package?com.keypoint;

import?java.awt.Image;
import?java.awt.image.ImageObserver;
import?java.awt.image.PixelGrabber;
import?java.io.ByteArrayOutputStream;
import?java.io.IOException;
import?java.util.zip.CRC32;
import?java.util.zip.Deflater;
import?java.util.zip.DeflaterOutputStream;

/**
?*?PngEncoder?takes?a?Java?Image?object?and?creates?a?byte?string?which?can?be
?*?saved?as?a?PNG?file.??The?Image?is?presumed?to?use?the?DirectColorModel.
?*
?*?
Thanks?to?Jay?Denny?at?KeyPoint?Software
?*????http://www.keypoint.com/
?*?who?let?me?develop?this?code?on?company?time.

?*
?*?
You?may?contact?me?with?（probably?very-much-needed）?improvements
?*?comments?and?bug?fixes?at:

?*
?*???
david@catcode.com

?*
?*?
This?library?is?free?software;?you?can?redistribute?it?and/or
?*?modify?it?under?the?terms?of?the?GNU?Lesser?General?Public
?*?License?as?published?by?the?Free?Software?Foundation;?either
?*?version?2.1?of?the?License?or?（at?your?option）?any?later?version.

?*
?*?
This?library?is?distributed?in?the?hope?that?it?will?be?useful
?*?but?WITHOUT?ANY?WARRANTY;?without?even?the?implied?warranty?of
?*?MERCHANTABILITY?or?FITNESS?FOR?A?PARTICULAR?PURPOSE.??See?the?GNU
?*?Lesser?General?Public?License?for?more?details.

?*
?*?
You?should?have?received?a?copy?of?the?GNU?Lesser?General?Public
?*?License?along?with?this?library;?if?not?write?to?the?Free?Software
?*?Foundation?Inc.?51?Franklin?Street?Fifth?Floor?Boston?MA??02110-1301
?*?USA.?A?copy?of?the?GNU?LGPL?may?be?found?at
?*?http://www.gnu.org/copyleft/lesser.html

?*
?*?@author?J.?David?Eisenberg
?*?@version?1.5?19?Oct?2003
?*
?*?CHANGES:
?*?--------
?*?19-Nov-2002?:?CODING?style?CHANGES?ONLY?（by?David?Gilbert?for?object
?*???????????????Refinery?Limited）;
?*?19-Sep-2003?:?Fix?for?platforms?using?EBCDIC?（contributed?by?Paulo?Soares）;
?*?19-Oct-2003?:?Change?private?fields?to?protected?fields?so?that
?*???????????????PngEncoderB?can?inherit?them?（JDE）
?*???????????????Fixed?bug?with?calculation?of?nRows
?*/

public?class?PngEncoder?{

????/**?Constant?specifying?that?alpha?channel?should?be?encoded.?*/
????public?static?final?boolean?ENCODE_ALPHA?=?true;

????/**?Constant?specifying?that?alpha?channel?should?not?be?encoded.?*/
????public?static?final?boolean?NO_ALPHA?=?false;

????/**?Constants?for?filter?（NONE）.?*/
????public?static?final?int?FILTER_NONE?=?0;

????/**?Constants?for?filter?（SUB）.?*/
????public?static?final?int?FILTER_SUB?=?1;

????/**?Constants?for?filter?（UP）.?*/
????public?static?final?int?FILTER_UP?=?2;

????/**?Constants?for?filter?（LAST）.?*/
????public?static?final?int?FILTER_LAST?=?2;

????/**?IHDR?tag.?*/
????protected?static?final?byte[]?IHDR?=?{73?72?68?82};

????/**?IDAT?tag.?*/
????protected?static?final?byte[]?IDAT?=?{73?68?65?84};

????/**?IEND?tag.?*/
????protected?static?final?byte[]?IEND?=?{73?69?78?68};

????protected?static?final?byte[]?PHYS?=?{（byte）‘p‘?（byte）‘H‘?（byte）‘Y‘?（byte）‘s‘};

???