1 /*
2  *******************************************************************************
3  * Copyright (C) 1998-2004, International Business Machines Corporation and    *
4  * others. All Rights Reserved.                                                *
5  *******************************************************************************
6  *
7  * Created on Dec 3, 2003
8  *
9  *******************************************************************************
10  */
11 package com.ibm.icu.dev.tool.layout;
12 
13 import com.ibm.icu.lang.UCharacter;
14 import com.ibm.icu.lang.UProperty;
15 
16 public class ArabicShaping {
17 
18     // arabic   shaping type code
19 
20     // shaping bit masks
21     static final int MASK_SHAPE_RIGHT   = 1; // if this bit set, shapes to right
22     static final int MASK_SHAPE_LEFT = 2;   // if this bit set, shapes to left
23     static final int MASK_TRANSPARENT   = 4; // if this bit set, is transparent (ignore other bits)
24     static final int MASK_NOSHAPE   = 8; // if this bit set, don't shape this char, i.e. tatweel
25 
26     // shaping values
27     public static final int VALUE_NONE = 0;
28     public static final int VALUE_RIGHT = MASK_SHAPE_RIGHT;
29     public static final int VALUE_LEFT = MASK_SHAPE_LEFT;
30     public static final int VALUE_DUAL = MASK_SHAPE_RIGHT | MASK_SHAPE_LEFT;
31     public static final int VALUE_TRANSPARENT = MASK_TRANSPARENT;
32     public static final int VALUE_NOSHAPE_DUAL = MASK_NOSHAPE | VALUE_DUAL;
33     public static final int VALUE_NOSHAPE_NONE = MASK_NOSHAPE;
34 
getShapeType(char ch)35     public static int getShapeType(char ch)
36     {
37         int tt = UCharacter.getIntPropertyValue(ch, UProperty.JOINING_TYPE);
38 
39         switch(tt) {
40             case UCharacter.JoiningType.JOIN_CAUSING:
41                 return VALUE_NOSHAPE_DUAL;
42 
43             case UCharacter.JoiningType.LEFT_JOINING:
44                 return VALUE_LEFT;
45 
46             case UCharacter.JoiningType.RIGHT_JOINING:
47                 return VALUE_RIGHT;
48 
49             case UCharacter.JoiningType.DUAL_JOINING:
50                 return VALUE_DUAL;
51 
52             case UCharacter.JoiningType.TRANSPARENT:
53                 return VALUE_TRANSPARENT;
54 
55             case UCharacter.JoiningType.NON_JOINING:
56             default:
57                 return VALUE_NOSHAPE_NONE;
58         }
59     }
60 
61     /*
62      * Chars in logical order.
63      * leftType is shaping code of char to logical left of range
64      * rightType is shaping code of char to logical right of range
65      */
66 
shape(char[] chars, int leftType, int rightType, ClassTable isolClassTable)67     public static void shape(char[] chars, int leftType, int rightType, ClassTable isolClassTable) {
68         // iterate in logical order from left to right
69         //
70         // the effective right char is the most recently encountered
71         // non-transparent char
72         //
73         // four boolean states:
74         //   the effective right char shapes
75         //   the effective right char causes right shaping
76         //   the current char shapes
77         //   the current char causes left shaping
78         //
79         // if both cause shaping, then
80         //   right += 2 (isolate to initial, or final to medial)
81         //   cur += 1 (isolate to final)
82 
83         // ern is effective right logical index
84         int ern = -1;
85 
86         boolean rightShapes = false;
87         boolean rightCauses = (rightType & MASK_SHAPE_LEFT) != 0;
88 
89         for (int n = 0; n < chars.length; n++) {
90             char c = chars[n];
91             int t = getShapeType(c);
92 
93             if ((t & MASK_TRANSPARENT) != 0) {
94                 continue;
95             }
96 
97             boolean curShapes = (t & MASK_NOSHAPE) == 0;
98             boolean curCauses = (t & MASK_SHAPE_RIGHT) != 0;
99 
100             if (rightCauses && curCauses) {
101                 if (rightShapes) {
102                     chars[ern] += 2;
103                 }
104 
105                 if (curShapes) {
106                     chars[n] = (char) (isolClassTable.getGlyphClassID(c) + 1);
107                 }
108             } else {
109                 if (curShapes) {
110                     chars[n] = (char) isolClassTable.getGlyphClassID(c);
111                 }
112             }
113 
114             rightShapes = curShapes;
115             rightCauses = (t & MASK_SHAPE_LEFT) != 0;
116             ern = n;
117         }
118 
119         if (rightShapes && rightCauses && (leftType & MASK_SHAPE_RIGHT) != 0) {
120             chars[ern] += 2;
121         }
122     }
123 }
124