org.metawidget.swing.layout.GridBagLayout Maven / Gradle / Ivy
// Metawidget
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
package org.metawidget.swing.layout;
import static org.metawidget.inspector.InspectionResultConstants.*;
import java.awt.Color;
import java.awt.Font;
import java.awt.GridBagConstraints;
import java.awt.Insets;
import java.util.Map;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
import javax.swing.SwingConstants;
import org.metawidget.layout.iface.AdvancedLayout;
import org.metawidget.swing.Facet;
import org.metawidget.swing.Stub;
import org.metawidget.swing.SwingMetawidget;
import org.metawidget.util.WidgetBuilderUtils;
import org.metawidget.util.simple.SimpleLayoutUtils;
import org.metawidget.util.simple.SimpleLayoutUtils.StrippedMnemonicAndFirstIndex;
/**
* Layout to arrange widgets using java.awt.GridBagLayout.
*
* Widgets are arranged in a table, with one column for labels and another for the widget.
*
* @author Richard Kennard
*/
public class GridBagLayout
implements AdvancedLayout {
//
// Private statics
//
private static final int SMALL_GAP = 3;
private static final Insets INSETS_COMPONENT = new Insets( 0, 0, SMALL_GAP, 0 );
private static final String LABEL_NAME_SUFFIX = "_label";
//
// Private members
//
private final int mNumberOfColumns;
private final int mLabelAlignment;
private final Font mLabelFont;
private final Color mLabelForeground;
private final boolean mSupportMnemonics;
private final String mLabelSuffix;
private final int mRequiredAlignment;
private final String mRequiredText;
//
// Constructor
//
public GridBagLayout() {
this( new GridBagLayoutConfig() );
}
public GridBagLayout( GridBagLayoutConfig config ) {
mNumberOfColumns = config.getNumberOfColumns();
mLabelAlignment = config.getLabelAlignment();
mLabelForeground = config.getLabelForeground();
mLabelFont = config.getLabelFont();
mSupportMnemonics = config.isSupportMnemonics();
mLabelSuffix = config.getLabelSuffix();
mRequiredAlignment = config.getRequiredAlignment();
mRequiredText = config.getRequiredText();
}
//
// Public methods
//
public void onStartBuild( SwingMetawidget metawidget ) {
// Do nothing
}
public void startContainerLayout( JComponent container, SwingMetawidget metawidget ) {
container.putClientProperty( GridBagLayout.class, null );
State state = getState( container );
// Calculate default label inset
//
// We top align all our labels, not just those belonging to 'tall' components,
// so that tall components, regular components and nested Metawidget components all line up.
// However, we still want the JLabels to be middle aligned for one-line components (such as
// JTextFields), so we top inset them a bit
java.awt.GridBagLayout layoutManager = new java.awt.GridBagLayout();
container.setLayout( layoutManager );
JTextField dummyTextField = new JTextField();
dummyTextField.setLayout( layoutManager );
double dummyTextFieldHeight = dummyTextField.getPreferredSize().getHeight();
JLabel dummyLabel = new JLabel( "X" );
dummyLabel.setLayout( layoutManager );
double dummyLabelHeight = dummyLabel.getPreferredSize().getHeight();
int defaultLabelVerticalPadding = (int) Math.max( 0, Math.floor( ( dummyTextFieldHeight - dummyLabelHeight ) / 2 ) );
state.defaultLabelInsetsFirstColumn = new Insets( defaultLabelVerticalPadding, 0, defaultLabelVerticalPadding, SMALL_GAP );
state.defaultLabelInsetsRemainderColumns = new Insets( defaultLabelVerticalPadding, SMALL_GAP, defaultLabelVerticalPadding, SMALL_GAP );
}
public void layoutWidget( JComponent component, String elementName, Map attributes, JComponent container, SwingMetawidget metawidget ) {
// Do not render empty stubs
if ( component instanceof Stub && ( (Stub) component ).getComponentCount() == 0 ) {
return;
}
// Special support for large components
State state = getState( container );
boolean spanAllColumns = willFillHorizontally( component, attributes );
if ( spanAllColumns && state.currentColumn > 0 ) {
state.currentColumn = 0;
state.currentRow++;
}
// Layout a label...
String labelText = null;
if ( attributes != null ) {
labelText = metawidget.getLabelString( attributes );
}
layoutBeforeChild( component, labelText, elementName, attributes, container, metawidget );
// ...and layout the component
GridBagConstraints componentConstraints = new GridBagConstraints();
setFillConstraints( component, componentConstraints );
componentConstraints.anchor = GridBagConstraints.WEST;
componentConstraints.gridx = state.currentColumn * ( mRequiredAlignment == SwingConstants.RIGHT ? 3 : 2 );
int numberOfColumns = getEffectiveNumberOfColumns( metawidget );
if ( labelText != null ) {
if ( numberOfColumns == 0 ) {
state.currentRow++;
} else {
componentConstraints.gridx++;
}
} else {
componentConstraints.gridwidth = 2;
}
componentConstraints.gridy = state.currentRow;
componentConstraints.weightx = 1.0f / numberOfColumns;
componentConstraints.insets = INSETS_COMPONENT;
if ( spanAllColumns ) {
componentConstraints.gridwidth = ( mRequiredAlignment == SwingConstants.RIGHT ? ( numberOfColumns * 3 - componentConstraints.gridx - 1 ) : GridBagConstraints.REMAINDER );
state.currentColumn = numberOfColumns - 1;
}
// Hack for spacer row (see JavaDoc for state.mNeedSpacerRow): assume components
// embedded in a JScrollPane are their own spacer row
if ( willFillVertically( component, attributes ) ) {
componentConstraints.weighty = 1.0f;
state.needSpacerRow = false;
}
// Add it
container.add( component, componentConstraints );
layoutAfterChild( component, attributes, container, metawidget );
state.currentColumn++;
if ( state.currentColumn >= numberOfColumns ) {
state.currentColumn = 0;
state.currentRow++;
}
}
public void endContainerLayout( JComponent container, SwingMetawidget metawidget ) {
// Spacer row: see JavaDoc for state.needSpacerRow
State state = getState( container );
if ( state.needSpacerRow && container.getComponentCount() > 0 ) {
if ( state.currentColumn > 0 ) {
state.currentColumn = 0;
state.currentRow++;
}
JPanel spacerPanel = new JPanel();
spacerPanel.setOpaque( false );
GridBagConstraints spacerConstraints = new GridBagConstraints();
spacerConstraints.gridy = state.currentRow;
spacerConstraints.weighty = 1.0f;
container.add( spacerPanel, spacerConstraints );
state.currentColumn = mNumberOfColumns;
}
}
public void onEndBuild( SwingMetawidget metawidget ) {
// Buttons
Facet buttonsFacet = metawidget.getFacet( "buttons" );
if ( buttonsFacet != null ) {
State state = getState( metawidget );
if ( state.currentColumn > 0 ) {
state.currentColumn = 0;
state.currentRow++;
}
GridBagConstraints buttonConstraints = new GridBagConstraints();
buttonConstraints.fill = GridBagConstraints.BOTH;
buttonConstraints.anchor = GridBagConstraints.WEST;
buttonConstraints.gridy = state.currentRow;
buttonConstraints.gridwidth = GridBagConstraints.REMAINDER;
metawidget.add( buttonsFacet, buttonConstraints );
}
}
//
// Protected methods
//
protected void layoutBeforeChild( JComponent child, String labelText, String elementName, Map attributes, JComponent container, SwingMetawidget metawidget ) {
State state = getState( container );
// Add label
if ( SimpleLayoutUtils.needsLabel( labelText, elementName ) ) {
JLabel label = new JLabel();
label.setName( attributes.get( NAME ) + LABEL_NAME_SUFFIX );
if ( mLabelFont != null ) {
label.setFont( mLabelFont );
}
if ( mLabelForeground != null ) {
label.setForeground( mLabelForeground );
}
label.setHorizontalAlignment( mLabelAlignment );
// Required
StrippedMnemonicAndFirstIndex strippedMnemonicAndFirstIndex = SimpleLayoutUtils.stripMnemonic( labelText );
String labelTextToUse = strippedMnemonicAndFirstIndex.getStrippedMnemonic();
if ( mRequiredText != null && TRUE.equals( attributes.get( REQUIRED ) ) && !WidgetBuilderUtils.isReadOnly( attributes ) && !metawidget.isReadOnly() ) {
if ( mRequiredAlignment == SwingConstants.CENTER ) {
labelTextToUse += mRequiredText;
} else if ( mRequiredAlignment == SwingConstants.LEFT ) {
labelTextToUse = mRequiredText + labelTextToUse;
}
}
if ( mLabelSuffix != null ) {
labelTextToUse += mLabelSuffix;
}
label.setText( labelTextToUse );
// Mnemonic
label.setLabelFor( child );
int mnemonicIndex = strippedMnemonicAndFirstIndex.getFirstIndex();
if ( mnemonicIndex != -1 && mSupportMnemonics ) {
label.setDisplayedMnemonic( labelTextToUse.charAt( mnemonicIndex ) );
label.setDisplayedMnemonicIndex( mnemonicIndex );
}
// GridBagConstraints
GridBagConstraints labelConstraints = new GridBagConstraints();
labelConstraints.gridx = state.currentColumn * ( mRequiredAlignment == SwingConstants.RIGHT ? 3 : 2 );
labelConstraints.gridy = state.currentRow;
labelConstraints.fill = GridBagConstraints.HORIZONTAL;
labelConstraints.weightx = 0.1f / getEffectiveNumberOfColumns( metawidget );
// Top align all labels, not just those belonging to 'tall' components,
// so that tall components, regular components and nested Metawidget
// components all line up
labelConstraints.anchor = GridBagConstraints.NORTHWEST;
// Apply some vertical padding, and some left padding on everything but the
// first column, so the label lines up with the component nicely
if ( state.currentColumn == 0 ) {
labelConstraints.insets = state.defaultLabelInsetsFirstColumn;
} else {
labelConstraints.insets = state.defaultLabelInsetsRemainderColumns;
}
container.add( label, labelConstraints );
}
}
/**
* @param child
* component being laid out
*/
protected void layoutAfterChild( JComponent child, Map attributes, JComponent container, SwingMetawidget metawidget ) {
State state = getState( container );
if ( mRequiredAlignment != SwingConstants.RIGHT ) {
return;
}
if ( attributes == null || !TRUE.equals( attributes.get( REQUIRED ) ) || WidgetBuilderUtils.isReadOnly( attributes ) || metawidget.isReadOnly() ) {
return;
}
JLabel star = new JLabel();
star.setText( mRequiredText );
GridBagConstraints starConstraints = new GridBagConstraints();
starConstraints.gridx = ( state.currentColumn * 3 ) + 2;
starConstraints.gridy = state.currentRow;
starConstraints.anchor = GridBagConstraints.NORTHWEST;
if ( state.currentColumn == 0 ) {
starConstraints.insets = state.defaultLabelInsetsFirstColumn;
} else {
starConstraints.insets = state.defaultLabelInsetsRemainderColumns;
}
container.add( star, starConstraints );
}
protected boolean willFillHorizontally( JComponent component, Map attributes ) {
if ( component instanceof JScrollPane ) {
return true;
}
if ( component instanceof SwingMetawidget ) {
return true;
}
return SimpleLayoutUtils.isSpanAllColumns( attributes );
}
protected boolean willFillVertically( JComponent component, Map attributes ) {
if ( attributes != null && TRUE.equals( attributes.get( LARGE ) ) ) {
return true;
}
if ( component instanceof JScrollPane ) {
return true;
}
return false;
}
/**
* Sets the fill constraints for this component. Defaults to
* GridBagConstraints.BOTH, unless the JComponent is
* a JButton.
*
* Clients can override this method to change how the fill constraints are set. For example, you
* may not want any fill constraints if the JComponent has
* getPreferredSize() != null.
*/
protected void setFillConstraints( JComponent component, GridBagConstraints componentConstraints ) {
if ( component instanceof JButton ) {
return;
}
componentConstraints.fill = GridBagConstraints.BOTH;
}
//
// Private methods
//
/**
* Get the number of columns to use in the layout.
*
* Nested Metawidgets are always just single column.
*/
private int getEffectiveNumberOfColumns( SwingMetawidget metawidget ) {
if ( metawidget.getParent() instanceof SwingMetawidget ) {
return 1;
}
return mNumberOfColumns;
}
private State getState( JComponent container ) {
State state = (State) container.getClientProperty( GridBagLayout.class );
if ( state == null ) {
state = new State();
container.putClientProperty( GridBagLayout.class, state );
}
return state;
}
//
// Inner class
//
/**
* Simple, lightweight structure for saving state.
*/
/* package private */static class State {
/* package private */int currentColumn;
/* package private */int currentRow;
/* package private */Insets defaultLabelInsetsFirstColumn;
/* package private */Insets defaultLabelInsetsRemainderColumns;
/**
* Whether a spacer row is required on the last row of the layout.
*
* By default, GridBagLayouts expand to fill their vertical space, and 'align middle' their
* group of components. To make them 'align top' at least one of the components must have a
* vertical constraint weighting > 0.
*/
/* package private */boolean needSpacerRow = true;
}
}