[JAVA][Beginning Java 8 Games Development]

Chapter 6 ■ The Foundation of Game Design: The JavaFX Scene Graph and the InvinciBagel Game Infrastructure
If an HBox has a border or a padding value specified, the contents of your HBox layout container will respect that
border or padding specification. A padding value is specified using the Insets class, which you will be using for exactly
this fine-tuned UI control bank application.
You will use the HBox class (object), along with the Pos class constant and the Insets class (object), to group the
UI Button objects together and, later, to fine-tune their position as a Button control bank. This HBox layout container
will thus become the Parent node (or a branch node) for the Button UI controls (or leaf nodes).
Think of an HBox object as a way to array children objects horizontally, in a row. These could be your image
assets, which would use the basic HBox constructor (with zero spacing), or UI controls, such as buttons, arranged next
to each other but spaced apart, using one of the overloaded constructors. The simplest constructor for an HBox object
creation would use the following empty constructor method call format:
HBox()
The overloaded constructor that you will be employing for your HBox object creation will use a spacing value to
put some space between the child Button objects inside the HBox, with the following constructor method call format:
HBox(double spacing)
There are also two other overloaded constructor method call formats. These will allow you to specify the children
Node objects (in this case, Button objects) inside the constructor method call itself, as follows:
HBox(double spacing, Nodes... children) - or, with zero spacing value in between Node objects:
HBox(Nodes... children)
You are going to be using the “long form,” and .getChildren().addAll() method chain, in your code, but you
could also declare the HBox, and its Button Node objects, by using the following constructor:
HBox buttonContainer = new HBox(12, gameButton, helpButton, scoreButton, legalButton);
The HBox layout container will control resizing of child elements, based on different screen sizes, aspect ratios,
and physical resolutions if the child objects are set to be resizable. If the HBox area will accommodate the child
objects’ preferred widths, they will be set to that value. In addition, a fillHeight attribute (boolean variable) is set to
true, as the default value, specifying whether a child object should fill (scale up to) the HBox height value.
Alignment of an HBox is controlled by the alignment attribute (property or variable), which defaults to the
TOP_LEFT constant from the Pos class (Pos.TOP_LEFT). If an HBox is sized above its specified width, the child
objects use their preferred width values, and the extra space goes unused. It is important to note that the HBox layout
engine will lay out the managed child elements, regardless of their visibility attribute (property or variable) setting.
Now that I have discussed the JavaFX geometry and layout classes, which you will be using to create the UI
(a bank of Button objects) design, let’s take a look at the digital image–related classes, from the javafx.scene.image
package, which will allow you to implement the digital image–compositing pipeline that you will put in place behind
these four JavaFX Button UI control element objects held inside an HBox UI layout container object.
The JavaFX Image Class: Referencing Digital Images in a Design
The Image class is a public class that directly extends the java.lang.Object masterclass, meaning that the Image class
was also coded from scratch to provide image loading (referencing) and scaling (resizing). You can lock the aspect
ratio for scaling and specify the scaling algorithm (quality) as well. All URLs that are supported by the java.net.URL
class are supported. This means that you can load images from the Internet (www.servername.com/image.png); from
the OS (file:image.png); or from the JAR file, using a forward slash (/image.png).
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