JTable.
*
*
* Implementation Note:
* This class inherits from JLabel, a standard component class.
* However JTable employs a unique mechanism for rendering
* its cells and therefore requires some slightly modified behavior
* from its cell renderer.
* The table class defines a single cell renderer and uses it as a
* as a rubber-stamp for rendering all cells in the table;
* it renders the first cell,
* changes the contents of that cell renderer,
* shifts the origin to the new location, re-draws it, and so on.
* The standard JLabel component was not
* designed to be used this way and we want to avoid
* triggering a revalidate each time the
* cell is drawn. This would greatly decrease performance because the
* revalidate message would be
* passed up the hierarchy of the container to determine whether any other
* components would be affected.
* As the renderer is only parented for the lifetime of a painting operation
* we similarly want to avoid the overhead associated with walking the
* hierarchy for painting operations.
* So this class
* overrides the validate, invalidate,
* revalidate, repaint, and
* firePropertyChange methods to be
* no-ops and override the isOpaque method solely to improve
* performance. If you write your own renderer,
* please keep this performance consideration in mind.
*
*
* 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}.
*
* @version 1.42 10/31/05
* @author Philip Milne
* @see JTable
*/
public class DefaultTableCellRenderer extends JLabel
implements TableCellRenderer, Serializable
{
protected static Border noFocusBorder = new EmptyBorder(1, 1, 1, 1);
private static final Border SAFE_NO_FOCUS_BORDER = new EmptyBorder(1, 1, 1, 1);
// We need a place to store the color the JLabel should be returned
// to after its foreground and background colors have been set
// to the selection background color.
// These ivars will be made protected when their names are finalized.
private Color unselectedForeground;
private Color unselectedBackground;
/**
* Creates a default table cell renderer.
*/
public DefaultTableCellRenderer() {
super();
setOpaque(true);
setBorder(getNoFocusBorder());
}
private static Border getNoFocusBorder() {
if (System.getSecurityManager() != null) {
return SAFE_NO_FOCUS_BORDER;
} else {
return noFocusBorder;
}
}
/**
* Overrides JComponent.setForeground to assign
* the unselected-foreground color to the specified color.
*
* @param c set the foreground color to this value
*/
public void setForeground(Color c) {
super.setForeground(c);
unselectedForeground = c;
}
/**
* Overrides JComponent.setBackground to assign
* the unselected-background color to the specified color.
*
* @param c set the background color to this value
*/
public void setBackground(Color c) {
super.setBackground(c);
unselectedBackground = c;
}
/**
* Notification from the UIManager that the look and feel
* [L&F] has changed.
* Replaces the current UI object with the latest version from the
* UIManager.
*
* @see JComponent#updateUI
*/
public void updateUI() {
super.updateUI();
setForeground(null);
setBackground(null);
}
// implements javax.swing.table.TableCellRenderer
/**
*
* Returns the default table cell renderer.
*
* @param table the JTable
* @param value the value to assign to the cell at
* [row, column]
* @param isSelected true if cell is selected
* @param hasFocus true if cell has focus
* @param row the row of the cell to render
* @param column the column of the cell to render
* @return the default table cell renderer
*/
public Component getTableCellRendererComponent(JTable table, Object value,
boolean isSelected, boolean hasFocus, int row, int column) {
if (isSelected) {
super.setForeground(table.getSelectionForeground());
super.setBackground(table.getSelectionBackground());
}
else {
super.setForeground((unselectedForeground != null) ? unselectedForeground
: table.getForeground());
super.setBackground((unselectedBackground != null) ? unselectedBackground
: table.getBackground());
}
setFont(table.getFont());
if (hasFocus) {
Border border = null;
if (isSelected) {
border = UIManager.getBorder("Table.focusSelectedCellHighlightBorder");
}
if (border == null) {
border = UIManager.getBorder("Table.focusCellHighlightBorder");
}
setBorder(border);
if (!isSelected && table.isCellEditable(row, column)) {
Color col;
col = UIManager.getColor("Table.focusCellForeground");
if (col != null) {
super.setForeground(col);
}
col = UIManager.getColor("Table.focusCellBackground");
if (col != null) {
super.setBackground(col);
}
}
} else {
setBorder(getNoFocusBorder());
}
setValue(value);
return this;
}
/*
* The following methods are overridden as a performance measure to
* to prune code-paths are often called in the case of renders
* but which we know are unnecessary. Great care should be taken
* when writing your own renderer to weigh the benefits and
* drawbacks of overriding methods like these.
*/
/**
* Overridden for performance reasons.
* See the Implementation Note
* for more information.
*/
public boolean isOpaque() {
Color back = getBackground();
Component p = getParent();
if (p != null) {
p = p.getParent();
}
// p should now be the JTable.
boolean colorMatch = (back != null) && (p != null) &&
back.equals(p.getBackground()) &&
p.isOpaque();
return !colorMatch && super.isOpaque();
}
/**
* Overridden for performance reasons.
* See the Implementation Note
* for more information.
*
* @since 1.5
*/
public void invalidate() {}
/**
* Overridden for performance reasons.
* See the Implementation Note
* for more information.
*/
public void validate() {}
/**
* Overridden for performance reasons.
* See the Implementation Note
* for more information.
*/
public void revalidate() {}
/**
* Overridden for performance reasons.
* See the Implementation Note
* for more information.
*/
public void repaint(long tm, int x, int y, int width, int height) {}
/**
* Overridden for performance reasons.
* See the Implementation Note
* for more information.
*/
public void repaint(Rectangle r) { }
/**
* Overridden for performance reasons.
* See the Implementation Note
* for more information.
*
* @since 1.5
*/
public void repaint() {
}
/**
* Overridden for performance reasons.
* See the Implementation Note
* for more information.
*/
protected void firePropertyChange(String propertyName, Object oldValue, Object newValue) {
// Strings get interned...
if (propertyName=="text") {
super.firePropertyChange(propertyName, oldValue, newValue);
}
}
/**
* Overridden for performance reasons.
* See the Implementation Note
* for more information.
*/
public void firePropertyChange(String propertyName, boolean oldValue, boolean newValue) { }
/**
* Sets the String object for the cell being rendered to
* value.
*
* @param value the string value for this cell; if value is
* null it sets the text value to an empty string
* @see JLabel#setText
*
*/
protected void setValue(Object value) {
setText((value == null) ? "" : value.toString());
}
/**
* A subclass of DefaultTableCellRenderer that
* implements UIResource.
* DefaultTableCellRenderer doesn't implement
* UIResource
* directly so that applications can safely override the
* cellRenderer property with
* DefaultTableCellRenderer subclasses.
*
* 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 UIResource extends DefaultTableCellRenderer
implements javax.swing.plaf.UIResource
{
}
}