Archive for the ‘Xamarin’ Category

GObservableCollection

Tuesday, December 16th, 2014

In the last year working at Xamarin, I have learned lots of new things (.NET, Cocoa, …), and since the beginning of that, I was thinking on bringing some of that nice stuff to GNOME, but didn’t really had the chance to finish anything. But, fortunately, being free now (on vacation), I finally finished the 1st thing: GObservableCollection, a thread-safe collection implementation which emits signals on changes.

It is based on ideas from .NET’s ObservableCollection and concurrent collections, which I’ve used successfully for building a multi-thread data processing app (with one thread updating the collection and another consuming it), so I thought it would be a good addition to GLib’s API. This class can be used on single-threaded apps to easily get notifications for changes in a collection, and in multi-threaded ones for, as mentioned above, easily share data between different threads (as can be seen on the simple test I wrote).

This is the 1st working version, so for sure it will need improvements, but instead of keeping it private for a few more months, I thought it would be better getting some feedback before I submit it as a patch for GLib’s GIO (if that’s the best place for it, which I guess it is).

C#/Cocoa – Animate a split view’s collapsing/expanding

Wednesday, June 25th, 2014

When I started working at Xamarin, I had the intention to blog about new technologies I was learning, but it’s been already 6 months and it didn’t happen at all, so better to start late than never. I’ll start then with a nice piece of code I came up with, and which is this:

public static class CocoaExtensions
{
	public static void AnimatedSetPositionOfDivider (this NSSplitView splitView, float position, int divider)
	{
		var view0 = splitView.Subviews [0];
		var view1 = splitView.Subviews [1];

		var newFrame0 = view0.Frame;
		var newFrame1 = view1.Frame;
		if (splitView.IsVertical) {
			newFrame0.Width = position == 0 ? 0 : position - splitView.DividerThickness;
			newFrame1.Width = position == splitView.MaxPositionOfDivider (divider)
				? 0
				: splitView.Bounds.Width - position - splitView.DividerThickness;
		} else {
			newFrame0.Height = position == 0 ? 0 : position - splitView.DividerThickness;
			newFrame1.Height = position == splitView.MaxPositionOfDivider (divider)
				? 0
				: splitView.Bounds.Height - position - splitView.DividerThickness;
		}

		newFrame0.Width = newFrame0.Width < 0 ? 0 : newFrame0.Width;
		newFrame0.Height = newFrame0.Height < 0 ? 0 : newFrame0.Height;
		newFrame1.Width = newFrame1.Width < 0 ? 0 : newFrame1.Width;
		newFrame1.Height = newFrame1.Height < 0 ? 0 : newFrame1.Height;

		view0.Hidden = view1.Hidden = false;
		view0.AutoresizesSubviews = view1.AutoresizesSubviews = true;

		if ((newFrame0.Width == 0 && newFrame0.Height == 0) ||
		    (newFrame1.Width == 0 && newFrame1.Height == 0)) {
			return;
		}

		var singleAnimation0 = new NSMutableDictionary ();
		singleAnimation0 [NSViewAnimation.TargetKey] = view0;
		singleAnimation0 [NSViewAnimation.EndFrameKey] = NSValue.FromRectangleF (newFrame0);

		var singleAnimation1 = new NSMutableDictionary ();
		singleAnimation1 [NSViewAnimation.TargetKey] = view1;
		singleAnimation1 [NSViewAnimation.EndFrameKey] = NSValue.FromRectangleF (newFrame1);

		var animation = new NSViewAnimation (new NSDictionary[] { singleAnimation0, singleAnimation1 });
		animation.Duration = 0.25f;
		animation.StartAnimation ();
	}
}

The main reason to share this code is because I couldn’t find anything that worked to do that (animate the collapsing and expanding of a NSSplitView, which is, yes, you got it right, a split view, like GTK’s GtkPaned), so I hope it is useful for someone. But it also shows a few interesting things about both C# and Cocoa:

  • The most obvious one: writing Cocoa apps in C# is much better than using Objective C (although, to be honest, I also like Objective C).
  • Cocoa (and CoreAnimation) lets you easily add animations to your UI, by having the animations layer tightly integrated into the API. Of course, animations are not always great, but in some cases, like this one where the collapsing/expansion of the split view’s subviews is animated, it makes such a huge difference to the UI that it’s very nice to be able to do it that easily.
  • C# allows extending existing classes, by writing extension methods (static methods in static classes that have a “this” modifier in the 1st argument, which specifies the class the method extends). This is a great way to extend existing classes, without having to do any subclassing. Once you have the extension method, you can just call it on any NSSplitView:
    mySplitView.AnimatedSetPositionOfDivider (position, divider);
    

    You can extend any class, and this what a lot of technologies (LINQ, Reactive Extensions, etc) in the .NET world use.

I started also, when I started working at Xamarin, getting some of the nice ideas from Cocoa and C# into GLib/GTK, so will publish that as soon as I get something useful from it. Hopefully it won’t be another 6 months :-D

And yes, Xamarin is hiring. If interested, drop me a mail, or just apply directly, as you wish.

Xamarin

Friday, January 10th, 2014

After some well deserved relaxing time, I am glad to announce that, since last Tuesday, I am a happy member of the Xamarin crew, where I’ll be working on the awesome cross-platform development tools the company makes.

This is indeed a change from what I have been doing in the last years, as I will be focusing on platforms other than Linux, as has been the case for the last 15 years, but to be honest, and after thinking a lot about it during my “well deserved relaxing time”, this is something that I really needed to boost my career. Not working on other platforms, but moving out of my comfort zone and find something new and exciting to work on. And Xamarin really seems to be the perfect place for this: the company is full of ex-Ximianites (Ximian is, till now, the best company I have ever worked for), lead by great people and focused on making great development tools/APIs, which is something that I have always liked but haven’t had the chance to work on as much as I would have wanted.

Of course, this doesn’t mean I will stop caring/using/developing GNOME. On the contrary, I think, and based on what I have been working on during my vacation, this will help me in making a better contribution to the project, as a lot of things I have been/will be learning, I think, are great for making GNOME better. But will talk about all that in separate blog posts, as things progress.

Many thanks to my girlfriend Yolanda and my friend Ismael Olea, who were the ones to pinpoint what I needed, which was to look for some exciting new stuff, rather than only wanting to stay on my comfort zone, and to Miguel, for the great coding challenge he got me to do, which made me learn exciting stuff and convince me finally that Xamarin was the best place for me.