R – What are your strategies for using Expression Blend on complex, decoupled WPF applications

expression-blendmvvmwpf

I've been doing WPF applications with the MVVM pattern using Visual Studio, coding C# and XAML mostly by hand.

Now I've gotten up to speed with Expression Blend so that I can click together WPF applications quickly just using the GUI, which is very nice, much more control of the layout than fiddling around with all the XAML elements 80% of your time.

But it seems that my applications in Expression Blend are simpler and necessarily coupled, using events that are handled in the code behind, etc.

I find it hard to imagine how I would go from this simpler approach of Expression Blend to a decoupled MVVM application with Views, ViewModels, routed events and commands, etc. other than to just take my whole project into Visual Studio and rearrange it to the point that I couldn't really edit it visually anymore in Blend, but would be back to using Blend to create little pieces of XAML that I paste into Visual Studio.

For those of you who are working with more complex applications with Expression Blend, what are your strategies for keeping your projects decoupled in an MVVM way, yet at the same time structured "in the Expression Blend way" (where you can still see and edit whole parts of your application in a way that makes sense visually) so that you can continue to edit them in the Blend GUI as they scale?

Best Answer

I've been using Blend first and foremost as a rapid-prototyping tool. For this purpose, I really like it. In particular, I find it very helpful when I'm not sure how to set things up to get the layout/behavior that I want.

I rarely edit my main project files directly in Blend. I find it creates markup that is unnecessarily complex or verbose. Also, as I become more familiar with WPF/XAML, I find myself using Blend less and less.

Related Solutions

C# – How should the ViewModel close the form

I was inspired by Thejuan's answer to write a simpler attached property. No styles, no triggers; instead, you can just do this:

<Window ...
        xmlns:xc="clr-namespace:ExCastle.Wpf"
        xc:DialogCloser.DialogResult="{Binding DialogResult}">

This is almost as clean as if the WPF team had gotten it right and made DialogResult a dependency property in the first place. Just put a bool? DialogResult property on your ViewModel and implement INotifyPropertyChanged, and voilà, your ViewModel can close the Window (and set its DialogResult) just by setting a property. MVVM as it should be.

Here's the code for DialogCloser:

using System.Windows;

namespace ExCastle.Wpf
{
    public static class DialogCloser
    {
        public static readonly DependencyProperty DialogResultProperty =
            DependencyProperty.RegisterAttached(
                "DialogResult",
                typeof(bool?),
                typeof(DialogCloser),
                new PropertyMetadata(DialogResultChanged));

        private static void DialogResultChanged(
            DependencyObject d,
            DependencyPropertyChangedEventArgs e)
        {
            var window = d as Window;
            if (window != null)
                window.DialogResult = e.NewValue as bool?;
        }
        public static void SetDialogResult(Window target, bool? value)
        {
            target.SetValue(DialogResultProperty, value);
        }
    }
}

I've also posted this on my blog.

C# – MVVM: Tutorial from start to finish

Your question really seems to be asking 2 questions:

Where are some good tutorials on WPF, assuming I have no previous WPF experience?
Where are some good tutorials on learning MVVM?

Some of these resources may be duplicated in previous answers...

Tutorials on WPF

A Guided Tour of WPF by Josh Smith

I wrote a series of introductory WPF articles on The Code Project. The goal of those articles is to bring someone with no WPF experience up-to-speed enough so that (s)he can fully understand how the series’ demo application works.
Bea Stollnitz (link is to her archives) has a number of great articles on WPF.
WPF: A Beginner's Guide - Part 1 of n by Sacha Barber
WindowsClient.net WPF Training Videos

MVVM Tutorials

WPF Apps With The Model-View-ViewModel Design Pattern by Josh Smith (duplicate link already provided by Yacoder)
Jason Dolinger's presentation on the Model-View-ViewModel (link to video embedded in article)
Dan Crevier's DataModel-View-ViewModel pattern series (similar to MVVM)

Composite WPF (Prism) Resources
Though not exactly what you asked, it is the natural progression with WPF and MVVM.

Best Answer

Related Solutions

C# – How should the ViewModel close the form

C# – MVVM: Tutorial from start to finish

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