColor("#FFFFFF"));
            FindViewById<TextView>(Resource.Id.txtAppVersion).SetTextColor(Android.Graphics.Color.ParseColor("#000000"));
        }

        // FindViewById<TextView>(Resource.Id.txtAppVersion).Text = $"Version {PackageManager.GetPackageInfo(PackageName, 0).VersionName}";

        //==================================== Code to hide the bottom 3 buttons on Android.
        int uiOptions = (int)Window.DecorView.SystemUiVisibility;
        uiOptions |= (int)SystemUiFlags.LowProfile;
        uiOptions |= (int)SystemUiFlags.Fullscreen;
        uiOptions |= (int)SystemUiFlags.HideNavigation;
        uiOptions |= (int)SystemUiFlags.ImmersiveSticky;
        Window.DecorView.SystemUiVisibility = (StatusBarVisibility)uiOptions;
        //===================================

        System.Threading.Tasks.Task startupWork = new System.Threading.Tasks.Task(() => { SimulateStartup(); });
        startupWork.Start();
    }

    // Simulates background work that happens behind the splash screen
    async void SimulateStartup()
    {
        await System.Threading.Tasks.Task.Delay(1000); // Simulate a bit of startup work.
        StartActivity(new Intent(Application.Context, typeof(MainActivity)));
    }

    public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Android.Content.PM.Permission[] grantResults)
    {
        Xamarin.Essentials.Platform.OnRequestPermissionsResult(requestCode, permissions, grantResults);
        base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
    }

    public override void OnBackPressed() { }
}
}
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