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CC#

•Created by RazorSharpFang on 6/19/2023 in #help

❔ Visual Studio break when Module Loaded

3 replies

CC#

•Created by RazorSharpFang on 5/18/2023 in #help

✅ Windows Joystick API

What's the recommended Windows API to use for Joystick/Gamepad input these days if one needs background (non-focused window, problem for Windows.Gaming.Input) input, and one is not willing to take a dependency on the GDK (Read: No GameInput) whilst also being able to read independently the two triggers of the Xbox-style gamepad controllers (Problem for DirectInput) and working with various types of controllers that are NOT XInput-compatible (Like the PS4 controllers, problem for XInput) ?

29 replies

CC#

•Created by RazorSharpFang on 12/13/2022 in #help

❔ SQLite in-memory Database read from ReadOnlyMemory bytes

I'm receiving an SQLite database payload from an AMQP-0-9-1 message in the form of ReadOnlyMemory<byte> Rather than writing these bytes to disk and then opening that file with the regular SQLite toolset, I want to be able to work with the sqlite database in a read-only form without having to hit the disk. Is this possible with the currently available SQLite toolset, or is this an impossible task?

75 replies

CC#

•Created by RazorSharpFang on 8/31/2022 in #help

Unmanaged struct backed INPC ViewModel, only raising PropertyChanged when backing field(s) changed

So, suppose we have a large unmanaged struct that we obtain from external source, suppose from a network resource. This unmanaged struct decomposes into a set of primitives, with various values.

public struct ExampleStruct
{
  public int StructId;
  public float StructRealAmount;
  public DateTimeOffset StructTimestamp;
}

public struct ExampleStruct
{
  public int StructId;
  public float StructRealAmount;
  public DateTimeOffset StructTimestamp;
}

and then we have our ViewModel class that implements INotifyPropertyChanged. I have made an example below, not using the above struct as a field.

public class ExampleViewModel : INotifyPropertyChanged 
{
  // INPC boilerplate, to be replaced perhaps with an MVVM toolkit later
  public event PropertyChangedEventHandler? PropertyChanged;
  public void OnPropertyChanged(string propertyName)
  {
      PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
  }
  public static bool CheckChange<T>(ref T oldValue, T newValue, [CallerMemberName] string propertyName = "")
  {
    if (!Equals(oldValue, newValue))
    {
      oldValue = newValue;
      OnPropertyChanged(propertyName);
      return true;
    }
    return false;
  } 
  // end INPC boilerplate

  private int _viewModelId;
  public int ViewModelId { get => _viewModelId; set => CheckChange(ref _viewModelId, value); }
  private float _viewModelRealAmount;
  public float ViewModelRealAmount { get => _viewModelRealAmount; set => CheckChange(ref _viewModelRealAmount, value); }
  private DateTimeOffset _viewModelTimestamp;
  public DateTimeOffset ViewModelTimestamp { get => _viewModelTimestamp; set => CheckChange(ref _viewModelTimestamp, value); }

  // TODO: On receive ExampleStruct, set properties to fire events if data has changed
}

public class ExampleViewModel : INotifyPropertyChanged 
{
  // INPC boilerplate, to be replaced perhaps with an MVVM toolkit later
  public event PropertyChangedEventHandler? PropertyChanged;
  public void OnPropertyChanged(string propertyName)
  {
      PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
  }
  public static bool CheckChange<T>(ref T oldValue, T newValue, [CallerMemberName] string propertyName = "")
  {
    if (!Equals(oldValue, newValue))
    {
      oldValue = newValue;
      OnPropertyChanged(propertyName);
      return true;
    }
    return false;
  } 
  // end INPC boilerplate

  private int _viewModelId;
  public int ViewModelId { get => _viewModelId; set => CheckChange(ref _viewModelId, value); }
  private float _viewModelRealAmount;
  public float ViewModelRealAmount { get => _viewModelRealAmount; set => CheckChange(ref _viewModelRealAmount, value); }
  private DateTimeOffset _viewModelTimestamp;
  public DateTimeOffset ViewModelTimestamp { get => _viewModelTimestamp; set => CheckChange(ref _viewModelTimestamp, value); }

  // TODO: On receive ExampleStruct, set properties to fire events if data has changed
}

I had a thought to in the View Model class just have a single field of the unmanaged struct, and then fire off events of property changed. But if I were to do that, how would one determine which properties were changed ? Would it be better to have the unmanaged struct as the sole backing field, or should I not do that?

3 replies

CC#

•Created by RazorSharpFang on 8/18/2022 in #help

How do you pass into a method a generic after you've reflected? [Answered]

Suppose I suspect that this IEnumerable (non-generic) is also an IReadOnlyList<T> where T : struct. Unfortunately due to the rules of casting, an IReadOnlyList<T> where T : struct is not castable to an IReadOnlyList<object> How unfortunate! But we have reflection! Suppose I have an IEnumerable called source. I can probe its types as follows

// source is of type System.Collections.IEnumerable
var type = source.GetType();
var interfaces = type.GetInterfaces();
for (int i = 0; i < interfaces.Length; i++)
{
    var @interface = interfaces[i];
    if (@interface is null)
        continue;
    // null check satisifed 
    if(@interface.GenericTypeArguments.Length == 1 && @interface.GetGenericTypeDefinition() == typeof(IReadOnlyList<>))
    {
        // found it. It is in fact an IReadOnlyList<T> where T : struct 
        // but now what? Can I get a strongly typed reference to an IReadOnlyList<T> where T : struct ? 
    }
}

// source is of type System.Collections.IEnumerable
var type = source.GetType();
var interfaces = type.GetInterfaces();
for (int i = 0; i < interfaces.Length; i++)
{
    var @interface = interfaces[i];
    if (@interface is null)
        continue;
    // null check satisifed 
    if(@interface.GenericTypeArguments.Length == 1 && @interface.GetGenericTypeDefinition() == typeof(IReadOnlyList<>))
    {
        // found it. It is in fact an IReadOnlyList<T> where T : struct 
        // but now what? Can I get a strongly typed reference to an IReadOnlyList<T> where T : struct ? 
    }
}

Another class takes in as an argument to its constructor, IReadOnlyList<T> Defined below:

public ReadOnlyListWrapper(IReadOnlyList<T> backingList) { /* BODY HERE */ }

public ReadOnlyListWrapper(IReadOnlyList<T> backingList) { /* BODY HERE */ }

How do I after probing call this constructor now that I know it implements the interface as required?

42 replies

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