java.lang.Object | +--java.awt.GridBagLayout
Safe: The GridBagLayout class is a flexible layout
manager that aligns components vertically and horizontally,
without requiring that the components be of the same size.
Each GridBagLayout object maintains a dynamic,
rectangular grid of cells, with each component occupying
one or more cells, called its display area.
Each component managed by a GridBagLayout is associated with
an instance of GridBagConstraints. The constraints object
specifies where a component's display area should be located on the grid
and how the component should be positioned within its display area. In
addition to its constraints object, the GridBagLayout also
considers each component's minimum and preferred sizes in order to
determine a component's size.
The overall orientation of the grid depends on the container's
ComponentOrientation property. For horizontal left-to-right
orientations, grid coordinate (0,0) is in the upper left corner of the
container with x increasing to the right and y increasing downward. For
horizontal right-to-left orientations, grid coordinate (0,0) is in the upper
right corner of the container with x increasing to the left and y
increasing downward.
To use a grid bag layout effectively, you must customize one or more
of the GridBagConstraints objects that are associated
with its components. You customize a GridBagConstraints
object by setting one or more of its instance variables:
GridBagConstraints.gridx,
GridBagConstraints.gridy
gridx = 0,
gridy = 0. For horizontal left-to-right layout,
a component's leading corner is its upper left. For horizontal
right-to-left layout, a component's leading corner is its upper right.
Use GridBagConstraints.RELATIVE (the default value)
to specify that the component be placed immediately following
(along the x axis for gridx or the y axis for
gridy) the component that was added to the container
just before this component was added.
GridBagConstraints.gridwidth,
GridBagConstraints.gridheight
gridwidth)
or column (for gridheight)
in the component's display area.
The default value is 1.
Use GridBagConstraints.REMAINDER to specify
that the component be the last one in its row (for gridwidth)
or column (for gridheight).
Use GridBagConstraints.RELATIVE to specify
that the component be the next to last one
in its row (for gridwidth)
or column (for gridheight).
GridBagConstraints.fill
GridBagConstraints.NONE (the default),
GridBagConstraints.HORIZONTAL
(make the component wide enough to fill its display area
horizontally, but don't change its height),
GridBagConstraints.VERTICAL
(make the component tall enough to fill its display area
vertically, but don't change its width), and
GridBagConstraints.BOTH
(make the component fill its display area entirely).
GridBagConstraints.ipadx,
GridBagConstraints.ipady
(ipadx * 2) pixels (since the padding
applies to both sides of the component). Similarly, the height of
the component will be at least the minimum height plus
(ipady * 2) pixels.
GridBagConstraints.insets
GridBagConstraints.anchor
ComponentOrientation property while absolute values
are not. Valid values are:
GridBagConstraints.NORTHGridBagConstraints.SOUTHGridBagConstraints.WESTGridBagConstraints.EASTGridBagConstraints.NORTHWESTGridBagConstraints.NORTHEASTGridBagConstraints.SOUTHWESTGridBagConstraints.SOUTHEASTGridBagConstraints.CENTER (the default)GridBagConstraints.PAGE_STARTGridBagConstraints.PAGE_ENDGridBagConstraints.LINE_STARTGridBagConstraints.LINE_ENDGridBagConstraints.FIRST_LINE_STARTGridBagConstraints.FIRST_LINE_ENDGridBagConstraints.LAST_LINE_STARTGridBagConstraints.LAST_LINE_END
GridBagConstraints.weightx,
GridBagConstraints.weighty
weightx) and column (weighty),
all the components clump together in the center of their container.
This is because when the weight is zero (the default),
the GridBagLayout object puts any extra space
between its grid of cells and the edges of the container.
The following figures show ten components (all buttons) managed by a grid bag layout. Figure 1 shows the layout for a horizontal, left-to-right container and Figure 2 shows the layout for a horizontal, right-to-left container.
Each of the ten components has the fill field
of its associated GridBagConstraints object
set to GridBagConstraints.BOTH.
In addition, the components have the following non-default constraints:
weightx = 1.0
weightx = 1.0,
gridwidth = GridBagConstraints.REMAINDER
gridwidth = GridBagConstraints.REMAINDER
gridwidth = GridBagConstraints.RELATIVE
gridwidth = GridBagConstraints.REMAINDER
gridheight = 2,
weighty = 1.0
gridwidth = GridBagConstraints.REMAINDER
Here is the code that implements the example shown above:
import java.awt.*;
import java.util.*;
import java.applet.Applet;
public class GridBagEx1 extends Applet {
protected void makebutton(String name,
GridBagLayout gridbag,
GridBagConstraints c) {
Button button = new Button(name);
gridbag.setConstraints(button, c);
add(button);
}
public void init() {
GridBagLayout gridbag = new GridBagLayout();
GridBagConstraints c = new GridBagConstraints();
setFont(new Font("Helvetica", Font.PLAIN, 14));
setLayout(gridbag);
c.fill = GridBagConstraints.BOTH;
c.weightx = 1.0;
makebutton("Button1", gridbag, c);
makebutton("Button2", gridbag, c);
makebutton("Button3", gridbag, c);
c.gridwidth = GridBagConstraints.REMAINDER; //end row
makebutton("Button4", gridbag, c);
c.weightx = 0.0; //reset to the default
makebutton("Button5", gridbag, c); //another row
c.gridwidth = GridBagConstraints.RELATIVE; //next-to-last in row
makebutton("Button6", gridbag, c);
c.gridwidth = GridBagConstraints.REMAINDER; //end row
makebutton("Button7", gridbag, c);
c.gridwidth = 1; //reset to the default
c.gridheight = 2;
c.weighty = 1.0;
makebutton("Button8", gridbag, c);
c.weighty = 0.0; //reset to the default
c.gridwidth = GridBagConstraints.REMAINDER; //end row
c.gridheight = 1; //reset to the default
makebutton("Button9", gridbag, c);
makebutton("Button10", gridbag, c);
setSize(300, 100);
}
public static void main(String args[]) {
Frame f = new Frame("GridBag Layout Example");
GridBagEx1 ex1 = new GridBagEx1();
ex1.init();
f.add("Center", ex1);
f.pack();
f.setSize(f.getPreferredSize());
f.show();
}
}
java.awt.GridBagConstraints,
java.awt.ComponentOrientation,
Serialized Formprotected Hashtable
comptable
protected GridBagConstraints
defaultConstraints
defaultConstraints.
protected static int
MAXGRIDSIZE
protected static int
PREFERREDSIZE
GridBagLayout()
void
addLayoutComponent(Component comp,
Object constraints)
constraints object.
void
addLayoutComponent(String name,
Component comp)
protected void
adjustForGravity(GridBagConstraints constraints,
Rectangle r)
protected void
AdjustForGravity(GridBagConstraints constraints,
Rectangle r)
adjustForGravity instead.
protected void
ArrangeGrid(Container parent)
arrangeGrid instead.
GridBagConstraints
getConstraints(Component comp)
int[][]
getLayoutDimensions()
protected GridBagLayoutInfo
getLayoutInfo(Container parent,
int sizeflag)
GridBagLayoutInfo for the
current set of managed children.
protected GridBagLayoutInfo
GetLayoutInfo(Container parent,
int sizeflag)
Point
getLayoutOrigin()
double[][]
getLayoutWeights()
protected Dimension
getMinSize(Container parent,
GridBagLayoutInfo info)
protected Dimension
GetMinSize(Container parent,
GridBagLayoutInfo info)
getMinSize instead.
void
invalidateLayout(Container target)
void
layoutContainer(Container parent)
Point
location(int x,
int y)
(x, y).
protected GridBagConstraints
lookupConstraints(Component comp)
Dimension
maximumLayoutSize(Container target)
Dimension
minimumLayoutSize(Container parent)
parent container
using this grid bag layout.
Dimension
preferredLayoutSize(Container parent)
parent
container using this grid bag layout.
private void
removeConstraints(Component comp)
void
removeLayoutComponent(Component comp)
void
setConstraints(Component comp,
GridBagConstraints constraints)
protected static final int MAXGRIDSIZE
protected static final int MINSIZE
protected static final int PREFERREDSIZE
protected Hashtable comptable
comptable are the components and the
values are the instances of GridBagConstraints.
java.awt.GridBagConstraintsprotected GridBagConstraints defaultConstraints
defaultConstraints.
protected GridBagLayoutInfo layoutInfo
layoutInfo is null
this indicates that there are no components in
the gridbag or if there are components, they have
not yet been validated.
getLayoutInfo(Container, int)public int[] columnWidths
null the values are
applied to the gridbag after all of the minimum columns
widths have been calculated.
If columnWidths has more elements than the number of
columns, columns are added to the gridbag to match
the number of elements in columnWidth.
getLayoutDimensions()public int[] rowHeights
rowHeights has more elements than the number of
rows, rowa are added to the gridbag to match
the number of elements in rowHeights.
getLayoutDimensions()public double[] columnWeights
null the values are
applied to the gridbag after all of the columns
weights have been calculated.
If columnWeights[i] > weight for column i, then
column i is assigned the weight in columnWeights[i].
If columnWeights has more elements than the number
of columns, the excess elements are ignored - they do
not cause more columns to be created.
public double[] rowWeights
rowWeights[i] > weight for row i, then
row i is assigned the weight in rowWeights[i].
If rowWeights has more elements than the number
of rows, the excess elements are ignored - they do
not cause more rows to be created.
transient boolean rightToLeft
static final long serialVersionUID
public GridBagLayout()
public void setConstraints(Component comp, GridBagConstraints constraints)
comp - the component to be modifiedconstraints - the constraints to be appliedpublic GridBagConstraints getConstraints(Component comp)
GridBagConstraints object is returned.
comp - the component to be queried
protected GridBagConstraints lookupConstraints(Component comp)
GridBagConstraints object used by the layout mechanism.
comp - the component to be queried
private void removeConstraints(Component comp)
comp - the component to be modifiedpublic Point getLayoutOrigin()
ComponentOrientation value of the container. This
is distinct from the grid origin given by the cell coordinates (0,0).
Most applications do not call this method directly.
java.awt.ComponentOrientationpublic int[][] getLayoutDimensions()
Most applications do not call this method directly.
public double[][] getLayoutWeights()
Most applications do not call this method directly.
public Point location(int x, int y)
(x, y). Each cell is identified
by its column index (ranging from 0 to the number of columns
minus 1) and its row index (ranging from 0 to the number of
rows minus 1).
If the (x, y) point lies
outside the grid, the following rules are used.
The column index is returned as zero if x lies to the
left of the layout for a left-to-right container or to the right of
the layout for a right-to-left container. The column index is returned
as the number of columns if x lies
to the right of the layout in a left-to-right container or to the left
in a right-to-left container.
The row index is returned as zero if y lies above the
layout, and as the number of rows if y lies
below the layout. The orientation of a container is determined by its
ComponentOrientation property.
x - the x coordinate of a pointy - the y coordinate of a point
java.awt.ComponentOrientationpublic void addLayoutComponent(String name, Component comp)
addLayoutComponent in interface LayoutManagername - the name of the componentcomp - the component to be addedpublic void addLayoutComponent(Component comp, Object constraints)
constraints object. Note that constraints
are mutable and are, therefore, cloned when cached.
addLayoutComponent in interface LayoutManager2comp - the component to be addedconstraints - an object that determines how
the component is added to the layoutpublic void removeLayoutComponent(Component comp)
Most applications do not call this method directly.
removeLayoutComponent in interface LayoutManagercomp - the component to be removed.java.awt.Container#remove(java.awt.Component),
java.awt.Container#removeAll()public Dimension preferredLayoutSize(Container parent)
parent
container using this grid bag layout.
Most applications do not call this method directly.
preferredLayoutSize in interface LayoutManagerparent - the container in which to do the layout
parent
containerjava.awt.Container#getPreferredSizepublic Dimension minimumLayoutSize(Container parent)
parent container
using this grid bag layout.
Most applications do not call this method directly.
minimumLayoutSize in interface LayoutManagerparent - the container in which to do the layout
parent containerjava.awt.Container#doLayoutpublic Dimension maximumLayoutSize(Container target)
maximumLayoutSize in interface LayoutManager2target - the container which needs to be laid out
Container,
minimumLayoutSize(Container),
preferredLayoutSize(Container)public float getLayoutAlignmentX(Container parent)
getLayoutAlignmentX in interface LayoutManager20.5f to indicate centeredpublic float getLayoutAlignmentY(Container parent)
getLayoutAlignmentY in interface LayoutManager20.5f to indicate centeredpublic void invalidateLayout(Container target)
invalidateLayout in interface LayoutManager2public void layoutContainer(Container parent)
GridBagLayout
object.
Most applications do not call this method directly.
layoutContainer in interface LayoutManagerparent - the container in which to do the layoutjava.awt.Container,
java.awt.Container#doLayoutpublic String toString()
protected GridBagLayoutInfo getLayoutInfo(Container parent, int sizeflag)
GridBagLayoutInfo for the
current set of managed children. This requires three passes through the
set of children:
parent - the layout containersizeflag - either PREFERREDSIZE or
MINSIZE
GridBagLayoutInfo for the set of childrenprotected GridBagLayoutInfo GetLayoutInfo(Container parent, int sizeflag)
getLayoutInfoprotected void adjustForGravity(GridBagConstraints constraints, Rectangle r)
constraints - the constraints to be appliedr - the Rectangle to be adjustedprotected void AdjustForGravity(GridBagConstraints constraints, Rectangle r)
adjustForGravity instead.
adjustForGravityprotected Dimension getMinSize(Container parent, GridBagLayoutInfo info)
parent - the layout containerinfo - the layout info for this parent
Dimension object containing the
minimum sizeprotected Dimension GetMinSize(Container parent, GridBagLayoutInfo info)
getMinSize instead.
getMinSizeprotected void arrangeGrid(Container parent)
parent - the layout containerprotected void ArrangeGrid(Container parent)
arrangeGrid instead.
arrangeGrid