Servis-Rhino 4211B Betriebsanweisung PDF herunterladen (Seite 255)

javafx.stage.Stage

We can loosely think of the stage object as being a representation of the top level window of the

application. The stage ties to the notion of the native operating system window. When a stage is

shown, it will have properties including size (width and height) as well as others.

A stage doesn't actually appear until and unless it is shown. It can be shown using its "show()"

method.

Some of the more important properties of Stage are:

• title – The title of the window

Following on with the metaphor of a play, contained upon a stage is the scene being shown and

JavaFX has the same notion. We can think of the Stage as where the action takes place but it is the

Scene that is the object of attention.

We can set the icon associated with an application using:

stage.getIcons().add(<Image>);

Consider adding multiple images of different sizes. Used 16x16 and 32x32 as a minimum. JavaFX

will correctly choose the appropriate sizes as needed.

For non desktop environments, the stage may be an area in a browser (an applet) or a mobile device

screen area.

javafx.?.Scene

Scenes can be created in a variety of ways but, once done, we can associate the scene with the stage

by calling the stage's "setScene(Scene)" method. Before we can talk further about Scenes, we

must now introduce the idea of a "scene graph". In JavaFX, what the user sees is built out as a set

of "Nodes" where each node represents some UI component. Examples of Nodes include the usual

suspects such as Buttons and Lists and JavaFX provides a rich set of additions. One of the notions

of a Node is that every node has a parent. This means that the nodes form a relationship model (a

tree or graph). This relationship model is the key to JavaFX. We can have simple Nodes such as

Button which are the "leaves" of the tree. They have no children themselves. However other nodes

called "containers" can have children (the parent of these children is the container that contains

them). If we follow the parent/child relationship upwards we will find a single node that is the root

of the tree. This node has no parent. This root node is what is associated with a Scene. When the

Scene is shown, it is the tree represented by the nodes that is actually used to describe what is made

visible to the users.

javafx.scene.image.Image

This class represents an image from a .png or other graphics file. It has a number of sources from

which the data of the image can be read.

For example, to load an image from a file that is in the same directory as a class we can use:

Image image = new Image(MyApplication.class.getResourceAsStream("myImage.png"));

This might be used as the icon image associated with a stage. An Image can also be constructed

from an InputStream. This means that if we can source the image data from elsewhere such as

a database … we can also create an Image.

Servis-Rhino 4211B Betriebsanweisung Seite 255