ReactiveUI：如何从ReactiveCommand取消可观察对象？

Question

I have the following:

Compress = this.WhenAnyValue(x => x.ImagesCount, x => x > 0).ToCommand();
var process = Compress.RegisterAsync(ConvertImages);
var subscription = process.Subscribe(x => Images.Remove(x));

CancelConversion = this.WhenAnyValue(x => x.ImagesCount, x => x.IsBusy, (count, busy) => count > 0 && busy).ToCommand();
CancelConversion.RegisterAsyncAction();

Where ConvertImages(object o) is a private method of the ViewModel that, in turn, calls and returns the result of ConvertImages(IEnumerable<ImageDto> images) in a service class that resizes and compresses the images and returns an IObservable<ImageDto> .

Paul Betts suggests here to implement cancellation via the implementation of my IObservable eg using Observable.create , so can anyone provide an example of how to implement such Observable?

Also what is the RxUI™ way to signal this cancellation? Should I subscription.Dispose() in CancelConversion.RegisterAsyncAction() ? Should I add .TakeUntil(CancelConversion.Execution_Signaled) to var process , how can I determine "CancelConversion.Execution_Signaled"?

Answer 1

This is fairly easy:

CancelConversion = this.WhenAnyValue(x => x.ImagesCount, x => x.IsBusy, (count, busy) => count > 0 && busy).ToCommand();

this.WhenAnyValue(x => x.ImagesCount, x => x > 0).ToCommand();

var process = Compress.RegisterAsync(x => ConvertImages().TakeUntil(CancelConversion));
var subscription = process.Subscribe(x => Images.Remove(x));

Handling the actual cancellation (ie stopping whatever work that ConvertImages is really doing) depends on your implementation of ConvertImages.