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
26package 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
44public 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}
144