c# - 自定义 UI 绑定(bind)对象到控件

Question

我正在创建自己的 UI 绑定(bind)系统，它将控件绑定(bind)到它们的关联对象。有什么比使用一系列 if 语句更好的呢？如果我添加新的控件来提供新的轨道项，我不想每次都更新这一系列的 if 语句。

TimelineTrackControl control;
Type objectType = track.GetType();

if (objectType == typeof(ShotTrack))
{
    control = new ShotTrackControl();
}
else if (objectType == typeof(AudioTrack))
{
    control = new AudioTrackControl();
}
else if (objectType == typeof(GlobalItemTrack))
{
    control = new GlobalItemTrackControl();
}
else
{
    control = new TimelineTrackControl();
}

control.TargetTrack = track;
timelineTrackMap.Add(track, control);

Answer 1

你可以:

1. 创建 Dictionary<Type, Type>包含轨道类型和相应的控件类型:

   private static readonly Dictionary<Type, Type> ControlTypes = new Dictionary<Type, Type>
   {
       { typeof(ShotTrack), typeof(ShotTrackControl) },
       ...
   };
   

   获取相应的控件:

   control = Activator.CreateInstance(ControlTypes[track.GetType()]);
   

2. 创建 Dictionary<Type, Func<Control>>包含轨道类型和相应的控件创建者:

   private static readonly Dictionary<Type, Func<Control>> ControlTypes = new Dictionary<Type, Func<Control>>
   {
       { typeof(ShotTrack), () => new ShotTrackControl() },
       ...
   };
   

   创建一个新的对应控件:

   control = ControlTypes[track.GetType()]();
   

3. 定义一个存储相应控件类型的自定义属性:

   [AttributeUsage(AttributeTargets.Class, AllowMultiple = false)]
   public class TrackControlAttribute : Attribute
   {
       public readonly Type ControlType;
   
       public TrackControlAttribute(Type controlType)
       {
           ControlType = controlType;
       }
   }
   
   [TrackControl(typeof(ShotTrackControl))]
   public class ShotTrack
   {
       ...
   }
   

   创建一个新的对应控件:

   object[] attrs = track.GetType().GetCustomAttributes(typeof(TrackControlAttribute), true);
   if (attrs.Length != 0);
       control = Activator.CreateInstance(((TrackControlAttribute)attrs[0]).ControlType);
   

   编辑
   在第三个选项中修复了错误。