1/*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.  Oracle designates this
7 * particular file as subject to the "Classpath" exception as provided
8 * by Oracle in the LICENSE file that accompanied this code.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26
27/*
28 *
29 * (C) Copyright IBM Corp. 1998-2009 - All Rights Reserved
30 *
31 */
32
33#ifndef __INDICLAYOUTENGINE_H
34#define __INDICLAYOUTENGINE_H
35
36#include "LETypes.h"
37#include "LEFontInstance.h"
38#include "LEGlyphFilter.h"
39#include "LayoutEngine.h"
40#include "OpenTypeLayoutEngine.h"
41
42#include "GlyphSubstitutionTables.h"
43#include "GlyphDefinitionTables.h"
44#include "GlyphPositioningTables.h"
45
46U_NAMESPACE_BEGIN
47
48class MPreFixups;
49class LEGlyphStorage;
50
51/**
52 * This class implements OpenType layout for Indic OpenType fonts, as
53 * specified by Microsoft in "Creating and Supporting OpenType Fonts for
54 * Indic Scripts" (http://www.microsoft.com/typography/otspec/indicot/default.htm)
55 *
56 * This class overrides the characterProcessing method to do Indic character processing
57 * and reordering, and the glyphProcessing method to implement post-GSUB processing for
58 * left matras. (See the MS spec. for more details)
59 *
60 * @internal
61 */
62class IndicOpenTypeLayoutEngine : public OpenTypeLayoutEngine
63{
64public:
65    /**
66     * This is the main constructor. It constructs an instance of IndicOpenTypeLayoutEngine for
67     * a particular font, script and language. It takes the GSUB table as a parameter since
68     * LayoutEngine::layoutEngineFactory has to read the GSUB table to know that it has an
69     * Indic OpenType font.
70     *
71     * @param fontInstance - the font
72     * @param scriptCode - the script
73     * @param langaugeCode - the language
74     * @param gsubTable - the GSUB table
75     * @param success - set to an error code if the operation fails
76     *
77     * @see LayoutEngine::layoutEngineFactory
78     * @see OpenTypeLayoutEngine
79     * @see ScriptAndLangaugeTags.h for script and language codes
80     *
81     * @internal
82     */
83    IndicOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,
84                            le_int32 typoFlags, le_bool version2, const LEReferenceTo<GlyphSubstitutionTableHeader> &gsubTable, LEErrorCode &success);
85
86    /**
87     * This constructor is used when the font requires a "canned" GSUB table which can't be known
88     * until after this constructor has been invoked.
89     *
90     * @param fontInstance - the font
91     * @param scriptCode - the script
92     * @param langaugeCode - the language
93     * @param success - set to an error code if the operation fails
94     *
95     * @see OpenTypeLayoutEngine
96     * @see ScriptAndLangaugeTags.h for script and language codes
97     *
98     * @internal
99     */
100    IndicOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,
101                              le_int32 typoFlags, LEErrorCode &success);
102
103    /**
104     * The destructor, virtual for correct polymorphic invocation.
105     *
106     * @internal
107     */
108   virtual ~IndicOpenTypeLayoutEngine();
109
110    /**
111     * ICU "poor man's RTTI", returns a UClassID for the actual class.
112     *
113     * @stable ICU 2.8
114     */
115    virtual UClassID getDynamicClassID() const;
116
117    /**
118     * ICU "poor man's RTTI", returns a UClassID for this class.
119     *
120     * @stable ICU 2.8
121     */
122    static UClassID getStaticClassID();
123
124protected:
125
126    /**
127     * This method does Indic OpenType character processing. It assigns the OpenType feature
128     * tags to the characters, and may generate output characters which have been reordered. For
129     * some Indic scripts, it may also split some vowels, resulting in more output characters
130     * than input characters.
131     *
132     * Input parameters:
133     * @param chars - the input character context
134     * @param offset - the index of the first character to process
135     * @param count - the number of characters to process
136     * @param max - the number of characters in the input context
137     * @param rightToLeft - <code>TRUE</code> if the characters are in a right to left directional run
138     * @param glyphStorage - the glyph storage object. The glyph and character index arrays will be set.
139     *                       the auxillary data array will be set to the feature tags.
140     *
141     * Output parameters:
142     * @param success - set to an error code if the operation fails
143     *
144     * @return the output character count
145     *
146     * @internal
147     */
148    virtual le_int32 characterProcessing(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft,
149            LEUnicode *&outChars, LEGlyphStorage &glyphStorage, LEErrorCode &success);
150
151    /**
152     * This method does character to glyph mapping, applies the GSUB table and applies
153     * any post GSUB fixups for left matras. It calls OpenTypeLayoutEngine::glyphProcessing
154     * to do the character to glyph mapping, and apply the GSUB table.
155     *
156     * Note that in the case of "canned" GSUB tables, the output glyph indices may be
157     * "fake" glyph indices that need to be converted to "real" glyph indices by the
158     * glyphPostProcessing method.
159     *
160     * Input parameters:
161     * @param chars - the input character context
162     * @param offset - the index of the first character to process
163     * @param count - the number of characters to process
164     * @param max - the number of characters in the input context
165     * @param rightToLeft - <code>TRUE</code> if the characters are in a right to left directional run
166     * @param featureTags - the feature tag array
167     * @param glyphStorage - the glyph storage object. The glyph and char index arrays will be set.
168     *
169     * Output parameters:
170     * @param success - set to an error code if the operation fails
171     *
172     * @return the number of glyphs in the output glyph index array
173     *
174     * Note: if the character index array was already set by the characterProcessing
175     * method, this method won't change it.
176     *
177     * @internal
178     */
179    virtual le_int32 glyphProcessing(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft,
180            LEGlyphStorage &glyphStorage, LEErrorCode &success);
181
182    le_bool fVersion2;
183
184private:
185
186    MPreFixups *fMPreFixups;
187
188};
189
190U_NAMESPACE_END
191#endif
192
193