Java tutorial
/* * Copyright (c) 1997, 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.accessibility; import java.awt.Color; import java.awt.Cursor; import java.awt.Dimension; import java.awt.Font; import java.awt.FontMetrics; import java.awt.Point; import java.awt.Rectangle; import java.awt.event.FocusListener; /** * The {@code AccessibleComponent} interface should be supported by any object * that is rendered on the screen. This interface provides the standard * mechanism for an assistive technology to determine and set the graphical * representation of an object. Applications can determine if an object supports * the {@code AccessibleComponent} interface by first obtaining its * {@code AccessibleContext} and then calling the * {@link AccessibleContext#getAccessibleComponent} method. If the return value * is not {@code null}, the object supports this interface. * * @author Peter Korn * @author Hans Muller * @author Willie Walker * @see Accessible * @see Accessible#getAccessibleContext * @see AccessibleContext * @see AccessibleContext#getAccessibleComponent */ public interface AccessibleComponent { /** * Gets the background color of this object. * * @return the background color, if supported, of the object; otherwise, * {@code null} * @see #setBackground */ public Color getBackground(); /** * Sets the background color of this object. * * @param c the new color for the background * @see #setBackground */ public void setBackground(Color c); /** * Gets the foreground color of this object. * * @return the foreground color, if supported, of the object; otherwise, * {@code null} * @see #setForeground */ public Color getForeground(); /** * Sets the foreground color of this object. * * @param c the new color for the foreground * @see #getForeground */ public void setForeground(Color c); /** * Gets the cursor of this object. * * @return the cursor, if supported, of the object; otherwise, {@code null} * @see #setCursor */ public Cursor getCursor(); /** * Sets the cursor of this object. * * @param cursor the new cursor for the object * @see #getCursor */ public void setCursor(Cursor cursor); /** * Gets the font of this object. * * @return the font, if supported, for the object; otherwise, {@code null} * @see #setFont */ public Font getFont(); /** * Sets the font of this object. * * @param f the new font for the object * @see #getFont */ public void setFont(Font f); /** * Gets the {@code FontMetrics} of this object. * * @param f the font for which font metrics is to be obtained * @return the {@code FontMetrics}, if supported, the object; otherwise, * {@code null} * @see #getFont */ public FontMetrics getFontMetrics(Font f); /** * Determines if the object is enabled. Objects that are enabled will also * have the {@code AccessibleState.ENABLED} state set in their * {@code AccessibleStateSets}. * * @return {@code true} if object is enabled; otherwise, {@code false} * @see #setEnabled * @see AccessibleContext#getAccessibleStateSet * @see AccessibleState#ENABLED * @see AccessibleStateSet */ public boolean isEnabled(); /** * Sets the enabled state of the object. * * @param b if {@code true}, enables this object; otherwise, disables it * @see #isEnabled */ public void setEnabled(boolean b); /** * Determines if the object is visible. Note: this means that the object * intends to be visible; however, it may not be showing on the screen * because one of the objects that this object is contained by is currently * not visible. To determine if an object is showing on the screen, use * {@link #isShowing()} * <p> * Objects that are visible will also have the * {@code AccessibleState.VISIBLE} state set in their * {@code AccessibleStateSets}. * * @return {@code true} if object is visible; otherwise, {@code false} * @see #setVisible * @see AccessibleContext#getAccessibleStateSet * @see AccessibleState#VISIBLE * @see AccessibleStateSet */ public boolean isVisible(); /** * Sets the visible state of the object. * * @param b if {@code true}, shows this object; otherwise, hides it * @see #isVisible */ public void setVisible(boolean b); /** * Determines if the object is showing. This is determined by checking the * visibility of the object and its ancestors. Note: this will return * {@code true} even if the object is obscured by another (for example, it * is underneath a menu that was pulled down). * * @return {@code true} if object is showing; otherwise, {@code false} */ public boolean isShowing(); /** * Checks whether the specified point is within this object's bounds, where * the point's x and y coordinates are defined to be relative to the * coordinate system of the object. * * @param p the point relative to the coordinate system of the object * @return {@code true} if object contains point; otherwise {@code false} * @see #getBounds */ public boolean contains(Point p); /** * Returns the location of the object on the screen. * * @return the location of the object on screen; {@code null} if this object * is not on the screen * @see #getBounds * @see #getLocation */ public Point getLocationOnScreen(); /** * Gets the location of the object relative to the parent in the form of a * point specifying the object's top-left corner in the screen's coordinate * space. * * @return An instance of {@code Point} representing the top-left corner of * the object's bounds in the coordinate space of the screen; * {@code null} if this object or its parent are not on the screen * @see #getBounds * @see #getLocationOnScreen */ public Point getLocation(); /** * Sets the location of the object relative to the parent. * * @param p the new position for the top-left corner * @see #getLocation */ public void setLocation(Point p); /** * Gets the bounds of this object in the form of a {@code Rectangle} object. * The bounds specify this object's width, height, and location relative to * its parent. * * @return A rectangle indicating this component's bounds; {@code null} if * this object is not on the screen. * @see #contains */ public Rectangle getBounds(); /** * Sets the bounds of this object in the form of a {@code Rectangle} object. * The bounds specify this object's width, height, and location relative to * its parent. * * @param r rectangle indicating this component's bounds * @see #getBounds */ public void setBounds(Rectangle r); /** * Returns the size of this object in the form of a {@code Dimension} * object. The {@code height} field of the {@code Dimension} object contains * this object's height, and the {@code width} field of the * {@code Dimension} object contains this object's width. * * @return A {@code Dimension} object that indicates the size of this * component; {@code null} if this object is not on the screen * @see #setSize */ public Dimension getSize(); /** * Resizes this object so that it has width and height. * * @param d The dimension specifying the new size of the object * @see #getSize */ public void setSize(Dimension d); /** * Returns the {@code Accessible} child, if one exists, contained at the * local coordinate {@code Point}. * * @param p The point relative to the coordinate system of this object * @return the {@code Accessible}, if it exists, at the specified location; * otherwise {@code null} */ public Accessible getAccessibleAt(Point p); /** * Returns whether this object can accept focus or not. Objects that can * accept focus will also have the {@code AccessibleState.FOCUSABLE} state * set in their {@code AccessibleStateSets}. * * @return {@code true} if object can accept focus; otherwise {@code false} * @see AccessibleContext#getAccessibleStateSet * @see AccessibleState#FOCUSABLE * @see AccessibleState#FOCUSED * @see AccessibleStateSet */ public boolean isFocusTraversable(); /** * Requests focus for this object. If this object cannot accept focus, * nothing will happen. Otherwise, the object will attempt to take focus. * * @see #isFocusTraversable */ public void requestFocus(); /** * Adds the specified focus listener to receive focus events from this * component. * * @param l the focus listener * @see #removeFocusListener */ public void addFocusListener(FocusListener l); /** * Removes the specified focus listener so it no longer receives focus * events from this component. * * @param l the focus listener * @see #addFocusListener */ public void removeFocusListener(FocusListener l); }