[Patchanim-commit] SF.net SVN: patchanim: [138] trunk/patchanim/src/com/mebigfatguy/apng/ APngEncoder.java

[<dbr...@us...>]

Revision: 138
          http://patchanim.svn.sourceforge.net/patchanim/?rev=138&view=rev
Author:   dbrosius
Date:     2008-02-09 22:59:23 -0800 (Sat, 09 Feb 2008)

Log Message:
-----------
YEAH! Crc32 to the rescue, APngs work!

Modified Paths:
--------------
    trunk/patchanim/src/com/mebigfatguy/apng/APngEncoder.java

Modified: trunk/patchanim/src/com/mebigfatguy/apng/APngEncoder.java
===================================================================
--- trunk/patchanim/src/com/mebigfatguy/apng/APngEncoder.java	2008-02-10 06:00:52 UTC (rev 137)
+++ trunk/patchanim/src/com/mebigfatguy/apng/APngEncoder.java	2008-02-10 06:59:23 UTC (rev 138)
@@ -25,6 +25,7 @@
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
+import java.util.zip.CRC32;
 
 import javax.imageio.ImageIO;
 
@@ -207,23 +208,7 @@
 	}
 	
 	static class Chunk {
-		private static long crcTable[] = new long[256];
-		static {
-			long c;
-		     int n, k;
-		   
-		     for (n = 0; n < 256; n++) {
-		       c = (long) n;
-		       for (k = 0; k < 8; k++) {
-		         if ((c & 1) != 0)
-		           c = 0xedb88320L ^ (c >> 1);
-		         else
-		           c = c >> 1;
-		       }
-		       crcTable[n] = c;
-		     }
-		}
-		
+	
 		public int length;
 		public int type;
 		public byte[] data;
@@ -256,13 +241,15 @@
 		}
 		
 		public void calcCRC() {
-			long c = -1;
-			for (int n = 0; n < length; n++) {
-				c = crcTable[(int)((c ^ data[n]) & 0x00FF)] ^ (c >> 8);
-			}
-			
-			c ^= -1;
-			crc = (int)c;
+			CRC32 crc32 = new CRC32();
+			byte[] typeBytes = new byte[4];
+			typeBytes[0] = (byte)(type >> 24 & 0x00FF);
+			typeBytes[1] = (byte)(type >> 16 & 0x00FF);
+			typeBytes[2] = (byte)(type >> 8 & 0x00FF);
+			typeBytes[3] = (byte)(type & 0x00FF);
+			crc32.update(typeBytes);
+			crc32.update(data);
+			crc = (int)crc32.getValue();
 		}
 	}
 }


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