Programming WPF, 2nd Edition

Code-Based Input Handling Versus Triggers

The input handling techniques shown in this chapter all involve writing code that runs in response to some user input. If your reason for handling input is simply to provide some visible feedback to the user, be aware that writing an event handler or a custom command is likely to be overkill. It is often possible to create the visual feedback you require entirely within the user interface markup by using triggers. Triggers offer a declarative approach, where WPF does more of the work for you.

Any discussion of input handling in WPF would be incomplete without some mention of triggers. However, trigger-based input handling is radically different from the more traditional approach shown in this chapter, and it depends on aspects of WPF not yet described. Accordingly, it is dealt with later, in Chapter 8 and Chapter 9. So, for now just be aware of the two techniques and their intended usage: triggers are best suited for superficial responses, such as making a button change color when the mouse moves over it; event handling is appropriate for more substantive behavior, such as performing an action when the user clicks a button.