1 files changed, 104 insertions, 0 deletions
diff --git a/includes/media/PNGMetadataExtractor.php b/includes/media/PNGMetadataExtractor.php
new file mode 100644
index 00000000..6a931e6c
--- /dev/null
+++ b/includes/media/PNGMetadataExtractor.php
@@ -0,0 +1,104 @@
+<?php
+/**
+ * PNG frame counter.
+ * Slightly derived from GIFMetadataExtractor.php
+ * Deliberately not using MWExceptions to avoid external dependencies, encouraging
+ * redistribution.
+ *
+ * @file
+ * @ingroup Media
+ */
+
+/**
+ * PNG frame counter.
+ *
+ * @ingroup Media
+ */
+class PNGMetadataExtractor {
+	static $png_sig;
+	static $CRC_size;
+
+	static function getMetadata( $filename ) {
+		self::$png_sig = pack( "C8", 137, 80, 78, 71, 13, 10, 26, 10 );
+		self::$CRC_size = 4;
+		
+		$frameCount = 0;
+		$loopCount = 1;
+		$duration = 0.0;
+
+		if (!$filename)
+			throw new Exception( __METHOD__ . ": No file name specified" );
+		elseif ( !file_exists($filename) || is_dir($filename) )
+			throw new Exception( __METHOD__ . ": File $filename does not exist" );
+		
+		$fh = fopen( $filename, 'r' );
+		
+		if (!$fh) {
+			throw new Exception( __METHOD__ . ": Unable to open file $filename" );
+		}
+		
+		// Check for the PNG header
+		$buf = fread( $fh, 8 );
+		if ( $buf != self::$png_sig ) {
+			throw new Exception( __METHOD__ . ": Not a valid PNG file; header: $buf" );
+		}
+
+		// Read chunks
+		while( !feof( $fh ) ) {
+			$buf = fread( $fh, 4 );
+			if( !$buf ) {
+				throw new Exception( __METHOD__ . ": Read error" );
+			}
+			$chunk_size = unpack( "N", $buf);
+			$chunk_size = $chunk_size[1];
+
+			$chunk_type = fread( $fh, 4 );
+			if( !$chunk_type ) {
+				throw new Exception( __METHOD__ . ": Read error" );
+			}
+
+			if ( $chunk_type == "acTL" ) {
+				$buf = fread( $fh, $chunk_size );
+				if( !$buf ) {
+					throw new Exception( __METHOD__ . ": Read error" );
+				}
+
+				$actl = unpack( "Nframes/Nplays", $buf );
+				$frameCount = $actl['frames'];
+				$loopCount = $actl['plays'];
+			} elseif ( $chunk_type == "fcTL" ) {
+				$buf = fread( $fh, $chunk_size );
+				if( !$buf ) {
+					throw new Exception( __METHOD__ . ": Read error" );
+				}
+				$buf = substr( $buf, 20 );	
+
+				$fctldur = unpack( "ndelay_num/ndelay_den", $buf );
+				if( $fctldur['delay_den'] == 0 ) $fctldur['delay_den'] = 100;
+				if( $fctldur['delay_num'] ) {
+					$duration += $fctldur['delay_num'] / $fctldur['delay_den'];
+				}
+			} elseif ( ( $chunk_type == "IDAT" || $chunk_type == "IEND" ) && $frameCount == 0 ) {
+				// Not a valid animated image. No point in continuing.
+				break;
+			} elseif ( $chunk_type == "IEND" ) {
+				break;
+			} else {
+				fseek( $fh, $chunk_size, SEEK_CUR );
+			}
+			fseek( $fh, self::$CRC_size, SEEK_CUR );
+		}
+		fclose( $fh );
+
+		if( $loopCount > 1 ) {
+			$duration *= $loopCount;
+		}
+
+		return array(
+			'frameCount' => $frameCount,
+			'loopCount' => $loopCount,
+			'duration' => $duration
+		);
+		
+	}
+}