bgfx/examples/common/font/text_metrics.cpp

/*
* Copyright 2013 Jeremie Roy. All rights reserved.
* License: https://github.com/bkaradzic/bgfx#license-bsd-2-clause
*/

#include <wchar.h> // wcslen

#include "text_metrics.h"
#include "utf8.h"

TextMetrics::TextMetrics(FontManager* _fontManager)
	: m_fontManager(_fontManager)
{
	clearText();
}

void TextMetrics::clearText()
{
	m_width = m_height = m_x = m_lineHeight = m_lineGap = 0;
}

void TextMetrics::appendText(FontHandle _fontHandle, const char* _string)
{
	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) )
		{
			const GlyphInfo* glyph = m_fontManager->getGlyphInfo(_fontHandle, codepoint);
			if (NULL != 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;
				}

				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)
{
	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];
		const GlyphInfo* glyph = m_fontManager->getGlyphInfo(_fontHandle, codepoint);
		if (NULL != 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;
			}

			m_x += glyph->advance_x;
			if(m_x > m_width)
			{
				m_width = m_x;
			}
		}
		else
		{
			BX_CHECK(false, "Glyph not found");
		}
	}
}

TextLineMetrics::TextLineMetrics(const FontInfo& _fontInfo)
{
	m_lineHeight = _fontInfo.ascender - _fontInfo.descender + _fontInfo.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;	
}