1
2/*
3 *
4 * (C) Copyright IBM Corp. 1998-2013 - All Rights Reserved
5 *
6 */
7
8#ifndef __GXLAYOUTENGINE_H
9#define __GXLAYOUTENGINE_H
10
11#include "LETypes.h"
12#include "LayoutEngine.h"
13
14#include "MorphTables.h"
15
16U_NAMESPACE_BEGIN
17
18class LEFontInstance;
19class LEGlyphStorage;
20
21/**
22 * This class implements layout for QuickDraw GX or Apple Advanced Typograyph (AAT)
23 * fonts. A font is a GX or AAT font if it contains a 'mort' table. See Apple's
24 * TrueType Reference Manual (http://fonts.apple.com/TTRefMan/index.html) for details.
25 * Information about 'mort' tables is in the chapter titled "Font Files."
26 *
27 * @internal
28 */
29class GXLayoutEngine : public LayoutEngine
30{
31public:
32    /**
33     * This is the main constructor. It constructs an instance of GXLayoutEngine for
34     * a particular font, script and language. It takes the 'mort' table as a parameter since
35     * LayoutEngine::layoutEngineFactory has to read the 'mort' table to know that it has a
36     * GX font.
37     *
38     * Note: GX and AAT fonts don't contain any script and language specific tables, so
39     * the script and language are ignored.
40     *
41     * @param fontInstance - the font
42     * @param scriptCode - the script
43     * @param langaugeCode - the language
44     * @param morphTable - the 'mort' table
45     * @param success - set to an error code if the operation fails
46     *
47     * @see LayoutEngine::layoutEngineFactory
48     * @see ScriptAndLangaugeTags.h for script and language codes
49     *
50     * @internal
51     */
52    GXLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode, const LEReferenceTo<MorphTableHeader> &morphTable, LEErrorCode &success);
53
54    /**
55     * The destructor, virtual for correct polymorphic invocation.
56     *
57     * @internal
58     */
59    virtual ~GXLayoutEngine();
60
61    /**
62     * ICU "poor man's RTTI", returns a UClassID for the actual class.
63     *
64     * @stable ICU 2.8
65     */
66    virtual UClassID getDynamicClassID() const;
67
68    /**
69     * ICU "poor man's RTTI", returns a UClassID for this class.
70     *
71     * @stable ICU 2.8
72     */
73    static UClassID getStaticClassID();
74
75protected:
76
77    /**
78     * The address of the 'mort' table
79     *
80     * @internal
81     */
82    LEReferenceTo<MorphTableHeader> fMorphTable;
83
84    /**
85     * This method does GX layout using the font's 'mort' table. It converts the
86     * input character codes to glyph indices using mapCharsToGlyphs, and then
87     * applies the 'mort' table.
88     *
89     * Input parameters:
90     * @param chars - the input character context
91     * @param offset - the index of the first character to process
92     * @param count - the number of characters to process
93     * @param max - the number of characters in the input context
94     * @param rightToLeft - <code>TRUE</code> if the text is in a right to left directional run
95     * @param glyphStorage - the glyph storage object. The glyph and char index arrays will be set.
96     *
97     * Output parameters:
98     * @param success - set to an error code if the operation fails
99     *
100     * @return the number of glyphs in the glyph index array
101     *
102     * @internal
103     */
104    virtual le_int32 computeGlyphs(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft,
105        LEGlyphStorage &glyphStorage, LEErrorCode &success);
106
107    /**
108     * This method adjusts the glyph positions using the font's
109     * 'kern', 'trak', 'bsln', 'opbd' and 'just' tables.
110     *
111     * Input parameters:
112     * @param glyphStorage - the object holding the glyph storage. The positions will be updated as needed.
113     *
114     * Output parameters:
115     * @param success - set to an error code if the operation fails
116     *
117     * @internal
118     */
119    virtual void adjustGlyphPositions(const LEUnicode chars[], le_int32 offset, le_int32 count, le_bool reverse,
120                                      LEGlyphStorage &glyphStorage, LEErrorCode &success);
121
122};
123
124U_NAMESPACE_END
125#endif
126
127