Include Multimedia - JavaFX: Developing Rich Internet Applications - page 222

you type the spurious slash as in

url: "{__DIR__}/figures/myImage.gif" // INCORRECT
As a result, the runtime system cannot locate the image file because __DIR__
already ends in a slash ( / ) character, and you end up with double slashes ( // ). This
issue has been raised on the JavaFX forums, and hopefully a fix will be imple-
mented to handle this automatically, but in the meantime be careful with this.

Now that we have an Image object, to view the image on the display, we need to
create a javafx.scene.image.ImageView . An ImageView is a scene graph node
that displays an image. Of course, one of its instance variables is image . Using
the image object we just created, we create an ImageView .

imageView = ImageView {
image: image = bind image

};

This creates a view that takes on the size of the underlying image. If the underlying
image is 100u100 pixels, the view will be sized accordingly. If you want to have
the image display with another size, you need to use the fitWidth and fitHeight
instance variables. Also, if you want to preserve the original aspect ratio for the
image, set preserveRatio to true. Just like the smooth variable in the Image object,
ImageView has a smooth variable. When smooth is set to true, scaling will favor
image quality over performance. On the other hand, when smooth is false, scaling
favors performance over quality. An example of doing this is shown in Listing 8.3.

Listing 8.3 ImageView Sizing

imageView = ImageView {
fitWidth: bind scene.width
fitHeight: bind scene.height - 25
preserveRatio : true
smooth: true
image: image = bind image
};

To improve performance, the ImageView can be cached in memory as a bitmap.
Do this by setting the variable cache to true. Caching improves performance at
the expense of memory. However, on some platforms with graphical processing
units (GPU), caching may not provide any benefit to performance at all. We sug-
gest that you try it either way and see if it helps.

Putting this all together in an example, SimpleImage , that is available on the topic's
Web site, we produce the displays in the figures that follow. In SimpleImage , we
used an image from the US National Aeronautics and Space Administration