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    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.
    4    *
    5    * This code is free software; you can redistribute it and/or modify it
    6    * under the terms of the GNU General Public License version 2 only, as
    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.
   20    *
   21    * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   22    * or visit www.oracle.com if you need additional information or have any
   23    * questions.
   24    */
   25   
   26   package java.awt.font;
   27   
   28   /**
   29   * The <code>LineMetrics</code> 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</code>
   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</code> methods of
   37   * {@link java.awt.Font Font} take some text as an argument
   38   * and return a <code>LineMetrics</code> 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</code> values) in the text whose
   49        * metrics are encapsulated by this <code>LineMetrics</code>
   50        * object.
   51        * @return the number of characters (<code>char</code> values) in the text with which
   52        *         this <code>LineMetrics</code> 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</code> then
  110        * <code>offsets[HANGING_BASELINE]</code> is usually
  111        * negative, <code>offsets[CENTER_BASELINE]</code>
  112        * is zero, and <code>offsets[ROMAN_BASELINE]</code>
  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   }

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