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 TIOParamsVals.TIFF_LZWCompFunc		  New Topic  Reply to Topic
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dave.sellers

United Kingdom
17 Posts
Posted - Mar 03 2014 :  13:30:36  Show Profile  Reply
Hi

What are TIOParams.TIFF_LZWCompFunc and TIOParams.TIFF_LZWDeCompFunc or rather, how/when are they used?

I can't see any mention in the Help file or in the 'A PROGRAMMERS INTRODUCTION TO USING THE IMAGEEN IMAGE LIBRARY' ebook.

Any info gratefully received.

Thanks
Dave

w2m

USA
1990 Posts
Posted - Mar 03 2014 :  15:19:18  Show Profile  Reply
You are correct. There is no discussion of this anywhere including in the source code. There is a demo PhotoEn that has this:

procedure TMainForm.FormCreate(Sender: TObject);
begin
// uncomment to enable Gif and TIFF-LZW
  (*
  DefGIF_LZWDECOMPFUNC:=GIFLZWDecompress;
  DefGIF_LZWCOMPFUNC:=GIFLZWCompress;
  DefTIFF_LZWDECOMPFUNC:=TIFFLZWDecompress;
  DefTIFF_LZWCOMPFUNC:=TIFFLZWCompress;
  //*)
end;

The only thing I can say about it is I do not personally use it, but it looks like it enables LZW compression for GIF and TIF files. I do know that the code has been around for a long, long, long... long time.

Nigel said in the forum:

These properties exist for legacy reasons. You should not need to use them as they are initialized automatically:

IEGlobalSettings().DefGIF_LZWDECOMPFUNC
IEGlobalSettings().DefGIF_LZWCOMPFUNC
IEGlobalSettings().DefTIFF_LZWDECOMPFUNC
IEGlobalSettings().DefTIFF_LZWCOMPFUNC

Nigel
Xequte Software
www.xequte.com
nigel@xequte.com

William Miller
Adirondack Software & Graphics
Email: w2m@frontiernet.net
EBook: http://www.imageen.com/ebook/
Apprehend: http://www.frontiernet.net/~w2m/index.html
Custom ImageEn Development
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dave.sellers

United Kingdom
17 Posts
Posted - Mar 04 2014 :  00:57:05  Show Profile  Reply
Hi William

Thanks for your reply. I had thought perhaps they looked like a means by which you could provide your own LZW implementations.

If I wanted to use LZW presumably I would just set e.g.

ImageEnMView1.MIO.Params[i].TIFF_Compression := ioTIFF_LZW;

for each page before ultimately:

ImageEnMView1.MIO.SaveToFileTIFF(aJob.FileName);
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w2m

USA
1990 Posts
Posted - Mar 04 2014 :  05:46:47  Show Profile  Reply
According to Nigel, you should not need to use them as they are initialized automatically.



William Miller
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xequte

38615 Posts
Posted - Mar 04 2014 :  20:37:40  Show Profile  Reply
Hi

Yes, you can assign functions if you want to use your own LZW implementation.

But this is fine too:

ImageEnMView1.MIO.Params[i].TIFF_Compression := ioTIFF_LZW;
ImageEnMView1.MIO.SaveToFileTIFF(aJob.FileName);


Nigel
Xequte Software
www.xequte.com
nigel@xequte.com
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