为什么我的自定义字体在Android应用程序发布模式下被默认字体替换？

Question

当我以Debug模式构建和部署包含自定义字体的Xamarin.android应用程序时，一切正常。我可以在应用程序中看到自定义ttf字体。但是，当我以Release模式构建和部署相同的应用程序时，运行它时我会看到默认字体。是否需要添加某些必需权限才能使自定义字体在应用程序中可见？

以下是我在应用程序中使用字体的方式：

1. Convert method in converter class:

   protected override Typeface Convert(string fontName, Type targetType, object parameter, System.Globalization.CultureInfo culture)
   {
       try
       {
           if (!fontName.StartsWith(@"font/")) fontName = @"font/" + fontName;
           if (!fontName.EndsWith(".ttf")) fontName += ".ttf";
   
           if (!_cache.ContainsKey(fontName))
           {
               _cache[fontName] = Typeface.CreateFromAsset(Application.Context.Assets, fontName);
           }
   
           return _cache[fontName];
       }
       catch (Exception e)
       {
           Android.Util.Log.Error("AndroidFont", e.ToString());
   
           return Typeface.Default;
       }
   }
   

2. Item in AXML

   <?xml version="1.0" encoding="utf-8"?>
   <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:local="http://schemas.android.com/apk/res-auto"
   android:orientation="horizontal"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:background="#ffffff"              
             >
   <TextView
     android:layout_width="180dp"
     android:layout_height="wrap_content"
     android:textColor="#AAAAAA"
     local:MvxBind="Typeface StringToFont('Lato'), Converter=StringToFontConverter" /></LinearLayout>
   

3. Registering converter in Setup.cs

   protected override void FillTargetFactories(IMvxTargetBindingFactoryRegistry registry)
   {
       registry.RegisterFactory(new MvxCustomBindingFactory<View>("StringToFont", view => new BackgroundBinding(view)));
   }
   

TTF字体位于Assets / fonts目录中。我使用的是Visual Studio Community 2015（C＃）。

在Debug模式下一切正常，但当我切换到Release模式时，我的字体（Lato）被默认的Android字体替换了。为什么？

- RadekR

Answer 1

1. Create MvxViewFontBinding

   public abstract class MvxViewFontBinding : MvxAndroidTargetBinding
   {
       protected TextView TextView => (TextView)base.Target;
       public MvxViewFontBinding(TextView view) : base(view)
       {
       }
   
       public override MvxBindingMode DefaultMode => MvxBindingMode.OneWay;
   
       public override Type TargetType => typeof(Android.Graphics.Typeface);
   }
   

2. Create MvxViewCustomFontBinding

   public class MvxViewCustomFontBinding : MvxViewFontBinding
   {
       public MvxViewCustomFontBinding(TextView view) : base(view)
       {
       }
   
       protected override void SetValueImpl(object target, object value)
       {
           var textView = (TextView)target;
           textView?.SetTypeface((Android.Graphics.Typeface)value, Android.Graphics.TypefaceStyle.Normal);
       }
   }
   

3. Registering in Setup.cs

   protected override void FillTargetFactories(IMvxTargetBindingFactoryRegistry registry)
   {
       registry.RegisterFactory(new MvxCustomBindingFactory<TextView>("CustomFont", textView => new MvxViewCustomFontBinding(textView)));
       base.FillTargetFactories(registry);
   }
   

4. You can bind it on axml

   <?xml version="1.0" encoding="utf-8"?>
   <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
       xmlns:local="http://schemas.android.com/apk/res-auto"
       android:orientation="horizontal"
       android:layout_width="match_parent"
       android:layout_height="match_parent"
       android:background="#ffffff">
   <TextView
       android:layout_width="180dp"
       android:layout_height="wrap_content"
       android:textColor="#AAAAAA"
       local:MvxBind="CustomFont StringToFont('Lato')" /></LinearLayout>
   

- Binh Nguyen