As promised, here is a blog post which shares source code and slides for the Rx talk I gave during last TechDays in Paris. I animated this session with my co-worker Charlotte and with Mitsu.
Download slides here.
Download source code here.
Demo1: Drag’n’drop in a WPF application
The goal was to implement a basic drag’n’drop functionality in a WPF application. The Rx query looks like the following:
var query = from mouseDown in this.image.GetMouseLeftButtonDownObservable()
let downPosition = mouseDown.EventArgs.GetPosition(this)
let rect = new Rect(downPosition.X - 10, downPosition.Y - 10, 20, 20)
let delta = mouseDown.EventArgs.GetPosition(this.image)
from mouseMove in this.GetMouseMoveObservable()
.Select(ea => ea.EventArgs.GetPosition(this))
.SkipWhile(p => rect.Contains(p))
.DoOnce(p => this.onMouseEnter.Begin(this.image))
.Select(p => p.Offset(delta))
.TakeUntil(this.GetMouseLeftButtonUpObservable())
.Finally(() => this.onMouseLeave.Begin(this.image))
select mouseMove;
query.Subscribe(p => this.image.SetPosition(p));
Demo2: online Twitter search and Bing map geolocalization
This time, the goal was to query Twitter asynchronously and to geolocalize the associated Tweets. The Rx query:
this.textbox.GetTextChangedObservable()
.DistinctUntilChanged((ea) => this.textbox.Text)
.Throttle(TimeSpan.FromMilliseconds(300))
.ObserveOnDispatcher()
.Do(ea => this.ShowLoadingIndicator())
.Select(ea => TweeterHelper.Search(this.textbox.Text))
.Switch()
.ObserveOn(Scheduler.Dispatcher)
.Select(page => TweeterHelper.ParseTwitterSearch(page))
.Subscribe((tweets) =>
{
this.HideLoadingIndicator();
this.listbox.ItemsSource = tweets;
TweeterHelper.LocalizeTweets(this.map, tweets);
});
Demo3: using the accelerometer in a Windows Phone 7 application
The last demo was about the usage of the accelerometer in a Windows Phone 7 application. Here is the relevant Rx query:
private void MoveEllipse(IObservable accelerationObservable)
{
accelerationObservable
.SlidingBuffer(2)
.Select(accCouple => new Acceleration(accCouple.First(), accCouple.Last()))
.ObserveOnDispatcher()
.Do(acc => this.textBlock.Text = acc.ToString())
.Scan(new Point(x0, y0), (point, acc) => point.Move(acc).ClipTo(horizontalInterval, verticaInterval))
.Subscribe(p => this.ellipse.SetCenter(p));
}
Doing this session was a really great experience ! I’d like to thank Charlotte and Mitsu for doing it with me. Also, I’d like to thank all users who came to the presentation !
I love every single post in your blog! Minor point: in some code snippets lambdas are being shown with “=>” instead of “=>”
… I mean “= & g t ;”
Thanks for the feedback Mikhail. I just fixed that.