awt/java/awt/font/TextHitInfo.java

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
/*
 * @author Oleg V. Khaschansky
 * @version $Revision$
 */

package java.awt.font;

import org.apache.harmony.misc.HashCode;


/**
 * The TextHitInfo class provides information about a caret position 
 * in a text model for insertion or deletion of a character in a text.
 * The TextHitInfo defines two biases of the character: leading or trailing.
 * Leading position means the left edge of the specified character 
 * (TextHitInfo.leading(2) method for "text" returns the left side of "x").
 * Trailing position means the right edge of the specified character
 * (TextHitInfo.trailing(2) method for "text" returns the right side of "x").
 */
public final class TextHitInfo {
    
    /** The char idx. */
    private int charIdx; // Represents character index in the line
    
    /** The is trailing. */
    private boolean isTrailing;

    /**
     * Instantiates a new text hit info.
     * 
     * @param idx the idx
     * @param isTrailing the is trailing
     */
    private TextHitInfo(int idx, boolean isTrailing) {
        charIdx = idx;
        this.isTrailing = isTrailing;
    }

    /**
     * To string.
     * 
     * @return the string
     */
    @Override
    public String toString() {
        return new String(
                "TextHitInfo[" + charIdx + ", " + //$NON-NLS-1$ //$NON-NLS-2$
                (isTrailing?"Trailing":"Leading") + "]" //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
        );
    }

    /**
     * Compares this TextHitInfo object with the specified object.
     * 
     * @param obj the Object to be compared.
     * 
     * @return true, if the specified object is a TextHitInfo object 
     * with the same data values as this TextHitInfo, false otherwise.
     */
    @Override
    public boolean equals(Object obj) {
        if (obj instanceof TextHitInfo) {
            return equals((TextHitInfo) obj);
        }
        return false;
    }

    /**
     * Compares this TextHitInfo object with the specified TextHitInfo
     * object.
     * 
     * @param thi the TextHitInfo object to be compared.
     * 
     * @return true, if this TextHitInfo object has the same data values as the
     * specified TextHitInfo object, false otherwise.
     */
    public boolean equals(TextHitInfo thi) {
        return
                thi != null &&
                thi.charIdx == charIdx &&
                thi.isTrailing == isTrailing;
    }

    /**
     * Gets a TextHitInfo object with its character index 
     * at the specified offset from the character index of 
     * this TextHitInfo.
     * 
     * @param offset the offset.
     * 
     * @return the TextHitInfo. 
     */
    public TextHitInfo getOffsetHit(int offset) {
        return new TextHitInfo(charIdx + offset, isTrailing);
    }

    /**
     * Gets a TextHitInfo associated with the other side of 
     * the insertion point. 
     *  
     * @return the other hit.
     */
    public TextHitInfo getOtherHit() {
        return isTrailing ?
                new TextHitInfo(charIdx+1, false) :
                new TextHitInfo(charIdx-1, true);
    }

    /**
     * Returns true if the leading edge of the character is hit,
     * false if the trailing edge of the character is hit.
     * 
     * @return true if the leading edge of the character is hit,
     * false if the trailing edge of the character is hit.
     */
    public boolean isLeadingEdge() {
        return !isTrailing;
    }

    /**
     * Hash code.
     * 
     * @return the int
     */
    @Override
    public int hashCode() {
        return HashCode.combine(charIdx, isTrailing);
    }

    /**
     * Gets the insertion index.
     * 
     * @return the insertion index: character index if the leading edge
     * is hit, or character index + 1 if the trailing edge is hit.   
     */
    public int getInsertionIndex() {
        return isTrailing ? charIdx+1 : charIdx;
    }

    /**
     * Gets the index of the character hit.
     * 
     * @return the character hit's index.
     */
    public int getCharIndex() {
        return charIdx;
    }

    /**
     * Returns a TextHitInfo associated with the trailing edge of 
     * the character at the specified char index.
     * 
     * @param charIndex the char index.
     * 
     * @return the TextHitInfo associated with the trailing edge of 
     * the character at the specified char index.
     */
    public static TextHitInfo trailing(int charIndex) {
        return new TextHitInfo(charIndex, true);
    }

    /**
     * Returns a TextHitInfo object associated with the leading edge 
     * of the character at the specified char index.
     * 
     * @param charIndex the char index.
     * 
     * @return the TextHitInfo object associated with the leading edge 
     * of the character at the specified char index.
     */
    public static TextHitInfo leading(int charIndex) {
        return new TextHitInfo(charIndex, false);
    }

    /**
     * Returns a (trailing) TextHitInfo object associated with the character 
     * before the specified offset.
     * 
     * @param offset the offset.
     * 
     * @return the TextHitInfo object associated with the character 
     * before the specified offset.
     */
    public static TextHitInfo beforeOffset(int offset) {
        return new TextHitInfo(offset-1, true);
    }

    /**
     * Returns a (leading) TextHitInfo object associated with the character 
     * after the specified offset.
     * 
     * @param offset the offset.
     * 
     * @return the TextHitInfo object associated with the character 
     * after the specified offset.
     */
    public static TextHitInfo afterOffset(int offset) {
        return new TextHitInfo(offset, false);
    }
}