Incremetal view of an image / Thumbnails generation
lazarus / 39-Graphics

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Mando · 2011-05-12 08:44

Hello:

I'm developing an application to make catalogs of articles.
The program shows a list withl the items (Name, Notes, Price.....) and
a thumbnail. When user clicks on an item, the program shows the image 
loaded from files (jpg) at full screen (images are in other computer).
Some of that are large images and the program still frozen until the
image is fully loaded. 
 Is there any way I can show the image while it loads? and cancel the
loading if the user press ESC.
I know that ACSEE v.2.4 (1995) does it!!

Another cuestion is that the thumbnails are generated by my program,
so when the thumbnail doesn`t exit, the program load the image, resize
it and saves it in a file with same name but another extension. At
this process, the program frozen also. How I can do this without the
program freezing.? (threads, I supose)



Regards.

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theo · 2011-05-12 08:57

Maybe you could take some ideas from my thumbnail-viewer:
http://www.theo.ch/lazarus/thumbview.zip
See also
http://www.lazarusforum.de/viewtopic.php?p=38891#p38891

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Mando · 2011-05-12 09:17

Thanks, I'll try it.


Regards

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Mando · 2011-05-12 09:38

Hi:

It works fine. But when i chage the directory while thumbnais are
loading with multitrhead, I get an exception.


Regards.

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theo · 2011-05-12 10:08

Quote from: Mando on May 12, 2011, 11:38:15 amIt works fine. But when
i chage the directory while thumbnais are loading with multitrhead, I
get an exception.

Hmm, it's possible. I've never tested/encountered this.
It needs some logic to abort pending threads before changing the
directory.
I have not enough time for this atm.
But as I said, the code was meant to give you some ideas.

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jeanchristophe · 2014-08-13 15:56

Hello!

I don't know if Theo will read this, but I have a lot of problems,
when I try to install his package on Mageia4 32bit and Lazarus 1.24 32
bit...