1 /*
   2  * Copyright (c) 1998, 2003, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   5  * This code is free software; you can redistribute it and/or modify it
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   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  25 
  26 package java.awt.font;
  27 
  28 /**
  29 * The {@code LineMetrics} class allows access to the
  30 * metrics needed to layout characters along a line
  31 * and to layout of a set of lines.  A {@code LineMetrics}
  32 * object encapsulates the measurement information associated
  33 * with a run of text.
  34 * <p>
  35 * Fonts can have different metrics for different ranges of
  36 * characters.  The {@code getLineMetrics} methods of
  37 * {@link java.awt.Font Font} take some text as an argument
  38 * and return a {@code LineMetrics} object describing the
  39 * metrics of the initial number of characters in that text, as
  40 * returned by {@link #getNumChars}.
  41 */
  42 
  43 
  44 public abstract class LineMetrics {
  45 
  46 
  47     /**
  48      * Returns the number of characters ({@code char} values) in the text whose
  49      * metrics are encapsulated by this {@code LineMetrics}
  50      * object.
  51      * @return the number of characters ({@code char} values) in the text with which
  52      *         this {@code LineMetrics} was created.
  53      */
  54     public abstract int getNumChars();
  55 
  56     /**
  57      * Returns the ascent of the text.  The ascent
  58      * is the distance from the baseline
  59      * to the ascender line.  The ascent usually represents the
  60      * the height of the capital letters of the text.  Some characters
  61      * can extend above the ascender line.
  62      * @return the ascent of the text.
  63      */
  64     public abstract float getAscent();
  65 
  66     /**
  67      * Returns the descent of the text.  The descent
  68      * is the distance from the baseline
  69      * to the descender line.  The descent usually represents
  70      * the distance to the bottom of lower case letters like
  71      * 'p'.  Some characters can extend below the descender
  72      * line.
  73      * @return the descent of the text.
  74      */
  75     public abstract float getDescent();
  76 
  77     /**
  78      * Returns the leading of the text. The
  79      * leading is the recommended
  80      * distance from the bottom of the descender line to the
  81      * top of the next line.
  82      * @return the leading of the text.
  83      */
  84     public abstract float getLeading();
  85 
  86     /**
  87      * Returns the height of the text.  The
  88      * height is equal to the sum of the ascent, the
  89      * descent and the leading.
  90      * @return the height of the text.
  91      */
  92     public abstract float getHeight();
  93 
  94     /**
  95      * Returns the baseline index of the text.
  96      * The index is one of
  97      * {@link java.awt.Font#ROMAN_BASELINE ROMAN_BASELINE},
  98      * {@link java.awt.Font#CENTER_BASELINE CENTER_BASELINE},
  99      * {@link java.awt.Font#HANGING_BASELINE HANGING_BASELINE}.
 100      * @return the baseline of the text.
 101      */
 102     public abstract int getBaselineIndex();
 103 
 104     /**
 105      * Returns the baseline offsets of the text,
 106      * relative to the baseline of the text.  The
 107      * offsets are indexed by baseline index.  For
 108      * example, if the baseline index is
 109      * {@code CENTER_BASELINE} then
 110      * {@code offsets[HANGING_BASELINE]} is usually
 111      * negative, {@code offsets[CENTER_BASELINE]}
 112      * is zero, and {@code offsets[ROMAN_BASELINE]}
 113      * is usually positive.
 114      * @return the baseline offsets of the text.
 115      */
 116     public abstract float[] getBaselineOffsets();
 117 
 118     /**
 119      * Returns the position of the strike-through line
 120      * relative to the baseline.
 121      * @return the position of the strike-through line.
 122      */
 123     public abstract float getStrikethroughOffset();
 124 
 125     /**
 126      * Returns the thickness of the strike-through line.
 127      * @return the thickness of the strike-through line.
 128      */
 129     public abstract float getStrikethroughThickness();
 130 
 131     /**
 132      * Returns the position of the underline relative to
 133      * the baseline.
 134      * @return the position of the underline.
 135      */
 136     public abstract float getUnderlineOffset();
 137 
 138     /**
 139      * Returns the thickness of the underline.
 140      * @return the thickness of the underline.
 141      */
 142     public abstract float getUnderlineThickness();
 143 }