Java Reference
In-Depth Information
for toolbar buttons and menu items are available. This outline version of
StatusBar
has two fields of type
StatusPane
that are the panes showing the current color and element type.
The
StatusPane
objects will be left-justified when they are added to the status bar, as a result of the
first argument to the
setLayout()
method call in the
StatusBar
constructor. The layout manager leaves a
10-pixel horizontal gap between successive panes in the status bar and a 3-pixel vertical gap between rows
of components. The border for the status bar is a single dark gray line that you add using the static
cre-
ateLineBorder()
method in the
BorderFactory
class.
The panes in the status bar need to display only a small amount of text, so you derive the
StatusPane
class from the
JLabel
class; a pane for the status bar is a specialized kind of
JLabel
. The
StatusBar
con-
structor updates the information to be displayed in each pane initially by calling the
setColorPane()
and
setTypePane()
methods. This ensures that the
StatusPane
objects display the default color and element
type that you defined for the application at startup. One or other of these methods is called whenever it is ne-
cessary to update the status bar. You will complete the definitions for
setColorPane()
and
setTypePane()
when you've defined the detail of the
StatusPane
class.
The
StatusPane
class that is nested in
StatusBar
is derived from
JPanel
. A
JPanel
object can display
text, or an icon, or both. You can provision for status bar panes in Sketcher that display text, or text with an
icon. You need two constructors to accommodate this. Here's the inner class definition:
class StatusPane extends JLabel {
// Constructor - text only
public StatusPane(String text) {
super(text, LEFT);
setupPane();
}
// Constructor - text with an icon
public StatusPane(String text, Icon icon) {
super(text, icon, LEFT);
setupPane();
}
// Helper method for use by constructors
private void setupPane() {
setBackground(Color.LIGHT_GRAY);
// Set background color
setForeground(Color.BLACK);
// Set foreground color
setFont(paneFont);
// Set the fixed font
setBorder(BorderFactory.createCompoundBorder(
BorderFactory.createBevelBorder(BevelBorder.LOWERED), // Outside border
BorderFactory.createEmptyBorder(0,5,0,3)));
// Inside border
setPreferredSize(new Dimension(80,20));
}
private Font paneFont =
new Font("Serif", Font.PLAIN, 10); // Font for pane text
}
