1 

     2 /*

     3  *

     4  * (C) Copyright IBM Corp. 1998-2005 - All Rights Reserved

     5  *

     6  */

     7 

     8 #ifndef __INDICLAYOUTENGINE_H

     9 #define __INDICLAYOUTENGINE_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 

    21 U_NAMESPACE_BEGIN

    22 

    23 class MPreFixups;

    24 class LEGlyphStorage;

    25 

    26 /**

    27  * This class implements OpenType layout for Indic OpenType fonts, as

    28  * specified by Microsoft in "Creating and Supporting OpenType Fonts for

    29  * Indic Scripts" (http://www.microsoft.com/typography/otspec/indicot/default.htm)

    30  *

    31  * This class overrides the characterProcessing method to do Indic character processing

    32  * and reordering, and the glyphProcessing method to implement post-GSUB processing for

    33  * left matras. (See the MS spec. for more details)

    34  *

    35  * @internal

    36  */

    37 class IndicOpenTypeLayoutEngine : public OpenTypeLayoutEngine

    38 {

    39 public:

    40     /**

    41      * This is the main constructor. It constructs an instance of IndicOpenTypeLayoutEngine for

    42      * a particular font, script and language. It takes the GSUB table as a parameter since

    43      * LayoutEngine::layoutEngineFactory has to read the GSUB table to know that it has an

    44      * Indic OpenType font.

    45      *

    46      * @param fontInstance - the font

    47      * @param scriptCode - the script

    48      * @param langaugeCode - the language

    49      * @param gsubTable - the GSUB table

    50      *

    51      * @see LayoutEngine::layoutEngineFactory

    52      * @see OpenTypeLayoutEngine

    53      * @see ScriptAndLangaugeTags.h for script and language codes

    54      *

    55      * @internal

    56      */

    57     IndicOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,

    58                             le_int32 typoFlags, const GlyphSubstitutionTableHeader *gsubTable);

    59 

    60     /**

    61      * This constructor is used when the font requires a "canned" GSUB table which can't be known

    62      * until after this constructor has been invoked.

    63      *

    64      * @param fontInstance - the font

    65      * @param scriptCode - the script

    66      * @param langaugeCode - the language

    67      *

    68      * @see OpenTypeLayoutEngine

    69      * @see ScriptAndLangaugeTags.h for script and language codes

    70      *

    71      * @internal

    72      */

    73     IndicOpenTypeLayoutEngine(const LEFontInstance *fontInstance, le_int32 scriptCode, le_int32 languageCode,

    74 			      le_int32 typoFlags);

    75 

    76     /**

    77      * The destructor, virtual for correct polymorphic invocation.

    78      *

    79      * @internal

    80      */

    81    virtual ~IndicOpenTypeLayoutEngine();

    82 

    83     /**

    84      * ICU "poor man's RTTI", returns a UClassID for the actual class.

    85      *

    86      * @stable ICU 2.8

    87      */

    88     virtual UClassID getDynamicClassID() const;

    89 

    90     /**

    91      * ICU "poor man's RTTI", returns a UClassID for this class.

    92      *

    93      * @stable ICU 2.8

    94      */

    95     static UClassID getStaticClassID();

    96 

    97 protected:

    98 

    99     /**

   100      * This method does Indic OpenType character processing. It assigns the OpenType feature

   101      * tags to the characters, and may generate output characters which have been reordered. For

   102      * some Indic scripts, it may also split some vowels, resulting in more output characters

   103      * than input characters.

   104      *

   105      * Input parameters:

   106      * @param chars - the input character context

   107      * @param offset - the index of the first character to process

   108      * @param count - the number of characters to process

   109      * @param max - the number of characters in the input context

   110      * @param rightToLeft - <code>TRUE</code> if the characters are in a right to left directional run

   111      * @param glyphStorage - the glyph storage object. The glyph and character index arrays will be set.

   112      *                       the auxillary data array will be set to the feature tags.

   113      *

   114      * Output parameters:

   115      * @param success - set to an error code if the operation fails

   116      *

   117      * @return the output character count

   118      *

   119      * @internal

   120      */

   121     virtual le_int32 characterProcessing(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft,

   122             LEUnicode *&outChars, LEGlyphStorage &glyphStorage, LEErrorCode &success);

   123 

   124     /**

   125      * This method does character to glyph mapping, applies the GSUB table and applies

   126      * any post GSUB fixups for left matras. It calls OpenTypeLayoutEngine::glyphProcessing

   127      * to do the character to glyph mapping, and apply the GSUB table.

   128      *

   129      * Note that in the case of "canned" GSUB tables, the output glyph indices may be

   130      * "fake" glyph indices that need to be converted to "real" glyph indices by the

   131      * glyphPostProcessing method.

   132      *

   133      * Input parameters:

   134      * @param chars - the input character context

   135      * @param offset - the index of the first character to process

   136      * @param count - the number of characters to process

   137      * @param max - the number of characters in the input context

   138      * @param rightToLeft - <code>TRUE</code> if the characters are in a right to left directional run

   139      * @param featureTags - the feature tag array

   140      * @param glyphStorage - the glyph storage object. The glyph and char index arrays will be set.

   141      *

   142      * Output parameters:

   143      * @param success - set to an error code if the operation fails

   144      *

   145      * @return the number of glyphs in the output glyph index array

   146      *

   147      * Note: if the character index array was already set by the characterProcessing

   148      * method, this method won't change it.

   149      *

   150      * @internal

   151      */

   152     virtual le_int32 glyphProcessing(const LEUnicode chars[], le_int32 offset, le_int32 count, le_int32 max, le_bool rightToLeft,

   153             LEGlyphStorage &glyphStorage, LEErrorCode &success);

   154 

   155 private:

   156 

   157     MPreFixups *fMPreFixups;

   158 };

   159 

   160 U_NAMESPACE_END

   161 #endif

   162