Beginning Web Development, Silverlight, and ASP.NET AJAX

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CHAPTER 16 ■ PROGRAMMING SILVERLIGHT WITH XAML AND JAVASCRIPT
The keyUp event will fire when the key has been released. It exposes the same parameters
as the keyDown event, and can be handled in the same manner. When processing
input, it is often better to capture it on keyUp instead of keyDown—that way, you can more
accurately assess the state of the Shift and Ctrl keys. For example, when the user types
Shift+S for an uppercase S, you’ll get two keyDown events: one for the initial Shift, and then
one for the S. However, for keyUp, you’ll only get an event for Shift+S.
Handling the Loading of Controls with the Loaded Event
Every XAML element exposes a Loaded event, which can be captured to do some processing
once the element is loaded. In most examples, you’ll see a Loaded event being captured on
the control itself, but if you want finer-grained processing, you can do it for each element.
This is very useful when you want to add event listeners at runtime. If you have a
lot of controls that you want to set up event listeners for, and you do them all in the control’s
Load event, you’ll end up with a lot of code in there that is difficult to maintain.
Note that if you specify the Load event for an element and that element’s child, the
child event will fire first, followed by the parent.
Handling Mouse Events
Controls can be interacted with using the mouse, and several events are provided that
allow you to control their behavior in different circumstances. Each of these events provide
a reference to the control as their first argument, and a MouseEventArgs object as their
second argument.
The MouseEventArgs object exposes a getPosition method that returns an object containing
x and y properties that are used to get the coordinates of the mouse on the screen.
In addition, it exposes a shift property that is used to determine whether the Shift key
was pressed, and a ctrl property that is used to determine if the Ctrl key was pressed.
The events that can be captured are as follows:
MouseEnter: This fires when the mouse enters the bounds of this control.
MouseLeave: This fires when the mouse leaves the bounds of this control.
MouseLeftButtonDown: This fires when the left mouse button is held down over the
control.
MouseLeftButtonUp: This fires when the left mouse button is released over the control
after being held down over the control.
MouseMove: This fires when the mouse is moved within the bounds of the control.