Java tutorial
/* * Copyright (c) 1997, 2014, 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; import java.awt.*; import java.awt.event.*; import java.io.*; import java.beans.PropertyChangeListener; import java.util.Locale; import java.util.Vector; import javax.accessibility.*; /** * This class is inserted in between cell renderers and the components that * use them. It just exists to thwart the repaint() and invalidate() methods * which would otherwise propagate up the tree when the renderer was configured. * It's used by the implementations of JTable, JTree, and JList. For example, * here's how CellRendererPane is used in the code the paints each row * in a JList: * <pre> * cellRendererPane = new CellRendererPane(); * ... * Component rendererComponent = renderer.getListCellRendererComponent(); * renderer.configureListCellRenderer(dataModel.getElementAt(row), row); * cellRendererPane.paintComponent(g, rendererComponent, this, x, y, w, h); * </pre> * <p> * A renderer component must override isShowing() and unconditionally return * true to work correctly because the Swing paint does nothing for components * with isShowing false. * <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 Hans Muller * @since 1.2 */ @SuppressWarnings("serial") // Same-version serialization only public class CellRendererPane extends Container implements Accessible { /** * Construct a CellRendererPane object. */ public CellRendererPane() { super(); setLayout(null); setVisible(false); } /** * Overridden to avoid propagating a invalidate up the tree when the * cell renderer child is configured. */ public void invalidate() { } /** * Shouldn't be called. */ public void paint(Graphics g) { } /** * Shouldn't be called. */ public void update(Graphics g) { } /** * If the specified component is already a child of this then we don't * bother doing anything - stacking order doesn't matter for cell * renderer components (CellRendererPane doesn't paint anyway). */ protected void addImpl(Component x, Object constraints, int index) { if (x.getParent() == this) { return; } else { super.addImpl(x, constraints, index); } } /** * Paint a cell renderer component c on graphics object g. Before the component * is drawn it's reparented to this (if that's necessary), it's bounds * are set to w,h and the graphics object is (effectively) translated to x,y. * If it's a JComponent, double buffering is temporarily turned off. After * the component is painted it's bounds are reset to -w, -h, 0, 0 so that, if * it's the last renderer component painted, it will not start consuming input. * The Container p is the component we're actually drawing on, typically it's * equal to this.getParent(). If shouldValidate is true the component c will be * validated before painted. * * @param g the {@code Graphics} object to draw on * @param c the {@code Component} to draw * @param p the {@code Container} component actually drawn on * @param x an int specifying the left side of the area draw in, in pixels, * measured from the left edge of the graphics context * @param y an int specifying the top of the area to draw in, in pixels * measured down from the top edge of the graphics context * @param w an int specifying the width of the area draw in, in pixels * @param h an int specifying the height of the area draw in, in pixels * @param shouldValidate if true, component {@code c} will be validated * before being painted */ public void paintComponent(Graphics g, Component c, Container p, int x, int y, int w, int h, boolean shouldValidate) { if (c == null) { if (p != null) { Color oldColor = g.getColor(); g.setColor(p.getBackground()); g.fillRect(x, y, w, h); g.setColor(oldColor); } return; } if (c.getParent() != this) { this.add(c); } c.setBounds(x, y, w, h); if (shouldValidate) { c.validate(); } boolean wasDoubleBuffered = false; if ((c instanceof JComponent) && ((JComponent) c).isDoubleBuffered()) { wasDoubleBuffered = true; ((JComponent) c).setDoubleBuffered(false); } Graphics cg = g.create(x, y, w, h); try { c.paint(cg); } finally { cg.dispose(); } if (wasDoubleBuffered && (c instanceof JComponent)) { ((JComponent) c).setDoubleBuffered(true); } c.setBounds(-w, -h, 0, 0); } /** * Calls this.paintComponent(g, c, p, x, y, w, h, false). * * @param g the {@code Graphics} object to draw on * @param c the {@code Component} to draw * @param p the {@code Container} component actually drawn on * @param x an int specifying the left side of the area draw in, in pixels, * measured from the left edge of the graphics context * @param y an int specifying the top of the area to draw in, in pixels * measured down from the top edge of the graphics context * @param w an int specifying the width of the area draw in, in pixels * @param h an int specifying the height of the area draw in, in pixels */ public void paintComponent(Graphics g, Component c, Container p, int x, int y, int w, int h) { paintComponent(g, c, p, x, y, w, h, false); } /** * Calls this.paintComponent() with the rectangles x,y,width,height fields. * * @param g the {@code Graphics} object to draw on * @param c the {@code Component} to draw * @param p the {@code Container} component actually drawn on * @param r the {@code Rectangle} to draw in */ public void paintComponent(Graphics g, Component c, Container p, Rectangle r) { paintComponent(g, c, p, r.x, r.y, r.width, r.height); } private void writeObject(ObjectOutputStream s) throws IOException { removeAll(); s.defaultWriteObject(); } ///////////////// // Accessibility support //////////////// /** * {@code AccessibleContext} associated with this {@code CellRendererPan} */ protected AccessibleContext accessibleContext = null; /** * Gets the AccessibleContext associated with this CellRendererPane. * For CellRendererPanes, the AccessibleContext takes the form of an * AccessibleCellRendererPane. * A new AccessibleCellRendererPane instance is created if necessary. * * @return an AccessibleCellRendererPane that serves as the * AccessibleContext of this CellRendererPane */ public AccessibleContext getAccessibleContext() { if (accessibleContext == null) { accessibleContext = new AccessibleCellRendererPane(); } return accessibleContext; } /** * This class implements accessibility support for the * <code>CellRendererPane</code> class. */ protected class AccessibleCellRendererPane extends AccessibleAWTContainer { // AccessibleContext methods // /** * Get the role of this object. * * @return an instance of AccessibleRole describing the role of the * object * @see AccessibleRole */ public AccessibleRole getAccessibleRole() { return AccessibleRole.PANEL; } } // inner class AccessibleCellRendererPane }