bgfx/examples/common/font/text_metrics.cpp

/*
 * Copyright 2013 Jeremie Roy. All rights reserved.
 * License: http://www.opensource.org/licenses/BSD-2-Clause
 */
#include "text_metrics.h"
#include <wchar.h>  // wcslen
#include "utf8.h"

TextMetrics::TextMetrics(FontManager* _fontManager): m_fontManager(_fontManager), m_width(0), m_height(0), m_x(0), m_lineHeight(0), m_lineGap(0)
{
}

void TextMetrics::appendText(FontHandle _fontHandle, const char* _string)
{
	GlyphInfo glyph;
	const FontInfo& font = m_fontManager->getFontInfo(_fontHandle);
	
	if(font.lineGap > m_lineGap) 
	{
		m_lineGap = font.lineGap;
	}

	if( (font.ascender - font.descender) > m_lineHeight)
	{
		m_height -= m_lineHeight;
		m_lineHeight = font.ascender - font.descender;
		m_height += m_lineHeight;
	}

	CodePoint codepoint = 0;
	uint32_t state = 0;
	
	for (; *_string; ++_string)
	{
		if (!utf8_decode(&state, (uint32_t*)&codepoint, *_string) )
		{
			if (m_fontManager->getGlyphInfo(_fontHandle, codepoint, glyph) )
			{
				if (codepoint == L'\n')
				{
					m_height += m_lineGap + font.ascender - font.descender;					
					m_lineGap = font.lineGap;
					m_lineHeight = font.ascender - font.descender;					
					m_x = 0;
					break;
				}
				//TODO handle kerning
				m_x += glyph.advance_x;
				if(m_x > m_width)
				{
					m_width = m_x;
				}
			}
			else
			{
				BX_CHECK(false, "Glyph not found");
			}
		}
	}

	BX_CHECK(state == UTF8_ACCEPT, "The string is not well-formed");
}

void TextMetrics::appendText(FontHandle _fontHandle, const wchar_t* _string)
{
	GlyphInfo glyph;
	const FontInfo& font = m_fontManager->getFontInfo(_fontHandle);
	
	if(font.lineGap > m_lineGap) 
	{
		m_lineGap = font.lineGap;
	}

	if( (font.ascender - font.descender) > m_lineHeight)
	{
		m_height -= m_lineHeight;
		m_lineHeight = font.ascender - font.descender;
		m_height += m_lineHeight;
	}

	for (uint32_t ii = 0, end = (uint32_t)wcslen(_string); ii < end; ++ii)
	{
		uint32_t codepoint = _string[ii];
		if (m_fontManager->getGlyphInfo(_fontHandle, codepoint, glyph) )
		{
			if (codepoint == L'\n')
			{
				m_height += m_lineGap + font.ascender - font.descender;
				m_lineGap = font.lineGap;
				m_lineHeight = font.ascender - font.descender;
				m_x = 0;
				break;
			}
			//TODO handle kerning
			m_x += glyph.advance_x;
			if(m_x > m_width)
			{
				m_width = m_x;
			}
		}
		else
		{
			BX_CHECK(false, "Glyph not found");
		}
	}
}

TextLineMetrics::TextLineMetrics(FontManager* _fontManager, FontHandle _fontHandle )
{
	const FontInfo& font = _fontManager->getFontInfo(_fontHandle);
	m_lineHeight = font.ascender - font.descender + font.lineGap;
}

uint32_t TextLineMetrics::getLineCount(const char* _string) const
{
	CodePoint codepoint = 0;
	uint32_t state = 0;
	uint32_t lineCount = 1;
	for (; *_string; ++_string)
	{
		if(utf8_decode(&state, (uint32_t*)&codepoint, *_string) == UTF8_ACCEPT)
		{
			if(codepoint == L'\n')
			{				
				++lineCount;
			}
		}
	}
	BX_CHECK(state == UTF8_ACCEPT, "The string is not well-formed");
	return lineCount;
}

uint32_t TextLineMetrics::getLineCount(const wchar_t* _string) const
{	
	uint32_t lineCount = 1;
	for ( ;*_string != L'\0'; ++_string)
	{
		if(*_string == L'\n')
		{
			++lineCount;
		}
	}
	return lineCount;
}


void TextLineMetrics::getSubText(const char* _string, uint32_t _firstLine, uint32_t _lastLine, const char*& _begin, const char*& _end)
{
	CodePoint codepoint = 0;
	uint32_t state = 0;
	// y is bottom of a text line
	uint32_t currentLine = 0;
	while(*_string && (currentLine < _firstLine))
	{
		for (; *_string; ++_string)
		{	
			if(utf8_decode(&state, (uint32_t*)&codepoint, *_string) == UTF8_ACCEPT)
			{
				if(codepoint == L'\n')
				{
					++currentLine;
					++_string;
					break;
				}
			}
		}
	}
	BX_CHECK(state == UTF8_ACCEPT, "The string is not well-formed");
	_begin = _string;
	
	while((*_string) && (currentLine < _lastLine) )
	{
		for (; *_string; ++_string)
		{	
			if(utf8_decode(&state, (uint32_t*)&codepoint, *_string) == UTF8_ACCEPT)
			{
				if(codepoint == L'\n')
				{
					++currentLine;
					++_string;
					break;
				}
			}
		}
	}
	BX_CHECK(state == UTF8_ACCEPT, "The string is not well-formed");
	_end = _string;
}

void TextLineMetrics::getSubText(const wchar_t* _string, uint32_t _firstLine, uint32_t _lastLine, const wchar_t*& _begin, const wchar_t*& _end)
{
	uint32_t currentLine = 0;	
	while((*_string != L'\0') && (currentLine < _firstLine))
	{
		for ( ;*_string != L'\0'; ++_string)
		{			
			if(*_string == L'\n')
			{
				++currentLine;
				++_string;
				break;
			}
		}
	}
	_begin = _string;

	while((*_string != L'\0') && (currentLine < _lastLine) )
	{
		for ( ;*_string != L'\0'; ++_string)
		{			
			if(*_string == L'\n')
			{
				++currentLine;
				++_string;
				break;
			}
		}
	}
	_end = _string;	
}

void TextLineMetrics::getVisibleText(const char* _string, float _top, float _bottom, const char*& _begin, const char*& _end)
{
	CodePoint codepoint = 0;
	uint32_t state = 0;
	// y is bottom of a text line
	float y = m_lineHeight;
	while(*_string && (y < _top))
	{
		for (; *_string; ++_string)
		{	
			if(utf8_decode(&state, (uint32_t*)&codepoint, *_string) == UTF8_ACCEPT)
			{
				if(codepoint == L'\n')
				{
					y += m_lineHeight;
					++_string;
					break;
				}
			}
		}
	}
	BX_CHECK(state == UTF8_ACCEPT, "The string is not well-formed");
	_begin = _string;

	// y is now top of a text line
	y -= m_lineHeight;
	while((*_string) && (y < _bottom) )
	{
		for (; *_string; ++_string)
		{	
			if(utf8_decode(&state, (uint32_t*)&codepoint, *_string) == UTF8_ACCEPT)
			{
				if(codepoint == L'\n')
				{
					y += m_lineHeight;
					++_string;
					break;
				}
			}
		}
	}
	BX_CHECK(state == UTF8_ACCEPT, "The string is not well-formed");
	_end = _string;
}

void TextLineMetrics::getVisibleText(const wchar_t* _string, float _top, float _bottom, const wchar_t*& _begin, const wchar_t*& _end)
{
	// y is bottom of a text line
	float y = m_lineHeight;
	
	const wchar_t* _textEnd = _string + wcslen(_string);

	while(y < _top)
	{
		for (const wchar_t* _current = _string; _current < _textEnd; ++_current)
		{			
			if(*_current == L'\n')
			{
				y += m_lineHeight;
				++_string;
				break;
			}
		}
	}
	_begin = _string;

	// y is now top of a text line
	y -= m_lineHeight;
	while(y < _bottom )
	{
		for (const wchar_t* _current = _string; _current < _textEnd; ++_current)
		{			
			if(*_current == L'\n')
			{
				y += m_lineHeight;
				++_string;
				break;
			}
		}
	}
	_end = _string;	
}