Twoway databinding to a MongoDB collection in WPF

I’ll show how to have a two-way databinding between a templated listbox and a MongoDB collection.
I’m finally got around toying with MongoDb.What I’ll show next might not be the most correct way, but it works for me.

Setup

I have a Listview defined in XAML with a datatemplate:

        <ListBox Name="mylistbox">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <TextBox Text="{Binding Naam, Mode=TwoWay}"></TextBox>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>

I created an Entity class (can be a composite if you wish) which is is simple POCO with INotifyPropertyChanged implented. This Entity class well be serialized to my MongoDB collection as-is. Explained here, for example:

        public class Entity
        {
            public string Naam { get; set; }
        }

Retrieve the data and databind

Next up, we need to retrieve the data using a query (coll being my collection a retrieved earlier on (not shown)):

var query = coll.AsQueryable<Entity>().ToList();

The ToList part is important.This will ensure that we get a simple list of Entity objects as our ItemSource and not an IQueryable, otherwise the next part won’t work.

Write changes to database

You can now edit your data in your listbox and once you are ready, you can update all the changes to your MongoDB collection:

            foreach (var item in mylistbox.ItemsSource)
            {
                coll.Save(item);
            }

What’s on my Windows Phone – my favourite apps

I’m often get asked what apps I have installed on my phone. After explaining I have a Windows Phone 8 (Lumia 720) the question usually results in an awkward “erm..okay, nevermind”. But sometimes a fellow Microsoft enthousiast can be found. It is for these people that I have compiled a list of the apps I have on my ‘start menu’ (e.g. use-a-lot-apps) and those installed (e.g. handy-apps) So without further ado: Read more of this post

Book review: Windows Phone 8 Game Development

6807OT“Sir, I want to be a game developer, what do I do?” is a question I got asked a lot during classes. The honest answer I usually give is :”work hard, keep trying and never stop trying”. I’ll keep on answering this, but I might also recommend a new book that has recently arrived titled “Windows Phone 8 Game Development – A practical guide to creating games for the Windows Phone 8 platform” by Marcin Jamro (Packt Publishing).
Remember the big bad-ass books by Andre Lamothe on (3D) Game programming, where many aspects of game programming were discussed? This new book has the same approach: more is better, plain simple.

A first glance at the index will immediately show the author is trying to describe all aspects of game development, not only the game (engine) coding itself, including social interaction, webservices, publishing, etc. What especially triggered my attention was chapter 3 titled “Mvvm design pattern”, a pretty ballsy approach because up until now I haven’t seen a single book on game development where this pattern is even just briefly mentioned.
Throughout the hefty 394 pages, the author will show how to (re)create a full-blown 3D space , asteroid-like shooter from the ground up. This is both good and bad news: bad because it means most chapters will depend on code of the previous ones, good because it shows how interdependent a lot of aspects are when developing a game. Many books who use this approach (i.e. build an application from start to end) sometimes fails because a) some important code-parts are missing or b) the code is to complex: the reader misses the keypoints the code wants to convey and thus loses time trying to get the code to work AND understand.
I haven’t made the game itself so I can’t vouch for the fact that a workable game can be made following this text but the code itself in the text is well-documented and clear.
A nice addition is the fact that a hybrid approach is used: managed code to harbour the menu/UI-related stuff, and a native part for the game itself. The game itself is written using DirectX, whereas the main game menus are in plain XAML (hence the MVVM approach mentioned earlier).

The text itself is very detailed, every step is explained, but sometimes a bit redundant: the author even explains how to place controls from the toolbox in your designer and how to debug using locals, autos, etc. A tad overkill? On the other hand, this makes the book ideal for anyone new to c#/xaml programming. So it could actually be used as an fun, introductionary book for experienced non-C#-developers who never used Visual Studio.

And yes, a lot is tackled: even augmented reality (AR) is in it: GPS coordinates of other players nearby are used to show their actual location when watching through the camera of the phone.
So in overall: if you need a primer on 3D/3D game programming for Windows Phone 8, this book is a must-have!

A clickable Windows Phone slider

The default behavior of the Windows Phone Slides control doens’t allow a user to click on the slider where the value should be set to. Instead, tapping anywhere on the slider will simply result in the slider incrementing by it’s default or given incrementsetting.

Following small piece of code shows how to have the wanted behavior by responding to the Tap- event of the Slider (named mySlider in the following codepiece).

        private void UIElement_OnTap(object sender, GestureEventArgs e)
        {
           if (mySlider.Orientation == System.Windows.Controls.Orientation.Horizontal)
            {
                var pos = e.GetPosition(mySlider).X;
                var width = mySlider.ActualWidth;
                mySlider.Value = (pos/width)*mySlider.Maximum;
            }
            else
            {
                var pos = e.GetPosition(mySlider).Y;
                var height = mySlider.ActualHeight;
                mySlider.Value =(1- (pos / height) )* mySlider.Maximum;
            }
        }

A WP7 databound graph control

For a project we are working on, we needed a simple (and free) WP7 graph usercontrol. The data which the usercontrol visualizes needs to be databound and each time new data arrives, the graph should update itself on-the-fly .In the following tutorial we’ll show how to create such a control from scratch (make note that normally this should also work in Silverlight or WPF projects).

A demo-solution of this tutorial can be downloaded here.

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Creating an Intellisense compatible enum-based Dependency Property

Actually, this post has a way too fancy title , because in fact I will merely show that enum-based dependency properties are IntelliSense compatible “out-of-the-box”. (by the way, if you know all about dependcy properties: simply read the line in bold and you’ll know all there is to know).

When creating a (WP7/SL/WPF) usercontrol, one often ends up creating one more dependency properties (DP). Most of the times you only want a discrete set of possible values that can be assigned to the DP. The logical choice then of course is to have an enum-based DP.

Now, for the Intellisense to work it is important that you define the enum type OUTSIDE the usercontrols class. For example, suppose we have define the following enum:

public enum GraphTypes {Default, Point, Line}

Now, all that remains is to add a DP that uses this enum (remember that you can use the ‘dependencyproperty’ snippet that comes with VS):

        public static readonly DependencyProperty GraphTypeProperty =
            DependencyProperty.Register("GraphType", typeof (GraphTypes), typeof (GraphControl), new PropertyMetadata(GraphTypes.Default));

        public GraphTypes GraphType
        {
            get { return (GraphTypes) GetValue(GraphTypeProperty); }
            set { SetValue(GraphTypeProperty, value); }
        }

Once you now add the usercontrol elsewhere in your xaml-code, IntelliSense will happily show what values can be assigned to the DP:

There we go. That’s all there was too it.

Next post I’ll show how to create a WP7 user control to plot graphs using data binding. Consider some of the code here a sneak preview.

Writing a WP7 website scraper application

In this tutorial I will explain how you write a WP7 application using the HtmlAgility Pack in order to use information scraped from a website.
Website scraping is the act of retrieving information from a website page. An act by some considered stealing, by others borrowing. Let’s leave that debate to the others. In this post I will show how easy it is to scrape content from a website so that you can (re)use it in your Windows Phone 7 application. As it is, this information will for the most part also work in other, non WP7, projects of course.
Sometimes website scraping is the only means available to consume certain information from a website. If the website doesn’t have some publicly available API or web service you can use you’re pretty much left with scraping, whether you like it or not.

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