Use Dependency Properties for global properties

I am new to WPF. I have been reading a lot about WPF and dependency properties. My understanding of Dependency Properties is to bind properties to XAML (XAML being the target). I have envisioned a program in which a single configuration window would control all visual elements of the rest of the program (font, font size, colors, etc).

In my first attempt, I created a separate window that would contain all the different configuration options. This failed because I was unable to figure out how to use the dependency properties in separate XAML files.

Also, the dependency properties can only be registered in a class that implements directly or indirectly the DependecyObject class. How do I know which wpf objects implement it? It appears the window does not, but I could be wrong. My second attempt was this, to register the dependencies in the top window, so the whole visual tree would have access to it. I had exceptions being thrown and the only thing I could think of was that the window does not implement to DependencyObject. (I could be mistaken, and the visual tree thing is still sort of a mystery to me. I am learning though)

So now I'm at a loss. Is what I am attempting even possible? The whole purpose of this project was to help me learn WPF and now I'm wondering if I should lower my expectations of what I can accomplish with WPF.

Edit:

What kind of exception? What are you trying to do? Could you paste some code?

public partial class MainWindow : Window {
public Color BackColor {
   get { return (Color)GetValue(BackColorProperty); }
   set { SetValue(BackColorProperty, value); }
}
public static readonly DependencyProperty BackColorProperty =
   DependencyProperty.Register("BackColor",typeof(Color),typeof(MainWindow),
       new UIPropertyMetadata(0));

It appears that Color was causing the exception. I changed it to int and no e开发者_Go百科xception was thrown. So are primitive types only able to be registered?

WPF is a framework to help you bulit really good looking apps (it includes also Printing etc.) What are you trying to do? Should it be a part of Visual Tree?

Again, this project was only meant to get me to learn WPF. My idea was to create a main UI with different pages. A configuration button would bring up a window with options to change font, fontsize, background color, etc. These changes would be applied in the main UI as the user made the changes. My issue has been how do I access those dependency properties outside of the configuration class where they were registered? How do I have one window that can have slider and combo boxes, and any other class can access those configuration settings?

Put simply, I would like that a single configuration (fonts and colors) be somehow inherited by all UIs. And that that configuration can be changed and seen by the user.

Also, the dependency properties can only be registered in a class that implements directly or indeirectly the DependecyObject class. How do I know which wpf objects implement it? It appears the window does not, but I could be wrong.

http://msdn.microsoft.com/en-us/library/system.windows.window.aspx

look at the Inheritance Hierarchy it does implement DependecyObject

My second attempt was this, to register the dependencies in the top window, so the whole visual tree would have access to it. I had exceptions being thrown and the only thing I could thing of was that the window does not implement to DependencyObject.

What kind of exception? What are you trying to do? Could you paste some code?

So now I'm at a loss. Is what I am attempting even possible? The whole purpose of this project was to help me learn wpf and now I'm wondering if I should lower my expectations of what I can accomplish with wpf.

WPF is a framework to help you bulit really good looking apps (it includes also Printing etc.) What are you trying to do? Should it be a part of Visual Tree?

We cannot tackle here the big task of learning a whole new framework and designing your whole program. That will take time. It can be daunting but stick with it.

As for your exception, the problem is that the mysterious:

UIPropertyMetadata(0)

is actually providing the default value for the dependency property and this value must match the type specified in the second argument to Register. Since 0 is an integer and your property is a Color the dependency property subsystem throws an exception. Instead you can use:

UIPropertyMetadata(new Color())

or any other color as the default.

Dependency properties are a newer design specifically created for WPF. One of the problems they solve is to create faster resolves of the property values because they don't use older, slower, techniques (Read up on why they were created).

They are hard at first, to understand, because it's not exactly clear why they are needed when there is support for the Interface named INotifyPropertyChanged. But one main reason (among others) is that if you implement a DependencyProperty correctly, you will be able to change the design time property values of that property in the property window! Now this is a very cool thing to do because you can very easily set all of your default properties that way.

Doing this for the sake of design time property editing allows you to learn a lot more about DPs and why they are used. In fact, some prefer them everywhere, as they just are not that hard to code up.

DPs are also used when creating custom controls using the "Generic" folder method. This is how Microsoft themselves create all their controls.

There are some caveats to be aware of when using them. You cannot see the design time properties of a DPs until that particular control is contained by something else. In other words a UserControl with DPs will not show those Dps in the UserControl design. They will; however, show up in the control that contains that user control.

DPs bring maximum control using Metadata, PropertyChanged callbacks, default values, and Cohersion and other techniques which give you 100% control of what they contain. The DP is the ultimate in property control.

Keep scouring the internet as there are tons of articles out there on the topic.