Popular Topics on StackOverflow

by Miguel de Icaza

I am probably the last person to find about this, but I find the number of questions/tagged on StackOverflow fascinating:

Posted on 21 Jul 2009

TreemapViewer: Building Silverlight Applications on Unix

by Miguel de Icaza

A few months ago, to get an idea of what contributed to the size of Mono libraries I wrote a small Treemap visualizer using Moonlight:

Moonlight's assemblies; area represents the codesize.

You can browser the code or get a copy from our AnonSVN repository.

There are a couple of tools here:

My Treemap is not very ambitious, and it is nowhere as complete as the new Treemap control that is part of the open source Silverlight Toolkit. But it was a fun learning experience for me.

Reusable Engine

I did not really know where we would use this control, on the web or on the desktop when I started. So I split the actual engine that does the heavy lifting from the actual chrome for the application.

This is why I ended up with a Silverlight user interface and a Gtk# user interface. This idea in general might be useful for other developers as well.

The Custom Control

The custom control is very simple, it is called TreemapRenderer and derives from UserControl. The code overwrites two methods: MeasureOverride and ArrangeOverride. These methods are used to allow the control to participate in the Silverlight layout system (for example, the control can be embedded in a table that can auto-stretch). Silverlight invokes your MeasureOverride to find out the desired size that you control would like to consume:

public class TreemapRenderer : UserControl {
	protected override Size MeasureOverride(Size availableSize)

	protected override Size ArrangeOverride(Size finalSize)

Silverlight will invoke your control's ArrangeOverride to layout its contents once it has determined the size that the control will use.

This is where my TreemapRenderer lays out its contents.

This code renders an actual region on the treemap, I like the C# 3.0 initializer syntax for the text created:

public void SetRegion (Rect newRegion)
        region = newRegion;
        content.Children.Clear ();
        content.Width = region.Width;
        content.Height = region.Height;
        if (caption != ""){
                int max;
                string formatted = MakeCaption (caption, out max);
                double w = region.Width * 1.60;
                double s = w / max;

                var text = new TextBlock () {
                        FontSize = s,
                        Text = formatted,
                        Foreground = new SolidColorBrush (Color.FromArgb (255, 0x5c, 0x5c, 0x5c))

                Canvas.SetTop (text, (region.Height-text.ActualHeight)/2);
                Canvas.SetLeft (text, (region.Width-text.ActualWidth)/2);
                content.Children.Add (text);
        Rect emptyArea = region;
        Squarify (emptyArea, root.Children);
        Plot (root.Children);

To provide feedback to the user, I change the background color of the treemap on enter/leave. I use anonymous two anonymous methods, one for MouseEnter, one for MouseLeave.

Notice that state is shared by these two blocks of code using C# variable capturing. A key feature of the language:

	bool inside = false;
	host.MouseEnter += delegate {
	        host.Background = new SolidColorBrush (Colors.Yellow);
	        if (text != null)
	                text.Foreground = new SolidColorBrush (Colors.Black);
	        inside = true;
	host.MouseLeave += delegate {
	        host.Background = transparentBrush;
	        if (text != null)
	                text.Foreground = borderBrush;
	        inside = false;

One thing that proved very useful was the ability to zoom-into an area. If you click on an assembly, you will get a rendering of the code size used by a type; If you click on that, you get a method breakdown on a class:

drill-down into mscorlib's sizes.

To transition, I added a cute animation where I render the new image and animate it from the area occupied in the larger view into the final size. This is the code that queues the animation:

        // Render a child
        void Clicked (Node n)
		// This is the child rendered, configure it to its final size
                TreemapRenderer c = new TreemapRenderer (n, n.Name);

                Size ns = new Size(region.Width, region.Height);
                c.Measure (ns);

		// Scale it and position on the spot that it currently
		// occupies on the screen
                var xlate = new TranslateTransform () {
                        X = n.Rect.X,
                        Y = n.Rect.Y };

                var scale = new ScaleTransform () {
                        ScaleX = n.Rect.Width / region.Width,
                        ScaleY = n.Rect.Height / region.Height };

                c.RenderTransform = new TransformGroup { Children = { scale, xlate } };
                c.Opacity = 0.5;
                content.Children.Add (c);
                activeChild = c;

		// Animate this to its final location
                TimeSpan time = TimeSpan.FromSeconds (0.3);

                var s = new Storyboard () {
                        Children = {
                                Animate (time, xlate, "X", 0),
                                Animate (time, xlate, "Y", 0),
                                Animate (time, scale, "ScaleX", 1.0),
                                Animate (time, scale, "ScaleY", 1.0),
                                Animate (time, c, "Opacity", 1.0),

                s.Begin ();

	// Helper method;   
        static Timeline Animate (TimeSpan time, DependencyObject target, string path, double to)
                var animation = new DoubleAnimation () {
                        Duration = time,
                        To = to

                Storyboard.SetTarget (animation, target);
                Storyboard.SetTargetProperty (animation, new PropertyPath (path));

                return animation;

The Silverlight Application

Using the control is fairly simple, but since it loads a large XML files (feel free to change this to use a web service) I use the downloader and a callback to render the control.

        private void Application_Startup(object sender, StartupEventArgs e)
            var webclient = new WebClient();
            webclient.DownloadStringCompleted += delegate (object sender2, DownloadStringCompletedEventArgs ee){
                try {
                    RootVisual.Dispatcher.BeginInvoke(() => LoadNodesFromString(ee.Result));
                catch (Exception ex) {
                    main.BackButton.Content = ex.ToString();

            webclient.DownloadStringAsync(new Uri("../mscorlib.xml", UriKind.Relative));

The actual creation of the control happens in LoadNodesFromString:

        void LoadNodesFromString(String s)
	    // Use Size for the area.
            Node n = LoadNodes(s, "Size", "Extra");
            while (n.Children.Count == 1)
                n = n.Children[0];
            treemap = new TreemapRenderer(n, "");
            Grid.SetColumn(treemap, 0);
            Grid.SetRow(treemap, 1);

Building a Gtk# Out-of-Browser Client

The above works great for Silverlight, but I like my application on the desktop, so I created a Gtk# version of it.

Moonlight provides a Gtk# widget that can be embedded into C# desktop applications. This is what it looks like when running on the desktop. I know this screenshot is not too exciting as I did not do much with the Gtk+ side of things:

Gtk# is rendering, seriously.

The core of embedding Moonlight as a Gtk# widget is very simple, here it is:

using Moonlight.Gtk;
using Moonlight;

        public static void Main(string[] args)
                n = LoadNodes (args [0], "Size", "Foo");

                Gtk.Application.Init ();
                MoonlightRuntime.Init ();

		// My container window.
                Gtk.Window w = new Gtk.Window ("Foo");
                w.DeleteEvent += delegate {
                        Gtk.Application.Quit ();
                w.SetSizeRequest (width, height);

		// The Moonlight widget that will host my UI.
                MoonlightHost h = new MoonlightHost ();

		// Add Moonlight widget, show window.
                w.Add (h);
                w.ShowAll ();

                // Make it pretty, skip all levels that are just 1 element
                while (n.Children.Count == 1)
                        n = n.Children [0];

                // Render
                TreemapRenderer r = new TreemapRenderer (n, "");
                Size available = new Size (width, height);
                r.Measure (available);
                r.Arrange (new Rect (0, 0, width, height));

		// This informs the widget which widget is the root
                h.Application.RootVisual = r;
                Gtk.Application.Run ();

There are Visual Studio and MonoDevelop solutions on the SVN for folks to try out.

You can also try a sample live on the web.

Posted on 20 Jul 2009

MiggyTour 2009

by Miguel de Icaza

In the third and fourth weeks of August, Laura and I will be spending a couple of days in Madrid visiting friends.

Then a couple of days hanging out with Nat, Stephanie and a bunch of awesome friends and family friends in Florence.

And then we are spending a week in Morocco, most likely in Marrakesh.

If you live in Madrid or Marrakesh and would like to get together to meet and talk, send me an email.

Posted on 17 Jul 2009

StackOverflow DevDays in Boston

by Miguel de Icaza

Joel Spolsky and Jeff Atwood have invited me to participate on StackOverflow's DevDays in Boston on October 7th.

I will be talking about Mono, Mono and Visual Studio and Mono on iPhone. Come equipped with questions.

Shocking, I know.

Posted on 17 Jul 2009

LLVM powered Mono

by Miguel de Icaza

Mono from SVN is now able to use LLVM as a backend for code generation in addition to Mono's built-in JIT compiler.

This allows Mono to benefit from all of the compiler optimizations done in LLVM. For example the SciMark score goes from 482 to 610.

This extra performance comes at a cost: it consumes more time and more memory to JIT compile using LLVM than using Mono's built-in JIT, so it is not a solution for everyone.

Long running desktop applications like Banshee and Gnome-Do want to keep memory usage low and also would most likely not benefit from better code generation. Our own tests show that ASP.NET applications do not seem to benefit very much (but web apps are inherently IO-bound).

But computationally intensive applications will definitely benefit from this. Financial and scientific users will surely appreciate this performance boosthttp://www.mono-project.com/.

Taking it out for a spin

Note: the notes here are no longer relevant, these applied to Mono back in 2009. LLVM has now been integrated into Mono, follow the steps in http://www.mono-project.com/Mono_LLVM instead

You need to install both LLVM and Mono from SVN.

Get and install LLVM like this:

$ svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm
$ cd llvm
$ ./configure --prefix=/mono --enable-optimized
$ make && make install

Then get Mono, and you need to apply a tiny patch to configure.in.

$ wget http://tirania.org/tmp/m7a9da378.txt
$ svn co svn://anonsvn.mono-project.com/source/trunk/mcs 
$ svn co svn://anonsvn.mono-project.com/source/trunk/mono 
$ cd mono
$ patch -p1 < m7a9da378.txt
$ ./autogen.sh --prefix=/mono --enable-llvm=yes
$ make && make install

Now you have an LLVM-powered Mono.

LLVM is not able to support some of the features that Mono needs, so in those cases the JIT compiler will still fall back to Mono's JIT engine (methods that contain try/catch clauses or methods that do interface calls).

This backend was written by Zoltan.

Posted on 16 Jul 2009

Banshee as a Platform?

by Miguel de Icaza

Aaron Bockover recently discussed Banshee's modular architecture. Aaron discusses using Banshee as a foundation for managing not only music, and videos but merging with F-Spot to manage photos as well:

The slides from his talk go into a bit more detail.

Jonathan Pobst takes the platform idea one step further and suggests that Banshee's core could also be used to replace YAST's Software Installer UI:

Jonathan says:

Every time I use YaST's Software Manager, I wonder if it would be better implemented using Banshee. Banshee's interface has been tuned for usability, both on its own, and what it borrows from iTunes. Software management is a naturally scary operation, and using an interface that the user is already familiar with could help reduce user fear.

Of course, it would just be the interface pieces of Banshee in a new app, you wouldn't actually start Banshee for software installation.

Another feature I would like to see taken from iTunes/Banshee is downloading/installing in the background. Once I hit Install, go ahead and download the application in the background, and install it in the background. I can click on the "Downloading/Installing.." menu item if I want to see what's going on. Most of the time, I'd rather be looking at other things to download.

I think this is a brilliant idea.

Posted on 15 Jul 2009

From Microsoft: C# and CLI under the Community Promise

by Miguel de Icaza

First the big news: Microsoft will be applying the Community Promise patent licensing to both C# and the CLI.

The announcement was done by Peter Galli at Microsoft over at Port25 and it states (emphasis is mine):

I have some good news to announce: Microsoft will be applying the Community Promise to the ECMA 334 and ECMA 335 specs.

ECMA 334 specifies the form and establishes the interpretation of programs written in the C# programming language, while the ECMA 335 standard defines the Common Language Infrastructure (CLI) in which applications written in multiple high-level languages can be executed in different system environments without the need to rewrite those applications to take into consideration the unique characteristics of those environments.

"The Community Promise is an excellent vehicle and, in this situation, ensures the best balance of interoperability and flexibility for developers," Scott Guthrie, the Corporate Vice President for the .Net Developer Platform, told me July 6.

It is important to note that, under the Community Promise, anyone can freely implement these specifications with their technology, code, and solutions.

You do not need to sign a license agreement, or otherwise communicate to Microsoft how you will implement the specifications.

The Promise applies to developers, distributors, and users of Covered Implementations without regard to the development model that created the implementations, the type of copyright licenses under which it is distributed, or the associated business model.

Under the Community Promise, Microsoft provides assurance that it will not assert its Necessary Claims against anyone who makes, uses, sells, offers for sale, imports, or distributes any Covered Implementation under any type of development or distribution model, including open-source licensing models such as the LGPL or GPL.

You can find the terms of the Microsoft Community Promise here.

I told you this was good news!

A few months ago we approached Bob Muglia and Brian Goldfarb (@bgoldy) at Microsoft with a request to clarify the licensing situation for the ECMA standards covering C# and the CLI (also ISO standards, for the ISO loving among you).

Previously Microsoft had detailed the patent license plans and today they have delivered on those plans.

Astute readers will point out that Mono contains much more than the ECMA standards, and they will be correct.

In the next few months we will be working towards splitting the jumbo Mono source code that includes ECMA + A lot more into two separate source code distributions. One will be ECMA, the other will contain our implementation of ASP.NET, ADO.NET, Winforms and others.

Depending on how you get Mono today, you might already have the this split in house or not.

Thanks to everyone at Microsoft that worked to get this approved and released. We appreciate that they made this a priority when we approached them, and we know that everyone in the .NET team was also incredibly busy with various betas: .NET 4, Visual Studio 2010, Silverlight, MVC, MEF and much more.

I am overflowing with joy right now. Cheers!

Update: Send your thanks to @bgoldy on tweeter, who crossed all the t's and dotted all the i's to make this happen.

Update: Moderation of comments is taking place. Off topic messages will be removed immediatly. Trolling, as mild as it might be will be deleted. If you want to argue what language is the best one take the debate to a newsgroup.

Posted on 06 Jul 2009

PhyreSharp runs on the PS3

by Miguel de Icaza

Mono on the PS3 has been making some nice progress. Supporting the PS3 requires some special features in Mono, for instance, a static compiler for .NET code for the PowerPC/Cell processor.

PhyreSharp, our .NET binding to Sony's PhyreEngine game engine ran on Thursday for the first time.

Posted on 03 Jul 2009

MonoSpace Conference Announced

by Miguel de Icaza

Scott Bellware has announced the MonoSpace Conference in Austin Texas on October 27-30th.

Scott has made a Call for Speakers:

The Monospace Conference is looking for teachers to give tutorials on the Mono framework, tools, languages, and platforms supported by Mono.

Some tutorials are aimed at .NET developers with little experience with operating systems other than Windows, and others are geared to experienced Mono developers with exposure to the various Mono platforms.

The tutorials are two hour to three hour interactive sessions that can be any combination of follow-along examples, labs, and lecture.

We're looking for tutorials on subjects such as Linux, Mac, Windows, web, desktop, servers, message queues, databases, iPhone, Android, Amazon's EC2, among others.

You can track the progress of the conference at the MonoSpace Conf Blog.

You can also follow the progress on twitter.

Scott was one of the founders of the Alt.Net series of conferences.

Posted on 30 Jun 2009

Some Cool Mono Announcements

by Miguel de Icaza

Yesterday we shipped Mono 2.4.2, our long-term supported version of Mono. It ships Microsoft's opensourced ASP.NET MVC stack for the first time (you could get it before on your own, but now it is integrated) and fixes over 150 reported bugs.

Chris Toshok announced M/Invoke a tool to port applications that use P/Invokes on Win32 to Linux and MacOS.

What Chris does not talk about on his post is that he was trying to use some .NET software that interfaces via USB to his glucose meter and was trying to get this to run on Linux. The tool is mostly .NET with the usual handful of P/Invokes to Win32. And this is how M/Invoke was born: a tool to retarget P/Invoke happy applications into becoming pure managed applications.

This opens new doors to forcefully port more apps to Linux.

Alan McGovern released a new version of Mono.Nat one of the libraries used by MonoTorrent.

Jordi Mas released a new version of Mistelix a DVD authoring tool for Linux:

Jordi's GBrainy brain teaser game was picked up by MoLinux, a regional Linux distribution, and shipped it translated to Spanish:

Joe Audette's mojoPortal was being installed four times as much when it got included in in Microsoft's Web Platform Installer site (more stats here).

For years I have loved the Joel on Software rules for software engineering. And one of those rules is "Build in one step". We have not always succeeded, but we have always tried. Lluis delivers the one step to build and run for MonoDevelop on Windows: Load solution, Hit F5, up and running.

Google Chrome really lead the way here, and I want very badly to have all of Mono building in Visual Studio with one keystroke, but we are not there yet.

Stephane reports on some nice startup performance improvements for F-Spot. Loading time for 10 images from Stephane's own image collection went from 1.2 seconds to .5 seconds.

MonoDevelop got some enhanced support for autoconf integration.

Jeremy Laval released another version of ZenComic a desktop Comic reader:

David Siegel announced a new release of Gnome Do on behalf of the Gnome Do team. In particular, it is now easier to write "Docklets" for the Gnome Do panel and for those of us that like the Emacs keybindings, it is now possible to use C-N and C-P for navigation

And of course the Google Summer of Code is in full swing:

And we have various very exciting projects brewing.

Jonathan Pobst has been exploring integration points for Mono and Visual Studio 2010:

Guadec: I will sadly not be attending the Guadec/Akademy conference in Canaria next week. This is going to be a busy summer for us as we are shipping a lot of code in the next few months: Moonlight 2.0, Mono for Visual Studio, MonoTouch 1.0 and Mono 2.6.

Posted on 30 Jun 2009

« Newer entries | Older entries »