Naming and conventions in XAML

I think the naming and code/markup conventions in XAML is a bit unclear. This post will raise some of the issues.

I posted a new thread in the Silverlight.net forums about why there is no PART_ convention in Silverlight when this convention exists in WPF. I described the problem like this:

"In WPF there is a convention for TemplateElements in controls that distinguishes controls that must exist in a template from other controls. This means that if I edit a control template I know that all elements named PART_* must be in the template and all other parts I can remove or do whatever I like to.

When I looked in Silverlight Toolkit and the shipped controls there are no such standard, why? How should the user know which controls that must be in the template? I think it is sad that the framework doesn't look the same in all parts (yes I know that the Silverlight Toolkit is not in the framework, but realize that it will be a template and a teacher for many control developers). Is there a reason?"

I did not get a clear answer for why they have made it this way but the replies made me realize that PART_ convention can probably not be entered in the future because this will break the released code. And on the other side, in WPF the PART_ convention can not be removed because that will break the WPF code. I think the problem is that the two so similar frameworks differ in conventions and readability. What about the problem?

Yes, I know about the TemplatePart attribute and I know that the functionality does not change because of the naming convention. I think that the problem is that the tools does not use this information today. Tools like Visual Studio and Blend will soon be consuming the attribute but there are a lot of other tools that won't. This brings us to my second opinion.

I think this is a usability and design issue. If you read Framework Design Guidelines (K. Cwalina, B. Abrams) they have an important point when they say that the .NET Framework should "look the same" wherever you are. Therefore I think its a bad thing that Silverlight and WPF differs. A developer should recognize himself/herself when adopting a new area within the framework, and the framework code should be clear and readable. This is not a big issue and maybe I'm whining a little bit too much about this, but I think it is important that we create conventions for markup (XAML) in the same way that we use camelCasing and PascalCasing in e.g. C#. I have seen some unclear naming within the framework (in XAML), are there any conventions for naming and so on and do people use them?

Another part that is related to this is how you should name your members in XAML. Your XAML-file are compiled into the same container as the code behind (in the case of a UserControl) and there they will be members of that class. This means that if you name e.g. a Button "MyButton" it will appear as a member of the class with a field name "MyButton". In C# and in standard naming conventions fields should be named with camelCasing which means that the right name for MyButton should be myButton. The same thing for naming resources. Right now the naming is unclear and it differs within Silverlight and WPF and also between XAML and e.g. C#.

I think it is sad that Silverlight/WPF differs and I think it is important to create conventions for writing XAML. This is not about the functionality of the code you write, it is about the usability and the experience for the next developer that will read and try to understand your code. What do you think?

The Misuse of var in .NET - it's bad programming!

This post will argue that many .NET developers misuse implicit typing (var) in their programming. I see this more often and I really think this is really, really bad programming. This is why:

About implicit variables
Fist of all, what does the documentation say about var?
var keyword[C#]:
"Variables that are declared at method scope can have an implicit type var. An implicitly typed local variable is strongly typed just as if you had declared the type yourself, but the compiler determines the type. The following two declarations of i are functionally equivalent:

var i = 10; // implicitly typed
int i = 10; //explicitly typed

Remarks
Overuse of var can make source code less readable for others. It is recommended to use var only when it is necessary, that is, when the variable will be used to store an anonymous type or a collection of anonymous types." Many developers do not read the remarks text and I can also add that if you are looking at var [C#] instead of the var keyword [C#] this warning is less obvious. So when should you use it?

How to use var
var is a way of implicitly create a type, an temporary anonymous type. Note that this is not the same as variant in other languages. This means that the variable is still typesafe and can not change its type. For example the variable "i" in var i=10; can not be set to i="foo";. When declaring "i" we will implicitly say that i is an int. var is powerful for example when we use LINQ. It is a way of letting .NET help us create a temporary type for us (it is often temporary since it can only be used for local variables).

var somePerson = new { SomeProperty1 = 10, SomeProperty2 = "Foo" };

var persons1 = from p in Person
where p.Age == 30
select p.Name;

var persons2 = from p in Person
where p.Age == 30
select new { p.Name, p.Age, p.EyeColor };

In persons1 the type will be a string (if p.Name is a string) and in persons2 it will be a temporary type containing name, age and eye color. This is a ok syntax and it is also a very powerful feature. Implicit typing can also be used in lambda expressions but sometimes I think it makes the code unreadable. What about my rage against var?

How not to use var!
A colleague of mine has a motto that says: "Any fool can write code that a computer can understand. Good programmers write code that humans can understand." In a time where usability and collaboration with people is key features you must write code that anyone can understand and that is self-explaining. Lately I have see more and more misuse of var and here are some examples of misuse:

var sample1 = 10; // Why not just type int? Maybe I really wanted a double?
var sample2 = GetPersonName(person); // What will be returned, an object, a string?
var sample3 = someReference.DoSomethingReallyFancy<ReallyStrangeObject>(); // Same as above!
var sample4 = new MyClass(); // Maybe ok?

The first sample is just stupid and makes the code hard to read. As the comment say, maybe you really wanted a double but forgot the ".0", this can be hard to see in debugging a calculation. In sample2 you really have no clue what type of object the method is returning. Sure you have intellisense but you should NEVER have to use intellisense to read code, maybe you are in an editor without intellisense. Sample3 is the same as sample2 but in a more complex format. I see this a lot and I hate it! Sample4 is not my favorite but it can be ok if you have a really long class name. In this samploe you can see the type in the declaration. I see a small risk here and that is if you refactor sample4 to a factory or some method, then sample4 will be the same as sample2. In this short context these use of var might not seem to ugly, but try a method that only uses var to declare its variables and get all instances from other methods and then do some fancy stuff with it. I promise you that the code will be hard to read bot for you and especially for another developer.

I think this use of var is really bad programming and I think that developers that use this type of coding are bad developers writing bad code, so please stop the misuse of var! Please!

Oredev 2008 - First day

The first day of Öredev 2008 is at its end and it's really been a great day. I just love the exchange of knowledge and all the people you meet at the conference. Today the highlight were: meeting people, Glenn Block talking about Composite WPF/Silverlight and the keynote speaker Ted Neward talking about "The New Big Thing".

Seminar - Composite WPF

Dotway will present a seminar about Composite WPF in Stockholm, Malmö, Göteborg and Linköping, Sweden. Speaker will be my colleague George Bolsch. Composite WPF, former known as Prism, is a Composite Application Guidance for WPF and is a project from the Microsoft Patters & Practices team. This is a really interesting seminar about building scalable, modular applications in the Windows Presentation Foundation. George has a tremendous knowledge about .NET and is also a member of the Patters & Practices reference team. The seminar is free and you can register by sending an email to one of the addresses below.

Linköping 21/10 2008 (07.30-09.30) - linkoping at dotway.se
Stockholm 21/10 2008 (17.00-19.00) - stockholm at dotway.se
Göteborg 22/10 2008 (07.30-09.30) - goteborg at dotway.se
Malmö 23/10 2008 (07.30-09.30) - seminarie at dotway.se

Dotway.WPF - A library with WPF controls, effects and panels

A first version of a WPF library has been published at CodePlex. It contains custom controls, pixel shader effects and custom panels. More functionality will be added later. Go to the project site and download source code or only the libraries. You can also download and try the sample application. Example of controls: color picker, editable slider, grayscale effect, pixelate effect, interaction controls, halftoning effect, a auto fitted wrap panel and more.
 
The sample application with a custom WPF control, a color picker much like the one in Expression Blend.

A Greeting Creator - Silverlight

This is a reference to a project on CodePlex. It refers to a Silverlight 2 Beta 2 sample application (with source code) that will show solutions to a set of problems in Silverlight. E.g. creating custom controls, communicating with a WCF service, use replaceable GUI (templating), captcha functionality, creating custom panels, multi templated ListBox. 

I hade the privilege to post one of my project at work on CodePlex. It is a Silverlight application where you in edit mode can create a greeting with text, images and magnetic poetry and then send it to your friends or save it to a database. The receiver can then read the message or you can embed your message on a web site. I had a lot of help from Johan Normén and Robert Folkesson in this project.
You find the project here!

Scale, Move and rotate controls in your GUI - WPF

In this blog post I will describe and share a custom control in WPF (Windows Presentation Foundation) that you can use to encapsulate other WPF-controls. This control will add functionality so that you can move, rotate and scale your WPF-controls with your mouse. It also adds a control that will rasie an event (Click-event) when clicked. You can download a sample project with the control at the bottom of the page.

In the image above the red square is a control that will raise a click-event. The outer gray squares are for rotation and the inner ones are for scaling. In the middle the control can be moved (translated).

Background
In a previous post I did this control in Silverlight. This is the WPF version and I have made some adjustments and used some other solutions in this version. These will be described below.

Problem
Many times when you design an application you do not only want to present information to a user, you also want the user to interact with your program and your controls. Sometimes this interaction involves moving, scaling and rotating an object. I missed a simple control to wrap other controls in that would add this.

How does it work?
Feel free to compare this solution with the Silverligh version. To start with, this is a control that can be used as a container for other controls. This means that you do not have to modify any other code in your existing controls. This control just adds the ability to interact (move, scale and rotate) with your control.
To do this we need a bock of Transforms in our custom control:

<Grid.RenderTransform>
    <TransformGroup>
        <ScaleTransform ScaleX="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=Scale}" ScaleY="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=Scale}" />
        <RotateTransform Angle="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=Angle}"/>
        <TranslateTransform X="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=X}" Y="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=Y}"/>
    </TransformGroup>
</Grid.RenderTransform>

This is the first different to the Silverlight version. In Silverlight we used the PART_-convension and set the ScaleX, Angle etc. in code behind through these variables. We still have dependency properties in code behind but we don't need to have the reference to the Transforms. Instead we use a binding to our properties. The RelativeSource property is something that doesn't exist in Silverlight and therefore we need the PART_-solution in that example. In WPF we can solve the problem by using a binding and in that way we doesn't restrict us as much in the template. It also results in less code in code behind (a lot of code/logic is removed) and that will make this control simpler and easier to maintain.

The templates are much the same in WPF/Silverlight. One other difference than the binding is that the VisualStateManager doen't exist in WPF (but I think it will be implmeneted in future versions). I love the VisualStateManager and its separation between control and template. In WPF we instead put all the interaction controls in a Panel and then set the Visibility of that panel in code behind.

To get all the interaction working we hook up on mouse events in both our interaction controls (panels) and also in our base the custom control (inherited from ContentControl). When I first translated from Silverlight to WPF the whole control froze after the first interaction. The listeners for mouse event looks like this:

private void OnScaleControlsMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
    _previousPosition = e.GetPosition(this);
    this.CaptureMouse();
    _iteractionMode = InteractionMode.Scaling;
}

We call CaptureMouse() and in Silverlight this will be automatically released then the mouse button is released. In WPF we need to do this manually by setting:

private void OnControlMouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
    _iteractionMode = InteractionMode.None;
    Mouse.Capture(null);
}

With Mouse.Capture(null) the mouse will be released.

WPF also have more Cursors that we can use. We use more common cursors for moving and sizing which makes the interaction more intuitive.

 
Code and sample project can be found here.

Scale, Move and rotate controls in your GUI - Silverlight

In this blog post I will describe and share a custom control in Silverlight 2 that you can use to encapsulate other Silverlight-controls. This control will add functionality so that you can move, rotate and scale your Silverlight-controls with your mouse. It also adds a control that will rasie an event (Click-event) when clicked. You can download a sample project with the control at the bottom of the page.

In the image above the red square is the are that will raise a click-event when pressed. The outer squares at the other corners is controls for rotation and the inner squares are controls for scaling.

Problem
Many times when you design an application you do not only want to present information to a user, you also want the user to interact with your program and your controls. Sometimes this interaction involves moving, scaling and rotating an object. I missed a simple control to wrap other controls in that would add this.

How does it work?
A custom control in Silverlight and WPF is a control that contains some functionality and it is look-less. This means that you can change and switch the presentation of a control by changing its template. The base class chosen for this control is ContentControl and this base class is extremely powerful for encapsulating other controls (the content).
The functionality we want in this control is logic for clicking, moving, rotating and scaling. This includes listening to mouse-events of different kinds and the acting on those. What we need is some way of catching these events for the different type of transforms that we want to do.

<Grid x:Name="PART_TranslateControls">
<Rectangle Fill="Transparent" Cursor="Hand" />
</Grid>
<Grid x:Name="PART_ClickControls">
<Rectangle Fill="Red" Stroke="Black" Cursor="Arrow"/>
</Grid>
<Grid x:Name="PART_RotateControls">
<Rectangle Fill="DimGray" Stroke="Black"/>
<Rectangle Fill="DimGray" Stroke="Black"/>
<Rectangle Fill="DimGray" Stroke="Black"/>
</Grid>
<Grid x:Name="PART_ScaleControls">
<Rectangle Fill="LightGray" Stroke="DimGray"/>
<Rectangle Fill="LightGray" Stroke="DimGray"/>
<Rectangle Fill="LightGray" Stroke="DimGray"/>
</Grid>

The rectangles in the snippet above is only the appearance of the control and since we are listening to events from the panels we can set any look and feel of the clickable areas. Also not that we use the PART_ convention for creating custom controls.

In code behind, we add listeners for mousedown events for the different panels and calculates new position, rotation or size when the mouse is moved. The ContentControl contains a TransformGroup with a ScaleTransform, RotateTransform and a TranslateTransform which is the values that we are adjusting.

<TransformGroup>
<ScaleTransform x:Name="PART_Scale"/>
<RotateTransform x:Name="PART_Rotation" />
<TranslateTransform x:Name="PART_Translation" />
</TransformGroup>

We also have dependency properties that we can bind to in this control. The most beautiful solution for this would be to skip using PART_ for the transform and bind to the properties instead. The problem is that you can not bind to ScaleX, Angle, X etc. and therefore we need to get these parts in code-behind and then set the properties manually.

In the sample project below you can see all the mechanisms for this control.


Update 1: The sample code is now updated to Silverlight 2 RTW and I also added an sample of a transformable TextBox and functionality for ZIndex.
Update 2: The sample code has been updated. Hal9000Lives pointed out that the calculations for the rotation used the upper left corner as its center point. This has now been changed to use the middple point as center.
Code and sample project can be found here.

WPF-version of this control can be found here.

How to use Sessions in WCF and Silverlight (basicHttpBinding)

I was writing a WCF Service for a Silverlight application and I needed to use Sessions in my WCF service to store some info. As you know Silverlight 2 (beta 2) only supports basicHttpBinding and therefore we can not use sessions as in wsHttpBinding. I wanted to write something like:

HttpContext.Current.Application.Add("MyKey", someInfo);

But HttpContext.Current returned null. After reading some threads in forums I found this workaround, make your WCF Service ASP.NET compatible:

1. Put this attribute on your WCF Sevice class: [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]:

[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
public class MyService : IMyService
{
  ...
} 

2. In your Web.config for your WCF Service project set:

<system.serviceModel>
   <serviceHostingEnvironment aspNetCompatibilityEnabled="true"/>
</system.serviceModel>

This will make HttpContext.Current return something and you can now store your sessions. The difference I found in my solutions from some others is that I had a separate project for my WCF service than my ASP.NET web-project and that made the HttpContext fail.

Read more here: https://silverlight.net/forums/p/14175/57586.aspx

WCF - The type name ServiceReference1 does not exist in the type Namespace.ClassName

This is a short blog post about a strange error when adding a WCF service reference. A WCF service was created and I wanted to add a service reference to a client project. I added the reference through Visual Studio and everything went fine until I compiled. Then I got this error:
Error    3    The type name 'ServiceReference1' does not exist in the type 'MyWorld.MyWorld' ...\Service References\ServiceReference1\Reference.cs

I found that this is caused by me having the same namespace name as class name (MyWorld.MyWorld = Namespace.ClassName). Change your namespace to a name that is not the same name as your class and this will compile.