Java tutorial
/* * Copyright (c) 1997, 1998, 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. */ /* * (C) Copyright Taligent, Inc. 1996 - 1997, All Rights Reserved * (C) Copyright IBM Corp. 1996 - 1998, All Rights Reserved * * The original version of this source code and documentation is * copyrighted and owned by Taligent, Inc., a wholly-owned subsidiary * of IBM. These materials are provided under terms of a License * Agreement between Taligent and Sun. This technology is protected * by multiple US and International patents. * * This notice and attribution to Taligent may not be removed. * Taligent is a registered trademark of Taligent, Inc. * */ package java.awt.font; import java.lang.String; /** * The {@code TextHitInfo} class represents a character position in a * text model, and a <b>bias</b>, or "side," of the character. Biases are * either <EM>leading</EM> (the left edge, for a left-to-right character) * or <EM>trailing</EM> (the right edge, for a left-to-right character). * Instances of {@code TextHitInfo} are used to specify caret and * insertion positions within text. * <p> * For example, consider the text "abc". TextHitInfo.trailing(1) * corresponds to the right side of the 'b' in the text. * <p> * {@code TextHitInfo} is used primarily by {@link TextLayout} and * clients of {@code TextLayout}. Clients of {@code TextLayout} * query {@code TextHitInfo} instances for an insertion offset, where * new text is inserted into the text model. The insertion offset is equal * to the character position in the {@code TextHitInfo} if the bias * is leading, and one character after if the bias is trailing. The * insertion offset for TextHitInfo.trailing(1) is 2. * <p> * Sometimes it is convenient to construct a {@code TextHitInfo} with * the same insertion offset as an existing one, but on the opposite * character. The {@code getOtherHit} method constructs a new * {@code TextHitInfo} with the same insertion offset as an existing * one, with a hit on the character on the other side of the insertion offset. * Calling {@code getOtherHit} on trailing(1) would return leading(2). * In general, {@code getOtherHit} for trailing(n) returns * leading(n+1) and {@code getOtherHit} for leading(n) * returns trailing(n-1). * <p> * <strong>Example</strong>:<p> * Converting a graphical point to an insertion point within a text * model * <blockquote><pre> * TextLayout layout = ...; * Point2D.Float hitPoint = ...; * TextHitInfo hitInfo = layout.hitTestChar(hitPoint.x, hitPoint.y); * int insPoint = hitInfo.getInsertionIndex(); * // insPoint is relative to layout; may need to adjust for use * // in a text model * </pre></blockquote> * * @see TextLayout */ public final class TextHitInfo { private int charIndex; private boolean isLeadingEdge; /** * Constructs a new {@code TextHitInfo}. * @param charIndex the index of the character hit * @param isLeadingEdge {@code true} if the leading edge of the * character was hit */ private TextHitInfo(int charIndex, boolean isLeadingEdge) { this.charIndex = charIndex; this.isLeadingEdge = isLeadingEdge; } /** * Returns the index of the character hit. * @return the index of the character hit. */ public int getCharIndex() { return charIndex; } /** * Returns {@code true} if the leading edge of the character was * hit. * @return {@code true} if the leading edge of the character was * hit; {@code false} otherwise. */ public boolean isLeadingEdge() { return isLeadingEdge; } /** * Returns the insertion index. This is the character index if * the leading edge of the character was hit, and one greater * than the character index if the trailing edge was hit. * @return the insertion index. */ public int getInsertionIndex() { return isLeadingEdge ? charIndex : charIndex + 1; } /** * Returns the hash code. * @return the hash code of this {@code TextHitInfo}, which is * also the {@code charIndex} of this {@code TextHitInfo}. */ public int hashCode() { return charIndex; } /** * Returns {@code true} if the specified {@code Object} is a * {@code TextHitInfo} and equals this {@code TextHitInfo}. * @param obj the {@code Object} to test for equality * @return {@code true} if the specified {@code Object} * equals this {@code TextHitInfo}; {@code false} otherwise. */ public boolean equals(Object obj) { return (obj instanceof TextHitInfo) && equals((TextHitInfo) obj); } /** * Returns {@code true} if the specified {@code TextHitInfo} * has the same {@code charIndex} and {@code isLeadingEdge} * as this {@code TextHitInfo}. This is not the same as having * the same insertion offset. * @param hitInfo a specified {@code TextHitInfo} * @return {@code true} if the specified {@code TextHitInfo} * has the same {@code charIndex} and {@code isLeadingEdge} * as this {@code TextHitInfo}. */ public boolean equals(TextHitInfo hitInfo) { return hitInfo != null && charIndex == hitInfo.charIndex && isLeadingEdge == hitInfo.isLeadingEdge; } /** * Returns a {@code String} representing the hit for debugging * use only. * @return a {@code String} representing this * {@code TextHitInfo}. */ public String toString() { return "TextHitInfo[" + charIndex + (isLeadingEdge ? "L" : "T") + "]"; } /** * Creates a {@code TextHitInfo} on the leading edge of the * character at the specified {@code charIndex}. * @param charIndex the index of the character hit * @return a {@code TextHitInfo} on the leading edge of the * character at the specified {@code charIndex}. */ public static TextHitInfo leading(int charIndex) { return new TextHitInfo(charIndex, true); } /** * Creates a hit on the trailing edge of the character at * the specified {@code charIndex}. * @param charIndex the index of the character hit * @return a {@code TextHitInfo} on the trailing edge of the * character at the specified {@code charIndex}. */ public static TextHitInfo trailing(int charIndex) { return new TextHitInfo(charIndex, false); } /** * Creates a {@code TextHitInfo} at the specified offset, * associated with the character before the offset. * @param offset an offset associated with the character before * the offset * @return a {@code TextHitInfo} at the specified offset. */ public static TextHitInfo beforeOffset(int offset) { return new TextHitInfo(offset - 1, false); } /** * Creates a {@code TextHitInfo} at the specified offset, * associated with the character after the offset. * @param offset an offset associated with the character after * the offset * @return a {@code TextHitInfo} at the specified offset. */ public static TextHitInfo afterOffset(int offset) { return new TextHitInfo(offset, true); } /** * Creates a {@code TextHitInfo} on the other side of the * insertion point. This {@code TextHitInfo} remains unchanged. * @return a {@code TextHitInfo} on the other side of the * insertion point. */ public TextHitInfo getOtherHit() { if (isLeadingEdge) { return trailing(charIndex - 1); } else { return leading(charIndex + 1); } } /** * Creates a {@code TextHitInfo} whose character index is offset * by {@code delta} from the {@code charIndex} of this * {@code TextHitInfo}. This {@code TextHitInfo} remains * unchanged. * @param delta the value to offset this {@code charIndex} * @return a {@code TextHitInfo} whose {@code charIndex} is * offset by {@code delta} from the {@code charIndex} of * this {@code TextHitInfo}. */ public TextHitInfo getOffsetHit(int delta) { return new TextHitInfo(charIndex + delta, isLeadingEdge); } }