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.

Creating a WP7 app: Supporting dark and light themes

In this post I will show how to create an application that supports both the dark and the light themes, without the hassle of creating two sets of images, icons or styles.

This post is part of a series of posts I’ve planned on my findings while writing a windows phone 7 application (see the previous┬ápost, on the problem of caching urls, here).
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XML-databinding in WPF using Blend 4

This tutorial shows how easy it is to use XML-databinding in Blend without writing a single line of code and mostly using the drag-and-drop magic of Blend. We will create a very simple rss-reader that shows the content of a single rss-feed. This post was inspired by the great talk by Isabel Gomez Miragaya and Katrien De Graeve they gave at TechDays 2011 Belgium titled “Designing and Building a Windows Phone 7 Application end-to-end” (video of the talk). Read more of this post

Using Linq to filter a databound listbox in WPF/Silverlight

In this short tutorial I show how to use Linq in order to filter the items shown in a listbox, which in turn is databound to an ObservableCollection.

Suppose we use the listbox created in the previous tutorial where we show the age and name of each user in the collection. All our databinding code-remains the same as before. What we have to add is a new collection in between our original source and the listbox. The in between collection is our Linq-query result. Each time we wish to change our filter, we change the query. Read more of this post

Adding buttons to databound listbox items in WPF

Introduction

In this tutorial I will demonstrate how to create a listbox in WPF which is databound to a collection, we then would like to add a button to each item in the listbox. Clicking this button will button will delete that item from the collection.

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Tutorial on Silverlight 4 databinding in code-behind, custom user controls, etc.

Introduction

This small tutorial was written to show the students the following aspects of Silverlight:

  • Writing a class that can be used for databinding
  • Perform data-binding through code instead of XAML
  • Creating a custom user control
  • Writing simple data converters

Suppose we are creating a Silverlight game in which each player is represented as a pawn. However, the player class itself is somewhere deep inside the game-engine and we would like the pawn user control to be only loosely coupled to this player class. By doing this, we are able to make a rapid Silverlight prototype and if we later decide that the frontend is pretty lame, we can simply redesign it without too much fuss.

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