`.
*
* Usage:
*
* $font = new ezcGraphSvgFont();
* var_dump(
* $font->calculateStringWidth( '../tests/data/font.svg', 'Just a test string.' ),
* $font->calculateStringWidth( '../tests/data/font2.svg', 'Just a test string.' )
* );
*
*
* @version //autogentag//
* @package Graph
* @mainclass
*/
class ezcGraphSvgFont
{
/**
* Units per EM
*
* @var float
*/
protected $unitsPerEm;
/**
* Used glyphs
*
* @var array
*/
protected $usedGlyphs = array();
/**
* Cache for glyph size to save XPath lookups.
*
* @var array
*/
protected $glyphCache = array();
/**
* Used kernings
*
* @var array
*/
protected $usedKerns = array();
/**
* Path to font
*
* @var string
*/
protected $fonts = array();
/**
* Initialize SVG font
*
* Loads the SVG font $filename. This should be the path to the file
* generated by ttf2svg.
*
* Returns the (normlized) name of the initilized font.
*
* @param string $fontPath
* @return string
*/
protected function initializeFont( $fontPath )
{
if ( isset( $this->fonts[$fontPath] ) )
{
return $fontPath;
}
// Check for existance of font file
if ( !is_file( $fontPath ) || !is_readable( $fontPath ) )
{
throw new ezcBaseFileNotFoundException( $fontPath );
}
$this->fonts[$fontPath] = simplexml_load_file( $fontPath )->defs->font;
// SimpleXML requires us to register a namespace for XPath to work
$this->fonts[$fontPath]->registerXPathNamespace( 'svg', 'http://www.w3.org/2000/svg' );
// Extract the number of units per Em
$this->unitsPerEm[$fontPath] = (int) $this->fonts[$fontPath]->{'font-face'}['units-per-em'];
return $fontPath;
}
/**
* Get name of font
*
* Get the name of the given font, by extracting its font family from the
* SVG font file.
*
* @param string $fontPath
* @return string
*/
public static function getFontName( $fontPath )
{
$font = simplexml_load_file( $fontPath )->defs->font;
// SimpleXML requires us to register a namespace for XPath to work
$font->registerXPathNamespace( 'svg', 'http://www.w3.org/2000/svg' );
// Extract the font family name
return (string) $font->{'font-face'}['font-family'];
}
/**
* XPath has no standard means of escaping ' and ", with the only solution
* being to delimit your string with the opposite type of quote. ( And if
* your string contains both concat( ) it ).
*
* This method will correctly delimit $char with the appropriate quote type
* so that it can be used in an XPath expression.
*
* @param string $char
* @return string
*/
protected static function xpathEscape( $char )
{
return "'" . str_replace(
array( '\'', '\\' ),
array( '\\\'', '\\\\' ),
$char ) . "'";
}
/**
* Returns the associated with $char.
*
* @param string $fontPath
* @param string $char
* @return float
*/
protected function getGlyph( $fontPath, $char )
{
// Check if glyphwidth has already been calculated.
if ( isset( $this->glyphCache[$fontPath][$char] ) )
{
return $this->glyphCache[$fontPath][$char];
}
$matches = $this->fonts[$fontPath]->xpath(
$query = "glyph[@unicode=" . self::xpathEscape( $char ) . "]"
);
if ( count( $matches ) === 0 )
{
// Just ignore missing glyphs. The client will still render them
// using a default font. We try to estimate some width by using a
// common other character.
return $this->glyphCache[$fontPath][$char] =
( $char === 'o' ? false : $this->getGlyph( $fontPath, 'o' ) );
}
$glyph = $matches[0];
if ( !in_array( $glyph, $this->usedGlyphs ) )
{
$this->usedGlyphs[$fontPath][] = $glyph;
}
// There should only ever be one match
return $this->glyphCache[$fontPath][$char] = $glyph;
}
/**
* Returns the amount of kerning to apply for glyphs $g1 and $g2. If no
* valid kerning pair can be found 0 is returned.
*
* @param string $fontPath
* @param SimpleXMLElement $g1
* @param SimpleXMLElement $g2
* @return int
*/
public function getKerning( $fontPath, SimpleXMLElement $glyph1, SimpleXMLElement $glyph2 )
{
// Get the glyph names
$g1Name = self::xpathEscape( ( string ) $glyph1['glyph-name'] );
$g2Name = self::xpathEscape( ( string ) $glyph2['glyph-name'] );
// Get the unicode character names
$g1Uni = self::xpathEscape( ( string ) $glyph1['unicode'] );
$g2Uni = self::xpathEscape( ( string ) $glyph2['unicode'] );
// Search for kerning pairs
$pair = $this->fonts[$fontPath]->xpath(
"svg:hkern[( @g1=$g1Name and @g2=$g2Name )
or
( @u1=$g1Uni and @g2=$g2Uni )]"
);
// If we found anything return it
if ( count( $pair ) )
{
if ( !in_array( $pair[0], $this->usedKerns ) )
{
$this->usedKerns[$fontPath][] = $pair[0];
}
return ( int ) $pair[0]['k'];
}
else
{
return 0;
}
}
/**
* Calculates the width of $string in the current font in Em's.
*
* @param string $fontPath
* @param string $string
* @return float
*/
public function calculateStringWidth( $fontPath, $string )
{
// Ensure font is properly initilized
$fontPath = $this->initializeFont( $fontPath );
$strlen = strlen( $string );
$prevCharInfo = null;
$length = 0;
// @TODO: Add UTF-8 support here - iterating over the bytes does not
// really help.
for ( $i = 0; $i < $strlen; ++$i )
{
// Find the font information for the character
$charInfo = $this->getGlyph( $fontPath, $string[$i] );
// Handle missing glyphs
if ( $charInfo === false )
{
$prevCharInfo = null;
$length += .5 * $this->unitsPerEm[$fontPath];
continue;
}
// Add the horizontal advance for the character to the length
$length += (float) $charInfo['horiz-adv-x'];
// If we are not the first character, look for kerning pairs
if ( $prevCharInfo !== null )
{
// Apply kerning (if any)
$length -= $this->getKerning( $fontPath, $prevCharInfo, $charInfo );
}
$prevCharInfo = clone $charInfo;
}
// Divide by _unitsPerEm to get the length in Em
return (float) $length / $this->unitsPerEm[$fontPath];
}
/**
* Add font definitions to SVG document
*
* Add the SVG font definition paths for all used glyphs and kernings to
* the given SVG document.
*
* @param DOMDocument $document
* @return void
*/
public function addFontToDocument( DOMDocument $document )
{
$defs = $document->getElementsByTagName( 'defs' )->item( 0 );
$fontNr = 0;
foreach ( $this->fonts as $path => $definition )
{
// Just import complete font for now.
// @TODO: Only import used characters.
$font = dom_import_simplexml( $definition );
$font = $document->importNode( $font, true );
$font->setAttribute( 'id', 'Font' . ++$fontNr );
$defs->appendChild( $font );
}
}
}
?>