ArabicLayoutEngine.h revision c73f511526464f8e56c242df80552e9b0d94ae3d 
1
2/*
3 *
4 * (C) Copyright IBM Corp. 1998-2013 - All Rights Reserved
5 *
6 */
7
8#ifndef __ARABICLAYOUTENGINE_H
9#define __ARABICLAYOUTENGINE_H
10
11#include "LETypes.h"
12#include "LEFontInstance.h"
13#include "LEGlyphFilter.h"
14#include "LayoutEngine.h"
15#include "OpenTypeLayoutEngine.h"
16
17#include "GlyphSubstitutionTables.h"
18#include "GlyphDefinitionTables.h"
19#include "GlyphPositioningTables.h"
20
21U_NAMESPACE_BEGIN
22
23/**
24 * This class implements OpenType layout for Arabic fonts. It overrides
25 * the characerProcessing method to assign the correct OpenType feature
26 * tags for the Arabic contextual forms. It also overrides the adjustGlyphPositions
27 * method to guarantee that all vowel and accent glyphs have zero advance width.
28 *
29 * @internal
30 */
31class ArabicOpenTypeLayoutEngine : public OpenTypeLayoutEngine
32{
33public:
34    /**
35     * This is the main constructor. It constructs an instance of ArabicOpenTypeLayoutEngine for
36     * a particular font, script and language. It takes the GSUB table as a parameter since
37     * LayoutEngine::layoutEngineFactory has to read the GSUB table to know that it has an
38     * Indic OpenType font.
39     *
40     * @param fontInstance - the font
41     * @param scriptCode - the script
42     * @param langaugeCode - the language
43     * @param gsubTable - the GSUB table
44     * @param success - set to an error code if the operation fails
45     *
46     * @see LayoutEngine::layoutEngineFactory
47     * @see OpenTypeLayoutEngine
48     * @see ScriptAndLanguageTags.h for script and language codes
49     *
50     * @internal
51     */
52    ArabicOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,
53                            le_int32 typoFlags, const LEReferenceTo<GlyphSubstitutionTableHeader> &gsubTable, LEErrorCode &success);
54
55    /**
56     * This constructor is used when the font requires a "canned" GSUB table which can't be known
57     * until after this constructor has been invoked.
58     *
59     * @param fontInstance - the font
60     * @param scriptCode - the script
61     * @param langaugeCode - the language
62     * @param success - set to an error code if the operation fails
63     *
64     * @see OpenTypeLayoutEngine
65     * @see ScriptAndLanguageTags.h for script and language codes
66     *
67     * @internal
68     */
69    ArabicOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,
70			       le_int32 typoFlags, LEErrorCode &success);
71
72    /**
73     * The destructor, virtual for correct polymorphic invocation.
74     *
75     * @internal
76     */
77    virtual ~ArabicOpenTypeLayoutEngine();
78
79    /**
80     * ICU "poor man's RTTI", returns a UClassID for the actual class.
81     *
82     * @stable ICU 2.8
83     */
84    virtual UClassID getDynamicClassID() const;
85
86    /**
87     * ICU "poor man's RTTI", returns a UClassID for this class.
88     *
89     * @stable ICU 2.8
90     */
91    static UClassID getStaticClassID();
92
93protected:
94
95    /**
96     * This method does Arabic OpenType character processing. It assigns the OpenType feature
97     * tags to the characters to generate the correct contextual forms and ligatures.
98     *
99     * Input parameters:
100     * @param chars - the input character context
101     * @param offset - the index of the first character to process
102     * @param count - the number of characters to process
103     * @param max - the number of characters in the input context
104     * @param rightToLeft - <code>TRUE</code> if the characters are in a right to left directional run
105     *
106     * Output parameters:
107     * @param outChars - the output character arrayt
108     * @param charIndices - the output character index array
109     * @param featureTags - the output feature tag array
110     * @param success - set to an error code if the operation fails
111     *
112     * @return the output character count
113     *
114     * @internal
115     */
116    virtual le_int32 characterProcessing(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft,
117            LEUnicode *&outChars, LEGlyphStorage &glyphStorage, LEErrorCode &success);
118
119    /**
120     * This method applies the GPOS table if it is present, otherwise it ensures that all vowel
121     * and accent glyphs have a zero advance width by calling the adjustMarkGlyphs method.
122     * If the font contains a GDEF table, that is used to identify voewls and accents. Otherwise
123     * the character codes are used.
124     *
125     * @param chars - the input character context
126     * @param offset - the offset of the first character to process
127     * @param count - the number of characters to process
128     * @param reverse - <code>TRUE</code> if the glyphs in the glyph array have been reordered
129     * @param glyphs - the input glyph array
130     * @param glyphCount - the number of glyphs
131     * @param positions - the position array, will be updated as needed
132     * @param success - output parameter set to an error code if the operation fails
133     *
134     * @internal
135     */
136    virtual void adjustGlyphPositions(const LEUnicode chars[], le_int32 offset, le_int32 count, le_bool reverse, LEGlyphStorage &glyphStorage, LEErrorCode &success);
137
138    // static void adjustMarkGlyphs(const LEUnicode chars[], le_int32 offset, le_int32 count, le_bool rightToLeft, LEGlyphStorage &glyphStorage, LEErrorCode &success);
139
140};
141
142/**
143 * The class implements OpenType layout for Arabic fonts which don't
144 * contain a GSUB table, using a canned GSUB table based on Unicode
145 * Arabic Presentation Forms. It overrides the mapCharsToGlyphs method
146 * to use the Presentation Forms as logical glyph indices. It overrides the
147 * glyphPostProcessing method to convert the Presentation Forms to actual
148 * glyph indices.
149 *
150 * @see ArabicOpenTypeLayoutEngine
151 *
152 * @internal
153 */
154class UnicodeArabicOpenTypeLayoutEngine : public ArabicOpenTypeLayoutEngine
155{
156public:
157    /**
158     * This constructs an instance of UnicodeArabicOpenTypeLayoutEngine for a specific font,
159     * script and language.
160     *
161     * @param fontInstance - the font
162     * @param scriptCode - the script
163     * @param languageCode - the language
164     * @param success - set to an error code if the operation fails
165     *
166     * @see LEFontInstance
167     * @see ScriptAndLanguageTags.h for script and language codes
168     *
169     * @internal
170     */
171    UnicodeArabicOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,
172		le_int32 typoFlags, LEErrorCode &success);
173
174    /**
175     * The destructor, virtual for correct polymorphic invocation.
176     *
177     * @internal
178     */
179    virtual ~UnicodeArabicOpenTypeLayoutEngine();
180
181protected:
182
183    /**
184     * This method converts the Arabic Presentation Forms in the temp glyph array
185     * into actual glyph indices using ArabicOpenTypeLayoutEngine::mapCharsToGlyps.
186     *
187     * Input paramters:
188     * @param tempGlyphs - the input presentation forms
189     * @param tempCharIndices - the input character index array
190     * @param tempGlyphCount - the number of Presentation Froms
191     *
192     * Output parameters:
193     * @param glyphs - the output glyph index array
194     * @param charIndices - the output character index array
195     * @param success - set to an error code if the operation fails
196     *
197     * @return the number of glyph indices in the output glyph index array
198     *
199     * @internal
200     */
201    virtual le_int32 glyphPostProcessing(LEGlyphStorage &tempGlyphStorage, LEGlyphStorage &glyphStorage, LEErrorCode &success);
202
203    /**
204     * This method copies the input characters into the output glyph index array,
205     * for use by the canned GSUB table. It also generates the character index array.
206     *
207     * Input parameters:
208     * @param chars - the input character context
209     * @param offset - the offset of the first character to be mapped
210     * @param count - the number of characters to be mapped
211     * @param reverse - if <code>TRUE</code>, the output will be in reverse order
212     * @param mirror - if <code>TRUE</code>, do character mirroring
213     * @param glyphStorage - the glyph storage object. Glyph and char index arrays will be updated.
214     *
215     * @param success - set to an error code if the operation fails
216     *
217     * @internal
218     */
219    virtual void mapCharsToGlyphs(const LEUnicode chars[], le_int32 offset, le_int32 count, le_bool reverse, le_bool mirror,
220        LEGlyphStorage &glyphStorage, LEErrorCode &success);
221
222    /**
223     * This method ensures that all vowel and accent glyphs have a zero advance width by calling
224     * the adjustMarkGlyphs method. The character codes are used to identify the vowel and mark
225     * glyphs.
226     *
227     * @param chars - the input character context
228     * @param offset - the offset of the first character to process
229     * @param count - the number of characters to process
230     * @param reverse - <code>TRUE</code> if the glyphs in the glyph array have been reordered
231     * @param glyphStorage - the glyph storage object. The glyph positions will be updated as needed.
232     * @param success - output parameter set to an error code if the operation fails
233     *
234     * @internal
235     */
236    virtual void adjustGlyphPositions(const LEUnicode chars[], le_int32 offset, le_int32 count, le_bool reverse, LEGlyphStorage &glyphStorage, LEErrorCode &success);
237};
238
239U_NAMESPACE_END
240#endif
241
242