Coding4Fun

Building the HealthBar Behaviors

As you've noticed, in both the Security Actor and in the Skeleton actor, we've been subtracting the value of the HealthBar property. Now we need to visually show the value of the health decreasing when the Health property changes.

Building a Custom Code Behavior for Updating the HealthBar's HealthValue

Click on the HealthBar actor, switch to its list of behaviors, and click the custom code event to add a new custom code behavior for the HealthBar actor. For the custom code event, select the Property Change event and set it so that whenever the Health property changes, the custom code event will fire (see Figure 2-65).

Figure 2-65. Setting the event to fire whenever the Health property changes

Next, we'll add the code in Example 2-6 for the custom code event. This code gets a reference to the top-level root of the Silverlight document, finds an XAML object named HealthValue, and then sets the Width of the HealthValue rectangle to the value of the game's Health property.

Example 2-6. Updating the width of the HealthValue Silverlight rectangle

this.GetVisualRoot().FindName("HealthValue").Width =
  Game.GetValue("Health").toString();

This is what happens in the game:

• When the game starts, the Health property is set to 100 (see Figure 2-29).

• When the Main actor collides with the Fire Bullet actor, we reduce the value of the Health property by 20.

• Once this happens, ...