c# - 缓冲 PropertyChanged 事件

Question

我有一个 wpf 应用程序，其中所有 viewModel 都继承自实现 INotifyPropertyChanged 的​​类 NotifyPropertyChangeClass(见下文)。

我想限制发送到 View 的通知，以避免由于发送太多通知而导致延迟。到目前为止，我实现的是使用响应式扩展示例方法延迟每个属性。

问题是 Gui 在 throttlingPeriod 之后刷新。像这样在周期开始时引发第一个事件会感觉更灵敏:

NotifyPropertyChangeClass 代码:

using System;
using System.ComponentModel;
using System.Reactive.Linq;

namespace MyNameSpace
{
    public class NotifyPropertyChangeClass : INotifyPropertyChanged
    {
        public NotifyPropertyChangeClass(int throttlingPeriod)
        {
            var obs = Observable.FromEventPattern<PropertyChangedEventHandler, PropertyChangedEventArgs>(
               h => this.privatePropertyChanged += h, h => this.privatePropertyChanged -= h);
            var groupedByName = obs.Select(o => o.EventArgs.PropertyName).GroupBy(x => x).SelectMany(o => o.Sample(TimeSpan.FromMilliseconds(throttlingPeriod)));
            groupedByName.Subscribe(o =>
            {
                PropertyChangedEventHandler handler = PropertyChanged;
                if (handler != null)
                    handler(this, new PropertyChangedEventArgs(o));
            });
        }
        public event PropertyChangedEventHandler PropertyChanged;
        private event PropertyChangedEventHandler privatePropertyChanged;

        protected virtual void OnPropertyChanged(string propertyName)
        {
            PropertyChangedEventHandler handler = privatePropertyChanged;
            if (handler != null)
                handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

我怎样才能实现我想要的？

Answer 1

我没试过，但你可以试试这个:

using System;
using System.ComponentModel;
using System.Reactive.Linq;

namespace MyNameSpace
{
    public class NotifyPropertyChangeClass : INotifyPropertyChanged
    {
        private bool _isThrottling = false;

        public NotifyPropertyChangeClass(int throttlingPeriod)
        {
            var obs = Observable.FromEventPattern<PropertyChangedEventHandler, PropertyChangedEventArgs>(
               h => this.privatePropertyChanged += h, h => this.privatePropertyChanged -= h);
            var groupedByName = obs.Select(o => o.EventArgs.PropertyName).GroupBy(x => x).SelectMany(o => o.Sample(TimeSpan.FromMilliseconds(throttlingPeriod)));
            groupedByName.Subscribe(o =>
            {
                PropertyChangedEventHandler handler = PropertyChanged;
                if (handler != null)
                    handler(this, new PropertyChangedEventArgs(o));
                _isThrottling = false;
            });
        }
        public event PropertyChangedEventHandler PropertyChanged;
        private event PropertyChangedEventHandler privatePropertyChanged;

        protected virtual void OnPropertyChanged(string propertyName)
        {
            // Will fire the first time, the event is raised
            if (!_isThrottling)
            {
                PropertyChangedEventHandler handler = PropertyChanged;
                if (handler != null)
                    handler(this, new PropertyChangedEventArgs(o));
            }

            // Setting to true here will suppress raising the public event 
            // for every subsequent call, until the event is raised
            // by the observable pattern and the flag is set to false again.
            _isThrottling = true;

            // Will always be raised
            PropertyChangedEventHandler handler = privatePropertyChanged;
            if (handler != null)
                handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}