KhmerLayoutEngine.h revision c73f511526464f8e56c242df80552e9b0d94ae3d 
1
2/*
3 *
4 * (C) Copyright IBM Corp. 1998-2013 - All Rights Reserved
5 *
6 * This file is a modification of the ICU file IndicLayoutEngine.h
7 * by Jens Herden and Javier Sola for Khmer language
8 *
9 */
10
11#ifndef __KHMERLAYOUTENGINE_H
12#define __KHMERLAYOUTENGINE_H
13
14// #include "LETypes.h"
15// #include "LEFontInstance.h"
16// #include "LEGlyphFilter.h"
17// #include "LayoutEngine.h"
18// #include "OpenTypeLayoutEngine.h"
19
20// #include "GlyphSubstitutionTables.h"
21// #include "GlyphDefinitionTables.h"
22// #include "GlyphPositioningTables.h"
23
24U_NAMESPACE_BEGIN
25
26// class MPreFixups;
27// class LEGlyphStorage;
28
29/**
30 * This class implements OpenType layout for Khmer OpenType fonts, as
31 * specified by Microsoft in "Creating and Supporting OpenType Fonts for
32 * Khmer Scripts" (http://www.microsoft.com/typography/otspec/indicot/default.htm) TODO: change url
33 *
34 * This class overrides the characterProcessing method to do Khmer character processing
35 * and reordering (See the MS spec. for more details)
36 *
37 * @internal
38 */
39class KhmerOpenTypeLayoutEngine : public OpenTypeLayoutEngine
40{
41public:
42    /**
43     * This is the main constructor. It constructs an instance of KhmerOpenTypeLayoutEngine for
44     * a particular font, script and language. It takes the GSUB table as a parameter since
45     * LayoutEngine::layoutEngineFactory has to read the GSUB table to know that it has an
46     * Khmer OpenType font.
47     *
48     * @param fontInstance - the font
49     * @param scriptCode - the script
50     * @param langaugeCode - the language
51     * @param gsubTable - the GSUB table
52     * @param success - set to an error code if the operation fails
53     *
54     * @see LayoutEngine::layoutEngineFactory
55     * @see OpenTypeLayoutEngine
56     * @see ScriptAndLangaugeTags.h for script and language codes
57     *
58     * @internal
59     */
60    KhmerOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,
61                            le_int32 typoFlags, const LEReferenceTo<GlyphSubstitutionTableHeader> &gsubTable, LEErrorCode &success);
62
63    /**
64     * This constructor is used when the font requires a "canned" GSUB table which can't be known
65     * until after this constructor has been invoked.
66     *
67     * @param fontInstance - the font
68     * @param scriptCode - the script
69     * @param langaugeCode - the language
70     * @param success - set to an error code if the operation fails
71     *
72     * @see OpenTypeLayoutEngine
73     * @see ScriptAndLangaugeTags.h for script and language codes
74     *
75     * @internal
76     */
77    KhmerOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,
78			      le_int32 typoFlags, LEErrorCode &success);
79
80    /**
81     * The destructor, virtual for correct polymorphic invocation.
82     *
83     * @internal
84     */
85   virtual ~KhmerOpenTypeLayoutEngine();
86
87    /**
88     * ICU "poor man's RTTI", returns a UClassID for the actual class.
89     *
90     * @stable ICU 2.8
91     */
92    virtual UClassID getDynamicClassID() const;
93
94    /**
95     * ICU "poor man's RTTI", returns a UClassID for this class.
96     *
97     * @stable ICU 2.8
98     */
99    static UClassID getStaticClassID();
100
101protected:
102
103    /**
104     * This method does Khmer OpenType character processing. It assigns the OpenType feature
105     * tags to the characters, and may generate output characters which have been reordered.
106     * It may also split some vowels, resulting in more output characters than input characters.
107     *
108     * Input parameters:
109     * @param chars - the input character context
110     * @param offset - the index of the first character to process
111     * @param count - the number of characters to process
112     * @param max - the number of characters in the input context
113     * @param rightToLeft - <code>TRUE</code> if the characters are in a right to left directional run
114     * @param glyphStorage - the glyph storage object. The glyph and character index arrays will be set.
115     *                       the auxillary data array will be set to the feature tags.
116     *
117     * Output parameters:
118     * @param success - set to an error code if the operation fails
119     *
120     * @return the output character count
121     *
122     * @internal
123     */
124    virtual le_int32 characterProcessing(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft,
125            LEUnicode *&outChars, LEGlyphStorage &glyphStorage, LEErrorCode &success);
126
127};
128
129U_NAMESPACE_END
130#endif
131
132