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loengine.h

/*
 * @(#)loengine.h 1.0 00/12/11
 *
 * (C) Copyright IBM Corp. 1998, 1999, 2000 - All Rights Reserved
 *
 */

#ifndef __LOENGINE_H
#define __LOENGINE_H

#include "unicode/utypes.h"
#include "unicode/uscript.h"
#include "unicode/unistr.h"

#include "layout/LETypes.h"
#include "layout/LayoutEngine.h"

U_NAMESPACE_BEGIN

/**
 * This is a wrapper class designed to allow ICU clients to
 * use LayoutEngine in a way that is consistent with the rest
 * of ICU.
 *
 * (LayoutEngine was developed seperately from ICU and
 * the same source is used in non-ICU environments, so it cannot
 * be changed to match ICU coding conventions).
 *
 * This class is designed for clients who wish to use LayoutEngine
 * to layout complex text. If you need to subclass LayoutEngine,
 * you'll need to use the LayoutEngine interfaces directly.
 *
 * Basically, it creates an instance of LayoutEngine, stashes
 * it in fLayoutEngine, and uses it to implement the layout
 * functionality.
 *
 * Use the createInstance method to create an ICULayoutEngine. Use
 * delete to destroy it. The layoutChars method computes the glyphs
 * and positions, and saves them in the ICULayoutEngine object.
 * Use getGlyphs, getPositions and getCharIndices to retreive this
 * data.
 *
 * You'll also need an implementation of LEFontInstance for your platform.
 *
 * @see LayoutEngine.h
 * @see LEFontInstance.h
 */
00048 class U_LAYOUT_API ICULayoutEngine
{
private:
    /**
     * This holds the instance of LayoutEngine that does all
     * the work.
     */
00055     LayoutEngine *fLayoutEngine;

    /**
     * This no argument constructor is private so that clients
     * can't envoke it. Clients should use createInstance.
     *
     * @see createInstance
     */
    ICULayoutEngine();

    /**
     * The main constructor. It is defined as private to
     * stop clients from invoking it. Clients should use
     * createInstance.
     *
     * @param layoutEngine - the LayoutEngine that this instance wraps.
     *
     * @see createInstance
     */
    ICULayoutEngine(LayoutEngine *layoutEngine);

public:

    /**
     * The destructor. At least on Windows it needs to be
     * virtual to ensure that it deletes the object from the
     * same heap that createInstance will allocate it from. We
     * don't know why this is...
     *
     * @see createInstance
     */
    virtual ~ICULayoutEngine();

    /**
     * This method computes the glyph, character index and position arrays
     * for the input characters.
     *
     * @param chars - the input character context
     * @param startOffset - the starting offset of the characters to process
     * @param endOffset - the ending offset of the characters to process
     * @param max - the number of characters in the input context
     * @param rightToLeft - true if the characers are in a right to left directional run
     * @param x - the initial X position
     * @param y - the initial Y position
     * @param success - output parameter set to an error code if the operation fails
     *
     * @return the number of glyphs in the glyph array
     *
     * Note; the glyph, character index and position array can be accessed
     * using the getter method below.
     */
    int32_t layoutChars(const UChar chars[],
                        int32_t startOffset,
                        int32_t endOffset,
                        int32_t maxOffset,
                        UBool rightToLeft,
                        float x, float y,
                        UErrorCode &success);


    /**
     * This method computes the glyph, character index and position arrays
     * for the input characters.
     *
     * @param str - the input character context
     * @param startOffset - the starting offset of the characters to process
     * @param endOffset - the ending offset of the characters to process
     * @param rightToLeft - true if the characers are in a right to left directional run
     * @param x - the initial X position
     * @param y - the initial Y position
     * @param success - output parameter set to an error code if the operation fails
     *
     * @return the number of glyphs in the glyph array
     *
     * Note; the glyph, character index and position array can be accessed
     * using the getter method below.
     */
    int32_t layoutString(const UnicodeString &str,
                         int32_t startOffset,
                         int32_t endOffset,
                         UBool rightToLeft,
                         float x, float y,
                         UErrorCode &success);

    /**
     * This method returns the number of glyphs in the glyph array. Note
     * that the number of glyphs will be greater than or equal to the number
     * of characters used to create the LayoutEngine.
     *
     * @return the number of glyphs in the glyph array
     */
    int32_t countGlyphs() const;

    /**
     * This method copies the glyph array into a caller supplied array.
     * The caller must ensure that the array is large enough to hold all
     * the glyphs.
     *
     * @param glyphs - the destiniation glyph array
     * @param success - output parameter set to an error code if the operation fails
     */
    void getGlyphs(uint16_t glyphs[], UErrorCode &success);

    /**
     * This method copies the character index array into a caller supplied array.
     * The caller must ensure that the array is large enough to hold a character
     * index for each glyph.
     *
     * @param charIndices - the destiniation character index array
     * @param success - output parameter set to an error code if the operation fails
     */
    void getCharIndices(int32_t charIndices[], UErrorCode &success);

    /**
     * This method copies the character index array into a caller supplied array.
     * The caller must ensure that the array is large enough to hold a character
     * index for each glyph.
     *
     * @param charIndices - the destiniation character index array
     * @param indexBase - an offset which will be added to each index
     * @param success - output parameter set to an error code if the operation fails
     */
    void getCharIndices(int32_t charIndices[], int32_t indexBase, UErrorCode &success);

    /**
     * This method copies the position array into a caller supplied array.
     * The caller must ensure that the array is large enough to hold an
     * X and Y position for each glyph, plus an extra X and Y for the
     * advance of the last glyph.
     *
     * @param glyphs - the destiniation position array
     * @param success - output parameter set to an error code if the operation fails
     */
    void getGlyphPositions(float positions[], UErrorCode &success);

    /**
     * This method returns the X and Y position of the glyph at the
     * given index.
     *
     * Input parameters:
     * @param glyphIndex - the index of the glyph
     *
     * Output parameters:
     * @param x - the glyph's X position
     * @param y - the glyph's Y position
     * @param success - output parameter set to an error code if the operation fails
     *
     */
    void getGlyphPosition(int32_t glyphIndex, float &x, float &y, UErrorCode &success);

    /**
     * This method returns an ICULayoutEngine capable of laying out text
     * in the given font, script and langauge.
     *
     * @param fontInstance - the font of the text
     * @param scriptCode - the script of the text
     * @param locale - used to determine the language of the text
     * @param success - output parameter set to an error code if the operation fails
     *
     * @return an ICULayoutEngine which can layout text in the given font.
     *
     * NOTE: currently, locale is ignored...
     *
     * @see LEFontInstance
     */
    static ICULayoutEngine *createInstance(const LEFontInstance *fontInstance,
                                           UScriptCode script, Locale &locale,
                                           UErrorCode &success);
};

00225 inline ICULayoutEngine::ICULayoutEngine()
{
    // nothing at all...
}

00230 inline ICULayoutEngine::ICULayoutEngine(LayoutEngine *layoutEngine)
    : fLayoutEngine(layoutEngine)
{
    // nothing else to do
}

00236 inline ICULayoutEngine::~ICULayoutEngine()
{
    delete fLayoutEngine;
    fLayoutEngine = 0;
}

00242 inline int32_t ICULayoutEngine::layoutChars(const UChar chars[],
                                            int32_t startOffset,
                                            int32_t endOffset,
                                            int32_t maxOffset,
                                            UBool rightToLeft,
                                            float x, float y,
                                            UErrorCode &success)
{
    // NOTE: call reset() so that clients can safely reuse
    fLayoutEngine->reset();
    return fLayoutEngine->layoutChars(chars,
                                      startOffset,
                                      endOffset - startOffset,
                                      maxOffset,
                                      rightToLeft,
                                      x, y,
                                      (LEErrorCode &) success);
}

00261 inline int32_t ICULayoutEngine::layoutString(const UnicodeString &str,
                                            int32_t startOffset,
                                            int32_t endOffset,
                                            UBool rightToLeft,
                                            float x, float y,
                                            UErrorCode &success)
{
    int32_t glyphCount = 0;
    int32_t max = str.length();
    UChar *chars = new UChar[max];

    str.extract(0, max, chars);

    // NOTE: call reset() so that clients can safely reuse
    fLayoutEngine->reset();
    glyphCount = fLayoutEngine->layoutChars(chars,
                                      startOffset,
                                      endOffset - startOffset,
                                      max,
                                      rightToLeft,
                                      x, y,
                                      (LEErrorCode &) success);

    delete[] chars;

    return glyphCount;
}

00289 inline int32_t ICULayoutEngine::countGlyphs() const
{
    return fLayoutEngine->getGlyphCount();
}

00294 inline void ICULayoutEngine::getGlyphs(uint16_t glyphs[], UErrorCode &success)
{
    fLayoutEngine->getGlyphs(glyphs, (LEErrorCode &) success);
}

00299 inline void ICULayoutEngine::getCharIndices(int32_t charIndices[], UErrorCode &success)
{
    fLayoutEngine->getCharIndices(charIndices, (LEErrorCode &) success);
}

00304 inline void ICULayoutEngine::getCharIndices(int32_t charIndices[], int32_t indexBase, UErrorCode &success)
{
    fLayoutEngine->getCharIndices(charIndices, indexBase, (LEErrorCode &) success);
}

00309 inline void ICULayoutEngine::getGlyphPositions(float positions[], UErrorCode &success)
{
    fLayoutEngine->getGlyphPositions(positions, (LEErrorCode &) success);
}

00314 inline void ICULayoutEngine::getGlyphPosition(int32_t glyphIndex, float &x, float &y, UErrorCode &success)
{
    fLayoutEngine->getGlyphPosition(glyphIndex, x, y, (LEErrorCode &) success);
}

00319 inline ICULayoutEngine *ICULayoutEngine::createInstance(const LEFontInstance *fontInstance,
                                                        UScriptCode script,
                                                        Locale &locale, UErrorCode &success)
{
    LayoutEngine *engine = LayoutEngine::layoutEngineFactory(fontInstance,
                                                             (le_int32) script,
                                                             0,
                                                             (LEErrorCode &) success);

    return new ICULayoutEngine(engine);
}

U_NAMESPACE_END
#endif

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