GraphicAttribute


1   /*
2    * @(#)GraphicAttribute.java    1.18 03/12/19
3    *
4    * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7   
8   /*
9    * (C) Copyright Taligent, Inc. 1996 - 1997, All Rights Reserved
10   * (C) Copyright IBM Corp. 1996 - 1998, All Rights Reserved
11   *
12   * The original version of this source code and documentation is
13   * copyrighted and owned by Taligent, Inc., a wholly-owned subsidiary
14   * of IBM. These materials are provided under terms of a License
15   * Agreement between Taligent and Sun. This technology is protected
16   * by multiple US and International patents.
17   *
18   * This notice and attribution to Taligent may not be removed.
19   * Taligent is a registered trademark of Taligent, Inc.
20   *
21   */
22  
23  package java.awt.font;
24  
25  import java.awt.geom.Rectangle2D  ;
26  import java.awt.Graphics2D  ;
27  import java.awt.Font  ;
28  
29  /**
30   * This class is used with the CHAR_REPLACEMENT attribute.
31   * <p>
32   * The <code>GraphicAttribute</code> class represents a graphic embedded
33   * in text. Clients subclass this class to implement their own char
34   * replacement graphics.  Clients wishing to embed shapes and images in
35   * text need not subclass this class.  Instead, clients can use the
36   * {@link ShapeGraphicAttribute} and {@link ImageGraphicAttribute} 
37   * classes.
38   * <p>
39   * Subclasses must ensure that their objects are immutable once they
40   * are constructed.  Mutating a <code>GraphicAttribute</code> that
41   * is used in a {@link TextLayout} results in undefined behavior from the
42   * <code>TextLayout</code>.
43   */
44  public abstract class GraphicAttribute {
45  
46      private int fAlignment;
47  
48      /** 
49       * Aligns top of graphic to top of line. 
50       */
51      public static final int TOP_ALIGNMENT = -1;
52  
53      /** 
54       * Aligns bottom of graphic to bottom of line. 
55       */
56      public static final int BOTTOM_ALIGNMENT = -2;
57  
58      /** 
59       * Aligns origin of graphic to roman baseline of line. 
60       */
61      public static final int ROMAN_BASELINE = Font.ROMAN_BASELINE;
62  
63      /** 
64       * Aligns origin of graphic to center baseline of line. 
65       */
66      public static final int CENTER_BASELINE = Font.CENTER_BASELINE;
67  
68      /** 
69       * Aligns origin of graphic to hanging baseline of line. 
70       */
71      public static final int HANGING_BASELINE = Font.HANGING_BASELINE;
72  
73      /**
74       * Constructs a <code>GraphicAttribute</code>.
75       * Subclasses use this to define the alignment of the graphic.
76       * @param alignment an int representing one of the 
77       * <code>GraphicAttribute</code> alignment fields
78       */
79      protected GraphicAttribute(int alignment) {
80          if (alignment < BOTTOM_ALIGNMENT || alignment > HANGING_BASELINE) {
81        throw new IllegalArgumentException  ("bad alignment");
82          }
83          fAlignment = alignment;
84      }
85  
86      /**
87       * Returns the ascent of this <code>GraphicAttribute</code>.  A
88       * graphic can be rendered above its ascent.
89       * @return the ascent of this <code>GraphicAttribute</code>.
90       * @see #getBounds()
91       */
92      public abstract float getAscent();
93  
94      /**
95       * Returns the descent of this <code>GraphicAttribute</code>.  A
96       * graphic can be rendered below its descent.
97       * @return the descent of this <code>GraphicAttribute</code>.
98       * @see #getBounds()
99       */
100     public abstract float getDescent();
101 
102     /**
103      * Returns the advance of this <code>GraphicAttribute</code>.  The
104      * <code>GraphicAttribute</code> object's advance is the distance
105      * from the point at which the graphic is rendered and the point where
106      * the next character or graphic is rendered.  A graphic can be
107      * rendered beyond its advance
108      * @return the advance of this <code>GraphicAttribute</code>.
109      * @see #getBounds()
110      */
111     public abstract float getAdvance();
112 
113     /**
114      * Returns a {@link Rectangle2D} that encloses all of the
115      * bits drawn by this <code>GraphicAttribute</code> relative to the
116      * rendering position.
117      * A graphic may be rendered beyond its origin, ascent, descent,
118      * or advance;  but if it is, this method's implementation must
119      * indicate where the graphic is rendered.
120      * Default bounds is the rectangle (0, -ascent, advance, ascent+descent).
121      * @return a <code>Rectangle2D</code> that encloses all of the bits
122      * rendered by this <code>GraphicAttribute</code>.
123      */
124     public Rectangle2D   getBounds() {
125         float ascent = getAscent();
126         return new Rectangle2D.Float  (0, -ascent,
127                                         getAdvance(), ascent+getDescent());
128     }
129 
130     /**
131      * Renders this <code>GraphicAttribute</code> at the specified 
132      * location.
133      * @param graphics the {@link Graphics2D} into which to render the
134      * graphic
135      * @param x,&nbsp;y the user-space coordinates where
136      * the graphic is rendered
137      */
138     public abstract void draw(Graphics2D   graphics, float x, float y);
139 
140     /**
141      * Returns the alignment of this <code>GraphicAttribute</code>.
142      * Alignment can be to a particular baseline, or to the absolute top
143      * or bottom of a line.
144      * @return the alignment of this <code>GraphicAttribute</code>.
145      */
146     public final int getAlignment() {
147 
148         return fAlignment;
149     }
150 
151     /**
152      * Returns the justification information for this 
153      * <code>GraphicAttribute</code>.  Subclasses
154      * can override this method to provide different justification
155      * information.
156      * @return a {@link GlyphJustificationInfo} object that contains the
157      * justification information for this <code>GraphicAttribute</code>.
158      */
159     public GlyphJustificationInfo   getJustificationInfo() {
160 
161         // should we cache this?
162         float advance = getAdvance();
163 
164         return new GlyphJustificationInfo  (
165                                      advance,   // weight
166                                      false,     // growAbsorb
167                                      2,         // growPriority
168                                      advance/3, // growLeftLimit
169                                      advance/3, // growRightLimit
170                                      false,     // shrinkAbsorb
171                                      1,         // shrinkPriority
172                                      0,         // shrinkLeftLimit
173                                      0);        // shrinkRightLimit
174     }
175 }
176
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