From 3166b8a10ffdf8c5154752688f232825211bb9d9 Mon Sep 17 00:00:00 2001
From: "Edward Z. Yang" <ezyang@mit.edu>
Date: Wed, 5 May 2010 15:08:57 -0400
Subject: [PATCH] Fix bug in background-position with center keyword.

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>
---
 NEWS                                          |  1 +
 .../AttrDef/CSS/BackgroundPosition.php        | 21 ++++++++++++-------
 .../AttrDef/CSS/BackgroundPositionTest.php    | 10 ++++-----
 3 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/NEWS b/NEWS
index b78cf391..a8d9bc45 100644
--- a/NEWS
+++ b/NEWS
@@ -11,6 +11,7 @@ NEWS ( CHANGELOG and HISTORY )                                     HTMLPurifier
 
 4.1.1, unknown release date
 - Emit an error for CollectErrors if a body is extracted
+- Fix bug where in background-position for center keyword handling.
 
 4.1.0, released 2010-04-26
 ! Support proprietary height attribute on table element
diff --git a/library/HTMLPurifier/AttrDef/CSS/BackgroundPosition.php b/library/HTMLPurifier/AttrDef/CSS/BackgroundPosition.php
index 35df3985..fae82eae 100644
--- a/library/HTMLPurifier/AttrDef/CSS/BackgroundPosition.php
+++ b/library/HTMLPurifier/AttrDef/CSS/BackgroundPosition.php
@@ -59,7 +59,8 @@ class HTMLPurifier_AttrDef_CSS_BackgroundPosition extends HTMLPurifier_AttrDef
         $keywords = array();
         $keywords['h'] = false; // left, right
         $keywords['v'] = false; // top, bottom
-        $keywords['c'] = false; // center
+        $keywords['ch'] = false; // center (first word)
+        $keywords['cv'] = false; // center (second word)
         $measures = array();
 
         $i = 0;
@@ -79,6 +80,13 @@ class HTMLPurifier_AttrDef_CSS_BackgroundPosition extends HTMLPurifier_AttrDef
             $lbit = ctype_lower($bit) ? $bit : strtolower($bit);
             if (isset($lookup[$lbit])) {
                 $status = $lookup[$lbit];
+                if ($status == 'c') {
+                    if ($i == 0) {
+                        $status = 'ch';
+                    } else {
+                        $status = 'cv';
+                    }
+                }
                 $keywords[$status] = $lbit;
                 $i++;
             }
@@ -101,20 +109,19 @@ class HTMLPurifier_AttrDef_CSS_BackgroundPosition extends HTMLPurifier_AttrDef
 
         if (!$i) return false; // no valid values were caught
 
-
         $ret = array();
 
         // first keyword
         if     ($keywords['h'])     $ret[] = $keywords['h'];
-        elseif (count($measures))   $ret[] = array_shift($measures);
-        elseif ($keywords['c']) {
-            $ret[] = $keywords['c'];
-            $keywords['c'] = false; // prevent re-use: center = center center
+        elseif ($keywords['ch']) {
+            $ret[] = $keywords['ch'];
+            $keywords['cv'] = false; // prevent re-use: center = center center
         }
+        elseif (count($measures))   $ret[] = array_shift($measures);
 
         if     ($keywords['v'])     $ret[] = $keywords['v'];
+        elseif ($keywords['cv'])    $ret[] = $keywords['cv'];
         elseif (count($measures))   $ret[] = array_shift($measures);
-        elseif ($keywords['c'])     $ret[] = $keywords['c'];
 
         if (empty($ret)) return false;
         return implode(' ', $ret);
diff --git a/tests/HTMLPurifier/AttrDef/CSS/BackgroundPositionTest.php b/tests/HTMLPurifier/AttrDef/CSS/BackgroundPositionTest.php
index f5302c37..a216b267 100644
--- a/tests/HTMLPurifier/AttrDef/CSS/BackgroundPositionTest.php
+++ b/tests/HTMLPurifier/AttrDef/CSS/BackgroundPositionTest.php
@@ -28,13 +28,13 @@ class HTMLPurifier_AttrDef_CSS_BackgroundPositionTest extends HTMLPurifier_AttrD
 
         // reordered due to internal impl details
         $this->assertDef('top left', 'left top');
-        $this->assertDef('top center', 'center top');
+        $this->assertDef('top center', 'top');
         $this->assertDef('top right', 'right top');
-        $this->assertDef('center left', 'left center');
-        $this->assertDef('center center', 'center'); // two centers collide
-        $this->assertDef('center right', 'right center');
+        $this->assertDef('center left', 'left');
+        $this->assertDef('center center', 'center');
+        $this->assertDef('center right', 'right');
         $this->assertDef('bottom left', 'left bottom');
-        $this->assertDef('bottom center', 'center bottom');
+        $this->assertDef('bottom center', 'bottom');
         $this->assertDef('bottom right', 'right bottom');
 
         // more cases from the defined syntax