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.

Using delegates, func and lambdas: a tutorial with soldiers

In this tutorial, written for beginning programmers, I’d like to show a little demonstration on the usage of delegates and how we can go all crazy by refactoring and magically see all our duplicate code disappear.

Imagine we are writing the next ultimate Command&Conquer spinoff which can run on any computer …in console-mode. Read more of this post

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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New WP 7.5 ebook review copy arrived

I just received a review copy of a soon to be published book, titled “Windows Phone 7.5 Data Cookbook” by Ramesh Thalli from Packt Publishers. I will put up a review of it soon. However, I can already hint, after quickly flicking through the pages, that many who liked its unofficial predecessor “Silverlight 4 Data Services Cookbook” by Gill Cleeren and Kevi Dockx will also like this one a lot. If you can’t wait for my review, check out a sample chapter (chapter 2 on using Isolated Storage for data storage) here.

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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