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スレッドセーフなBindableBaseのつもり（UWPでシングルトンなModelのObservePropertyを複数ウィンドウにまたがって可能にしたかったやつ）
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| using System; | |
| using System.Collections.Generic; | |
| using System.ComponentModel; | |
| using System.Runtime.CompilerServices; | |
| using System.Threading; | |
| namespace NicoPlayerHohoema.FixPrism | |
| { | |
| /// <summary> | |
| /// Implementation of <see cref="INotifyPropertyChanged"/> to simplify models. | |
| /// </summary> | |
| public abstract class BindableBase : INotifyPropertyChanged | |
| { | |
| protected BindableBase() | |
| { | |
| } | |
| ReaderWriterLockSlim lockSlim = new ReaderWriterLockSlim(); | |
| Dictionary<SynchronizationContext, IList<PropertyChangedEventHandler>> _handlersByThread = new Dictionary<SynchronizationContext, IList<PropertyChangedEventHandler>>(); | |
| /// <summary> | |
| /// Occurs when a property value changes. | |
| /// </summary> | |
| public event PropertyChangedEventHandler PropertyChanged | |
| { | |
| add | |
| { | |
| lockSlim.EnterWriteLock(); | |
| try | |
| { | |
| var currentContext = SynchronizationContext.Current; | |
| if (_handlersByThread.TryGetValue(currentContext, out var list)) | |
| { | |
| list.Add(value); | |
| } | |
| else | |
| { | |
| _handlersByThread.Add(currentContext, new List<PropertyChangedEventHandler>() { value }); | |
| } | |
| } | |
| finally | |
| { | |
| lockSlim.ExitWriteLock(); | |
| } | |
| } | |
| remove | |
| { | |
| lockSlim.EnterWriteLock(); | |
| try | |
| { | |
| var currentContext = SynchronizationContext.Current; | |
| if (_handlersByThread.TryGetValue(currentContext, out var list)) | |
| { | |
| list.Remove(value); | |
| } | |
| } | |
| finally | |
| { | |
| lockSlim.ExitWriteLock(); | |
| } | |
| } | |
| } | |
| /// <summary> | |
| /// Checks if a property already matches a desired value. Sets the property and | |
| /// notifies listeners only when necessary. | |
| /// </summary> | |
| /// <typeparam name="T">Type of the property.</typeparam> | |
| /// <param name="storage">Reference to a property with both getter and setter.</param> | |
| /// <param name="value">Desired value for the property.</param> | |
| /// <param name="propertyName">Name of the property used to notify listeners. This | |
| /// value is optional and can be provided automatically when invoked from compilers that | |
| /// support CallerMemberName.</param> | |
| /// <returns>True if the value was changed, false if the existing value matched the | |
| /// desired value.</returns> | |
| protected virtual bool SetProperty<T>(ref T storage, T value, [CallerMemberName] string propertyName = null) | |
| { | |
| if (EqualityComparer<T>.Default.Equals(storage, value)) return false; | |
| storage = value; | |
| RaisePropertyChanged(propertyName); | |
| return true; | |
| } | |
| protected virtual bool SetProperty<T>(ref T? storage, T? value, [CallerMemberName] string propertyName = null) | |
| where T : struct | |
| { | |
| if (EqualityComparer<T?>.Default.Equals(storage, value)) | |
| return false; | |
| storage = value; | |
| RaisePropertyChanged(propertyName); | |
| return true; | |
| } | |
| /// <summary> | |
| /// Checks if a property already matches a desired value. Sets the property and | |
| /// notifies listeners only when necessary. | |
| /// </summary> | |
| /// <typeparam name="T">Type of the property.</typeparam> | |
| /// <param name="storage">Reference to a property with both getter and setter.</param> | |
| /// <param name="value">Desired value for the property.</param> | |
| /// <param name="propertyName">Name of the property used to notify listeners. This | |
| /// value is optional and can be provided automatically when invoked from compilers that | |
| /// support CallerMemberName.</param> | |
| /// <param name="onChanged">Action that is called after the property value has been changed.</param> | |
| /// <returns>True if the value was changed, false if the existing value matched the | |
| /// desired value.</returns> | |
| protected virtual bool SetProperty<T>(ref T storage, T value, Action onChanged, [CallerMemberName] string propertyName = null) | |
| { | |
| if (EqualityComparer<T>.Default.Equals(storage, value)) return false; | |
| storage = value; | |
| onChanged?.Invoke(); | |
| RaisePropertyChanged(propertyName); | |
| return true; | |
| } | |
| /// <summary> | |
| /// Raises this object's PropertyChanged event. | |
| /// </summary> | |
| /// <param name="propertyName">Name of the property used to notify listeners. This | |
| /// value is optional and can be provided automatically when invoked from compilers | |
| /// that support <see cref="CallerMemberNameAttribute"/>.</param> | |
| protected void RaisePropertyChanged([CallerMemberName]string propertyName = null) | |
| { | |
| lockSlim.EnterReadLock(); | |
| try | |
| { | |
| foreach (var pair in _handlersByThread) | |
| { | |
| var context = pair.Key; | |
| var handlers = pair.Value; | |
| if (SynchronizationContext.Current != context) | |
| { | |
| context.Post(_ => | |
| { | |
| var eventArgs = new PropertyChangedEventArgs(propertyName); | |
| foreach (var eventHandler in handlers) | |
| { | |
| OnPropertyChanged(eventHandler, eventArgs); | |
| } | |
| }, | |
| null ); | |
| } | |
| else | |
| { | |
| var eventArgs = new PropertyChangedEventArgs(propertyName); | |
| foreach (var eventHandler in handlers) | |
| { | |
| OnPropertyChanged(eventHandler, eventArgs); | |
| } | |
| } | |
| } | |
| } | |
| finally | |
| { | |
| lockSlim.ExitReadLock(); | |
| } | |
| } | |
| /// <summary> | |
| /// Raises this object's PropertyChanged event. | |
| /// </summary> | |
| /// <param name="args">The PropertyChangedEventArgs</param> | |
| protected virtual void OnPropertyChanged(PropertyChangedEventHandler handler, PropertyChangedEventArgs args) | |
| { | |
| handler?.Invoke(this, args); | |
| } | |
| } | |
| } |
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