- Implemented feature #10957: Embed glyphs for exact SVG font width estimation

# Lots of binary diffs, because font-family names are now enclosed in ' in SVG
# files.

2 files changed, 322 insertions, 14 deletions

diff --git a/src/driver/svg.php b/src/driver/svg.php
index d49ab45..9a814f1 100644
--- a/src/driver/svg.php
+++ b/src/driver/svg.php
@@ -100,6 +100,13 @@ class ezcGraphSvgDriver extends ezcGraphDriver
     protected $elementID = 0;
 
     /**
+     * Font storage for SVG font glyphs and kernings.
+     * 
+     * @var ezcGraphSvgFont
+     */
+    protected $font = null;
+
+    /**
      * Constructor
      * 
      * @param array $options Default option array
@@ -110,6 +117,7 @@ class ezcGraphSvgDriver extends ezcGraphDriver
     {
         ezcBase::checkDependency( 'Graph', ezcBase::DEP_PHP_EXTENSION, 'dom' );
         $this->options = new ezcGraphSvgDriverOptions( $options );
+        $this->font = new ezcGraphSvgFont();
     }
 
     /**
@@ -136,7 +144,6 @@ class ezcGraphSvgDriver extends ezcGraphDriver
 
             if ( $this->options->templateDocument !== false )
             {
-// @TODO: Add                $this->dom->format
                 $this->dom->load( $this->options->templateDocument );
 
                 $this->defs = $this->dom->getElementsByTagName( 'defs' )->item( 0 );
@@ -450,12 +457,25 @@ class ezcGraphSvgDriver extends ezcGraphDriver
      */
     protected function getTextBoundings( $size, ezcGraphFontOptions $font, $text )
     {
-        return new ezcGraphBoundings(
-            0,
-            0,
-            $this->getTextWidth( $text, $size ),
-            $size
-        );
+        if ( $font->type === ezcGraph::SVG_FONT )
+        {
+            return new ezcGraphBoundings(
+                0,
+                0,
+                $this->font->calculateStringWidth( $font->path, $text ) * $size,
+                $size
+            );
+        }
+        else
+        {
+            // If we didn't get a SVG font, continue guessing the font width.
+            return new ezcGraphBoundings(
+                0,
+                0,
+                $this->getTextWidth( $text, $size ),
+                $size
+            );
+        }
     }
 
     /**
@@ -655,7 +675,7 @@ class ezcGraphSvgDriver extends ezcGraphDriver
                 foreach ( $text['text'] as $line )
                 {
                     $string = implode( ' ', $line );
-                    if ( ( $strWidth = $this->getTextWidth( $string, $size ) ) > $width )
+                    if ( ( $strWidth = $this->getTextBoundings( $size, $text['font'], $string )->width ) > $width )
                     {
                         $width = $strWidth;
                     }
@@ -767,13 +787,13 @@ class ezcGraphSvgDriver extends ezcGraphDriver
                         break;
                     case ( $text['align'] & ezcGraph::RIGHT ):
                         $position = new ezcGraphCoordinate(
-                            $text['position']->x + ( $text['width'] - $this->getTextWidth( $string, $size ) ),
+                            $text['position']->x + ( $text['width'] - $this->getTextBoundings( $size, $text['font'], $string )->width ),
                             $text['position']->y + $yOffset
                         );
                         break;
                     case ( $text['align'] & ezcGraph::CENTER ):
                         $position = new ezcGraphCoordinate(
-                            $text['position']->x + ( ( $text['width'] - $this->getTextWidth( $string, $size ) ) / 2 ),
+                            $text['position']->x + ( ( $text['width'] - $this->getTextBoundings( $size, $text['font'], $string )->width ) / 2 ),
                             $text['position']->y + $yOffset
                         );
                         break;
@@ -785,12 +805,12 @@ class ezcGraphSvgDriver extends ezcGraphDriver
                     $textNode = $this->dom->createElement( 'text', $this->encode( $string ) );
                     $textNode->setAttribute( 'id', $text['id'] . '_shadow' );
                     $textNode->setAttribute( 'x', sprintf( '%.4F', $position->x + $this->options->graphOffset->x + $text['font']->textShadowOffset ) );
-                    $textNode->setAttribute( 'text-length', sprintf( '%.4Fpx', $this->getTextWidth( $string, $size ) ) );
+                    $textNode->setAttribute( 'text-length', sprintf( '%.4Fpx', $this->getTextBoundings( $size, $text['font'], $string )->width ) );
                     $textNode->setAttribute( 'y', sprintf( '%.4F', $position->y + $this->options->graphOffset->y + $text['font']->textShadowOffset ) );
                     $textNode->setAttribute( 
                         'style', 
                         sprintf(
-                            'font-size: %dpx; font-family: %s; fill: #%02x%02x%02x; fill-opacity: %.2F; stroke: none;',
+                            'font-size: %dpx; font-family: \'%s\'; fill: #%02x%02x%02x; fill-opacity: %.2F; stroke: none;',
                             $size,
                             $text['font']->name,
                             $text['font']->textShadowColor->red,
@@ -806,12 +826,12 @@ class ezcGraphSvgDriver extends ezcGraphDriver
                 $textNode = $this->dom->createElement( 'text', $this->encode( $string ) );
                 $textNode->setAttribute( 'id', $text['id'] . '_text' );
                 $textNode->setAttribute( 'x', sprintf( '%.4F', $position->x + $this->options->graphOffset->x ) );
-                $textNode->setAttribute( 'text-length', sprintf( '%.4Fpx', $this->getTextWidth( $string, $size ) ) );
+                $textNode->setAttribute( 'text-length', sprintf( '%.4Fpx', $this->getTextBoundings( $size, $text['font'], $string )->width ) );
                 $textNode->setAttribute( 'y', sprintf( '%.4F', $position->y + $this->options->graphOffset->y ) );
                 $textNode->setAttribute( 
                     'style', 
                     sprintf(
-                        'font-size: %dpx; font-family: %s; fill: #%02x%02x%02x; fill-opacity: %.2F; stroke: none;',
+                        'font-size: %dpx; font-family: \'%s\'; fill: #%02x%02x%02x; fill-opacity: %.2F; stroke: none;',
                         $size,
                         $text['font']->name,
                         $text['font']->color->red,
@@ -1186,6 +1206,9 @@ class ezcGraphSvgDriver extends ezcGraphDriver
     {
         $this->createDocument();  
         $this->drawAllTexts();
+
+        // Embed used glyphs
+        $this->font->addFontToDocument( $this->dom );
         $this->dom->save( $file );
     }
 }
diff --git a/src/driver/svg_font.php b/src/driver/svg_font.php
new file mode 100644
index 0000000..341fa48
--- /dev/null
+++ b/src/driver/svg_font.php
@@ -0,0 +1,285 @@
+<?php
+/**
+ * File containing the ezcGraphSVGDriver class
+ *
+ * @package Graph
+ * @version //autogentag//
+ * @copyright Copyright ( C ) 2005-2008 eZ systems as. All rights reserved.
+ * @author Freddie Witherden
+ * @license http://ez.no/licenses/new_bsd New BSD License
+ */
+
+/**
+ * Helper class, offering requrired calculation basics and font metrics to use
+ * SVG fonts with the SVG driver.
+ *
+ * You may convert any ttf font into a SVG font using the `ttf2svg` bianry from
+ * the batik package. Depending on the distribution it may only be available as
+ * `batik-ttf2svg-<version>`.
+ *
+ * Usage:
+ * <code>
+ *  $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.' )
+ *  );
+ * </code>
+ *
+ * @version //autogentag//
+ * @package Graph
+ * @mainclass
+ */
+class ezcGraphSvgFont
+{
+    /**
+     * Units per EM
+     *
+     * @var float
+     */
+    protected $unitsPerEm;
+
+    /**
+     * Used glyphs
+     *
+     * @var array
+     */
+    protected $usedGlyphs = 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 )
+    {
+        $fontPath = realpath( $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 <glyph> associated with $char.
+     *
+     * @param string $fontPath
+     * @param string $char
+     * @return SimpleXMLElement
+     */
+    protected function getGlyph( $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 ( $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 $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 );
+        }
+    }
+}
+
+?>