Sudoku Application - JavaFX: Developing Rich Internet Applications - page 341

// 20: Should never get here
"{__DIR__}images/blank.png",
// 21-29 represents editable spaces in conflict
"{__DIR__}images/1-red.png",
"{__DIR__}images/2-red.png",
...
"{__DIR__}images/9-red.png",
// 30: Should never get here
"{__DIR__}images/blank.png",
// 31-39 represents non-editable spaces in conflict
"{__DIR__}images/1-red-bold.png",
"{__DIR__}images/2-red-bold.png",
...
"{__DIR__}images/9-red-bold.png"
];
As you may have surmised, the image files coincide with the layout of a Space 's
number instance variable as described in Table 13.3. For example, imageFiles[0]
contains the URL "{__DIR__}images/blank.png" —a blank space—whereas
imageFiles[19] points to "{__DIR__}images/9-bold.png" —an image of the
number 9 in bold, representing a non-editable space. The imageFiles sequence,
however, only contains strings that refer to URLs. What we actually need here is
a sequence of type Image to serve as an Image cache. This is achieved by using
imageFiles with the following code:
// Cached copies of Number Images
var images = for(url in imageFiles) {
Image {
url: url
backgroundLoading: true
}
}
Next, each SpaceNode defines two instance variables, one called spaceImage ,
which holds the current image displayed for each instance, and number , which
contains the value of the corresponding Space 's number instance variable. Using
a combination of binding and triggers, we can achieve the effect of updating a
SpaceNode 's current image whenever its corresponding Space has a change in its
number variable. This is accomplished with the following code:
protected var spaceImage:Image;
public var number:Integer = bind space.number on replace {
spaceImage = images[number];
};