Java tutorial
/* * Copyright (c) 1998, 2017, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.swing.table; import javax.swing.*; import javax.swing.border.*; import java.awt.Component; import java.awt.Color; import java.awt.Rectangle; import java.io.Serializable; import sun.swing.DefaultLookup; import sun.swing.SwingUtilities2; /** * The standard class for rendering (displaying) individual cells * in a <code>JTable</code>. * <p> * * <strong><a id="override">Implementation Note:</a></strong> * This class inherits from <code>JLabel</code>, a standard component class. * However <code>JTable</code> 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 <code>JLabel</code> component was not * designed to be used this way and we want to avoid * triggering a <code>revalidate</code> each time the * cell is drawn. This would greatly decrease performance because the * <code>revalidate</code> 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 <code>validate</code>, <code>invalidate</code>, * <code>revalidate</code>, <code>repaint</code>, and * <code>firePropertyChange</code> methods to be * no-ops and override the <code>isOpaque</code> method solely to improve * performance. If you write your own renderer, * please keep this performance consideration in mind. * <p> * * <strong>Warning:</strong> * 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 JavaBeans™ * has been added to the <code>java.beans</code> package. * Please see {@link java.beans.XMLEncoder}. * * @author Philip Milne * @see JTable */ @SuppressWarnings("serial") // Same-version serialization only public class DefaultTableCellRenderer extends JLabel implements TableCellRenderer, Serializable { /** * An empty <code>Border</code>. This field might not be used. To change the * <code>Border</code> used by this renderer override the * <code>getTableCellRendererComponent</code> method and set the border * of the returned component directly. */ private static final Border SAFE_NO_FOCUS_BORDER = new EmptyBorder(1, 1, 1, 1); private static final Border DEFAULT_NO_FOCUS_BORDER = new EmptyBorder(1, 1, 1, 1); /** * A border without focus. */ protected static Border noFocusBorder = DEFAULT_NO_FOCUS_BORDER; // 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()); setName("Table.cellRenderer"); } private Border getNoFocusBorder() { Border border = DefaultLookup.getBorder(this, ui, "Table.cellNoFocusBorder"); if (System.getSecurityManager() != null) { if (border != null) return border; return SAFE_NO_FOCUS_BORDER; } else if (border != null) { if (noFocusBorder == null || noFocusBorder == DEFAULT_NO_FOCUS_BORDER) { return border; } } return noFocusBorder; } /** * Overrides <code>JComponent.setForeground</code> 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 <code>JComponent.setBackground</code> 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 <code>UIManager</code> that the look and feel * [L&F] has changed. * Replaces the current UI object with the latest version from the * <code>UIManager</code>. * * @see JComponent#updateUI */ public void updateUI() { super.updateUI(); setForeground(null); setBackground(null); } // implements javax.swing.table.TableCellRenderer /** * * Returns the default table cell renderer. * <p> * During a printing operation, this method will be called with * <code>isSelected</code> and <code>hasFocus</code> values of * <code>false</code> to prevent selection and focus from appearing * in the printed output. To do other customization based on whether * or not the table is being printed, check the return value from * {@link javax.swing.JComponent#isPaintingForPrint()}. * * @param table the <code>JTable</code> * @param value the value to assign to the cell at * <code>[row, column]</code> * @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 * @see javax.swing.JComponent#isPaintingForPrint() */ public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) { if (table == null) { return this; } Color fg = null; Color bg = null; JTable.DropLocation dropLocation = table.getDropLocation(); if (dropLocation != null && !dropLocation.isInsertRow() && !dropLocation.isInsertColumn() && dropLocation.getRow() == row && dropLocation.getColumn() == column) { fg = DefaultLookup.getColor(this, ui, "Table.dropCellForeground"); bg = DefaultLookup.getColor(this, ui, "Table.dropCellBackground"); isSelected = true; } if (isSelected) { super.setForeground(fg == null ? table.getSelectionForeground() : fg); super.setBackground(bg == null ? table.getSelectionBackground() : bg); } else { Color background = unselectedBackground != null ? unselectedBackground : table.getBackground(); if (background == null || background instanceof javax.swing.plaf.UIResource) { Color alternateColor = DefaultLookup.getColor(this, ui, "Table.alternateRowColor"); if (alternateColor != null && row % 2 != 0) { background = alternateColor; } } super.setForeground(unselectedForeground != null ? unselectedForeground : table.getForeground()); super.setBackground(background); } setFont(table.getFont()); if (hasFocus) { Border border = null; if (isSelected) { border = DefaultLookup.getBorder(this, ui, "Table.focusSelectedCellHighlightBorder"); } if (border == null) { border = DefaultLookup.getBorder(this, ui, "Table.focusCellHighlightBorder"); } setBorder(border); if (!isSelected && table.isCellEditable(row, column)) { Color col; col = DefaultLookup.getColor(this, ui, "Table.focusCellForeground"); if (col != null) { super.setForeground(col); } col = DefaultLookup.getColor(this, ui, "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 <a href="#override">Implementation Note</a> * 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 <a href="#override">Implementation Note</a> * for more information. * * @since 1.5 */ public void invalidate() { } /** * Overridden for performance reasons. * See the <a href="#override">Implementation Note</a> * for more information. */ public void validate() { } /** * Overridden for performance reasons. * See the <a href="#override">Implementation Note</a> * for more information. */ public void revalidate() { } /** * Overridden for performance reasons. * See the <a href="#override">Implementation Note</a> * for more information. */ public void repaint(long tm, int x, int y, int width, int height) { } /** * Overridden for performance reasons. * See the <a href="#override">Implementation Note</a> * for more information. */ public void repaint(Rectangle r) { } /** * Overridden for performance reasons. * See the <a href="#override">Implementation Note</a> * for more information. * * @since 1.5 */ public void repaint() { } /** * Overridden for performance reasons. * See the <a href="#override">Implementation Note</a> * for more information. */ protected void firePropertyChange(String propertyName, Object oldValue, Object newValue) { // Strings get interned... if (propertyName == "text" || propertyName == "labelFor" || propertyName == "displayedMnemonic" || ((SwingUtilities2.isScaleChanged(propertyName, oldValue, newValue) || propertyName == "font" || propertyName == "foreground") && oldValue != newValue && getClientProperty(javax.swing.plaf.basic.BasicHTML.propertyKey) != null)) { super.firePropertyChange(propertyName, oldValue, newValue); } } /** * Overridden for performance reasons. * See the <a href="#override">Implementation Note</a> * for more information. */ public void firePropertyChange(String propertyName, boolean oldValue, boolean newValue) { } /** * Sets the <code>String</code> object for the cell being rendered to * <code>value</code>. * * @param value the string value for this cell; if value is * <code>null</code> 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 <code>DefaultTableCellRenderer</code> that * implements <code>UIResource</code>. * <code>DefaultTableCellRenderer</code> doesn't implement * <code>UIResource</code> * directly so that applications can safely override the * <code>cellRenderer</code> property with * <code>DefaultTableCellRenderer</code> subclasses. * <p> * <strong>Warning:</strong> * 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 JavaBeans™ * has been added to the <code>java.beans</code> package. * Please see {@link java.beans.XMLEncoder}. */ @SuppressWarnings("serial") // Same-version serialization only public static class UIResource extends DefaultTableCellRenderer implements javax.swing.plaf.UIResource { } }