* The Box class can create several kinds
* of invisible components
* that affect layout:
* glue, struts, and rigid areas.
* If all the components your Box contains
* have a fixed size,
* you might want to use a glue component
* (returned by createGlue)
* to control the components' positions.
* If you need a fixed amount of space between two components,
* try using a strut
* (createHorizontalStrut or createVerticalStrut).
* If you need an invisible component
* that always takes up the same amount of space,
* get it by invoking createRigidArea.
*
* If you are implementing a BoxLayout you
* can find further information and examples in
* How to Use BoxLayout,
* a section in The Java Tutorial.
*
* Warning:
* Serialized objects of this class will not be compatible with
* future Swing releases. The current serialization support is
* appropriate for short term storage or RMI between applications running
* the same version of Swing. As of 1.4, support for long term storage
* of all JavaBeansTM
* has been added to the java.beans package.
* Please see {@link java.beans.XMLEncoder}.
*
* @see BoxLayout
*
* @author Timothy Prinzing
*/
public class Box extends JComponent implements Accessible {
/**
* Creates a Box that displays its components
* along the the specified axis.
*
* @param axis can be {@link BoxLayout#X_AXIS},
* {@link BoxLayout#Y_AXIS},
* {@link BoxLayout#LINE_AXIS} or
* {@link BoxLayout#PAGE_AXIS}.
* @throws AWTError if the axis is invalid
* @see #createHorizontalBox
* @see #createVerticalBox
*/
public Box(int axis) {
super();
super.setLayout(new BoxLayout(this, axis));
}
/**
* Creates a Box that displays its components
* from left to right. If you want a Box that
* respects the component orientation you should create the
* Box using the constructor and pass in
* BoxLayout.LINE_AXIS, eg:
*
* Box lineBox = new Box(BoxLayout.LINE_AXIS);
*
*
* @return the box
*/
public static Box createHorizontalBox() {
return new Box(BoxLayout.X_AXIS);
}
/**
* Creates a Box that displays its components
* from top to bottom. If you want a Box that
* respects the component orientation you should create the
* Box using the constructor and pass in
* BoxLayout.PAGE_AXIS, eg:
*
* Box lineBox = new Box(BoxLayout.PAGE_AXIS);
*
*
* @return the box
*/
public static Box createVerticalBox() {
return new Box(BoxLayout.Y_AXIS);
}
/**
* Creates an invisible component that's always the specified size.
*
*
* @param d the dimensions of the invisible component
* @return the component
* @see #createGlue
* @see #createHorizontalStrut
* @see #createVerticalStrut
*/
public static Component createRigidArea(Dimension d) {
return new Filler(d, d, d);
}
/**
* Creates an invisible, fixed-width component.
* In a horizontal box,
* you typically use this method
* to force a certain amount of space between two components.
* In a vertical box,
* you might use this method
* to force the box to be at least the specified width.
* The invisible component has no height
* unless excess space is available,
* in which case it takes its share of available space,
* just like any other component that has no maximum height.
*
* @param width the width of the invisible component, in pixels >= 0
* @return the component
* @see #createVerticalStrut
* @see #createGlue
* @see #createRigidArea
*/
public static Component createHorizontalStrut(int width) {
return new Filler(new Dimension(width,0), new Dimension(width,0),
new Dimension(width, Short.MAX_VALUE));
}
/**
* Creates an invisible, fixed-height component.
* In a vertical box,
* you typically use this method
* to force a certain amount of space between two components.
* In a horizontal box,
* you might use this method
* to force the box to be at least the specified height.
* The invisible component has no width
* unless excess space is available,
* in which case it takes its share of available space,
* just like any other component that has no maximum width.
*
* @param height the height of the invisible component, in pixels >= 0
* @return the component
* @see #createHorizontalStrut
* @see #createGlue
* @see #createRigidArea
*/
public static Component createVerticalStrut(int height) {
return new Filler(new Dimension(0,height), new Dimension(0,height),
new Dimension(Short.MAX_VALUE, height));
}
/**
* Creates an invisible "glue" component
* that can be useful in a Box
* whose visible components have a maximum width
* (for a horizontal box)
* or height (for a vertical box).
* You can think of the glue component
* as being a gooey substance
* that expands as much as necessary
* to fill the space between its neighboring components.
*
* * * For example, suppose you have * a horizontal box that contains two fixed-size components. * If the box gets extra space, * the fixed-size components won't become larger, * so where does the extra space go? * Without glue, * the extra space goes to the right of the second component. * If you put glue between the fixed-size components, * then the extra space goes there. * If you put glue before the first fixed-size component, * the extra space goes there, * and the fixed-size components are shoved against the right * edge of the box. * If you put glue before the first fixed-size component * and after the second fixed-size component, * the fixed-size components are centered in the box. * *
*
* To use glue,
* call Box.createGlue
* and add the returned component to a container.
* The glue component has no minimum or preferred size,
* so it takes no space unless excess space is available.
* If excess space is available,
* then the glue component takes its share of available
* horizontal or vertical space,
* just like any other component that has no maximum width or height.
*
* @return the component
*/
public static Component createGlue() {
return new Filler(new Dimension(0,0), new Dimension(0,0),
new Dimension(Short.MAX_VALUE, Short.MAX_VALUE));
}
/**
* Creates a horizontal glue component.
*
* @return the component
*/
public static Component createHorizontalGlue() {
return new Filler(new Dimension(0,0), new Dimension(0,0),
new Dimension(Short.MAX_VALUE, 0));
}
/**
* Creates a vertical glue component.
*
* @return the component
*/
public static Component createVerticalGlue() {
return new Filler(new Dimension(0,0), new Dimension(0,0),
new Dimension(0, Short.MAX_VALUE));
}
/**
* Throws an AWTError, since a Box can use only a BoxLayout.
*
* @param l the layout manager to use
*/
public void setLayout(LayoutManager l) {
throw new AWTError("Illegal request");
}
/**
* Paints this Box. If this Box has a UI this
* method invokes super's implementation, otherwise if this
* Box is opaque the Graphics is filled
* using the background.
*
* @param g the Graphics to paint to
* @throws NullPointerException if g is null
* @since 1.6
*/
protected void paintComponent(Graphics g) {
if (ui != null) {
// On the off chance some one created a UI, honor it
super.paintComponent(g);
} else if (isOpaque()) {
g.setColor(getBackground());
g.fillRect(0, 0, getWidth(), getHeight());
}
}
/**
* An implementation of a lightweight component that participates in
* layout but has no view.
*
* Warning:
* Serialized objects of this class will not be compatible with
* future Swing releases. The current serialization support is
* appropriate for short term storage or RMI between applications running
* the same version of Swing. As of 1.4, support for long term storage
* of all JavaBeansTM
* has been added to the java.beans package.
* Please see {@link java.beans.XMLEncoder}.
*/
public static class Filler extends JComponent implements Accessible {
/**
* Constructor to create shape with the given size ranges.
*
* @param min Minimum size
* @param pref Preferred size
* @param max Maximum size
*/
@ConstructorProperties({"minimumSize", "preferredSize", "maximumSize"})
public Filler(Dimension min, Dimension pref, Dimension max) {
setMinimumSize(min);
setPreferredSize(pref);
setMaximumSize(max);
}
/**
* Change the size requests for this shape. An invalidate() is
* propagated upward as a result so that layout will eventually
* happen with using the new sizes.
*
* @param min Value to return for getMinimumSize
* @param pref Value to return for getPreferredSize
* @param max Value to return for getMaximumSize
*/
public void changeShape(Dimension min, Dimension pref, Dimension max) {
setMinimumSize(min);
setPreferredSize(pref);
setMaximumSize(max);
revalidate();
}
// ---- Component methods ------------------------------------------
/**
* Paints this Filler. If this
* Filler has a UI this method invokes super's
* implementation, otherwise if this Filler is
* opaque the Graphics is filled using the
* background.
*
* @param g the Graphics to paint to
* @throws NullPointerException if g is null
* @since 1.6
*/
protected void paintComponent(Graphics g) {
if (ui != null) {
// On the off chance some one created a UI, honor it
super.paintComponent(g);
} else if (isOpaque()) {
g.setColor(getBackground());
g.fillRect(0, 0, getWidth(), getHeight());
}
}
/////////////////
// Accessibility support for Box$Filler
////////////////
/**
* Gets the AccessibleContext associated with this Box.Filler.
* For box fillers, the AccessibleContext takes the form of an
* AccessibleBoxFiller.
* A new AccessibleAWTBoxFiller instance is created if necessary.
*
* @return an AccessibleBoxFiller that serves as the
* AccessibleContext of this Box.Filler.
*/
public AccessibleContext getAccessibleContext() {
if (accessibleContext == null) {
accessibleContext = new AccessibleBoxFiller();
}
return accessibleContext;
}
/**
* This class implements accessibility support for the
* Box.Filler class.
*/
protected class AccessibleBoxFiller extends AccessibleAWTComponent {
// AccessibleContext methods
//
/**
* Gets the role of this object.
*
* @return an instance of AccessibleRole describing the role of
* the object (AccessibleRole.FILLER)
* @see AccessibleRole
*/
public AccessibleRole getAccessibleRole() {
return AccessibleRole.FILLER;
}
}
}
/////////////////
// Accessibility support for Box
////////////////
/**
* Gets the AccessibleContext associated with this Box.
* For boxes, the AccessibleContext takes the form of an
* AccessibleBox.
* A new AccessibleAWTBox instance is created if necessary.
*
* @return an AccessibleBox that serves as the
* AccessibleContext of this Box
*/
public AccessibleContext getAccessibleContext() {
if (accessibleContext == null) {
accessibleContext = new AccessibleBox();
}
return accessibleContext;
}
/**
* This class implements accessibility support for the
* Box class.
*/
protected class AccessibleBox extends AccessibleAWTContainer {
// AccessibleContext methods
//
/**
* Gets the role of this object.
*
* @return an instance of AccessibleRole describing the role of the
* object (AccessibleRole.FILLER)
* @see AccessibleRole
*/
public AccessibleRole getAccessibleRole() {
return AccessibleRole.FILLER;
}
} // inner class AccessibleBox
}