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Date Posted: 10:07:59 08/12/02 Mon
Author: Gurkan Karagoz
Subject: Re: Manipulating Multipage Tiffs in streams
In reply to:
's message, "Re: Manipulating Multipage Tiffs in streams" on 07:02:26 08/12/02 Mon
I am loading a multipage tif file by using the loadfromfile function with a parameter of 0. The help file says that 0 means, imagescrollbox will load all pages. That's correct, if I load a 39 pages tiff file, my application eats 47MB of memory, which is the proof of loading all images into memory. So, if I do a transformation,
I can see the result, but when I go to the next frame and then back to the first one, the transformation disappears. After loading a multipage tif file, I will insert it into a blob field, I won't use a disk file anymore. How can I do permanent transformations for frames?
>The key is to make sure you manipulate the images
>before saving them in the tiff file. Keep 6 pages in
>memory is not a problem. You can keep them in
>individual TDibGraphic objects, in a TList, in
>>I also need the same thing but for in memory frames.
>>For a project, customer scans not more than 6 pages,
>>some pages need to be rotated 90 deg. left or right.
>>That's why I always load all the images to memory.
>>Is it possible doing permanent transformations for in
>>memory multiple images?
>>>If you need to change an image within an existing
>>>multipage file, unforntunately you need to create a
>>>new file and copy the pages back to the new file.
>>>Your approach is good, but you could use a
>>>TTiffGraphic directly instead of a TImageScrollBox.
>>>Look up TFileStream in the Delphi help and the
>>>TTiffGraphic.AppendToStream method in the Envision
>>>help file. If you tiff file is not too large (a few
>>>megabytes) you may want to use a TMemoryStream to
>>>speed things up.
>>>>I need sample code on how to use streams with
>>>>envision. Here is the problem:
>>>>I need to be able to rotate page three, then save
>>>>entire file with the changes to number three,
>>>>appending the new version of three to the end of the
>>>>file. The pages must stay in order, and the old
>>>>version of page three is replaced with the new
>>>>I have been able to achieve this through the
>>>>imagescrollbox control, by assigning page three to a
>>>>second(hidden) imagescrollbox control, and then
>>>>looping through the original appending the images
>>>>i hit the one i have changed, and then appending
>>>>changed image from the second control, and
>>>>on through the original. this works fine unless the
>>>>file is large, then it takes a long time to loop
>>>>through the entire file.
>>>>I thought maybe doing it with streams might speed up
>>>>the process, but am unsure how to do it.(I have not
>>>>used streams very much at all). Any help or example
>>>>code you could give me would be helpful, the demo
>>>>project that came with it did not help me on this
>>>>Thank you in advance for any help you can give.
>>>>David L. Bracken
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