haiku/headers/private/interface/WidthBuffer.h

/*
 * Copyright 2003-2010, Haiku, Inc.
 * Distributed under the terms of the MIT License.
 */
#ifndef __WIDTHBUFFER_H
#define __WIDTHBUFFER_H


#include <Locker.h>
#include <TextView.h>

#include "TextViewSupportBuffer.h"


class BFont;


namespace BPrivate {

class TextGapBuffer;

struct _width_table_ {
	BFont font;				// corresponding font
	int32 hashCount;		// number of hashed items
	int32 tableCount;		// size of table
	void* widths;			// width table
};


class WidthBuffer : public _BTextViewSupportBuffer_<_width_table_> {
public:
	WidthBuffer();
	virtual ~WidthBuffer();

	float StringWidth(const char* inText, int32 fromOffset, int32 length,
		const BFont* inStyle);
	float StringWidth(TextGapBuffer& gapBuffer, int32 fromOffset,
		int32 length, const BFont* inStyle);

private:
	bool FindTable(const BFont* font, int32* outIndex);
	int32 InsertTable(const BFont* font);

	bool GetEscapement(uint32 value, int32 index, float* escapement);
	float HashEscapements(const char* chars, int32 numChars, int32 numBytes,
		int32 tableIndex, const BFont* font);

	static uint32 Hash(uint32);

private:
	BLocker	fLock;
};

extern WidthBuffer* gWidthBuffer;

} // namespace BPrivate

using BPrivate::WidthBuffer;

#if __GNUC__ < 3
//! NetPositive binary compatibility support

class _BWidthBuffer_ : public _BTextViewSupportBuffer_<BPrivate::_width_table_> {
	_BWidthBuffer_();
	virtual ~_BWidthBuffer_();
};

extern
_BWidthBuffer_* gCompatibilityWidthBuffer;

#endif // __GNUC__ < 3

#endif // __WIDTHBUFFER_H