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Top reviews from other countries. Verified Purchase. These are pretty much the only books out there I have to say this book is the best of them all. I haven't written any reviews for the other books only this one. That's how much i like this book. Trust me if you're new to WPF this book is the best one. Although Pro WPF 4. High Points of this book: 1 Less Garbage to filter out. Other books just assume you know how to set everything up. How It Works Section: This is very helpful and to the point.
This book is it's well organized, and to the point. So the reviews praise this book, for the most part, but from a learning aspect, the book lacks a great deal. The following are the problems: 1 For a great deal of the examples, the author fails to mention that certain Namespaces Using Statements are required for the code. The author does not ever show the user what the entire XML or C code should look like after explaining what he has done. Seeing the code would let the user know where things go, in case things aren't working out.
Just so users know, the examples in this book are very involved and a great deal of the examples are things that will not be normally used. The author should have put some examples in that would be used on a regular basis. I've read a great deal of code books over the decades and this one is lacking, from a learning perspective.
Report abuse. Data binding gets a passing mention with regard to UI elements but an in-depth treatment is missing. I write business apps and have a data model to bind to my UI. I need to bind objects and sets of objects, and I've found most WPF books lacking in this area. If a property does not seem to get the expected value, there's a good chance we missed some provider that's "stronger" than the one we expected to win.
The Visual Studio debugger has a visualizer that can be used to view the current property values of elements, and very important the provider that's effectively providing this value. Here's an example for our famous second TextBlock :. Note the Local reading of the Source column. The CH InheritDemo project, available with the downloadable source for this chapter, can be used to test it out. To get to this dialog, set a breakpoint where you have easy access to the required variable in this case it could be done in the MainWindow constructor after InitializeComponent , and then click on the small magnifying glass near the variable's value column:.
The Source column clearly indicates that the value was set because of visual inheritance. This information is also available by using other tools that don't require Visual Studio or a debugger of any kind. This tool can look at any WPF window and drill down into the visual tree, showing property values with their source ; since it does not require anything special, it can be used in production environments, where tools such as Visual Studio are not typically found.
As mentioned, there are 11 levels, or priorities, of dependency property providers. Here's the complete list highest to lowest precedence :. Property coercion : The coercion mechanism allows a delegate to execute before the final value is set for the property.
That coercion delegate is provided as part of the property metadata at registration time. For example, if a property signifies an hour in the day, it should have a value between 0 and The coercion callback can look at the suggested value, and if say it's greater than 23, return 23 as the final value. Active animation : If an animation is active, it provides the property's current value. Template parent properties : If the control was created as part of a ControlTemplate or DataTemplate , these properties apply we'll discuss data templates in Chapter 6 and control templates in Chapter 8.
Implicit style : We'll discuss implicit styles in Chapter 8. Style triggers from Windows or the application we'll discuss triggers in Chapter 8. Template triggers : Triggers that are part of a template again, Chapter 8. Style setters : Values from styles defined in the Window or the application styles are discussed in Chapter 8. Default style : Set by the control creator and can be based on the current Windows theme. Inheritance : As discussed in a previous section.
Default value : As set in the property metadata. Attached properties are curious beings. There is no direct analogue to anything else in the. NET framework. The closest may be extension methods, introduced in C 3. Extension methods are a way of extending a type without inheriting from it even if that type is sealed. Attached properties are dependency properties that are defined by some type, but can be used by almost any other typed object. That is, they can extend a type's properties without code derivation.
In this recipe, we'll see how to use an existing attached property, and in the next one we'll learn how to create a new attached property.
We'll create an application that creates a rectangle and places it inside a canvas at exact coordinates using attached properties:. This creates a grid which hosts a Canvas and that canvas hosts a RepeatButton.
Let's add a Rectangle element to the Canvas and place it in some position:. The Canvas. Left and Canvas. Top are attached properties. They are defined by the Canvas type, but they can be applied to any element technically, anything that derives from DependencyObject. In this case, these two properties are applied to the Rectangle , essentially "extending" its property set with two new properties.
The syntax DefiningClassName. Now let's try changing these properties in code. When the repeat button is clicked, let's move the rectangle a little bit to the right.
First, let's name the Rectangle , so we can easily refer to it in code:. Add a Click event handler to the RepeatButton. In the handler, add the following code:. An attached property is accessed in code using a set of static methods on the class declaring the property in this case, the Canvas. The first argument to these methods is the intended target of the property in this case the Rectangle.
Click on the button and hold ; you should see the rectangle moving along to the right, 5 units at a time. An attached property is first and foremost a dependency property, meaning it supports all the capabilities of dependency properties. However, as an attached property is "attached" to an object that did not define it, a simple property like syntax is not possible — as C does not support the concept of attached properties natively. Instead, the declaring class provides two static methods, named DeclaringType.
SetPropertyName and DeclaringType. GetPropertyName , that provide a way to set or get the property value for some object passed in as the first argument as demonstrated in the last code snippet. PropertyName attribute to the aforementioned Set method. This means that the code to move the rectangle could have been written as follows:.
One may wonder why to go to all this trouble for the Left and Top properties. Would it not be simpler to define the Left and Top properties on the for example UIElement class and be done with it?
These properties could have been normal dependency properties and enjoy the simpler syntax they carry. The reason is, that a Left or Top property may not always make sense.
In fact, it only makes sense when the element is placed within a Canvas. What if the rectangle is inside a Grid? Or a StackPanel? This leads to the conclusion that attached properties are a kind of contextual property — they are relevant under particular circumstances, so they can be "attached" if and when actually needed.
The previous example may lead to a wrong conclusion. It seems Canvas. Left and the like are only relevant when the element is inside a Canvas. Similarly, the Grid. Row and Grid. Column attached properties only make sense for elements placed inside a Grid. Is this somehow necessary from an attached property point of view?
Not at all. This is just coincidence. The above properties in fact make sense only for elements placed inside their respective declaring type, but that does not have to be the case. For example, suppose we have a button with a tool tip defined:. If the button is disabled IsEnabled set to true , the tool tip does not appear at runtime. To make it appear even if the control is disabled, we must set the ToolTipService.
ShowOnDisabled attached property to true :. We set the property on the button, but it's defined in the ToolTipService class. This class is not an element unlike the Canvas for example. In fact, it's a static class instances of it cannot be created. The way this connection is established so it can have some effect will be revealed in the next recipe in this chapter. To create your own attached properties, refer to the next recipe, Creating an attached property.
An attached property can be used to somehow "enhance" or extend another object. In the case outlined in the previous recipe, Using an attached property , an element was placed at exact coordinates within a Canvas using the attached Canvas.
Top properties. An attached property is a powerful tool for extending the behavior of any object without the need to inherit from the type of the object.
In this task, we'll see this in action. Open MainWindow. Add some elements in a Canvas replace the default Grid as follows:. Suppose we want to rotate a particular element around its center. We would have to write something like this example for the Ellipse :.
Although this is certainly possible, this makes for a lot of typing. Now imagine doing something similar for other elements. Let's make it shorter by defining and using an attached property. We'll register a new attached property within this class; a property any other object can use.
To do that, we'll take advantage of a Visual Studio code snippet, propa similar in concept to propdp discussed in the task Creating a dependency property in this chapter. Inside the class definition, type propa without the quotes.
This is how it should look at this point:. Press Tab once, and fill in the property details as follows: the property type should be double, its name should be Angle , its owner class RotationManager , and its default value zero. You'll have to add a using statement for System. Windows namespace. The generated code should look as follows after removing the comment and some formatting :. Now that we have an attached property definition, let's use it. We'll set it on our various elements. Now let's set the property with various values on the various elements.
Here's an example for the Ellipse notice the intellisense popping up to help :. Add similar settings for the Rectangle and Button like as follows:. Notice that the designer preview shows no change. If you run the application, nothing happens. And why would anything happen? We declared a property and nothing else. Let's add some behavior logic if the property is actually used. For that, we'll add a property changed handler notification.
Go back to RotationManager. The OnAngleChanged method will be called for any change in the property value on any object it's applied to. Let's add some simple logic that will rotate the element:. If we switch back to the designer, we'll see the elements rotated according to the specified angles.
If we run the application, we'll see something like this:. Attached properties are registered similarly to regular dependency properties. In terms of functionality, they are dependency properties. This means they support everything a dependency property supports: data binding, animation, and so on.
An attached property can be defined by any class RotationManager in our example and can be applied to any object whose type derives from DependencyObject. Simply registering an attached property has no effect on its own. There must be some "extra" code that looks for that property and does something when it's applied or changed. In the example shown, this is done by specifying a property changed handler, called by WPF whenever the property is changed on any object. This also shows the weakness of attached properties: it's not possible to know whether specifying the property on some object is beneficial.
We could have thrown an exception if the object was not UIElement -derived to somewhat rectify this albeit at runtime rather than compile time , but this is not typically employed although we could have written something with Debug. WriteLine to indicate this needs attention , as there may be other code that does not consider this an invalid setting. The property change notification scheme is typically used by WPF with attached properties that are defined by panels, such as Canvas , DockPanel , and Grid.
Note that the panels only look for the relevant attached properties on their immediate children and not grandchildren. This is not a limitation of attached properties, it's simply the way these panels work. Although attached properties within panels are common, there are other ways these properties can be used. One possibility is to use the existence of these property values within styles a complete treatment of styles is in given Chapter 8 or templates templates are discussed in Chapter 6 and Chapter 8.
For now, think of a style as a grouping of related settings that can be applied as a group to an element. Latest commit. Git stats 23 commits. Failed to load latest commit information.
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