gecko/gfx/thebes/gfxTextRunCache.h

/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
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 * Software distributed under the License is distributed on an "AS IS" basis,
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 * License.
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 * The Original Code is Mozilla Foundation code.
 *
 * The Initial Developer of the Original Code is Mozilla Foundation.
 * Portions created by the Initial Developer are Copyright (C) 2006
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Vladimir Vukicevic <vladimir@pobox.com>
 *
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 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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#ifndef GFX_TEXT_RUN_CACHE_H
#define GFX_TEXT_RUN_CACHE_H

#include "gfxFont.h"

/**
 * A simple textrun cache for textruns that do not carry state
 * (e.g., actual or potential linebreaks) and do not need complex initialization.
 * The lifetimes of these textruns are managed by the cache (they are auto-expired
 * after a certain period of time).
 */
class THEBES_API gfxTextRunCache {
public:
    /**
     * Get a textrun for the given text, using a global cache. The textrun
     * must be released via ReleaseTextRun, not deleted.
     * Do not set any state in the textrun (e.g. actual or potential linebreaks).
     * Flags IS_8BIT and IS_ASCII are automatically set appropriately.
     * Flag IS_PERSISTENT must NOT be set unless aText is guaranteed to live
     * forever.
     * The string can contain any characters, invalid ones will be stripped
     * properly.
     */
    static gfxTextRun *MakeTextRun(const PRUnichar *aText, PRUint32 aLength,
                                   gfxFontGroup *aFontGroup,
                                   gfxContext *aRefContext,
                                   PRUint32 aAppUnitsPerDevUnit,
                                   PRUint32 aFlags);

    /**
     * As above, but allows a full Parameters object to be passed in.
     */
    static gfxTextRun *MakeTextRun(const PRUnichar *aText, PRUint32 aLength,
                                   gfxFontGroup *aFontGroup,
                                   const gfxTextRunFactory::Parameters* aParams,
                                   PRUint32 aFlags);

    /**
     * Get a textrun for the given text, using a global cache. The textrun
     * must be released via ReleaseTextRun, not deleted.
     * Do not set any state in the textrun (e.g. actual or potential linebreaks).
     * Flags IS_8BIT, IS_ASCII and HAS_SURROGATES are automatically set
     * appropriately.
     * Flag IS_PERSISTENT must NOT be set unless aText is guaranteed to live
     * forever.
     * The string can contain any characters, invalid ones will be stripped
     * properly.
     */
    static gfxTextRun *MakeTextRun(const PRUint8 *aText, PRUint32 aLength,
                                   gfxFontGroup *aFontGroup,
                                   gfxContext *aRefContext,
                                   PRUint32 aAppUnitsPerDevUnit,
                                   PRUint32 aFlags);
    
    /**
     * Release a previously acquired textrun. Consider using AutoTextRun
     * instead of calling this.
     */
    static void ReleaseTextRun(gfxTextRun *aTextRun);

    class AutoTextRun {
    public:
    	AutoTextRun(gfxTextRun *aTextRun) : mTextRun(aTextRun) {}
    	AutoTextRun() : mTextRun(nsnull) {}
    	AutoTextRun& operator=(gfxTextRun *aTextRun) {
            gfxTextRunCache::ReleaseTextRun(mTextRun);
            mTextRun = aTextRun;
            return *this;
        }
        ~AutoTextRun() {
            gfxTextRunCache::ReleaseTextRun(mTextRun);
        }
        gfxTextRun *get() { return mTextRun; }
        gfxTextRun *operator->() { return mTextRun; }
    private:
        gfxTextRun *mTextRun;
    };

protected:
    friend class gfxPlatform;

    static nsresult Init();
    static void Shutdown();
};

#endif /* GFX_TEXT_RUN_CACHE_H */