Electronic Books

In other words, when the XAML parser meets the previous markup, it creates an instance
of each nested element and passes it to the Grid using the Grid.Children.Add() method:
txtQuestion = New TextBox()
...
grid1.Children.Add(txtQuestion)
cmdAnswer = New Button()
...
grid1.Children.Add(cmdAnswer)
txtAnswer = New TextBox()
...
grid1.Children.Add(txtAnswer)
What happens next depends entirely on how the control implements the content property.
The Grid displays all the controls it holds in an invisible layout of rows and columns, as
you??™ll see in Chapter 4.
The ContentProperty attribute is frequently used in WPF. Not only is it used for container
controls (such as Grid) and controls that contain a collection of visual items (such as the List-
Box and TreeView), it??™s also used for controls that contain singular content. For example, the
TextBox and Button are only able to hold a single element or piece of text, but they both use a
content property to deal with nested content like this:

[Place question here.]


Ask the Eight Ball


[Answer will appear here.]

The TextBox class uses the ContentProperty attribute to flag the TextBox.Text property.
The Button class uses the ContentProperty attribute to flag the Button.


Pages:
121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145