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📜  Java LayoutManagers-GridBagLayout

📅  最后修改于: 2020-10-01 03:58:42             🧑  作者: Mango

Java GridBagLayout

Java GridBagLayout类用于垂直，水平或沿其基线对齐组件。

组件的大小可能不同。每个GridBagLayout对象都维护一个动态的矩形单元格网格。每个组件占据一个或多个单元格(称为其显示区域)。每个组件都关联一个GridBagConstraints实例。借助约束对象，我们在网格上排列了组件的显示区域。 GridBagLayout管理每个组件的最小和首选大小，以确定组件的大小。

领域

Modifier and Type Field Description
double[] columnWeights It is used to hold the overrides to the column weights.
int[] columnWidths It is used to hold the overrides to the column minimum width.
protected Hashtable comptable It is used to maintains the association between a component and its gridbag constraints.
protected GridBagConstraints defaultConstraints It is used to hold a gridbag constraints instance containing the default values.
protected GridBagLayoutInfo layoutInfo It is used to hold the layout information for the gridbag.
protected static int MAXGRIDSIZE No longer in use just for backward compatibility
protected static int MINSIZE It is smallest grid that can be laid out by the grid bag layout.
protected static int PREFERREDSIZE It is preferred grid size that can be laid out by the grid bag layout.
int[] rowHeights It is used to hold the overrides to the row minimum heights.
double[] rowWeights It is used to hold the overrides to the row weights.

有用的方法

Modifier and Type Method Description
void addLayoutComponent(Component comp, Object constraints) It adds specified component to the layout, using the specified constraints object.
void addLayoutComponent(String name, Component comp) It has no effect, since this layout manager does not use a per-component string.
protected void adjustForGravity(GridBagConstraints constraints, Rectangle r) It adjusts the x, y, width, and height fields to the correct values depending on the constraint geometry and pads.
protected void AdjustForGravity(GridBagConstraints constraints, Rectangle r) This method is for backwards compatibility only
protected void arrangeGrid(Container parent) Lays out the grid.
protected void ArrangeGrid(Container parent) This method is obsolete and supplied for backwards compatibility
GridBagConstraints getConstraints(Component comp) It is for getting the constraints for the specified component.
float getLayoutAlignmentX(Container parent) It returns the alignment along the x axis.
float getLayoutAlignmentY(Container parent) It returns the alignment along the y axis.
int[][] getLayoutDimensions() It determines column widths and row heights for the layout grid.
protected GridBagLayoutInfo getLayoutInfo(Container parent, int sizeflag) This method is obsolete and supplied for backwards compatibility.
protected GridBagLayoutInfo GetLayoutInfo(Container parent, int sizeflag) This method is obsolete and supplied for backwards compatibility.
Point getLayoutOrigin() It determines the origin of the layout area, in the graphics coordinate space of the target container.
double[][] getLayoutWeights() It determines the weights of the layout grid’s columns and rows.
protected Dimension getMinSize(Container parent, GridBagLayoutInfo info) It figures out the minimum size of the master based on the information from getLayoutInfo.
protected Dimension GetMinSize(Container parent, GridBagLayoutInfo info) This method is obsolete and supplied for backwards compatibility only

例

import java.awt.Button;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;

import javax.swing.*;
public class GridBagLayoutExample extends JFrame{
public static void main(String[] args) {
        GridBagLayoutExample a = new GridBagLayoutExample();
    }
public GridBagLayoutExample() {
GridBagLayoutgrid = new GridBagLayout();
        GridBagConstraints gbc = new GridBagConstraints();
        setLayout(grid);
        setTitle("GridBag Layout Example");
        GridBagLayout layout = new GridBagLayout();
this.setLayout(layout);
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.gridx = 0;
gbc.gridy = 0;
this.add(new Button("Button One"), gbc);
gbc.gridx = 1;
gbc.gridy = 0;
this.add(new Button("Button two"), gbc);
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.ipady = 20;
gbc.gridx = 0;
gbc.gridy = 1;
this.add(new Button("Button Three"), gbc);
gbc.gridx = 1;
gbc.gridy = 1;
this.add(new Button("Button Four"), gbc);
gbc.gridx = 0;
gbc.gridy = 2;
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.gridwidth = 2;
this.add(new Button("Button Five"), gbc);
        setSize(300, 300);
        setPreferredSize(getSize());
        setVisible(true);
        setDefaultCloseOperation(EXIT_ON_CLOSE);

    }

}

输出：

例子2

public class GridBagLayoutDemo {
final static boolean shouldFill = true;
final static boolean shouldWeightX = true;
final static boolean RIGHT_TO_LEFT = false;

public static void addComponentsToPane(Container pane) {
if (RIGHT_TO_LEFT) {
pane.setComponentOrientation(ComponentOrientation.RIGHT_TO_LEFT);
}

JButton button;
pane.setLayout(new GridBagLayout());
GridBagConstraints c = new GridBagConstraints();
if (shouldFill) {
//natural height, maximum width
c.fill = GridBagConstraints.HORIZONTAL;
}

button = new JButton("Button 1");
if (shouldWeightX) {
c.weightx = 0.5;
}
c.fill = GridBagConstraints.HORIZONTAL;
c.gridx = 0;
c.gridy = 0;
pane.add(button, c);

button = new JButton("Button 2");
c.fill = GridBagConstraints.HORIZONTAL;
c.weightx = 0.5;
c.gridx = 1;
c.gridy = 0;
pane.add(button, c);

button = new JButton("Button 3");
c.fill = GridBagConstraints.HORIZONTAL;
c.weightx = 0.5;
c.gridx = 2;
c.gridy = 0;
pane.add(button, c);

button = new JButton("Long-Named Button 4");
c.fill = GridBagConstraints.HORIZONTAL;
c.ipady = 40;      //make this component tall
c.weightx = 0.0;
c.gridwidth = 3;
c.gridx = 0;
c.gridy = 1;
pane.add(button, c);

button = new JButton("5");
c.fill = GridBagConstraints.HORIZONTAL;
c.ipady = 0;       //reset to default
c.weighty = 1.0;   //request any extra vertical space
c.anchor = GridBagConstraints.PAGE_END; //bottom of space
c.insets = new Insets(10,0,0,0);  //top padding
c.gridx = 1;       //aligned with button 2
c.gridwidth = 2;   //2 columns wide
c.gridy = 2;       //third row
pane.add(button, c);
}


private static void createAndShowGUI() {
//Create and set up the window.
JFrame frame = new JFrame("GridBagLayoutDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

//Set up the content pane.
addComponentsToPane(frame.getContentPane());

//Display the window.
frame.pack();
frame.setVisible(true);
}

public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}

输出：